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Kumar R, Kumar A, Kumari S, Kumar A. Biomechanical Analysis of Trapezoidal Thread Screw-Rod Fixation in Pedicle Section of Cervical Spine: A Finite-Element Analysis. Indian J Orthop 2024; 58:771-777. [PMID: 38812871 PMCID: PMC11130091 DOI: 10.1007/s43465-024-01170-y] [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: 11/02/2023] [Accepted: 04/23/2024] [Indexed: 05/31/2024]
Abstract
Background Cervical pedicle screw-rod fixation presents a complex approach in spinal surgery, offering enhanced spine stabilization in variable conditions considering traumatic injuries, degenerative changes, as well as orthopaedic and oncological ailments. This technique employs small diameter screw implants strategically placed to bolster the mechanical integrity of the spine. Notably, it involves minimally invasive procedures, resulting in smaller incisions and reduced patient discomfort. This study aims to assess the effects of trapezoidal thread screws in pedicle sections of the cervical spine during flexion-extension loadings, focusing on factors such as range of motion (ROM), implant stress, and stress on adjacent bone. Methods Utilizing CT scan data, a finite element model of the cervical spine (C2-C7 vertebrae) was prepared. Trapezoidal thread screws were integrated into a single-level pedicle screw-rod fixation at the C5-C6 vertebrae. The C2 vertebra were given a compressive load of 50 N along with a moment of 1 Nm, resulting in the immobilization of the C7. Results and Discussion The results indicate a reduction in ROM at the C5-C6 level by 69% to 77% compared to the intact spine during flexion-extension loading, with a slight increase in ROM observed at adjacent cervical spine levels. Stress analysis revealed that the trapezoidal thread screws induced stresses ranging from 24 MPa to 29 MPa in PEEK trapezoidal screw-rod implants, which fall below the material's yield stress. Conclusions This suggests that the trapezoidal thread profile may be advantageous in minimizing stress concentration, attributed to its larger contact area with the vertebrae bone between the threads.
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Affiliation(s)
- Ram Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
| | - Amit Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
| | - Shabnam Kumari
- Department of Mathematics, Banaras Hindu University, Varanasi, India
| | - Alok Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
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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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Novel Dual-Threaded Pedicle Screws Provide Fixation Stability That Is Comparable to That of Traditional Screws with Relative Bone Preservation: An In Vitro Biomechanical Study. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12126172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Replacement with larger diameter screws is always used in pedicle screw loosening but carries a risk of pedicle wall violation. A pedicle screw with more preserved bone stock is the preferred primary fixation choice. The purpose of this study was to evaluate whether a newly designed proximal-conical dual-thread screw with less bone occupancy provides fixation strength comparable to that of a traditional screw. Six types of pedicle screws based on three different shapes (cylindrical, conical, and proximal-conical) and two thread profiles (single-thread and dual-thread) were grouped. Conical and proximal-conical screws differed mainly in the slope of the outer diameter from the hub to the tip. Conical screws had an outer diameter (6.5 mm) that differed from the hub and tapered by 30% to an outer diameter (4.5 mm) at the tip and proximal-conical screws had the same outer diameter from the hub and tapered by 30% (4.5 mm) at 20 mm from the hub and then maintained the outer diameter (45 mm) to the tip. A total of 36 L4 Sawbones® vertebrae were used in the study and six trials for each screw group. The results of the imaging, screw volume in bone, insertion torque, and pullout force were analyzed. For screws with the same shape, insertion torque and pullout force were significantly higher for those in the dual-thread groups than for those in the single-thread groups (p < 0.05). For screws with the same thread profile, there was no significant difference in either biomechanical test between the different screw shapes (p > 0.05). Our results demonstrated that these proximal-conical dual-thread screws, with the property of relative bone stock preservation, display a comparable biomechanical performance to traditional dual-thread screws and a better performance than single-thread screws. This screw design could serve as the primary pedicle screw choice to reduce revision difficulty.
