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Hu Y, Chen X, Chu Z, Luo L, Gan Z, Zhong J, Yuan Z, Zhu B, Dong W. Biomechanical Properties of Novel Porous Scaffold Core and Hollow Lateral Hole Pedicle Screws: A Comparative Study in Bama Pigs. Orthop Surg 2024; 16:1718-1725. [PMID: 38766934 PMCID: PMC11216838 DOI: 10.1111/os.14091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 04/09/2024] [Accepted: 04/23/2024] [Indexed: 05/22/2024] Open
Abstract
OBJECTIVE Screw loosening is a common complication of internal fixation of pedicle screw. Therefore, the development of a pedicle screw with low loosening rate and high biosafety is of great clinical significance. This study aimed to investigate whether the application of a porous scaffold structure can improve the stability of pedicle screws by comparing the biomechanical properties of novel porous scaffold core pedicle screws (PSCPSs) with those of hollow lateral hole pedicle screws (HLHPSs) in a porcine lumbar spine. METHODS Thirty-two pedicle screws of both types were implanted bilaterally into the L1-4 vertebrae of four Bama pigs, with our newly designed PSCPSs on the right and HLHPSs on the left. All the Bama pigs were sacrificed 16 weeks postoperatively, and the lumbar spine was freed into individual vertebrae. Biomechanical properties of both the pedicle screws were evaluated using pull-out tests, as well as cyclic bending and pull-out tests, while the mechanical properties were assessed using three-point bending tests. The data generated were statistically analyzed using paired-sample t-tests and two independent sample t-tests. RESULTS We found that the maximal pull-out forces before and after cyclic bending of the PSCPSs (1161.50 ± 337.98 N and 1075.25 ± 223.33 N) were significantly higher than those of the HLHPSs (948.38 ± 194.32 N and 807.13 ± 242.75 N) (p < 0.05, p < 0.05). In 800 cycles of the bending tests, neither PSCPS nor HLHPS showed loosening or visible detachment, but their maximal pull-out forces after cyclic bending tests decreased compared to those in cycles without cyclic bending tests (7.43% and 14.89%, respectively), with no statistical significance (p > 0.05 and p > 0.05, respectively). Additionally, both screws buckled rather than broke in the three-point bending tests, with no statistically significant differences between the maximal bending load and modulus of elasticity of the two screws (p > 0.05 and p > 0.05, respectively). CONCLUSIONS Compared with the HLHPSs, the PSCPSs have greater pull-out resistance and better fatigue tolerance with appropriate mechanical properties. Therefore, PSCPSs theoretically have significant potential for clinical applications in reducing the incidence of loosening after pedicle screw implantation.
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Affiliation(s)
- Yong Hu
- Department of Spine SurgeryNingbo No. 6 HospitalNingboChina
| | - Xijiong Chen
- Health Science CenterNingbo UniversityNingboChina
| | - Zhentao Chu
- Health Science CenterNingbo UniversityNingboChina
| | - Linwei Luo
- Health Science CenterNingbo UniversityNingboChina
| | - Zhiwei Gan
- Health Science CenterNingbo UniversityNingboChina
| | - Jianbin Zhong
- Department of Spine SurgeryNingbo No. 6 HospitalNingboChina
| | - Zhenshan Yuan
- Department of Spine SurgeryNingbo No. 6 HospitalNingboChina
| | - Bingke Zhu
- Department of Spine SurgeryNingbo No. 6 HospitalNingboChina
| | - Weixin Dong
- Department of Spine SurgeryNingbo No. 6 HospitalNingboChina
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Mathew J, Zuckerman SL, Lin H, Marciano G, Simhon M, Cerpa M, Lee NJ, Boddapati V, Lehman RA, Sardar ZM, Dyrszka MD, Lombardi JM, Lenke LG. Living with a C2-Sacrum Spinal Fusion: Surgical Outcomes and Quality of Life in Patients Fused from C2 to the Sacrum. Global Spine J 2024; 14:1542-1551. [PMID: 36604815 DOI: 10.1177/21925682221149389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
STUDY DESIGN Single center, retrospective cohort study. OBJECTIVES Little is known about the surgical outcomes and quality of life in patients with C2-sacrum posterior spinal fusion (PSF). Though it is thought to be a "final" construct, it remains unknown how patients fare postoperatively. We sought to evaluate the surgical outcomes and quality of life of patients after C2-sacrum PSF. METHODS Consecutive patients undergoing C2-Sacrum PSF from 2015-2020 by 4 surgeons at a single institution were included. The study time period for each patient began after their index operation that led to the C2-sacrum fusion. Dates of surgery, complications, reoperations, patient reported outcomes (PROs) including EuroQol 5 Dimensions (EQ-5D), Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) questionnaires, and activities of daily living (ADL) questions were collected and analyzed. Descriptive statistics, paired t-tests, student t-tests, and linear regression were used. RESULTS Of the 23 patients who underwent C2-sacrum PSF, 6 patients (26%) required a total of 10 reoperations after a mean of 1.5 years (range 0-4 years) after C2-sacrum PSF. Five reoperations were for mechanical failure; 3 for wound complications/infection; and 2 for instrumentation and spinous process prominence. PROs were collected on 18 patients with mean follow-up of 2.4 years (range .5-4.5) after their C2-sacrum PSF. At 6-months, both SRS-22 and ODI scores improved significantly after C2-sacrum PSF (SRS: 57.5 to 76.3, P = .0014; ODI: 47.0 to 31.7, P = .013). Similarly, at a mean 2.4 years postoperatively, mean ODI improved significantly (47.0 to 30.4, P = .0032). Six patients (33%) had minimal symptoms (ODI <20). The median postoperative EQ-5D score was .74 (range .19 to 1.0), which compares favorably to patients with hip/knee osteoarthritis (EQ-5D .63) and diabetes mellitus (DM) (EQ-5D .69) and hypertension (HTN). In terms of activities of daily living (ADL), 10 patients (56%) exercised regularly-a mean 4.5 days/week. 11 (61%) could do light aerobic activity (e.g. stationary bike). 10 (55%) were able to play with children/grandchildren as desired. Eight patients (44%) hiked, and 2 (11%) drove independently. 11 (61%) could tolerate short air-travel comfortably. Of the 17 patients who could toilet and perform basic hygiene preoperatively, 16 (94%) were able to do so postoperatively. CONCLUSION Though C2-sacrum PSF is thought to be a "final" construct, approximately 1 in 4 patients require subsequent operations. However, C2-sacrum PSF patients had a significant improvement in SRS and ODI scores by 6 months postop. Over 60% of patients were regularly performing light aerobic activity 2 years after their C2-sacrum PSF. EQ-5D suggests that this population fares better than those with degenerative hip/knee arthritis and similarly to those with common chronic conditions like DM and HTN.
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Affiliation(s)
- Justin Mathew
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Scott L Zuckerman
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Hannah Lin
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Gerard Marciano
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Matthew Simhon
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Meghan Cerpa
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Nathan J Lee
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Venkat Boddapati
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Ronald A Lehman
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Zeeshan M Sardar
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Marc D Dyrszka
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Joseph M Lombardi
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
| | - Lawrence G Lenke
- Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA
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Zhan X, Gao F, Yang Y, Tsai T, Wan Z, Yu Y. Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology-like Load. Orthop Surg 2024; 16:1461-1472. [PMID: 38714346 PMCID: PMC11144517 DOI: 10.1111/os.14080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/06/2024] [Accepted: 04/09/2024] [Indexed: 05/09/2024] Open
Abstract
OBJECTIVES It is now understood that pedicle screw loosening at the implant-bone interface can lead to poor screw-bone interface purchase and decreased fixation stability. Previous biomechanical tests used cadaveric vertebrae and pull-out or torque loads to assess the effect of the insertional direction of pedicle screws on screw loosening. However, these tests faced challenges in matching biomechanical differences among specimens and simulating in vivo loads applied on pedicle screws. This study aimed to evaluate the effect of the insertional direction of pedicle screws on screw loosening using tension-compression-bending loads and synthetic bone vertebrae. METHODS Polyaxial pedicle screws were inserted into nine synthetic bone vertebrae in three directions (three samples per group): cranial, parallel, and caudad (-10°, 0°, +10° of the pedicle screw rod to the upper plane of the vertebra, respectively). Pedicle screws in the vertebrae were loaded using a polyethylene block connected to a material testing machine. Tension-compression-bending loads (100N-250N) with 30,000 cycles were applied to the pedicle screws, and displacements were recorded and then cycle-displacement curve was drawn based on cycle number. Micro-CT scans were performed on the vertebrae after removing the pedicle screws to obtain images of the screw hole, and the screw hole volume was measured using imaging analysis software. Direct comparison of displacements was conducted via cycle-displacement curve. Screw hole volume was analyzed using analysis of variance. The correlation between the displacement, screw hole volume and the direction of pedicle screw was assessed by Spearman correlation analysis. RESULTS The smallest displacements were observed in the caudad group, followed by the parallel and cranial groups. The caudad group had the smallest screw hole volume (p < 0.001 and p = 0.009 compared to the cranial and parallel groups, respectively), while the volume in the parallel group was greater than that in the cranial group (p = 0.003). Correlation analysis revealed that the insertional direction of the pedicle screw was associated with the displacement (p = -0.949, p < 0.001) and screw hole volume (p = -0.944, p < 0.001). CONCLUSION Strong correlations were found between the insertional direction of the pedicle screw and relevant parameters, including displacement and screw hole volume. Pedicle screw insertion in the caudad direction resulted in the least pedicle screw loosening.
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Affiliation(s)
- Xuqiang Zhan
- Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration, Ministry of Education, Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
| | - Feng Gao
- Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration, Ministry of Education, Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
- Yuyao Maternity and Child Health Care Hospital (Yuyao Second People's Hospital)ZhejiangChina
| | - Yangyang Yang
- School of Biomedical Engineering & Med‐X Research Institute, Shanghai Jiao Tong UniversityShanghaiChina
| | - Tsung‐Yuan Tsai
- School of Biomedical Engineering & Med‐X Research Institute, Shanghai Jiao Tong UniversityShanghaiChina
| | - Zongmiao Wan
- The First Affiliated Hospital of NanChang UniversityNanchangChina
| | - Yan Yu
- Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration, Ministry of Education, Department of Spine SurgeryTongji Hospital, School of Medicine, Tongji UniversityShanghaiChina
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Pangnguriseng UA, Imade S, Furuya S, Nakazawa K, Shiraishi K, Sato M, Kawamura T, Uchio Y. Effect of bone density on the drill-hole diameter made by a cannulated drill bit in cancellous bone. J Orthop Sci 2024:S0949-2658(24)00058-7. [PMID: 38637192 DOI: 10.1016/j.jos.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/05/2024] [Accepted: 04/06/2024] [Indexed: 04/20/2024]
Abstract
BACKGROUND When a pilot hole is made prior to a screw's insertion into bone, the same drill bit is used irrespective of the bone quality. However, osteoporotic bone is fragile and this may affect the hole diameter, which is of particular concern in cancellous bone. In this study, the relationship between bone density and drill-hole diameter was investigated assuming a pre-drilling process in screw-only osteosynthesis in the metaphysis and epiphysis. METHODS Two types of drill bit (triple-flute [T] and quadruple-flute [Q]) with different shapes and diameters were prepared: type T bits with 3.5 mm and 4.4 mm diameters, and type Q bits with 3.5 mm and 4.2 mm diameters. Drilling was performed manually in simulated bones with four densities: 5, 10, 15, and 20 pounds per cubic foot. We measured the hole diameters with a coordinate measuring machine and analyzed the relationship between the drill-hole diameters and the densities of the simulated bones. We then compared the screw pull-out strength between the two 3.5-diameter drill bits. RESULTS In all cases, the diameters of the drill holes were larger than those of the drill bits. The relationship between the drill-hole diameters and the bone densities was a negative linear correlation. Enlarging the hole diameter decreased the screw pull-out strength. CONCLUSIONS For cannulated drill bits of 3.5, 4.2 and 4.4 mm diameter, the diameter of the drill hole in cancellous bone obtained by the manual drilling technique tends to be larger in low-density (e.g., osteoporotic) compared to high-density (e.g., healthy) bone.
