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Li YD, Lai PL, Hsieh MK, Chen WP, Lee DM, Tsai TT, Tai CL. Influence of various pilot hole profiles on pedicle screw fixation strength in minimally invasive and traditional spinal surgery: a comparative biomechanical study. Front Bioeng Biotechnol 2024; 12:1359883. [PMID: 38380264 PMCID: PMC10877418 DOI: 10.3389/fbioe.2024.1359883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 01/25/2024] [Indexed: 02/22/2024] Open
Abstract
Despite advancements in pedicle screw design and surgical techniques, the standard steps for inserting pedicle screws still need to follow a set of fixed procedures. The first step, known as establishing a pilot hole, also referred to as a pre-drilled hole, is crucial for ensuring screw insertion accuracy. In different surgical approaches, such as minimally invasive or traditional surgery, the method of creating pilot holes varies, resulting in different pilot hole profiles, including variations in size and shape. The aim of this study is to evaluate the biomechanical properties of different pilot hole profiles corresponding to various surgical approaches. Commercially available synthetic L4 vertebrae with a density of 0.16 g/cc were utilized as substitutes for human bone. Four different pilot hole profiles were created using a 3.0 mm cylindrical bone biopsy needle, 3.6 mm cylindrical drill, 3.2-5.0 mm conical drill, and 3.2-5.0 mm conical curette for simulating various minimally invasive and traditional spinal surgeries. Two frequently employed screw shapes, namely, cylindrical and conical, were selected. Following specimen preparation, screw pullout tests were performed using a material test machine, and statistical analysis was applied to compare the mean maximal pullout strength of each configuration. Conical and cylindrical screws in these four pilot hole configurations showed similar trends, with the mean maximal pullout strength ranking from high to low as follows: 3.0 mm cylindrical biopsy needle, 3.6 mm cylindrical drill bit, 3.2-5.0 mm conical curette, and 3.2-5.0 mm conical drill bit. Conical screws generally exhibited a greater mean maximal pullout strength than cylindrical screws in three of the four different pilot hole configurations. In the groups with conical pilot holes, created with a 3.2-5.0 mm drill bit and 3.2-5.0 mm curette, both conical screws exhibited a greater mean maximal pullout strength than did cylindrical screws. The strength of this study lies in its comprehensive comparison of the impact of various pilot hole profiles commonly used in clinical procedures on screw fixation stability, a topic rarely reported in the literature. Our results demonstrated that pilot holes created for minimally invasive surgery using image-guided techniques exhibit superior pullout strength compared to those utilized in traditional surgery. Therefore, we recommend prioritizing minimally invasive surgery when screw implantation is anticipated to be difficult or there is a specific need for stronger screw fixation. When opting for traditional surgery, image-guided methods may help establish smaller pilot holes and increase screw fixation strength.
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Affiliation(s)
- 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
- Department of Orthopedic Surgery, New Taipei Municipal TuCheng Hospital (Built and Operated by Chang Gung Medical Foundation), New Taipei City, 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
| | - Weng-Pin Chen
- Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - De-Mei Lee
- Department of Mechanical 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
| | - 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
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Einafshar M, Hashemi A, Kiapour A. Evaluation of the efficacy of modal analysis in predicting the pullout strength of fixation bone screws. JOR Spine 2022; 5:e1220. [PMID: 36601373 PMCID: PMC9799086 DOI: 10.1002/jsp2.1220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/06/2022] Open
Abstract
Background Pilot hole preparation has been shown to have an impact on the short and long-term stability of the screw fixation constructs. Purpose Investigation and comparison of two nondestructive modal analysis methods with conventional insertion torque (IT) and pullout tests in optimum pilot hole diameter detection. Methods Twenty conical core titanium screws were embedded in high-density polyethylene blocks with different pilot hole diameters. The maximum IT was recorded for each screw during implantation. Then, two modal analysis methods including accelerometer (classical modal analysis [CMA]) and acoustic modal analysis (AMA) were carried out to measure the natural frequency (NF) of the bone-screw structure. Finally, stiffness (S), pullout force (Fult), displacement at Fult (dult) and energy dissipation (ED) were obtained from the destructive pullout test. Results The IT increased, as the pilot hole diameter decreased. The maximum value of IT was observed in the smallest pilot hole diameter. The same trend was found for the Fult and the first NF derived from both modal methods except for 5.5 mm pilot hole diameter. The natural NFs derived from CMA and AMA showed high correlations in different groups (R2 = 0.94) and did not deviate from y = x hypothesis in linear regression analysis. The Fult, dult, and ED were measured 4800 ± 172 N, 3.10 ± 0.08 mm and 14.23 ± 1.10 N.mm, respectively. Discussion No significant change was observed in "S" between the groups. The highest Fult and first NF were obtained for the 5.5 mm pilot hole diameter. Both CMA and AMA were found to be reliable methods and can promote the undesirable contradiction between Fult and IT.