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Prediction of Sacral Screw Loosening after Lumbosacral Surgeries Involving Rigid Fixation of Sacral Bone Using Preoperative Computed Tomography Scans. BIOMED RESEARCH INTERNATIONAL 2022; 2022:7123139. [PMID: 35655477 PMCID: PMC9152424 DOI: 10.1155/2022/7123139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/04/2022] [Accepted: 04/30/2022] [Indexed: 11/21/2022]
Abstract
Objective To find a preoperative computed tomography-based method to predict the incidence of sacral screw loosening and assist surgical planning. Methods Surgically treated patients for degenerative lumbosacral disorders with rigid pedicle screw fixation of patients with L5-S1 vertebra in our center from January 2016 to January 2021 were retrospectively included in the current study. CT scan attenuation of the horizontal plane of the sacrum was measured with Hounsfield units (HU). Postoperative X-ray tests were used to diagnose screw loosening. The data was analyzed by independent sample t-tests, X2 analysis, Pearson correlation analysis, and ROC curve analysis. Results A total of 162 (114 male, 48 female, average age 63.7 ± 7.3 years) patients were included in the final analysis. Significant differences were found between the screw loosening group and nonloosening group concerning the HU value of the sacrum at the horizontal plane (P < 0.01). In ROC curve analysis, AUC was 0.674 (95% CI: 0.592-0.756). A cutoff of 200 HU provided 64.8% sensitivity and 62.4% specificity, and a cutoff of 150 HU provided 90.2% sensitivity. Conclusions Analyzing 162 patients with at least 12 months of follow-up, we propose cutoff CT attenuation values of 200 HU and 150 HU to take moderate and radical measures of screw augmentation to prevent screw loosening in the sacral bone.
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Xiu J, Bu T, Yan Y, Wu Z, Yin Z, Lei W. Biomechanical study of space frame structure based on bone cement screw. Exp Ther Med 2020; 19:3650-3656. [PMID: 32373193 PMCID: PMC7197252 DOI: 10.3892/etm.2020.8659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/03/2019] [Indexed: 11/23/2022] Open
Abstract
Stability of space frame structures with bone cement screw reinforcement by biomechanical testing was analyzed. Seven complete human spine specimens with osteoporosis were selected. Three specimens were separated into 18 vertebral bodies. Nine vertebral bodies were randomly selected and bone cement screws were implanted on both sides. Bone cement was used to form a bridge at the front end of the two screws (single vertebral group A). The other nine vertebral bodies were implanted with cement screws on both sides, but the front ends of the two screws were not bridged (single vertebral group B). The remaining spine specimens were used for biomechanical testing of the overall stability of the three-dimensional frame. The four specimens were osteotomized, and then two specimens were randomly selected. Bone cement screws were implanted on both sides of the vertebral body, and a bone cement bridge was formed at the front end of the two screws to establish a three-dimensional frame structure (multi-vertebral group A). The other two spine specimens were implanted with cement screws on both sides of the vertebral body, but the front ends of the two screws were not bridged (multi-vertebral group B). A statistical difference was found between the extractive force of bridged and non-bridged specimens. Group B showed some loosening of screws after the test. The stability of the triangle structure screw, which was formed after the bridge was established at the front end of the single-vertebral bone cement screw, was significantly enhanced. Moreover, the stability was significantly improved after the three-dimensional frame structure was established in the multi-vertebral body group, providing a new method for clinical improvement of the stability and reliability of internal fixation in patients with severe osteoporosis and spinal disease.