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Affiliation(s)
- Utomo Andi Pangnguriseng
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan; Department of Orthopaedic, Faculty of Medicine, Universitas Muslim Indonesia, Sulawesi Selatan, Indonesia
| | - Shinji Imade
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan.
| | - Satoshi Furuya
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Koichiro Nakazawa
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Kazuma Shiraishi
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Masaya Sato
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
| | - Toshihiko Kawamura
- Division of Medical Informatics, Shimane University Faculty of Medicine, Shimane, Japan
| | - Yuji Uchio
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
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Bennie S, Crowley JD, Wang T, Pelletier MH, Walsh WR. Pedicle screw pull-out testing in polyurethane foam blocks: Effect of block orientation and density. Proc Inst Mech Eng H 2024; 238:455-460. [PMID: 38480483 DOI: 10.1177/09544119241236873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Synthetic bone models such as polyurethane (PU) foam are a well-established substitute to cadaveric bone for screw pull-out testing; however, little attention has been given to the effect of PU foam anisotropy on orthopaedic implant testing. Compressive and screw pull-out performance in three PU foam densities; 0.16 g/cm3 (PCF 10), 0.32 g/cm3 (PCF 20) and 0.64 g/cm3 (PCF 40) were performed in each of the X, Y or Z orientations. The maximum compressive force, stiffness in the linear region, maximum stress and modulus were determined for all compression tests. Pedicle screws were inserted and pulled out axially to determine maximum pull-out force, energy to failure and stiffness. One-way ANOVA and post hoc tests were used to compare outcome variables between PU foam densities and orientations, respectively. Compression tests demonstrated the maximum force was significantly different between all orientations for PCF 20 (X, Y and Z) while stiffness and maximum stress were different between X versus Y and X versus Z. Maximum pull-out force was significantly different between all orientations for PCF 10 foam. No significant differences were noted for other foam densities. There is potential for screw pull-out testing results to be significantly affected by orientation in lower density PU foams. It is recommended that a single, known orientation of the PU foam block be used for experimental testing.
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Affiliation(s)
- Stephen Bennie
- Surgical & Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, NSW, Australia
| | - James Douglas Crowley
- Surgical & Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, NSW, Australia
| | - Tian Wang
- Surgical & Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, NSW, Australia
| | - Matthew Henry Pelletier
- Surgical & Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, NSW, Australia
| | - William Robert Walsh
- Surgical & Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, NSW, Australia
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Zhang Q, Zhao F, Zhang Y, Gong X. Longitudinal Study on Pre- and Post-Operation CT Imaging for Predicting Pedicle Screw Loosening in Patients with Lumbar Degenerative Disease. Ther Clin Risk Manag 2024; 20:185-194. [PMID: 38496352 PMCID: PMC10942252 DOI: 10.2147/tcrm.s453639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/08/2024] [Indexed: 03/19/2024] Open
Abstract
Purpose We conducted a longitudinal study to examine the predictive role of risk factors in the occurrence of pedicle screw loosening, assessed through pre- and post-operative computed tomography (CT) scans. Methods A total of 103 patients with degenerative lumbar disease who had undergone L4/5 pedicle screw fixation (involving 412 screws) were included in this study. They were subsequently categorized into two groups-the "loosening group" and the "non-loosening group". The axial and sagittal angles of the screw trajectory in pre- and post-operative CT images were measured, and the deviation angles were computed. Additionally, measurements were taken of the Hounsfield unit (HU) within the screw entry point area, the pedicle, and the vertebral body in preoperative CT images. Logistic regression analysis was employed to ascertain the risk factors influencing the occurrence of screw loosening. Results Elderly patients who experienced screw loosening tended to have bilateral screw issues at the L5 level (p < 0.005). The HU of the pedicle (p < 0.001), age (p < 0.001), and the axial deviation angle (p = 0.014) were identified as independent factors predicting screw loosening. Additionally, when HU of the pedicle < 126.5 or age ≥ 53.5 years, the axial deviation angle was found to be smaller in the group experiencing screw loosening (p = 0.018 and p = 0.019). Conclusion Loosening of screws positioned at L5 was found to be more prevalent in elderly patients, particularly exhibiting a bilateral occurrence. Independent predictors of this phenomenon included a low HU value in the pedicle, advanced age in patients, and a substantial axial deviation angle. In the case of elderly patients with a low HU value in the pedicle, a reduced axial surgical deflection was necessitated to prevent the occurrence of screw loosening.
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Affiliation(s)
- Qian Zhang
- Medical College of Soochow University, Suzhou, People’s Republic of China
- Department of Radiology, Zhejiang Provincial People’s Hospital (Affiliated People’s Hospital), Hangzhou Medical College, Hangzhou, People’s Republic of China
- Department of Radiology, The 901st Hospital of the Joint Logistics Support Force of PLA, Hefei, People’s Republic of China
| | - Fanfan Zhao
- Department of Radiology, Zhejiang Provincial People’s Hospital (Affiliated People’s Hospital), Hangzhou Medical College, Hangzhou, People’s Republic of China
| | - Yu Zhang
- Department of Radiology, The 901st Hospital of the Joint Logistics Support Force of PLA, Hefei, People’s Republic of China
| | - Xiangyang Gong
- Medical College of Soochow University, Suzhou, People’s Republic of China
- Department of Radiology, Zhejiang Provincial People’s Hospital (Affiliated People’s Hospital), Hangzhou Medical College, Hangzhou, People’s Republic of China
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Li Q, Zhao H, Yang J, Song S, Liu X. Optimization of Pedicle Screw Parameters for Enhancing Implant Stability Based on Finite Element Analysis. World Neurosurg 2024; 183:e345-e354. [PMID: 38151174 DOI: 10.1016/j.wneu.2023.12.099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/18/2023] [Indexed: 12/29/2023]
Abstract
OBJECTIVE To improve implant stability parameters, including pedicle screw (PS) outer diameter, thread depth, and pitch, by finite element analysis. METHODS Insertion and pullout of the PS were simulated by finite element analysis, and the precision of simulation was evaluated by comparison with mechanical tests. Influences of the parameters on the maximum insertion torque and maximum pullout force were analyzed by computational simulations, including single-factor analysis and orthogonal experiments. RESULTS The simulation results agreed with the mechanical test results. The order of parameters influencing insertion torque and pullout force was outer diameter > pitch > thread depth. When the pilot hole diameter is 0.1 mm larger than the inner diameter of the PS, the calculated Pearson correlation coefficient between the maximum insertion torque and maximum pullout force was r = 0.99. The optimized PS had a maximum insertion torque of 485.16 N·mm and a maximum pullout force of 1726.33 N, 23.9% and 9.1% higher, respectively, than the values of standard screws. CONCLUSIONS The presently used models are feasible for evaluating the implant stability of PSs. The maximum insertion torque and maximum pullout force of PSs are highly correlated and can be improved by increasing the outer diameter and decreasing pitch. Although with the parameters of the PS, pedicle size and bone mineral density are 2 additional factors to consider for better implant stability.
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Affiliation(s)
- Qiang Li
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China; Shanghai Engineering Research Center of High-Performance Medical Device Materials, Shanghai, People's Republic of China.
| | - Hu Zhao
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China
| | - Jinshuai Yang
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China
| | - Shihong Song
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China
| | - Xuyan Liu
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China
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Biswas JK, Mondal N, Choudhury S, Malas A, Rana M. A finite element study and mathematical modeling of lumbar pedicle screw along with various design parameters. J Orthop Sci 2023; 28:992-1003. [PMID: 36175251 DOI: 10.1016/j.jos.2022.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/04/2022] [Accepted: 08/24/2022] [Indexed: 10/14/2022]
Abstract
BACKGROUND Lumbar pedicle screw is one of the most common and important elements in the field of lumbar surgery. It plays a great role in rectifying the spinal alignment and stabilization providing strength and stability to the affected area of spine. In spinal surgery, minimally invasive techniques and minor incisions are made which makes it less painful for the patients than the traditional methods. Moreover, the screws are not needed to be removed after the surgery which is yet another great advantage of the pedicle screw. METHOD In this study, 3D Finite Element (FE) model of human L4 vertebrae is taken for analysis using image processing tool. Pedicle screw design with varying mechanical and geometrical properties has been carried out at different applied loads on it along with considering the effect of frictional forces between all contact surfaces. RESULT Mathematical relationship among stress, strain, pitch of the screw and diameter have been developed for different thread profiles which will be beneficial for researchers for further development of pedicle screw implants. CONCLUSION Results from the different analysis shows that bending stress on the screw for different loads at triangular pitch is higher than the trapezoidal. Hence, trapezoidal thread is efficacious than triangular thread. In case of vertebral bone, the magnitude of stress is less for trapezoidal screw than triangular and stress has a linear relationship with pitch length. In term of strain, triangular thread develops more strain than trapezoidal thread. A set of mathematical relation has been developed for different thread profile based on pitch length, stress and strain which gives the idea about von Mises stress and strain.
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Affiliation(s)
- Jayanta Kumar Biswas
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar - 800005, India
| | - Nitesh Mondal
- Department of Mechanical Engineering, Ghani Khan Choudhury Institute of Engineering & Technology, Narayanpur, Malda - 732141, India
| | - Sandeep Choudhury
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103, India
| | - Anindya Malas
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar - 800005, India
| | - Masud Rana
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103, India.
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Baisden JL, Varghese V, Banerjee A, Yoganandan N. Regional variations in C1-C2 bone density on quantitated computed tomography and clinical implications. NORTH AMERICAN SPINE SOCIETY JOURNAL 2023; 14:100228. [PMID: 37440985 PMCID: PMC10333715 DOI: 10.1016/j.xnsj.2023.100228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 07/15/2023]
Abstract
Background Our elderly population is growing and the number of spine fractures in the elderly is also growing. The elderly population in general may be considered as poor surgical candidates experience a high rate of fractures at C1 and C2 compared with the general population. Nonoperative management of upper cervical fractures is not benign as there is a high nonunion rate for both C1 and C2 fractures in the elderly, and orthosis compliance is often suboptimal, or complicated by skin breakdown. The optimal technique for upper cervical stabilization in the elderly may be different than in younger populations as the bone quality is inferior in the elderly. The objective of this basic science study is to determine whether the bone mineral density (BMD) of C1 and C2 vary by region, and if this is a gender difference in this elderly age group. Methods Twenty cadaveric spines from 45 to 83 years of age were used to obtain BMD using quantitated computed tomography (QCT). BMD was measured using a QCT. For C1, 8 regions were determined: anterior tubercle, bilateral anterior and medial lateral masses, bilateral posterior arches, and posterior tubercle. For C2, 7 regional BMDs were determined: top of odontoid, base of odontoid-body interface, mid body, bilateral lateral masses, anterior inferior body near the discs space, and the C2 spinous process. Results The BMD was greatest at the C1 anterior tubercle (564.4±175.8 mg/cm3) and C1 posterior ring (420.8±110.2 mg/cm3), and least at the anterior and medial lateral masses (262.8±59.5 mg/cm3, 316.9±72.6 mg/cm3). At C2 QCT BMD was greatest at the top of the dens (400.6±107.9 mg/cm3) decreasing down through the odontoid-C2 body junction (267.8±103.5 mg/cm3) and least in the mid C2 body 249.1±68.8 mg/cm3). The posterior arch of C1 and the spinous process of C2 had higher BMD's 420.8±110.2 mg/cm3 and 284.1±93.0 mg/cm3, respectively. A high correlation was observed between the BMD at the interface of the dens-vertebral body with the vertebral body with a Pearson correlation coefficient of 0.86. The BMD of the top of dens was significantly higher (p<.05) than all the regions in C2. Conclusions Regional and segmental BMD variations at C1 and C2 have clinical implications for surgical constructs in the elderly population. Given the higher BMDs of the C1 and C2 spinous process and posterior arches, consideration should be given to incorporate these areas using various C1-C2 wiring techniques. In the elderly, lateral masses particularly at C1 with lower BMD may result in potential screw loosening and nonunion in this age group. Old-school wiring techniques have a track record of efficacy and safety with less blood loss, reduced operative time, reduced X-ray exposure, and should be considered in the elderly as a primary stabilization technique or a belt-over suspenders approach based on regional variations in BMD in the elderly.