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Affiliation(s)
- Mohammadjavad Einafshar
- Biomechanical Engineering Group, Department of Biomedical EngineeringAmirkabir University of TechnologyTehranIran
- Department of Material and ProductionAalborg UniversityAalborgDenamrk
| | - Ata Hashemi
- Biomechanical Engineering Group, Department of Biomedical EngineeringAmirkabir University of TechnologyTehranIran
| | - Ali Kiapour
- Departments of NeurosurgeryMassachusetts General Hospital, Harvard Medical SchoolBostonMassachusettsUSA
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Sucu HK. A True Percutaneous Anterior Odontoid Screw Fixation: The Results of 42 Cases by a Single Surgeon. World Neurosurg 2022; 166:e892-e904. [PMID: 35948230 DOI: 10.1016/j.wneu.2022.07.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study aimed to analyze a clinical series of odontoid fractures treated with true percutaneous anterior odontoid screws. The technique we used is different from the traditional approach of using blunt dissection to arrive at the anterior surface of the vertebral body. METHODS Between 2004 and 2021, forty-two patients underwent anterior screw fixation of the odontoid process using the true percutaneous technique without dissection among the fascial planes. Instead, we pressed from the medial border of the sternocleidomastoideus muscle with our second and third fingers to feel the vertebrae under the skin. Thus, the carotid artery is pushed laterally, the trachea-esophageal complex is moved medially, and when no esophagus, great vessels, etc., can be felt under our fingers; we have reached the anterior surface of the spine. Advancing the Jamshidi needle between the fingers causes it to pass only through the fascial layers. The absence of a gap between the dilatation tubes prevents any tissue from escaping into the tubes. RESULTS We had no intraoperative complications, such as esophageal, tracheal, or carotid injury. One patient required screw revision. In total, 5 patients died during the follow-up period, and 3 were lost to follow-up. There was no residual neck pain in our cohort, and no instability was noted on flexion-extension radiographs, even in ten patients without solid bone fusion. CONCLUSIONS True percutaneous anterior odontoid screw fixation is a safe and reliable procedure for treating odontoid fractures. The fibrous union of odontoid fractures provides as much stability as a solid bone fusion.
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Affiliation(s)
- Hasan Kamil Sucu
- İzmir Atatürk Research and Training Hospital, Neurosurgery Department, İzmir, Turkey.