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Affiliation(s)
- Jintao Xiu
- Department of Orthopaedics, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi 710032, P.R. China.,Department of Orthopaedics, The First Affiliated Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Tao Bu
- Medical Department, Lintong Rehabilitation Center, Xi'an, Shaanxi 710600, P.R. China
| | - Yabo Yan
- Department of Orthopaedics, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Zixiang Wu
- Department of Orthopaedics, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Zhanhai Yin
- Department of Orthopaedics, The First Affiliated Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Wei Lei
- Department of Orthopaedics, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi 710032, P.R. China
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Kim JH, Ahn DK, Shin WS, Kim MJ, Lee HY, Go YR. Clinical Effects and Complications of Pedicle Screw Augmentation with Bone Cement: Comparison of Fenestrated Screw Augmentation and Vertebroplasty Augmentation. Clin Orthop Surg 2020; 12:194-199. [PMID: 32489541 PMCID: PMC7237251 DOI: 10.4055/cios19127] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 09/18/2019] [Indexed: 11/25/2022] Open
Abstract
Background Pedicle screw augmentation with bone cement has been experimentally demonstrated to increase the pullout strength. However, the mechanisms of screw loosening are complicated and interacting. Although vertebroplasty augmentation and fenestrated screw augmentation have been compared in many studies, there has been no comparative study on their clinical effects and complications in real clinical settings. We investigated clinical effects of bone cement augmentation of a pedicle screw and differences according to augmentation methods. Methods Of the total 241 patients who had osteoporosis and underwent posterior pedicle screw fixation without anterior bone graft between January 2010 and December 2016, 132 patients with ≥2 years of radiological follow-up were included in this retrospective study. The patients were divided into group I (unaugmented) and group II (bone cement augmented). Group II was subdivided into II-S group (solid screw augmented) and II-F group (fenestrated screw augmented). The incidence of screw loosening was compared between groups I and II. Cement leakage, screw loosening, and screw fractures were investigated in the subgroups. Results In total, 36 of 71 (52%, group I) unaugmented cases and 96 of 170 (56%, group II) augmented cases were followed up for ≥2 years. Of the total 78 solid screw augmented cases, 42 (56%) were in II-S group; 54 of the total 92 (59%) fenestrated screw augmented cases were in II-F group. Groups I and II were homogenous regarding demographic characteristics; II-S and II-F groups were also homogenous. The incidence of screw loosening was 50.0% (18/36) in group I and 7.3% (7/96) in group II (p < 0.001). Cement leakage developed in 2 of 42 (4.8%) cases in II-S group and in 5 of 54 (9.3%) cases in II-F group (p = 0.462). Screw loosening developed in 6 of 42 (14.3%) cases in II-S group and in 1 of 54 cases (1.9%) in II-F group (p = 0.041). Screw fracture developed in none of 42 cases in II-S group and in 3 of 54 cases (5.6%) in II-F group (p = 0.254). Conclusions In osteoporotic patients, bone cement augmentation of a pedicle screw decreased the incidence of screw loosening, and fenestrated screw augmentation was more effective than vertebroplasty augmentation.
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Affiliation(s)
- Jin Hak Kim
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Dong Ki Ahn
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Won Shik Shin
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Myung Jin Kim
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Ho Young Lee
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Young Rok Go
- Department of Orthopedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
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Liu MY, Tsai TT, Lai PL, Hsieh MK, Chen LH, Tai CL. Biomechanical comparison of pedicle screw fixation strength in synthetic bones: Effects of screw shape, core/thread profile and cement augmentation. PLoS One 2020; 15:e0229328. [PMID: 32084219 PMCID: PMC7034823 DOI: 10.1371/journal.pone.0229328] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/04/2020] [Indexed: 12/02/2022] Open
Abstract
Pedicle screw loosening resulting from insufficient bone-screw interfacial holding power is not uncommon. The screw shape and thread profile are considered important factors of the screw fixation strength. This work investigated the difference in pullout strength between conical and cylindrical screws with three different thread designs. The effects of the thread profiles on the screw fixation strength of cannulated screws with or without cement augmentation in osteoporotic bone were also evaluated. Commercially available artificial standard L4 vertebrae and low-density polyurethane foam blocks were used as substitutes for healthy vertebrae and osteoporotic bones, respectively. The screw pullout strengths of nine screw systems were investigated (six in each). These systems included the combination of three different screw shapes (solid/cylindrical, solid/conical and cannulated/cylindrical) with three different thread profiles (fine-thread, coarse-thread and dual-core/dual-thread). Solid screws were designed for the cementless screw fixation of vertebrae using the standard samples, whereas cannulated screws were designed for the cemented screw fixation of osteoporotic bone using low-density test blocks. Following specimen preparation, a screw pullout test was conducted using a material test machine, and the maximal screw pullout strength was compared among the groups. This study demonstrated that, in healthy vertebrae, both the conical and dual-core/dual-thread designs can improve pullout strength. A combination of the conical and dual-core/dual-thread designs may achieve optimal postoperative screw stability. However, in osteoporotic bone, the thread profile have little impact on the screw fixation strength when pedicle screws are fixed with cement augmentation. Cement augmentation is the most important factor contributing to screw pullout fixation strength as compared to screw designs.