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Affiliation(s)
- Jamie L Baisden
- Department of Neurosurgery, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, United States
| | - Vicky Varghese
- Department of Orthopedics, Skokie Hospital, NorthShore University Health System, 9600 Gross Point Rd, Skokie, IL 60076, United States
| | - Anjishnu Banerjee
- Department of Biostatistics, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Narayan Yoganandan
- Department of Neurosurgery, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, United States
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10
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Tandon V. Let's think beyond the pedicle: A biomechanical study of a new conceptual extra pedicular screw and hook construct. J Clin Orthop Trauma 2023; 41:102173. [PMID: 37483911 PMCID: PMC10362541 DOI: 10.1016/j.jcot.2023.102173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/25/2023] [Accepted: 05/28/2023] [Indexed: 07/25/2023] Open
Abstract
Background Transpedicular screws have proven the test of time, yet they are not devoid of complications. Many newer techniques such as 2 D and 3D fluoroscopy,O arm Navigation assisted surgery, robotic assisted surgery have come into existence to the increase precision in pedicle screw insertion. But, complications do occur in their presence. We propose an Extra pedicular screw and hook system (EPSH) system with similar biomechanical property, better safety profile and short learning curve compared to traditional pedicle screw. Purpose To Compare the pull out strength of Traditional Pedicle screw Vs Extra pedicular screw and hook system(EPSH). Methods Biomechanical testing was conducted according ASTM F543 guidelines to compare the pull-out strength of EPSH based construct and traditional pedicle screw construct. Six saw bone samples in each group considered. Screw of 5.5 mm diameter and length of 35 mm was used in both the groups. Pull out strength assessed by giving 5 mm/min axial load. The axial load Vs displacement of the screw were recorded and plotted. The maximum load required for screw failure is noted in both the group. Statistical analysis was done. Results The mean peak load of pedicle screw group was found to be 1670.9 ± 393.2 N with mean displacement at peak load was found to be 13.44 ± 1.7 mm and in EPSH group it was 1416.4 ± 341.4 N and 15.78 ± 3.9 mm respectively. A paired t-test showed no statistical difference(p < 0.05) between 2 groups. Conclusion EPSH has shown to have almost similar biomechanical property as that pedicle screw construct. With Addition of the hook, it provides an extra rotational stability as well. Being an extra-pedicular screw it has high safety profile and needs less expertise for insertion.
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Affiliation(s)
- Vikas Tandon
- Department of Spine Services, Indian Spinal Injuries Center, New Delhi, India
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11
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Computed Tomography-Based Prediction of Lumbar Pedicle Screw Loosening. BIOMED RESEARCH INTERNATIONAL 2023; 2023:8084597. [PMID: 36743516 PMCID: PMC9891825 DOI: 10.1155/2023/8084597] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 01/03/2023] [Accepted: 01/16/2023] [Indexed: 01/27/2023]
Abstract
Objective Pedicle screw loosening is one of the main complications after pedicle screw fixation. However, there are few reliable measures for prediction of screw loosening. The current study was carried out to find an effective method to use preoperative CT scanning as a predictor of screw loosening in the elderly patients and provide guidance for preoperative surgical planning. Methods Patients who were treated with lumbar pedicle screw fixation procedure in our department for degenerative lumbar disorders between January 2015 and January 2021 were retrospectively included in the current study. CT scan attenuation of each vertebra was measured with Hounsfield units (HU). Screw loosening was determined in postoperatively X-ray tests. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis were carried out with IBMSPSS 24.00 software. Results Screw loosening was observed in 44 of 215 patients (124 male, 91 female, average age 58.4 ± 7.6 years) during a mean follow-up time of 19.0 ± 11.2 months (range 12-32 months). No significant differences were found among the patients concerning patient gender, BMI, habit of smoking, and whether or not the patient had diabetes or suffered from spondylolisthesis (P > 0.05). The average HU value of lumbar vertebra was 122.4 ± 32.8 HU in the screw loosening group and 142.4 ± 38.2 HU in the control group, and the difference was significant (P < 0.01). ROC curve analysis revealed that the average HU value of L1-L5 has a relatively larger area under the curve (AUC) of 0.689 (95% CI: 0.605-0.773). With the sensitivity of 68% and specificity of 57%, a HU cut-off value of ≤124 HU is a plausible cut-off point to predict screw loosening. Conclusions A prospective CT scan HU value-based prediction can be used to decide whether or not to use screw augmentation methods. A cut-off L1-L5 average HU value of 124 HU can be used as an independent risk factor for screw loosening in instrumented lumbar vertebra. More predictive indexes should be involved to achieve higher sensitivity and specificity in future clinical practice.
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12
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Biomechanical evaluation of position and bicortical fixation of anterior lateral vertebral screws in a porcine model. Sci Rep 2023; 13:454. [PMID: 36624133 PMCID: PMC9829755 DOI: 10.1038/s41598-023-27433-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 01/02/2023] [Indexed: 01/10/2023] Open
Abstract
Although an anterior approach with anterior lateral screw fixation has been developed for stabilizing the thoracolumbar spine clinically, screw loosening still occurs. In this novel in vitro study, we attempted to elucidate the optimal screw position in the lateral lumbar vertebra and the effect of bicortical fixation. A total of 72 fresh-frozen lumbar vertebrae from L1-6 were harvested from 12 mature pigs and randomly assigned to two modalities: bicortical fixation (n = 36) and unicortical fixation (n = 36). Six groups of screw positions in the lateral vertebral body in each modality were designated as central-anterior, central-middle, central-posterior, lower-anterior, lower-middle, and lower- posterior; 6 specimens were used in each group. The correlations between screw fixation modalities, screw positions and axial pullout strength were analyzed. An appropriate screw trajectory and insertional depth were confirmed using axial and sagittal X-ray imaging prior to pullout testing. In both bicortical and unicortical fixation modalities, the screw pullout force was significantly higher in the posterior or middle position than in the anterior position (p < 0.05), and there was no significant differences between the central and lower positions. The maximal pullout forces from the same screw positions in unicortical fixation modalities were all significantly lower, decreases that ranged from 32.7 to 74%, than those in bicortical fixation modalities. Our study using porcine vertebrae showed that screws in the middle or posterior position of the lateral vertebral body had a higher pullout performance than those in the anterior position. Posteriorly positioned lateral vertebral screws with unicortical fixation provided better stability than anteriorly positioned screws with bicortical fixation.
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13
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Tai CL, Chen WP, Liu MY, Li YD, Tsai TT, Lai PL, Hsieh MK. Biomechanical comparison of pedicle screw fixation strength among three different screw trajectories using single vertebrae and one-level functional spinal unit. Front Bioeng Biotechnol 2022; 10:1054738. [PMID: 36568298 PMCID: PMC9780459 DOI: 10.3389/fbioe.2022.1054738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/29/2022] [Indexed: 12/14/2022] Open
Abstract
Three key factors are responsible for the biomechanical performance of pedicle screw fixation: screw mechanical characteristics, bone quality and insertion techniques. To the best of the authors' knowledge, no study has directly compared the biomechanical performance among three trajectories, i.e., the traditional trajectory (TT), modified trajectory (MT) and cortical bone trajectory (CBT), in a porcine model. This study compared the pullout strength and insertion torque of three trajectory methods in single vertebrae, the pullout strength and fixation stiffness including flexion, extension, and lateral bending in a one-level instrumented functional spinal unit (FSU) that mimics the in vivo configuration were clarified. A total of 18 single vertebrae and 18 FSUs were randomly assigned into three screw insertion methods (n = 6 in each trajectory group). In the TT group, the screw converged from its entry point, passed completely inside the pedicle, was parallel to the superior endplate, was located in the superior third of the vertebral body and reached to at least the anterior third of the vertebral body. In the MT group, the convergent angle was similar to that of the TT method but directed caudally to the anterior inferior margin of the vertebral body. The results of insertion torque and pullout strength in single vertebrae were analyzed; in addition, the stiffness and pullout strength in the one-level FSU were also investigated. This study demonstrated that, in single vertebrae, the insertion torque was significantly higher in CBT groups than in TT and MT groups (p < 0.05). The maximal pullout strength was significantly higher in MT groups than in TT and CBT groups (p < 0.05). There was no significant difference in stiffness in the three motions among all groups. The maximal pullout strength in FSUs of MT and CBT groups were significantly higher than the TT groups (p < 0.05). We concluded that either MT or CBT provides better biomechanical performance than TT in single vertebrae or FSUs. The lack of significance of stiffness in FSUs among three methods suggested that MT or CBT could be a reasonable alternative to TT if the traditional trajectory was not feasible.
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Affiliation(s)
- Ching-Lung Tai
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan,Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Weng-Pin Chen
- Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Mu-Yi Liu
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Yun-Da Li
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan,Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Tsung-Ting Tsai
- Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Po-Liang Lai
- Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Ming-Kai Hsieh
- Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan,*Correspondence: Ming-Kai Hsieh,
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Hu Y, Chu Z, Shen S, Zhong J, Zhu B, Wu J, Yuan Z, Dong W. Biomechanical Properties of Novel Lateral Hole Pedicle Screws and Solid Pedicle Screws: A Comparative Study in the Beagle Dogs. Orthop Surg 2022; 15:328-336. [PMID: 36411506 PMCID: PMC9837263 DOI: 10.1111/os.13596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Although pedicle screws are widely used to reconstruct the stability of the spine, screw loosening is a common complication after spine surgery. The main objective of this study was to investigate whether the application of the hollow lateral hole structure had the potential to improve the stability of the pedicle screw by comparing the biomechanical properties of the novel lateral hole pedicle screws (LHPSs) with those of the solid pedicle screws (SPSs) in beagle dogs. METHODS The cancellous bone of the distal femur, proximal femur, distal tibia, and proximal tibia were chosen as implantation sites in beagle dogs. In each of 12 dogs, four LHPSs, and four SPSs were implanted into both lower limbs. At 1, 2, and 3 months after surgery, four dogs were randomly sampled and sacrificed. The LHPS group and SPS group were subdivided into four subgroups according to the length of their duration of implantation (0, 1, 2, 3 months). The biomechanical properties of both pedicle screws were evaluated by pull-out and the cyclic bending tests. RESULTS The results of the study showed that no significant difference was found between LHPSs (276.62 ± 50.11 N) and SPSs (282.47 ± 42.98 N) in pull-out tests at time 0 (P > 0.05). At the same time point after implantations, LHPSs exhibited significantly higher maximal pullout strength than SPSs (month 1: 360.51 ± 25.63 vs 325.87 ± 28.11 N; month 2: 416.59 ± 23.78 vs 362.12 ± 29.27 N; month 3: 447.05 ± 38.26 vs 376.63 ± 32.36 N) (P < 0.05). Moreover, compared with SPSs, LHPSs withstood more loading cycles (month 2: 592 ± 21 vs 534 ± 48 times; month 3: 596 ± 10 vs 543 ± 59 times), and exhibiting less displacement before loosening at month 2 (1.70 ± 0.17 vs 1.96 ± 0.10 mm) and 3 (1.69 ± 0.19 vs 1.92 ± 0.14 mm) (P < 0.05), but no significant difference in time 0 and month 1 (P > 0.05). CONCLUSIONS The pedicle screw with the hollow lateral hole structure could allow bone to grow into the inner architecture, which improved biomechanical properties by extending the contact area between screw and bone tissue after implantation into the cancellous bone. It indicated that LHPS could reduce loosening of the pedicle screws in long term after surgery.