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NIE JIACHEN, DING LI, ZHANG QING, LIU SHENGHUI, SHI HUIJUAN, ZHANG ZHONGCAI, ZOU HAIBO. THE FIXATION EFFECT OF DIFFERENT TYPES OF SCREWS IN THE WHOLE OSTEOPOROTIC LUMBAR VERTEBRAE: AN FEA STUDY. J MECH MED BIOL 2022. [DOI: 10.1142/s0219519422500348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Purpose: The aim of this study is to explore how pedicle screws (PSs) and cortical bone trajectory (CBT) screws differ in fixation strength when implanted in L1–L5 with osteoporosis, providing support for choosing implants and trajectories in spine internal fixation surgeries. Methods: We filtered 30 lumbar segments out from CT images of eight osteoporotic participants and simulated PS or CBT screw implantation in each segment, generating 60 vertebra-screw assembly FE models. To evaluate the fixation effect, we performed a pull-out force test simulation in each model and analyzed the maximal pull-out force, pull-out stiffness, and equivalent stress of vertebrae and screws. Results: The maximal pull-out force of PS and CBT screws in L1–L5 was in the range of 905–1552 (N) and 587–1012 (N), while the pull-out stiffness was in the range of 1990–2617 (N/mm) and 1007–1681 (N/mm). The fixation strength of PS in L4 and L5 was higher ([Formula: see text]), while in L1–L3 PS and CBT screws are similar ([Formula: see text]). The maximal stress of vertebrae and screws when PS was pulled at 0.25[Formula: see text]mm was larger than that of CBT screws. Conclusions: For patients with moderate osteoporosis, it is recommended to insert PS into L4 and L5 to attain better fixation strength, but vertebrae are more prone to fracture. Consequently, under severe osteoporosis, the implantation of CBT screws should be considered first. Bone cement injection may be necessary to consolidate the screw-vertebrae interface with osteoporosis.
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Affiliation(s)
- JIACHEN NIE
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - LI DING
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - QING ZHANG
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - SHENGHUI LIU
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - HUIJUAN SHI
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - ZHONGCAI ZHANG
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - HAIBO ZOU
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
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Naik RR, Hoblidar A, Bhat SN, Ampar N, Kundangar R. A Hybrid 3D-2D Image Registration Framework for Pedicle Screw Trajectory Registration between Intraoperative X-ray Image and Preoperative CT Image. J Imaging 2022; 8:185. [PMID: 35877629 PMCID: PMC9324544 DOI: 10.3390/jimaging8070185] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/11/2022] [Accepted: 06/19/2022] [Indexed: 12/04/2022] Open
Abstract
Pedicle screw insertion is considered a complex surgery among Orthopaedics surgeons. Exclusively to prevent postoperative complications associated with pedicle screw insertion, various types of image intensity registration-based navigation systems have been developed. These systems are computation-intensive, have a small capture range and have local maxima issues. On the other hand, deep learning-based techniques lack registration generalizability and have data dependency. To overcome these limitations, a patient-specific hybrid 3D-2D registration principled framework was designed to map a pedicle screw trajectory between intraoperative X-ray image and preoperative CT image. An anatomical landmark-based 3D-2D Iterative Control Point (ICP) registration was performed to register a pedicular marker pose between the X-ray images and axial preoperative CT images. The registration framework was clinically validated by generating projection images possessing an optimal match with intraoperative X-ray images at the corresponding control point registration. The effectiveness of the registered trajectory was evaluated in terms of displacement and directional errors after reprojecting its position on 2D radiographic planes. The mean Euclidean distances for the Head and Tail end of the reprojected trajectory from the actual trajectory in the AP and lateral planes were shown to be 0.6-0.8 mm and 0.5-1.6 mm, respectively. Similarly, the corresponding mean directional errors were found to be 4.90 and 20. The mean trajectory length difference between the actual and registered trajectory was shown to be 2.67 mm. The approximate time required in the intraoperative environment to axially map the marker position for a single vertebra was found to be 3 min. Utilizing the markerless registration techniques, the designed framework functions like a screw navigation tool, and assures the quality of surgery being performed by limiting the need of postoperative CT.
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Affiliation(s)
- Roshan Ramakrishna Naik
- Manipal Institute of Technology, Manipal Academy of Higher Education Manipal, Manipal 576104, India;
| | - Anitha Hoblidar
- Manipal Institute of Technology, Manipal Academy of Higher Education Manipal, Manipal 576104, India;
| | - Shyamasunder N. Bhat
- Kasturba Medical College, Manipal Academy of Higher Education Manipal, Manipal 576104, India; (N.A.); (R.K.)
| | - Nishanth Ampar
- Kasturba Medical College, Manipal Academy of Higher Education Manipal, Manipal 576104, India; (N.A.); (R.K.)
| | - Raghuraj Kundangar
- Kasturba Medical College, Manipal Academy of Higher Education Manipal, Manipal 576104, India; (N.A.); (R.K.)