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Affiliation(s)
- Mu-Yi Liu
- Ph.D. Program in Biomedical Engineering, Collage of Engineering, Chang Gung University, 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
| | - Lih-Huei Chen
- Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
- * E-mail: (CLT); (LHC)
| | - Ching-Lung Tai
- Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
- Graduate Institute of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan
- * E-mail: (CLT); (LHC)
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Yu Y, Xie Y, Jian Q, Shi Y, Zhang G, Fan X. Biomechanical analysis and optimization of screw fixation technique for the cortical bone channel of lower thorax: Study protocol clinical trial (SPIRIT Compliant). Medicine (Baltimore) 2020; 99:e19046. [PMID: 32049803 PMCID: PMC7035084 DOI: 10.1097/md.0000000000019046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
It is well known that the main segments of spinal fracture is thoracolumbar (T11-L11). Therefore, in addition to the lumbar, the lower thoracic vertebra (T9-T12) often has the clinical needs of implantation of cortical bone trajectory (CBT) screws. However, the anatomic parameters of the lower thoracic vertebrae are quite different from those of the lumbar vertebrae, which means that if CBT screws are to be implanted in the lower thoracic vertebrae, the selection of the screw entry point, the length, diameter, angle and path of the screws in each segment need to be redefined. Methods In this part, 3-dimensional finite element model was established to analyze the stress and fixation efficiency of CBT screws in thoracic vertebrae after 5000 times of fatigue loading of normal model and osteoporosis model. Discussion If the outcomes indicate the trial is feasible and there is evidence to provide some basic anatomical parameters for CBT screw implantation in the lower thoracic spine, so that the ideal insertion point, length, diameter, and angle of CBT screw in different segments of the lower thoracic spine were determined.Trial Registration Chinese Clinical Trial Registry, ChiCTR1900026915.Registered on September 26, 2019.
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Affiliation(s)
- Yang Yu
- Hospital of Chengdu University of Traditional Chinese Medicine
| | - YiZhou Xie
- Chengdu University of Traditional Chinese Medicine, Sichuan Province, P.R.China
| | - Qiang Jian
- Chengdu University of Traditional Chinese Medicine, Sichuan Province, P.R.China
| | - Yin Shi
- Chengdu University of Traditional Chinese Medicine, Sichuan Province, P.R.China
| | - Guilong Zhang
- Hospital of Chengdu University of Traditional Chinese Medicine
| | - Xiaohong Fan
- Hospital of Chengdu University of Traditional Chinese Medicine
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Wang Z, Liu Y, Rong Z, Wang C, Liu X, Zhang F, Zhang Z, Xu J, Dai F. Clinical evaluation of a bone cement-injectable cannulated pedicle screw augmented with polymethylmethacrylate: 128 osteoporotic patients with 42 months of follow-up. Clinics (Sao Paulo) 2019; 74:e346. [PMID: 31188908 PMCID: PMC6537661 DOI: 10.6061/clinics/2019/e346] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 12/21/2018] [Indexed: 12/02/2022] Open
Abstract
OBJECTIVES To evaluate the safety and efficacy of a novel bone cement-injectable cannulated pedicle screw augmented with polymethylmethacrylate in osteoporotic spinal surgery. METHODS This study included 128 patients with osteoporosis (BMD T-score -3.2±1.9; range, -5.4 to -2.5) who underwent spinal decompression and instrumentation with a polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screw. Postoperative Visual Analogue Scale scores and the Oswestry Disability Index were compared with preoperative values. Postoperative plain radiographs and computed tomography (CT) scans were performed immediately after surgery; at 1, 3, 6, and 12 months; and annually thereafter. RESULTS The mean follow-up time was 42.4±13.4 months (range, 23 to 71 months). A total of 418 polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screws were used. Cement extravasations were detected in 27 bone cement-injectable cannulated pedicle screws (6.46%), mainly in cases of vertebral fracture, without any clinical sequela. The postoperative low back and lower limb Visual Analogue Scale scores were significantly reduced compared with the preoperative scores (<0.01), and similar results were noted for the Oswestry Disability Index score (p<0.01). No significant screw migration was noted at the final follow-up relative to immediately after surgery (p<0.01). All cases achieved successful bone fusion, and no case required revision. No infection or blood clots occurred after surgery. CONCLUSIONS The polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screw is safe and effective for use in osteoporotic patients who require spinal instrumentation.