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Affiliation(s)
- Yong Hu
- Department of Spine SurgeryThe Ningbo No. 6 HospitalNingboChina
| | | | | | - Jian‐bin Zhong
- Department of Spine SurgeryThe Ningbo No. 6 HospitalNingboChina
| | - Bing‐ke Zhu
- Department of Spine SurgeryThe Ningbo No. 6 HospitalNingboChina
| | - Jia‐da Wu
- School of MedicineNingbo UniversityNingboChina
| | - Zhen‐shan Yuan
- Department of Spine SurgeryThe Ningbo No. 6 HospitalNingboChina
| | - Wei‐xin Dong
- Department of Spine SurgeryThe Ningbo No. 6 HospitalNingboChina
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Kim KH, Kim TH, Kim SW, Kim JH, Lee HS, Chang IB, Song JH, Hong YK, Oh JK. Significance of Measuring Lumbar Spine 3-Dimensional Computed Tomography Hounsfield Units to Predict Screw Loosening. World Neurosurg 2022; 165:e555-e562. [PMID: 35772704 DOI: 10.1016/j.wneu.2022.06.104] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/19/2022] [Accepted: 06/20/2022] [Indexed: 12/14/2022]
Abstract
BACKGROUND Osteoporosis is a well-known risk factor of screw loosening. Classically, dual-energy x-ray absorptiometry (DEXA) scan is an easy and cost-effective method of detecting bone mineral density (BMD). However, T-score on DEXA scan can be overestimated in patients with degenerative changes of the spine. Our objective was to identify correlation between Hounsfield unit (HU) measured by 3-dimensional computed tomography (3D-CT) and screw loosening. METHODS A total of 113 patients treated with lumbosacral spinal fusion were reviewed and categorized into a screw loosening group and a normal group to compare their average values of preoperative CT HU. Screw loosening was defined as radiolucent area around screw that was thicker than 1 mm with a "double halo sign". RESULTS There were statistically significant differences in patient age and steroid use between screw loosening and non-loosening groups. There was no significant difference in BMD or T-score between the 2 groups. However, HU values measured in axial, coronal, and sagittal images were significantly different between the 2 groups. In the receiver operating characteristic for HU values measured in CT images, the greatest area under the curve was 0.774 and that was in case of Hounsfield unit measured by axial CT images from L1 to L4. CONCLUSIONS Preoperative CT HU is associated with screw loosening. It can be a better predictor of screw loosening than DEXA scan. The best predictor of screw loosening in this study is the average value of HU from L1 to L4 in axial cut.
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Affiliation(s)
- Kyeong Hwan Kim
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Tae-Hwan Kim
- Department of Orthopedics, Hallym University Sacred Heart Hospital, Anyang, Korea; Spine Center, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Seok Woo Kim
- Department of Orthopedics, Hallym University Sacred Heart Hospital, Anyang, Korea; Spine Center, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Ji Hee Kim
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Heui Seung Lee
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - In Bok Chang
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Joon Ho Song
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Yong-Kil Hong
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Jae Keun Oh
- Department of Neurosurgery, Hallym University Sacred Heart Hospital, Anyang, Korea; Spine Center, Hallym University Sacred Heart Hospital, Anyang, Korea.
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16
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Huang ZB, Nie MD, Zhang NZ, Liu S, Yuan JB, Lin XM, Cheng CK, Shi ZC, Mao NF. Biomechanical evaluation of a short-rod technique for lumbar fixation surgery. Front Bioeng Biotechnol 2022; 10:959210. [PMID: 36032712 PMCID: PMC9403742 DOI: 10.3389/fbioe.2022.959210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Objective: The purpose of this study was to analyze the stability and instrument-related complications associated with fixation of the lumbar spine using the Short-Rod (SR) technique. Methods: Using finite element analysis, this study assessed the stability of a bilateral lumbar fixation system when inserting the pedicle screws at angles of 10°, 15°, and 20° to the endplate in the sagittal plane. Using the most stable construct with a screw angle, the model was then assessed with different rod lengths of 25, 30, 35, and 45 mm. The optimal screw inclination angle and rod length were incorporated into the SR model and compared against traditional parallel screw insertion (pedicle screws in parallel to the endplate, PPS) in terms of the stability and risk of instrument-related complications. The following parameters were evaluated using the validated L4–L5 lumbar finite element model: axial stiffness, range of motion (ROM), stress on the endplate and facet joint, von-Mises stress on the contact surface between the screw and rod (CSSR), and screw displacement. Results: The results showed that the SR model with a 15° screw inclination angle and 35 mm rod length was superior in terms of construct stability and risk of complications. Compared to the PPS model, the SR model had lower stiffness, lower ROM, less screw displacement, and lower stress on the facet cartilage, the CSSR, and screws. However, the SR model also suffered more stress on the endplate in flexion and lateral bending. Conclusion: The SR technique with a 15° screw inclination and 35 mm rod length offers good lumbar stability with a low risk of instrument-related complications.
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Affiliation(s)
- Ze-Bin Huang
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Mao-Dan Nie
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Ning-Ze Zhang
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Shu Liu
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Jia-Bin Yuan
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Xu-Miao Lin
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Cheng-Kung Cheng
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Cheng-Kung Cheng, ; Zhi-Cai Shi, ; Ning-Fang Mao,
| | - Zhi-Cai Shi
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
- *Correspondence: Cheng-Kung Cheng, ; Zhi-Cai Shi, ; Ning-Fang Mao,
| | - Ning-Fang Mao
- Department of Spine Surgery, First Affiliated Hospital of Naval Medical University, Shanghai, China
- *Correspondence: Cheng-Kung Cheng, ; Zhi-Cai Shi, ; Ning-Fang Mao,
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17
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Song F, Feng W, Yang D, Li G, Iqbal K, Liu Y, Yang H. A Novel Screw Modeling Approach to Study the Effects of Screw Parameters on Pullout Strength. J Biomech Eng 2022; 145:1143328. [PMID: 35864784 DOI: 10.1115/1.4055035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Indexed: 11/08/2022]
Abstract
Screw loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries and is affected by screw parameters (e.g., diameter, pitch and thread angle). However, the individual and interactive effects of these parameters on screw fixation are not fully understood. Furthermore, current finite element modeling of an threaded screw is less computationally efficient. To address these issues, we (1) explored a novel "simulated threaded screw" approach (virtual threads assigned to the contact elements of a simplified screw) and compared its performance with threaded and simplified screws, and (2) examined with this approach the individual and interactive effects of altering screw diameter (5.5-6.5 mm), pitch (1-2 mm) and half-thread angle (20-30°) on pullout strength of normal vertebrae. Results demonstrated that the "simulated threaded screw" approach equivalently predicted pullout strength compared to the "threaded screw" approach (R2 = 0.99, slope = 1). We further found that the pullout strength was most sensitive to the change in screw diameter, followed by thread angle, pitch and interactions of diameter*pitch or diameter*angle. In conclusion, the "simulated threaded screw" approach can achieve the same predictive capability compared to threaded modeling of the screw. The current findings may serve as useful references for planning of screw parameters, so as to improve the complication of screw loosening.
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Affiliation(s)
- Fei Song
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Wentian Feng
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Dongyue Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Guanghui Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Kamran Iqbal
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Yuxuan Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
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18
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Tanaka M, Mehta R, Yamauchi T, Arataki S, Fujiwara Y, Shinohara K, Yamane K. Triangular fixation to prevent proximal screw pullout for adult spinal deformity Surgery: A technical note. INTERDISCIPLINARY NEUROSURGERY 2022. [DOI: 10.1016/j.inat.2022.101514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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19
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Wang Y, Yang L, Li C, Sun H. The Biomechanical Properties of Cement-Augmented Pedicle Screws for Osteoporotic Spines. Global Spine J 2022; 12:323-332. [PMID: 33611971 PMCID: PMC8907649 DOI: 10.1177/2192568220987214] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
STUDY DESIGN This is a broad, narrative review of the literature. OBJECTIVE In this review, we describe recent biomechanics studies on cement-augmented pedicle screws for osteoporotic spines to determine which factors influence the effect of cement augmentation. METHODS A search of Medline was performed, combining the search terms "pedicle screw" and ("augmentation" OR "cement"). Articles published in the past 5 years dealing with biomechanical testing were included. RESULTS Several factors have been identified to impact the effect of cement augmentation in osteoporotic spines. These include the type of augmentation material, the volume of injected cement, the timing of augmentation, the severity of osteoporosis, the design of the pedicle screw, and the specific augmenting technique, among others. CONCLUSIONS This review elaborates the biomechanics of cement-augmented pedicle screws, determines which factors influence the augmentation effect, and identifies the risk factors of cement leakage in osteoporotic bone, which might offer some guidance when using this technique in clinical practice. Further, we provide information about newly designed screws and recently developed augmentation materials that provide higher screw stability as well as fewer cement-related complications.
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Affiliation(s)
- Yuetian Wang
- Department of Orthopedics, Peking University First
Hospital, Beijing, China
| | - Lei Yang
- Center for Health Science and
Engineering(CHSE), School of Materials Science and Engineering, Hebei University of
Technology, Tianjin, China
| | - Chunde Li
- Department of Orthopedics, Peking University First
Hospital, Beijing, China
| | - Haolin Sun
- Department of Orthopedics, Peking University First
Hospital, Beijing, China,Haolin Sun, Peking University First
Hospital, Beijing 100034, China.
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20
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Improved fixation stability for repairing pedicle screw loosening using a modified cement filling technique in porcine vertebrae. Sci Rep 2022; 12:2739. [PMID: 35177724 PMCID: PMC8854567 DOI: 10.1038/s41598-022-06724-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 02/04/2022] [Indexed: 01/20/2023] Open
Abstract
Polymethylmethacrylate (PMMA) has been applied clinically and biomechanically repair loose pedicle screws. Controversies have arisen over data due to uncontrolled cement properties, various locations and sizes of fenestrated holes in repair screws, irregular holes and different bone densities of specimens. In this study, the pullout strength was compared for two techniques, the modified technique to use PMMA to augment a threaded hole and the traditional technique with retrograde injection of a PMMA filling, for standard loose screws in porcine vertebrae. Both techniques provided statistically significant results for sufficiently randomized specimens and experimental procedures. The difference in the pullout strength between conical and cylindrical screws for the aforementioned cement augmentation techniques was also investigated. Twenty-four single-level fresh-frozen lumbar vertebrae from L1 to L6 were harvested from four mature pigs. A total of 0.8 ml of PMMA was retrograde injected into screw holes with a 5.5 mm diameter, followed by insertion of a 5.0 mm diameter repair screw in the traditional group (n = 12). A stiff threaded PMMA hole was created with a 4.5 mm tapping screw before insertion of repair screws in the modified group (n = 12). Two screw geometries were randomly assigned as cylindrical (n = 6) and conical (n = 6) in each group. The correlations between filling techniques, screw geometries and axial pullout strength were analyzed. An appropriate screw trajectory and insertion depth were confirmed using X-ray imaging prior to pullout testing in both groups. For a given screw geometry (cylindrical or conical), the pullout force of the modified group was significantly higher than that of the traditional group. There was no significant difference in the pullout force between the screw geometries for a given filling technique. The cement augmentation technique is far more influential than the screw outer geometry. The modified PMMA technique created a greater anchor force than the traditional method and could be an alternative for revision of pedicle screw loosening.
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21
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Recommendations for standardised screw pull-out from polyurethane foam - The influence of density variations of the test foam and the insertion method. Med Eng Phys 2022; 100:103750. [DOI: 10.1016/j.medengphy.2022.103750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 12/07/2021] [Accepted: 01/01/2022] [Indexed: 12/18/2022]
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22
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Singla A, Sahlstrom AD, Tommasini SM, Yoo BJ. Lag Screw Trajectory in Supination-External Rotation Fractures: Does the Direction of the Fibula Lag Screw Have an Effect? Clin Orthop Surg 2021; 13:456-460. [PMID: 34868493 PMCID: PMC8609208 DOI: 10.4055/cios20304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 11/06/2022] Open
Abstract
Background The fracture obliquity of supination-external rotation injury of the fibula is often amenable to lag screw insertion. The purpose of the study was to determine whether biomechanical differences exist between lag screws inserted from an anterior to posterior direction and from a posterior to anterior direction and the thickness of the anterior and posterior fibular cortices were correlated with biomechanical testing. Methods Ten cadaver fibulae were harvested and submitted to material testing following 3.5-mm cortical screw insertion from either an anterior to posterior direction or a posterior to anterior direction. Screw torsional insertion strength and axial pullout strength were measured. Computed tomography images of 40 consecutive patients undergoing preoperative planning for fractures excluding the fibula were examined to define fibular cortical thickness and correlate anatomic findings with the biomechanical testing. Results The axial pullout strength of lag screws inserted from posterior to anterior was significantly greater than that of lag screws inserted from anterior to posterior (p < 0.05). Screw insertion torque measurements demonstrated a similar trend although the data did not reach statistical significance (p = 0.056). The anterior cortex of the distal fibula exhibited a radiographically greater thickness than that of the posterior cortex at the same level (p < 0.001). Conclusions For oblique fractures of the distal fibula, posterior to anterior lag screw insertion exhibited improved biomechanical properties when compared with a similar screw inserted from anterior to posterior. These results correlated with the thicker cortical bone present along the anterior fibula.
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Affiliation(s)
- Amit Singla
- Department of Orthopaedics and Rehabilitation, Yale New Haven Hospital, New Haven, CT, USA
| | - Adam D Sahlstrom
- Department of Orthopaedics and Rehabilitation, Yale New Haven Hospital, New Haven, CT, USA
| | - Steven M Tommasini
- Department of Orthopaedics and Rehabilitation, Yale New Haven Hospital, New Haven, CT, USA
| | - Brad J Yoo
- Department of Orthopaedics and Rehabilitation, Yale New Haven Hospital, New Haven, CT, USA
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Biomechanical Comparison of Fixation Stability among Various Pedicle Screw Geometries: Effects of Screw Outer/Inner Projection Shape and Thread Profile. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11219901] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The proper screw geometry and pilot-hole size remain controversial in current biomechanical studies. Variable results arise from differences in specimen anatomy and density, uncontrolled screw properties and mixed screw brands, in addition to the use of different tapping methods. The purpose of this study was to evaluate the effect of bone density and pilot-hole size on the biomechanical performance of various pedicle screw geometries. Six screw designs, involving three different outer/inner projections of screws (cylindrical/conical, conical/conical and cylindrical/cylindrical), together with two different thread profiles (square and V), were examined. The insertional torque and pullout strength of each screw were measured following insertion of the screw into test blocks, with densities of 20 and 30 pcf, predrilled with 2.7-mm/3.2-mm/3.7-mm pilot holes. The correlation between the bone volume embedded in the screw threads and the pullout strength was statistically analyzed. Our study demonstrates that V-shaped screw threads showed a higher pullout strength than S-shaped threads in materials of different densities and among different pilot-hole sizes. The configuration, consisting of an outer cylindrical shape, an inner conical shape and V-shaped screw threads, showed the highest insertional torque and pullout strength at a normal and higher-than-normal bone density. Even with increasing pilot-hole size, this configuration maintained superiority.
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24
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Caprara S, Fasser MR, Spirig JM, Widmer J, Snedeker JG, Farshad M, Senteler M. Bone density optimized pedicle screw instrumentation improves screw pull-out force in lumbar vertebrae. Comput Methods Biomech Biomed Engin 2021; 25:464-474. [PMID: 34369827 DOI: 10.1080/10255842.2021.1959558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Pedicle screw instrumentation is performed in the surgical treatment of a wide variety of spinal pathologies. A common postoperative complication associated with this procedure is screw loosening. It has been shown that patient-specific screw fixation can be automated to match standard clinical practice and that failure can be estimated preoperatively using computed tomography images. Hence, we set out to optimize three-dimensional preoperative planning to achieve more mechanically robust screw purchase allowing deviation from intuitive, standard screw parameters. Toward this purpose, we employed a genetic algorithm optimization to find optimal screw sizes and trajectories by maximizing the CT derived bone mechanical properties. The method was tested on cadaveric lumbar vertebrae (L1 to L5) of four human spines (2 female/2 male; age range 60-78 years). The main boundary conditions were the predefined, level-dependent areas of possible screw entry points, as well as the automatically located pedicle structures. Finite element analysis was used to compare the genetic algorithm output to standard clinical planning of screw positioning in terms of the simulated pull-out strength. The genetic algorithm optimization successfully found screw sizes and trajectories that maximize the sum of the Young's modulus within the screw's volume for all 40 pedicle screws included in this study. Overall, there was a 26% increase in simulated pull-out strength for optimized compared to traditional screw trajectories and sizes. Our results indicate that optimizing pedicle screw instrumentation in lumbar vertebrae based on bone quality measures improves screw purchase as compared to traditional instrumentation.
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Affiliation(s)
- Sebastiano Caprara
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - José Miguel Spirig
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jonas Widmer
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Jess G Snedeker
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
| | - Marco Senteler
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
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25
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Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test. Sci Rep 2021; 11:12968. [PMID: 34155224 PMCID: PMC8217271 DOI: 10.1038/s41598-021-90686-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 05/10/2021] [Indexed: 12/23/2022] Open
Abstract
At present, the pedicle screw is the most commonly used internal fixation device. However, there are many kinds of common posterior pedicle screw insertion techniques performed to reconstruct the lumbar stability. Therefore, spinal surgeons often face a difficult choice. The stress distribution of internal fixation system is an important index for evaluating safety. Unfortunately, little had been known about the difference of stress distribution of screw-rod systems that established by Roy-Camille, Magerl and Krag insertion techniques. Here, combination of finite element analysis and model measurement research was adopted to evaluate the difference of stress. Following different pedicle screw insertion techniques, three lumbar posterior surgery models were established after modeling and validation of the L1–S1 vertebrae finite element model. By analyzing the data, we found that stress concentration phenomenon was in all the postoperative models. Roy-Camille and Magerl insertion techniques led to the great stress on screw-rod systems. Then, fresh frozen calf spines were selected as a model for subsequent measurements. Fitted with a specially designed test pedicle screw, L5–L6 vertebrae were selected to repeat and verify the results of the finite element analysis. With the aid of universal testing machine and digital torque wrench, models simulated flexion, extension, lateral bending and rotation. Finally, the strain value was captured by the strain gauge and was then calculated as the stress value. Krag and Magerl were found to be the safer choice for pedicle screw insertion. Overall, our combination method obtained the reliable result that Krag insertion technique was the safer approach for pedicle screw implantation due to its relatively dispersive stress. Therefore, without the consideration of screw size, pedicle fill, bone density, and bone structures, we recommend the Krag insertion technique as the first choice to reconstruction of lumbar stability. Additionally, the combination method of finite element analysis and strain gauge measurement can provide a feasible way to study the stress distribution of spinal internal fixation.
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26
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27
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Bokov A, Pavlova S, Bulkin A, Aleynik A, Mlyavykh S. Potential contribution of pedicle screw design to loosening rate in patients with degenerative diseases of the lumbar spine: An observational study. World J Orthop 2021; 12:310-319. [PMID: 34055588 PMCID: PMC8152435 DOI: 10.5312/wjo.v12.i5.310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/15/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The majority of published data report the results of biomechanical tests of various design pedicle screw performance. The clinical relevance and relative contribution of screw design to instrumentation stability have been insufficiently studied.
AIM To estimate the contribution of screw design to rate of pedicle screw loosening in patients with degenerative diseases of the lumbar spine.
METHODS This study is a prospective evaluation of 175 patients with degenerative diseases and instability of the lumbar spine segments. Participants underwent spinal instrumentation employing pedicle screws with posterior only or transforaminal interbody fusion. Follow-up was for 18 mo. Patients with signs of pedicle screw loosening on computed tomography were registered; logistic regression analysis was used to identify the factors that influenced the rate of loosening.
RESULTS Parameters included in the analysis were screw geometry, type of thread, external and internal screw diameter and helical pitch, bone density in Hounsfield units, number of levels fused, instrumentation without anterior support, laminectomy, and unilateral and bilateral total facet joint resection. The rate of screw loosening decreased with the increment in outer diameter, decrease in core diameter and helical pitch. The rate of screw loosening correlated positively with the number of fused levels and decreasing bone density. Bilateral facet joint removal significantly favored pedicle screw loosening. The influence of other factors was insignificant.
CONCLUSION Screw parameters had a significant impact on the loosening rate along with bone quality characteristics, the number of levels fused and the extensiveness of decompression. The significance of the influence of screw parameters was comparable to those of patient- and surgery-related factors. Pedicle screw loosening was influenced by helical pitch, inner and outer diameter, but screw geometry and thread type were insignificant factors.
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Affiliation(s)
- Andrey Bokov
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Svetlana Pavlova
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Anatoliy Bulkin
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Alexandr Aleynik
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Sergey Mlyavykh
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
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28
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Kok J, Širka A, Liu Y, Tarasevičius Š, Belickas J, Tägil M, Lidgren L, Isaksson H, Raina DB. Augmenting a dynamic hip screw with a calcium sulfate/hydroxyapatite biomaterial. Med Eng Phys 2021; 92:102-109. [PMID: 34167704 DOI: 10.1016/j.medengphy.2021.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/30/2021] [Accepted: 05/09/2021] [Indexed: 11/28/2022]
Abstract
Internal fixation failure in hip fractures can lead to reoperation. Calcium sulfate/hydroxyapatite (CaS/HA) is a biomaterial that can be used for augmenting fracture fixation. We aimed to determine whether an injection of 2 ml CaS/HA increases the fixation of a dynamic hip screw inserted in synthetic and human trabecular bone. The study consists of two parts: 1) synthetic bone blocks (n = 74), with three subgroups: empty (cannulated screw, no injection), cannulated, and fenestrated; and 2) osteoporotic human femoral heads (n = 29), with the same subgroups. The heads were imaged using µCT. Bone volume fraction, insertion angle, and head diameter were measured. Pullout tests were performed and peak force, stiffness, and work were measured. The fenestrated group showed increases in pullout strength compared to no injection in the synthetic blocks. The cannulated group showed a higher pullout strength in low-density blocks. In the femoral heads, the variation was larger and there were no significant differences between groups. The bone volume fraction correlated with the peak force and work, and the insertion angle correlated with the stiffness. CaS/HA can improve the fixation of a dynamic hip screw. For clinical use, spreading of the material around the threads of the screw must be ensured.
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Affiliation(s)
- Joeri Kok
- Department of Biomedical Engineering, Lund University, Box 118, 22100 Lund, Sweden.
| | - Aurimas Širka
- Department of Orthopedics and Traumatology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Eiveniu ave.2, Kaunas, Lithuania.
| | - Yang Liu
- Department of Clinical Sciences, Orthopedics, Faculty of Medicine, Lund University, BMC C12, 22184 Lund, Sweden.
| | - Šarūnas Tarasevičius
- Department of Orthopedics and Traumatology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Eiveniu ave.2, Kaunas, Lithuania.
| | - Juozas Belickas
- Department of Orthopedics and Traumatology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Eiveniu ave.2, Kaunas, Lithuania.
| | - Magnus Tägil
- Department of Clinical Sciences, Orthopedics, Faculty of Medicine, Lund University, BMC C12, 22184 Lund, Sweden.
| | - Lars Lidgren
- Department of Clinical Sciences, Orthopedics, Faculty of Medicine, Lund University, BMC C12, 22184 Lund, Sweden.
| | - Hanna Isaksson
- Department of Biomedical Engineering, Lund University, Box 118, 22100 Lund, Sweden; Department of Clinical Sciences, Orthopedics, Faculty of Medicine, Lund University, BMC C12, 22184 Lund, Sweden.
| | - Deepak Bushan Raina
- Department of Clinical Sciences, Orthopedics, Faculty of Medicine, Lund University, BMC C12, 22184 Lund, Sweden.
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29
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Einafshar M, Hashemi A, van Lenthe GH. Homogenized finite element models can accurately predict screw pull-out in continuum materials, but not in porous materials. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 202:105966. [PMID: 33662802 DOI: 10.1016/j.cmpb.2021.105966] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVE Bone screw fixation can be estimated with several test methods such as insertion torque, pull-out, push-in and bending tests. A basic understanding of the relationship between screw fixation and bone microstructure is still lacking. Computational models can help clarify this relationship. The objective of the paper is to evaluate homogenized finite element (hFE) models of bone screw pull-out. METHODS Experimental pull-out tests were performed on three materials: two polyurethane (PU) foams having a porous microstructure, and a high density polyethylene (HDPE) which is a continuum material. Forty-five titanium pedicle screws were inserted to 10, 20, and 30 mm in equally sized blocks of all three materials (N = 5/group). Pull-out characteristics i.e. stiffness (S), yield force (Fy), peak pull-out force (Fult) and displacement at Fult (dult) were measured. hFE models were created replicating the experiments. The screw was modeled as a rigid body and 5 mm axial displacement was applied to the head of the screw. Simulations were performed evaluating two different conditions at the bone-screw interface; once in which the screw fitted the pilot hole exactly ("free-stressed") and once in which interface stresses resulting from the insertion process were taken into account ("pre-stressed"). RESULTS The simulations representing the pre-stressed condition in HDPE matched the experimental data well; S, Fy, and Fult differed less than 11%, 2% and 0.5% from the experimental data, respectively, whereas dult differed less than 16%. The free-stressed simulations were less accurate, especially stiffness (158% higher than the pre-stressed condition) and dult (30% lower than pre-stressed condition) were affected. The simulations representing PU did not match the experiments well. For the 20 mm insertion depth, S, Fy and Fult differed by more than 104%, 89% and 66%, respectively from the experimental values. Agreement did not improve for 10 and 30 mm insertion depths. CONCLUSIONS We found that hFE models can accurately quantify screw pull-out in continuum materials such as HDPE, but not in materials with a porous structure, such as PU. Pre-stresses in the bone induced by the insertion process cannot be neglected and need to be included in the hFE simulations.