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Affiliation(s)
- Zhengdong Wang
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
- Corresponding authors. E-mail: /
| | - Yaoyao Liu
- Department of Spine Surgery, Daping Hospital, Army Medical University, Daping Hospital, 400410, Chongqing, China
- Corresponding authors. E-mail: /
| | - Zhigang Rong
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
| | - Cheng Wang
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
| | - Xun Liu
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
| | - Fei Zhang
- Department of Orthopaedics, General Hospital of Xin Jiang Military Region, 830000, Xinjiang, China
| | - Zehua Zhang
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
| | - Jianzhong Xu
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
- Corresponding authors. E-mail: /
| | - Fei Dai
- Department of Orthopedics, National & Regional United Engineering Laboratory of Tissue Engineering, Southwest Hospital, Army Medical University, 400038, Chongqing, China
- Corresponding authors. E-mail: /
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Wanderman N, Freedman B, Currier B, Huddleston P, Yaszemski M, Nassr A. Interpreting the DXA analysis: When should you hold off on spinal fusion? ACTA ACUST UNITED AC 2018. [DOI: 10.1053/j.semss.2017.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Pull-out strength of patient-specific template-guided vs. free-hand fluoroscopically controlled thoracolumbar pedicle screws: a biomechanical analysis of a randomized cadaveric study. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2017; 26:2865-2872. [DOI: 10.1007/s00586-017-5025-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/20/2016] [Accepted: 02/28/2017] [Indexed: 10/20/2022]
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Liu D, Zhang B, Xie QY, Kang X, Zhou JJ, Wang CR, Lei W, Zheng W. Biomechanical comparison of pedicle screw augmented with different volumes of polymethylmethacrylate in osteoporotic and severely osteoporotic cadaveric lumbar vertebrae: an experimental study. Spine J 2016; 16:1124-32. [PMID: 27130374 DOI: 10.1016/j.spinee.2016.04.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 02/14/2016] [Accepted: 04/21/2016] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Polymethylmethacrylate (PMMA) is widely used for pedicle screw augmentation in osteoporosis. Intriguingly, there have been no biomechanical comparisons of the stability of pedicle screws augmented with different volumes of PMMA or studies of the relationship between screw stability and volume of PMMA, especially in different degrees of osteoporosis. PURPOSE The purposes of the study reported here were to compare screw stability by different volumes of PMMA augmentation, to analyze the relationship between screw stability and PMMA volume, and to make a preliminary determination of the optimum volume of PMMA augmentation for different degrees of osteoporosis. STUDY DESIGN This study is a biomechanical comparison of pedicle screws augmented with various volumes of PMMA in cadaveric lumbar vertebrae. METHODS Thirty-six pedicles from 18 osteoporotic lumbar vertebrae were randomly divided into groups A0 through A5, and 36 pedicles from 18 severely osteoporotic lumbar vertebrae were randomly divided into groups B0 through B5. A different volume of PMMA was injected into each one of groups A0 through A5 (0, 0.5, 1.0, 1.5, 2.0, and 2.5 mL, respectively) and into each one of groups B0 through B5 (0, 1.0, 1.5, 2.0, 2.5, and 3.0 mL, respectively), and then pedicle screws were inserted in all vertebrae. After complete solidification of the PMMA, we examined pedicle X-rays, performed axial pullout tests, and determined the maximum axial pullout strength (Fmax) for all samples. RESULTS No PMMA was found around the screws in groups A0 and B0. In groups A1 to A5 and B1 to B5, screws were wrapped by gradually increasing amounts of PMMA. There was no PMMA leakage or screw malpositioning in any samples. The Fmax in groups A1 