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Affiliation(s)
- Mohammadjavad Einafshar
- Biomechanical engineering group, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Ata Hashemi
- Biomechanical engineering group, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
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30
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Hu Y, Fan Z, Zhang H, Zhang C, Fu W. Surface quality and pullout strength of ultrasonically-assisted drilling cortical bone. Proc Inst Mech Eng H 2020; 235:378-388. [PMID: 33356906 DOI: 10.1177/0954411920983662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bone surgery is a complex process involving sustainable and healthy human recuperation, but poor surface quality and loose implant fixtures can affect the recovery time of orthopedic patients. However, it has been demonstrated that the application of ultrasonic vibration during drilling procedures can improve the success of bone remediation procedures. The focus of the present paper was on the investigation of surface quality and pullout strength of drilled holes. After analyzing the special kinematic characteristics of the ultrasonically-assisted drilling (UAD), UAD testing using fresh cortical bone was carried out and compared with the results obtained after conventional drilling (CD) procedures. Surface roughness measurements and microscope examination were used to evaluate surface quality, and an electro-mechanical tensile machine was used to measure pullout resistance. The test findings indicated that surface roughness was reduced by 17-68.7% when using UAD; the axial pullout strength of screws inserted into UAD holes was significantly increased by 4.28-30.1% compared to that of CD. It was found also that low spindle speeds and high feed rates reduced surface quality and the stability of the inserted cortical screws. The findings demonstrated that UAD produced better surface quality and higher pullout strengths, which could provide greater stability for implants and improved post-operative recovery.
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Affiliation(s)
- Yahui Hu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Zhenhao Fan
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Huaiyu Zhang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Chunqiu Zhang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Weihua Fu
- Department of General Surgery, Tianjin Medical University General Hospital, Tianjin, China
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31
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Rana M, Biswas JK, Roy S, Ghosh N, Bhattacharya S, Karmakar SK, Roychowdhury A. Measurement of strain in the rod for lumbar pedicle screw fixation: An experimental and finite element study. Biomed Phys Eng Express 2020; 6. [PMID: 35042203 DOI: 10.1088/2057-1976/abc607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/29/2020] [Indexed: 02/05/2023]
Abstract
Spinal fusion with pedicle-screw-rod is being used widely for treating spinal deformities diseases. Several biomechanical studies on screw rod based implant failure through screw pullout, bending, screw breakage have been performed. But few studies are available regarding the effect of strain for breakage of rod. So, the purpose of the present study is to observe strain at the rod connected with the pedicle screw for different loading condition. The strain in stainless steel (SS) connecting rods for pedicle screw fixation were measured using strain gauge. In order to investigate the bio-mechanical response of lumbar spine with reference to strain in the rod, a simple experimental setup was developed using a specimen of L1-S spine segment. SS rods were used for pedicle screw implant on prototyped lumbar Spine. Prior to testing with pedicle screw, the lumbar spine specimen was also compared with FE results. The strain measured using strain gauges at L3-L4 level on SS rod were within a range of 85 to 310 microstrain under 6, 8, 10 Nm flexion and extension, and for L4-L5 level, these values were within a range of 95 to 440 microstrain. It was found that FE result was higher than the strain gauge result and the error varied between 10.5% to 33% with average error of 22.8%. However similar stain behavior was observed by the FE analysis. The proposed method, as well as the qualitative data, might be helpful for the researchers to understand biomechanical behavior of pedicle-screw implanted spine.
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Affiliation(s)
- Masud Rana
- Department of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, West Bengal, 711103, India
| | - Jayanta Kumar Biswas
- Department of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, West Bengal, 711103, India.,Department of Mechanical Engineering, JIS College of Engineering, Kalyani, West Bengal, 741235, India
| | - Sandipan Roy
- Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, Chennai 603203, India
| | - Niloy Ghosh
- Department of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, West Bengal, 711103, India
| | - Shambo Bhattacharya
- Department of Mechanical Engineering, Indian Institute of Technology, Delhi, 110016, India
| | - Santanu Kumar Karmakar
- Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, West Bengal, 711103, India
| | - Amit Roychowdhury
- Department of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, West Bengal, 711103, India
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Lam TN, Trinh MG, Huang CC, Kung PC, Huang WC, Chang W, Amalia L, Chin HH, Tsou NT, Shih SJ, Chen SY, Wang CC, Tsai PI, Wu MH, Huang EW. Investigation of Bone Growth in Additive-Manufactured Pedicle Screw Implant by Using Ti-6Al-4V and Bioactive Glass Powder Composite. Int J Mol Sci 2020; 21:ijms21207438. [PMID: 33050160 PMCID: PMC7587946 DOI: 10.3390/ijms21207438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/30/2020] [Accepted: 10/06/2020] [Indexed: 01/25/2023] Open
Abstract
In this study, we optimized the geometry and composition of additive-manufactured pedicle screws. Metal powders of titanium-aluminum-vanadium (Ti-6Al-4V) were mixed with reactive glass-ceramic biomaterials of bioactive glass (BG) powders. To optimize the geometry of pedicle screws, we applied a novel numerical approach to proposing the optimal shape of the healing chamber to promote biological healing. We examined the geometry and composition effects of pedicle screw implants on the interfacial autologous bone attachment and bone graft incorporation through in vivo studies. The addition of an optimal amount of BG to Ti-6Al-4V leads to a lower elastic modulus of the ceramic-metal composite material, effectively reducing the stress-shielding effects. Pedicle screw implants with optimal shape design and made of the composite material of Ti-6Al-4V doped with BG fabricated through additive manufacturing exhibit greater osseointegration and a more rapid bone volume fraction during the fracture healing process 120 days after implantation, per in vivo studies.
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Affiliation(s)
- Tu-Ngoc Lam
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
- Department of Physics, College of Education, Can Tho University, Can Tho City 900000, Vietnam
| | - Minh-Giam Trinh
- International Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, No. 250, Wuxing St, Xinyi District, Taipei 11031, Taiwan;
- Department of Trauma-Orthopaedics, College of Medicine, Pham Ngoc Thach Medical University, No. 02, Duong Quang Trung St, 10th District, Ho Chi Minh City 700000, Vietnam
| | - Chih-Chieh Huang
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Pei-Ching Kung
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Wei-Chin Huang
- Laser and Additive Manufacturing Technology Center, Industrial Technology Research Institute, Hsinchu 31040, Taiwan;
| | - Wei Chang
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Lia Amalia
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Hsu-Hsuan Chin
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Nien-Ti Tsou
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Shao-Ju Shih
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Road, Taipei 10607, Taiwan;
| | - San-Yuan Chen
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
| | - Chun-Chieh Wang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan;
| | - Pei-I Tsai
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan;
| | - Meng-Huang Wu
- Department of Orthopaedics, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wuxing St, Xinyi District, Taipei 11031, Taiwan
- Department of Orthopedics, Taipei Medical University Hospital, No. 252, Wuxing St, Xinyi District, Taipei 11031, Taiwan
- Correspondence: (M.-H.W.); (E.-W.H.)
| | - E-Wen Huang
- Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; (T.-N.L.); (C.-C.H.); (P.-C.K.); (W.C.); (L.A.); (H.-H.C.); (N.-T.T.); (S.-Y.C.)
- Correspondence: (M.-H.W.); (E.-W.H.)
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Chang M, Canseco JA, Nicholson KJ, Patel N, Vaccaro AR. The Role of Machine Learning in Spine Surgery: The Future Is Now. Front Surg 2020; 7:54. [PMID: 32974382 PMCID: PMC7472375 DOI: 10.3389/fsurg.2020.00054] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022] Open
Abstract
The recent influx of machine learning centered investigations in the spine surgery literature has led to increased enthusiasm as to the prospect of using artificial intelligence to create clinical decision support tools, optimize postoperative outcomes, and improve technologies used in the operating room. However, the methodology underlying machine learning in spine research is often overlooked as the subject matter is quite novel and may be foreign to practicing spine surgeons. Improper application of machine learning is a significant bioethics challenge, given the potential consequences of over- or underestimating the results of such studies for clinical decision-making processes. Proper peer review of these publications requires a baseline familiarity of the language associated with machine learning, and how it differs from classical statistical analyses. This narrative review first introduces the overall field of machine learning and its role in artificial intelligence, and defines basic terminology. In addition, common modalities for applying machine learning, including classification and regression decision trees, support vector machines, and artificial neural networks are examined in the context of examples gathered from the spine literature. Lastly, the ethical challenges associated with adapting machine learning for research related to patient care, as well as future perspectives on the potential use of machine learning in spine surgery, are discussed specifically.
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Affiliation(s)
- Michael Chang
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- Rothman Orthopaedic Institute, Philadelphia, PA, United States
| | - Jose A. Canseco
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- Rothman Orthopaedic Institute, Philadelphia, PA, United States
| | | | - Neil Patel
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- Rothman Orthopaedic Institute, Philadelphia, PA, United States
| | - Alexander R. Vaccaro
- Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA, United States
- Rothman Orthopaedic Institute, Philadelphia, PA, United States
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Le Cann S, Tudisco E, Tägil M, Hall SA, Isaksson H. Bone Damage Evolution Around Integrated Metal Screws Using X-Ray Tomography - in situ Pullout and Digital Volume Correlation. Front Bioeng Biotechnol 2020; 8:934. [PMID: 32850760 PMCID: PMC7419699 DOI: 10.3389/fbioe.2020.00934] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/20/2020] [Indexed: 12/22/2022] Open
Abstract
Better understanding of the local deformation of the bone network around metallic implants subjected to loading is of importance to assess the mechanical resistance of the bone-implant interface and limit implant failure. In this study, four titanium screws were osseointegrated into rat tibiae for 4 weeks and screw pullout was conducted in situ under x-ray microtomography, recording macroscopic mechanical behavior and full tomographies at multiple load steps before failure. Images were analyzed using Digital Volume Correlation (DVC) to access internal displacement and deformation fields during loading. A repeatable failure pattern was observed, where a ∼300–500 μm-thick envelope of bone detached from the trabecular structure. Fracture initiated close to the screw tip and propagated along the implant surface, at a distance of around 500 μm. Thus, the fracture pattern appeared to be influenced by the microstructure of the bone formed closely around the threads, which confirmed that the model is relevant for evaluating the effect of pharmacological treatments affecting local bone formation. Moreover, cracks at the tibial plateau were identified by DVC analysis of the tomographic images acquired during loading. Moderate strains were first distributed in the trabecular bone, which localized into higher strains regions with subsequent loading, revealing crack-formation not evident in the tomographic images. The in situ loading methodology followed by DVC is shown to be a powerful tool to study internal deformation and fracture behavior of the newly formed bone close to an implant when subjected to loading. A better understanding of the interface failure may help improve the outcome of surgical implants.
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Affiliation(s)
- Sophie Le Cann
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Erika Tudisco
- Division of Geotechnical Engineering, Lund University, Lund, Sweden
| | - Magnus Tägil
- Department of Orthopaedics, Clinical Sciences, Lund University, Lund, Sweden
| | - Stephen A Hall
- Division of Solid Mechanics, Lund University, Lund, Sweden.,Lund Institute for Advanced Neutron and X-ray Science, Lund, Sweden
| | - Hanna Isaksson
- Department of Biomedical Engineering, Lund University, Lund, Sweden.,Department of Orthopaedics, Clinical Sciences, Lund University, Lund, Sweden
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Xu F, Zou D, Li W, Sun Z, Jiang S, Zhou S, Li Z. Hounsfield units of the vertebral body and pedicle as predictors of pedicle screw loosening after degenerative lumbar spine surgery. Neurosurg Focus 2020; 49:E10. [DOI: 10.3171/2020.5.focus20249] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 05/12/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVEThe authors aimed to compare the efficacy of lumbar vertebral body Hounsfield units (HUs) and pedicle HUs at predicting pedicle screw loosening.METHODSThe authors retrospectively assessed 143 patients with L3–5 instrumentation. The patients were classified into one of two groups based on the status of their L3 screws (a screw loosening group or a control group). The pedicle HUs and vertebral HUs of L3 were measured using preoperative lumbar CT scans, and the pedicle HUs were measured in two ways: by excluding or by including cortical bone.RESULTSThe screw loosening rate was 20.3% (n = 29/143) at the 12-month follow-up. The vertebral body HUs and pedicle HUs in the screw loosening group were lower than those in the control group (vertebral body group: 98.6 HUs vs 121.4 HUs, p < 0.001; pedicle excluding cortical bone: 208.9 HUs vs 290.5 HUs, p = 0.002; pedicle including cortical bone: 249.4 HUs vs 337.5 HUs, p < 0.001). The pedicle HUs tended to have a higher area under the receiver operating characteristic curve value in predicting screw loosening, compared with that of vertebral body HUs, but the difference was not statistically significant (p > 0.05). Among patients with low vertebral body HUs of ≤ 130, the loosening rate was much lower in patients with pedicle HUs of ≤ 340 than in those with pedicle HUs of > 340 (31.0% vs 13.0%, respectively; p < 0.05).CONCLUSIONSVertebral body HUs alone are insufficient to accurately evaluate the risk of pedicle screw loosening. Therefore, it is important to collect both the pedicle HU and vertebral body HU measurements for surgical planning.
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Affiliation(s)
- Fei Xu
- 1Orthopaedic Department, Peking University Third Hospital; and
- 2Peking University Health Science Center, Haidian District, Beijing, China
| | - Da Zou
- 1Orthopaedic Department, Peking University Third Hospital; and
| | - Weishi Li
- 1Orthopaedic Department, Peking University Third Hospital; and
| | - Zhuoran Sun
- 1Orthopaedic Department, Peking University Third Hospital; and
| | - Shuai Jiang
- 1Orthopaedic Department, Peking University Third Hospital; and
| | - Siyu Zhou
- 1Orthopaedic Department, Peking University Third Hospital; and
| | - Zhuofu Li
- 1Orthopaedic Department, Peking University Third Hospital; and
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Abstract
With the recent increase in the elderly population, many people suffer from spinal diseases, and, accordingly, spinal fusion surgery using pedicle screws has been widely applied to treat them. However, most research on pedicle screw design has been focused on the test results rather than the behavior of the screws and vertebrae. In this study, a design platform with a series of biomechanical tests and analyses were presented for pedicle screw improvement and evaluation. The platform was then applied to an alternative hybrid screw design with quadruple and double threads. An experimental apparatus was developed to investigate the bending strength of the screw, and several tests were performed based on the ASTM F1717 standard. In the experiments, it was confirmed that the alternative pedicle screw has the highest bending strength. To examine the stress distribution of pedicle screws, finite element models were established, through which it was found that the proposed pedicle screw has sufficient mechanical safety to make it acceptable for spinal fusion treatment. Finally, we conclude that the platform has good potential for the design and evaluation of pedicle screws, and the alternative dual screw design is one of the best options for spinal fusion surgery.
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Xu C, Hou Q, Chu Y, Huang X, Yang W, Ma J, Wang Z. How to improve the safety of bicortical pedicle screw insertion in the thoracolumbar vertebrae: analysis base on three-dimensional CT reconstruction of patients in the prone position. BMC Musculoskelet Disord 2020; 21:444. [PMID: 32635944 PMCID: PMC7341646 DOI: 10.1186/s12891-020-03473-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 07/02/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Through the comparison of three-dimensional CT reconstruction between the supine position and the prone position, the relative position of thoracolumbar great vessels and vertebral body was studied, and the shortest safe distance between them was measured to improve the safety of bicortical pedicle screw insertion and reduce the risk of vascular injury. METHODS Forty adults were selected to participate the research. Three-dimensional reconstruction of thoracolumbar (T9-L3) CT was performed in the prone position and the supine position. The relative distance between the Aorta/Inferior Vena Cava (IVC) and vertebral body was obtained as AVD/VVD respectively. The relative angle of the Aorta/ IVC and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and the supine positions, and the data obtained were analyzed using SPSS 22.0 statistical software. RESULTS The AVD of the prone position and the supine position was the shortest at T12 (3.18 ± 0.68 mm), but the difference was not statistically significant. The aorta of the T9-L3 segment was shifted from the anterolateral to the anteromedial. The ∠AOY of the other groups differed significantly between the prone and supine positions in all vertebrae except T12 and L1 (P < 0.05), and the aorta in the prone position was more anteromedial than that of supine position. With regard to VVD/∠VOY, there was no significant difference between the prone and supine positions (P ≥ 0.05), and the minimum VVD of L3 segment is greater than 5.4 mm. The IVC has no obvious mobility and is fixed in the range of 20 ° ~ 30 ° near the midline. CONCLUSION When using bicortical anchoring of pedicle screws, it is safe to ensure that the protruding tips of the screw is less than 3 mm. Due to the mobility of the aorta in different postures and individual differences in anatomy, the prone position CT can help doctors to make better preoperative plans and decisions.
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Affiliation(s)
- Chao Xu
- Qingdao University Medical College, Qingdao, 266071, Shandong, China
| | - Qingxian Hou
- Department of Spine Surgery, The Affiliated Hospital of Qingdao University, Qingdao, 266555, Shandong, China
| | - Yanchen Chu
- Department of Spine Surgery, The Affiliated Hospital of Qingdao University, Qingdao, 266555, Shandong, China
| | - Xiuling Huang
- Clinical Labororatory, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Wenjiu Yang
- Department of Spine Surgery, The Affiliated Hospital of Qingdao University, Qingdao, 266555, Shandong, China
| | - Jinglong Ma
- Qingdao University Medical College, Qingdao, 266071, Shandong, China
| | - Zhijie Wang
- Department of Spine Surgery, The Affiliated Hospital of Qingdao University, Qingdao, 266555, Shandong, China.
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Use of longer sized screws is a salvage method for broken pedicles in osteoporotic vertebrae. Sci Rep 2020; 10:10441. [PMID: 32591573 PMCID: PMC7320151 DOI: 10.1038/s41598-020-67489-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 06/05/2020] [Indexed: 11/09/2022] Open
Abstract
Screw loosening due to broken pedicles is a common complication resulting from the insertion of screws either with inadequate diameters or into an osteoporotic pedicle. In this novel in vitro study, we tried to clarify the contribution of the pedicle to screw fixation and subsequent salvage strategies using longer or larger-diameter screws in broken pedicles. Sixty L4 fresh-frozen lumbar vertebrae harvested from mature pigs were designed as the normal-density group (n = 30) and decalcified as the osteoporosis group (n = 30). Three modalities were randomly assigned as intact pedicle (n = 30), semi-pedicle (n = 15), and non-pedicle (n = 15) in each group. Three sizes of polyaxial screws (diameter × length of 6.0 mm × 45 mm, 6.0 mm × 50 mm, and 6.5 mm × 45 mm) over five trials were used in each modality. The associations between bone density, pedicle modality and screw pullout strength were analyzed. After decalcification for 4 weeks, the area bone mineral density decreased to approximately 56% (p < 0.05) of the normal-density group, which was assigned as the osteoporosis group. An appropriate screw trajectory and insertional depth were confirmed using X-ray imaging prior to pullout testing in both groups. The pullout forces of larger-diameter screws (6.5 mm × 45 mm) and longer screws (6.0 mm × 50 mm) were significantly higher (p < 0.05) in the semi- and non-pedicle modalities in the normal-density group, whereas only longer screws (6.0 mm × 50 mm) had a significantly higher (p < 0.05) pullout force in the non-pedicle modalities in the osteoporosis group. The pedicle plays an important role in both the normal bone density group and the osteoporosis group, as revealed by analyzing the pullout force percentage contributed by the pedicle. Use of a longer screw would be a way to salvage a broken pedicle of osteoporotic vertebra.
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A novel parameter for the prediction of pedicle screw fixation in cancellous bone - A biomechanical study on synthetic foam. Med Eng Phys 2020; 79:44-51. [DOI: 10.1016/j.medengphy.2020.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 01/17/2020] [Accepted: 03/01/2020] [Indexed: 11/21/2022]
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Liao JC. Impact of Osteoporosis on Different Type of Short-Segment Posterior Instrumentation for Thoracolumbar Burst Fracture-A Finite Element Analysis. World Neurosurg 2020; 139:e643-e651. [PMID: 32325261 DOI: 10.1016/j.wneu.2020.04.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 04/07/2020] [Accepted: 04/09/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVE In Taiwan (my country), the proportion of people 65 years or older was over 14% in 2018, which is known as entering "aged society." More and more thoracolumbar burst fractures in the setting of osteoporosis happen nowadays. In this study, a finite element model on thoracolumbar burst fracture was established and 4 types of posterior short-segment fixations were tested under normal bone quality and osteoporotic conditions. METHODS The intact T11-L1 spine finite element model was created, and one-half of the spongy bone of the T12 vertebra was removed to simulate burst fracture. Four fixation models with posterior fusion devices were established: 1) a link (S-L); 2) intermediate bilateral screws (S-I); 3) a link and calcium sulfate cement (S-L-C); and 4) intermediate bilateral screws and calcium sulfate cement (S-I-C). The Young modulus of the osteoporotic cancellous bone was set at 70 MPa. Range of motion, as well as the maximum value and distribution of the implant stress on T11 and L1, were compared between normal bone and osteoporotic status. RESULTS The strongest construct was the S-I-C group of both normal bone and osteoporosis condition. In osteoporotic status, the range of motion of construct in 4 types would be increased when comparing with normal bone. The stress on pedicle screws at the T11 and L1 level would also be increased in osteoporosis. The value of the maximal von Mises stress on the superior vertebral body (T11) for all loading conditions was larger than that on the inferior vertebral body (L1) in both normal bone and osteoporosis. CONCLUSIONS The S-I-C provided the strongest construct even in osteoporosis status. But osteoporosis would result in weakness for spinal construct, which might lead to implant failure.
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Affiliation(s)
- Jen-Chung Liao
- Department of Orthopedic Surgery, Bone and Joint Research Center, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.
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41
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Krishnan V, Varghese V, Kumar GS, Yoganandan N. Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae. Asian Spine J 2020; 14:273-279. [PMID: 31940715 PMCID: PMC7280910 DOI: 10.31616/asj.2019.0174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 08/06/2019] [Indexed: 12/04/2022] Open
Abstract
Study Design A biomechanical study. Purpose To determine the actual load path and compare pullout strengths as a function of screw size used in revision surgeries using postmortem human subject specimens. Overview of Literature Pedicle screw fixation has become the standard of care in the surgical management of spinal instability. However, pullout failures are widely observed in osteoporotic spines and treated by revision surgeries using a higher diameter screw, performing cement augmentation, or increasing the levels of fixation. While the peak forces to final pullout are reported, the actual load path to achieve the final force level is not available. Methods Six osteoporotic lumbar spines (L2–L5) were instrumented with 5.5×40 mm polyaxial screws and loaded along the axis of the screw using a material testing machine according to American Society for Testing of Materials 543-07 test protocol. Tests were again conducted by replacing them with 6.5×40 mm (group A) or 7.5×40 mm (group B) screws. Force-displacement data were grouped and load paths (mean±1 standard deviation) were compared. Results Pullout strength decreased by 36% when the size of the revision screw was increased by 1 mm, while it increased by 35% when the size of the revision screw was increased by 2 mm compared to the index screw value. While the morphologies of the load paths were similar in all cases, they differ between the two groups: the larger screw responded with generally elevated stiffer path than the smaller screw, suggesting that revision surgery using a larger screw has more purchase along the inserted body-pedicle axis. Conclusions A larger screw enhances strength and increases biomechanical stability in revision surgeries, although the final surgical decision is made by the clinician, which includes the patient’s anatomy and associated characteristics.