through A5 increased by 32.40%, 64.42%, 116.02%, 174.07%, and 207.42%, respectively, compared with that in group A0. There were no significant differences in Fmax between groups A0 and A1, A1 and A2, A2 and A3, A3 and A4, and A4 and A5 (p>.05), but there were significant differences in Fmax between any other two groups (p<.05). The Fmax in groups B1 through B5 increased by 23.48%, 48.40%, 106.60%, 134.73%, and 210.04%, respectively, compared with that in group B0. There were no significant differences in Fmax between groups B0 and B1, B0 and B2, B1 and B2, B2 and B3, B3 and B4 (p>.05), but there were significant differences in Fmax between any other two groups (p<.05). There was a significant positive correlation between Fmax and volume of PMMA in both osteoporotic and severely osteoporotic lumbar vertebrae (p<.05). CONCLUSIONS Polymethylmethacrylate can significantly enhance stability of pedicle screws in both osteoporotic and severely osteoporotic lumbar vertebrae. There is a significant positive correlation between screw stability and volume of PMMA. Within a certain range, nevertheless, increasing the volume of PMMA does not significantly improve screw stability. We suggest that 1.5 and 3 mL, respectively, are the volumes of injected PMMA that will optimize pedicle screw stability in osteoporotic and severely osteoporotic lumbar vertebrae.
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Affiliation(s)
- Da Liu
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China
| | - Bo Zhang
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China
| | - Qing-Yun Xie
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China
| | - Xia Kang
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China
| | - Jiang-Jun Zhou
- Department of Orthopaedics, 184 Hospital of Nanjing Military Region, No. 4, Hudong St, Yingtan, Jiangxi Province 335000, China
| | - Cai-Ru Wang
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China
| | - Wei Lei
- Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, No. 15, Changle West Rd, Xi'an, Shaanxi Province 710032, China
| | - Wei Zheng
- Department of Orthopaedics, Chengdu Military General Hospital, No. 270, Rongdu Ave, Jinniu District, Chengdu, Sichuan Province 610083, China.
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Biomechanical Comparison of Pedicle Screw Augmented with Different Volumes of Polymethylmethacrylate in Osteoporotic and Severely Osteoporotic Synthetic Bone Blocks in Primary Implantation: An Experimental Study. BIOMED RESEARCH INTERNATIONAL 2016; 2016:9627504. [PMID: 26885525 PMCID: PMC4739206 DOI: 10.1155/2016/9627504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Revised: 12/17/2015] [Accepted: 12/27/2015] [Indexed: 11/18/2022]
Abstract
This study was designed to compare screw stabilities augmented with different volumes of PMMA and analyze relationship between screw stability and volume of PMMA and optimum volume of PMMA in different bone condition. Osteoporotic and severely osteoporotic synthetic bone blocks were divided into groups A0-A5 and B0-B5, respectively. Different volumes of PMMA were injected in groups A0 to A5 and B0 to B5. Axial pullout tests were performed and Fmax was measured. Fmax in groups A1-A5 were all significantly higher than group A0. Except between groups A1 and A2, A3 and A4, and A4 and A5, there were significant differences on Fmax between any other two groups. Fmax in groups B1-B5 were all significantly higher than group B0. Except between groups B1 and B2, B2 and B3, and B4 and B5, there were significant differences on Fmax between any other two groups. There was significantly positive correlation between Fmax and volume of PMMA in osteoporotic and severely osteoporotic blocks. PMMA can significantly enhance pedicle screw stability in osteoporosis and severe osteoporosis. There were positive correlations between screw stability and volume of PMMA. In this study, injection of 3 mL and 4 mL PMMA was preferred in osteoporotic and severely osteoporotic blocks, respectively.