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Affiliation(s)
- Venkatesh Krishnan
- Spinal Disorders and Surgery Unit, Christian Medical College, Vellore, India
| | - Vicky Varghese
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Narayan Yoganandan
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
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Widmer J, Fasser MR, Croci E, Spirig J, Snedeker JG, Farshad M. Individualized prediction of pedicle screw fixation strength with a finite element model. Comput Methods Biomech Biomed Engin 2020; 23:155-167. [PMID: 31910656 DOI: 10.1080/10255842.2019.1709173] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Pedicle screws are used for the treatment of a wide variety of spinal pathologies. A good screw holding power in bone is required for treatment success, but has so far not been predictable computationally. The goal of this study was to develop an automated tool able to predict patient-specific screw fixation strength through finite element simulation. We compared the simulation results with results from biomechanical pull-out tests performed on animal lumbar specimens. Experimental and simulation pull-out strengths were highly correlated [Formula: see text] and the mean error was 20.25%. The fixation strength was also associated to great extent with pull-out stiffness and strain energy, as well as the screw size and mean vertebral density.
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Affiliation(s)
- Jonas Widmer
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Eleonora Croci
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - José Spirig
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jess G Snedeker
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
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3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling. J Mech Behav Biomed Mater 2019; 103:103608. [PMID: 32090935 DOI: 10.1016/j.jmbbm.2019.103608] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/16/2019] [Accepted: 12/25/2019] [Indexed: 11/22/2022]
Abstract
Additive manufacturing has significant advantages, in the biomedical field, allowing for customized medical products where complex architectures can be achieved directly. While additive manufacturing can be used to fabricate synthetic bone models, this approach is limited by the printing resolution, at the level of the trabecular bone architecture. Therefore, the aim of this study was to evaluate the possibilities of using fused deposition modeling (FDM) to this end. To better mimic real bone, both in terms of mechanical properties and biodegradability, a composite of degradable polymer, poly(lactic acid) (PLA), and hydroxyapatite (HA) was used as the filament. Three PLA/HA composite formulations with 5-10-15 wt% HA were evaluated, and scaled up human trabecular bone models were printed using these materials. Morphometric and mechanical properties of the printed models were evaluated by micro-computed tomography, compression and screw pull out tests. It was shown that the trabecular architecture could be reproduced with FDM and PLA by applying a scaling factor of 2-4. The incorporation of HA particles reduced the printing accuracy, with respect to morphology, but showed potential for enhancement of the mechanical properties. The scaled-up models displayed comparable, or slightly enhanced, strength compared to the commonly used polymeric foam synthetic bone models (i.e. Sawbones). Reproducing the trabecular morphology by 3D printed PLA/HA composites appears to be a promising strategy for synthetic bone models, when high printed resolution can be achieved.
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44
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Varghese V, Krishnan V, Kumar GS. Comparison of pullout strength of pedicle screws following revision using larger diameter screws. Med Eng Phys 2019; 74:180-185. [DOI: 10.1016/j.medengphy.2019.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/06/2019] [Accepted: 09/08/2019] [Indexed: 02/03/2023]
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45
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Hollensteiner M, Esterer B, Fürst D, Schrempf A, Augat P. Development of open-cell polyurethane-based bone surrogates for biomechanical testing of pedicle screws. J Mech Behav Biomed Mater 2019; 97:247-253. [DOI: 10.1016/j.jmbbm.2019.05.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/14/2019] [Accepted: 05/14/2019] [Indexed: 11/29/2022]
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46
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Carlson BC, Robinson WA, Wanderman NR, Sebastian AS, Nassr A, Freedman BA, Anderson PA. A Review and Clinical Perspective of the Impact of Osteoporosis on the Spine. Geriatr Orthop Surg Rehabil 2019; 10:2151459319861591. [PMID: 31360592 PMCID: PMC6637832 DOI: 10.1177/2151459319861591] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 06/03/2019] [Accepted: 06/05/2019] [Indexed: 01/08/2023] Open
Abstract
Introduction Osteopenia and osteoporosis are common conditions in the United States. The health consequences of low bone density can be dire, from poor surgical outcomes to increased mortality rates following a fracture. Significance This article highlights the impact low bone density has on spine health in terms of vertebral fragility fractures and its adverse effects on elective spine surgery. It also reviews the clinical importance of bone health assessment and optimization. Results Vertebral fractures are the most common fragility fractures with significant consequences related to patient morbidity and mortality. Additionally, a vertebral fracture is the best predictor of a subsequent fracture. These fractures constitute sentinel events in osteoporosis that require further evaluation and treatment of the patient's underlying bone disease. In addition to fractures, osteopenia and osteoporosis have deleterious effects on elective spine surgery from screw pullout to fusion rates. Adequate evaluation and treatment of a patient's underlying bone disease in these situations have been shown to improve patient outcomes. Conclusion With an increased understanding of the prevalence of low bone mass and its consequences as well an understanding of how to identify these patients and appropriately intervene, spine surgeons can effectively decrease the rates of adverse health outcomes related to low bone mass.
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Affiliation(s)
- Bayard C Carlson
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
| | | | | | | | - Ahmad Nassr
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Brett A Freedman
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Paul A Anderson
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
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Huang X, Huang Z, Xu L, Liang D, Zhang M, Zhang H. Pullout strength of reinserted pedicle screws using the previous entry point and trajectory. J Orthop Surg Res 2019; 14:205. [PMID: 31272476 PMCID: PMC6611027 DOI: 10.1186/s13018-019-1240-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/13/2019] [Indexed: 11/10/2022] Open
Abstract
PURPOSE This study compared the biomechanics of reinserted pedicle screws using the previous entry point and trajectory with those of correctly inserted pedicle screws. METHODS The study used 18 lumbar vertebrae (L1-6) from three fresh calf spines to insert 6.5 × 40-mm pedicle screws. A control screw was inserted correctly along the axis of one pedicle, while an experimental screw was reinserted completely using the previous entry point and trajectory in the other pedicle. The experimental screw was removed after being completely inserted in group A and after 80% of the total trajectory inserted in group B. And the experimental screw was removed after 60% of the total trajectory was reached in group C. The biomechanical values of the pedicle screws were measured. RESULTS There were no significant differences in pedicle screw axial pullout strength between reinserted screws and correct screws in the 3 groups (PA = 0.463, PB = 0.753, PC = 0.753). Stiffness measurement increased for the reinserted screw compared with that of the control screw. Fracturing was observed between the vertebral body and pedicle. CONCLUSION Theoretically, a surgeon can remove the pedicle screw when necessary, inspect the trajectory, and reinsert the screw using the previous entry point and trajectory.
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Affiliation(s)
- Xuanwu Huang
- Department of Orthopedics, Zhujiang Hospital, Southern Medical University, No. 253, Gongye Road, Haizhu District, Guangzhou, 510282, China
| | - Zixiang Huang
- Department of Spine Surgery, Guangdong Second Provincial General Hospital, No. 466, Xingang Road, Haizhu District, Guangzhou, 510317, China
| | - Liwei Xu
- The Second School of Clinical Medicine, Southern Medical University, No. 253, Gongye Road, Haizhu District, Guangzhou, 510282, China.,Department of Spine Surgery, Guangdong Second Provincial General Hospital, No. 466, Xingang Road, Haizhu District, Guangzhou, 510317, China
| | - Dongzhu Liang
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, Guangzhou, China
| | - Meichao Zhang
- Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, Guangzhou, China
| | - Hui Zhang
- The Second School of Clinical Medicine, Southern Medical University, No. 253, Gongye Road, Haizhu District, Guangzhou, 510282, China. .,Department of Spine Surgery, Guangdong Second Provincial General Hospital, No. 466, Xingang Road, Haizhu District, Guangzhou, 510317, China.
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Feng X, Lin G, Fang CX, Lu WW, Chen B, Leung FKL. Bone resorption triggered by high radial stress: The mechanism of screw loosening in plate fixation of long bone fractures. J Orthop Res 2019; 37:1498-1507. [PMID: 30908687 DOI: 10.1002/jor.24286] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 03/08/2019] [Indexed: 02/04/2023]
Abstract
Screw loosening is a common complication in plate fixation. However, the underlying mechanism is unclear. This study investigated screw loosening mechanisms by finite element analysis (FEA) simulation and clinical X-ray feature analysis. Two FEA models incorporated bone heterogeneity and orthotropy, representing fracture fixation using dynamic compression plate (DCP) and locking compression plate (LCP), were developed. These models were used to examine the volume of bone exceeding a certain stress value around each screw under physiologically-relevant loading conditions. These damaged bone was then separated and compared by the axial stress and radial stress of each screw. In addition, features of patients' X-ray images showing screw loosening were analyzed to validate the loosening features simulated by the models. The FEA study showed that more damaged bone was found at the central two screws which gradually decreased toward the two end screws in all groups. More bone was damaged by the radial stress of each screw than by the axial stress. The radiological analysis of screw loosening showed that bone loss occurred at the screw closest to the fracture line first then subsequent bone loss at the screws further away from the fracture line occurred. This study found that the two screws nearest to the fracture line are more vulnerable to loosening. The radial stress of the screw plays a larger role in screw loosening than the axial stress. Bone resorption triggered by the high radial stress of screws is indicated as the mechanism of screw loosening in the diaphyseal plate fixation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1498-1507, 2019.
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Affiliation(s)
- Xiaoreng Feng
- Department of Orthopaedics and Traumatology, Queen Mary Hospital, the University of Hong Kong, Pok Fu Lam, Hong Kong
| | - Guanghu Lin
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Christian X Fang
- Department of Orthopaedics and Traumatology, Queen Mary Hospital, the University of Hong Kong, Pok Fu Lam, Hong Kong
| | - William W Lu
- Department of Orthopaedics and Traumatology, Queen Mary Hospital, the University of Hong Kong, Pok Fu Lam, Hong Kong
| | - Bin Chen
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Frankie K L Leung
- Department of Orthopaedics and Traumatology, Queen Mary Hospital, the University of Hong Kong, Pok Fu Lam, Hong Kong.,Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong-Shenzhen Hospital, Shenzhen, 518000, China
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Khatri R, Varghese V, Sharma S, Kumar GS, Chhabra HS. Pullout Strength Predictor: A Machine Learning Approach. Asian Spine J 2019; 13:842-848. [PMID: 31154706 PMCID: PMC6773988 DOI: 10.31616/asj.2018.0243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 03/10/2019] [Indexed: 11/29/2022] Open
Abstract
Study Design A biomechanical study. Purpose To develop a predictive model for pullout strength. Overview of Literature Spine fusion surgeries are performed to correct joint deformities by restricting motion between two or more unstable vertebrae. The pedicle screw provides a corrective force to the unstable spinal segment and arrests motions at the unit that are being fused. To determine the hold of a screw, surgeons depend on a subjective perioperative feeling of insertion torque. The objective of the paper was to develop a machine learning based model using density of foam, insertion angle, insertion depth, and reinsertion to predict the pullout strength of pedicle screw. Methods To predict the pullout strength of pedicle screw, an experimental dataset of 48 data points was used as training data to construct a model based on different machine learning algorithms. A total of five algorithms were tested in the Weka environment and the performance was evaluated based on correlation coefficient and error matrix. A sensitive study of various parameters for obtaining the best combination of parameters for predicting the pullout strength was also preformed using the L9 orthogonal array of Taguchi Design of Experiments. Results Random forest performed the best with a correlation coefficient of 0.96, relative absolute error of 0.28, and root relative squared error of 0.29. The difference between the experimental and predicted value for the six test cases was not significant (p >0.05). Conclusions This model can be used clinically for understanding the failure of pedicle screw pullout and pre-surgical planning for spine surgeon.
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Affiliation(s)
- Ravi Khatri
- Biomechanics Lab, Indian Spinal Injuries Centre, New Delhi, India.,Department of Engineering Design, IIT Madras, Chennai, India
| | - Vicky Varghese
- Biomechanics Lab, Indian Spinal Injuries Centre, New Delhi, India
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Abstract
Since FDA approval in 2002, teriparatide has gained popularity as an anabolic therapy for the treatment of osteoporosis. Animal studies have suggested a role for teriparatide in spine surgery. Several recent studies have demonstrated adjunctive use of teriparatide in osteoporotic patients undergoing spine fusions improves fusion rates, decreases time to union, and decreases osteoporosis-related complications such as proximal junctional kyphosis. On the basis of the available literature, we outline an algorithm for the use of teriparatide in spine surgery.
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