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Gates TA, Moldavsky M, Salloum K, Dunbar GL, Park J, Bucklen B. Biomechanical Analysis of a Novel Pedicle Screw Anchor Designed for the Osteoporotic Population. World Neurosurg 2015; 83:965-9. [DOI: 10.1016/j.wneu.2015.01.057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 01/22/2015] [Accepted: 01/28/2015] [Indexed: 11/30/2022]
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Balancing rigidity and safety of pedicle screw fixation via a novel expansion mechanism in a severely osteoporotic model. BIOMED RESEARCH INTERNATIONAL 2015; 2015:318405. [PMID: 25705655 PMCID: PMC4331393 DOI: 10.1155/2015/318405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/03/2015] [Accepted: 01/03/2015] [Indexed: 11/17/2022]
Abstract
Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone. Maximum pullout strength, stiffness, energy to failure, energy to removal, and size of the resulting block damage were statistically compared among conditions. While expandable pedicle screws produced maximum pullout forces less than or comparable to standard screws, they required a higher amount of energy to be fully removed from both models. Furthermore, damage to the cortical layer in the composite test blocks was smaller in all measured directions for tests involving expandable pedicle screws than those involving standard pedicle screws. This indicates that while initial fixation may not differ in the presence of cortical bone, the expandable pedicle screw offers an increased level of postfailure stability and safety to patients awaiting revision surgery.
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Farshad M, Farshad-Amacker NA, Bachmann E, Snedeker JG, Schmid SL. Biomechanical comparison of sagittal-parallel versus non-parallel pedicle screw placement. Acta Neurochir (Wien) 2014; 156:2147-51. [PMID: 25257136 DOI: 10.1007/s00701-014-2244-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/15/2014] [Indexed: 12/01/2022]
Abstract
BACKGROUND While convergent placement of pedicle screws in the axial plane is known to be more advantageous biomechanically, surgeons intuitively aim toward a parallel placement of screws in the sagittal plane. It is however not clear whether parallel placement of screws in the sagittal plane is biomechanically superior to a non-parallel construct. The hypothesis of this study is that sagittal non-parallel pedicle screws do not have an inferior initial pull-out strength compared to parallel placed screws. METHODS The established lumbar calf spine model was used for determination of pull-out strength in parallel and non-parallel intersegmental pedicle screw constructs. Each of six lumbar calf spines (L1-L6) was divided into three levels: L1/L2, L3/L4 and L5/L6. Each segment was randomly instrumented with pedicle screws (6/45 mm) with either the standard technique of sagittal parallel or non-parallel screw placement, respectively, under fluoroscopic control. CT was used to verify the intrapedicular positioning of all screws. The maximum pull-out forces and type of failure were registered and compared between the groups. RESULTS The pull-out forces were 5,394 N (range 4,221 N to 8,342 N) for the sagittal non-parallel screws and 5,263 N (range 3,589 N to 7,554 N) for the sagittal-parallel screws (p = 0.838). Interlevel comparisons also showed no statistically significant differences between the groups with no relevant difference in failure mode. CONCLUSION Non-parallel pedicle screws in the sagittal plane have at least equal initial fixation strength compared to parallel pedicle screws in the setting of the here performed cadaveric calf spine experiments.
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Affiliation(s)
- Mazda Farshad
- Orthopaedic Surgery, Balgrist University Hospital, University of Zürich, Forchstrasse 340, 8008, Zürich, Switzerland,
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Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: current status. BIOMED RESEARCH INTERNATIONAL 2014; 2014:748393. [PMID: 24724097 PMCID: PMC3958762 DOI: 10.1155/2014/748393] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/16/2014] [Accepted: 01/22/2014] [Indexed: 12/21/2022]
Abstract
Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein.
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