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Qiu L, Niu F, Wu Z, Zhang W, Chen F, Tan J, Yan J, Xia P. Comparative outcomes of cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion: A meta-analysis. World Neurosurg 2022; 164:e436-e445. [PMID: 35533950 DOI: 10.1016/j.wneu.2022.04.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pedicular screws (PS) is often used in lumbar fusion. Cortical bone trajectory (CBT) is a novel technology in lumbar fusion with less clinical outcomes evidence. So we conduct a meta-analysis to compare the efficacy and safety between cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion surgery. METHODS Multiple databases were searched for the articles about comparison of cortical bone trajectory (CBT) and traditional pedicle screws (PS) in lumbar fusion surgeries. The Meta-analysis was conducted by Revman 5.3 software. The following indicators were abstracted: visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA), surgical duration, complications, and blood loss. The quality of the articles was assessed by the Newcastle-Ottawa Scale or Cochrane Handbook. RESULTS 25 studies were included involving a total of 1735 patients. There is no difference in preoperative VAS scores, JOA, ODI, postoperative VAS scores and fusion rates. Besides, postoperative JOA(MD = 0.78, P = 0.02), ODI (MD = -2.09, P=0.03), surgical duration(MD = -26.90, P = 0.02), complications(MD = 0.70, P = 0.03), and blood loss(MD = -85.27, P=0.0009) showed greater improvement trends in CBT group than PS group with significant difference. CONCLUSION CBT reduced the rate of complications, surgical duration, blood loss, postoperative ODI and JOA scores. CBT technique with better postoperative outcomes achieved similar fusion rates compared with PS technique.
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Affiliation(s)
- Ling Qiu
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Fei Niu
- The Wuhan Hospital of Traditional Chinese And Western Medicine, 215 Zhong Shan Road, Wuhan 430022, P.R. China
| | - Zhedong Wu
- Hubei University of Chinese Medicine, 188 Tan Hua-lin Road, Wuhan 430065, P.R. China
| | - Wei Zhang
- The Wuhan Hospital of Traditional Chinese And Western Medicine, 215 Zhong Shan Road, Wuhan 430022, P.R. China
| | - Feifei Chen
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Jun Tan
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Jun Yan
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Ping Xia
- Hubei University of Chinese Medicine, 188 Tan Hua-lin Road, Wuhan 430065, P.R. China.
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Hoon QJ, Wang T, Hall E, Walsh WR, Johnson KA. Influence of Screw-Hole Defect Size on the Biomechanical Properties of Feline Femora in an Ex Vivo Model. Vet Comp Orthop Traumatol 2021; 35:33-46. [PMID: 34488233 DOI: 10.1055/s-0041-1735551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The study aims to evaluate the biomechanical properties of feline femora with craniocaudal screw-hole defects of increasing diameter, subjected to three-point bending and torsion to failure at two different loading rates. STUDY DESIGN Eighty femoral pairs were harvested from adult cat cadavers. For each bending and torsional experiment, there were five groups (n = 8 pairs) of increasing craniocaudal screw-hole defects (intact, 1.5 mm, 2.0 mm, 2.4 mm, 2.7mm). Mid-diaphyseal bicortical defects were created with an appropriate pilot drill-hole and tapped accordingly. Left and right femora of each pair were randomly assigned to a destructive loading protocol at low (10 mm/min; 0.5 degrees/s) or high rates (3,000 mm/min; 90 degrees/s) respectively. Stiffness, load/torque-to-failure, energy-to-failure and fracture morphology were recorded. RESULTS Defect size to bone diameter ratio was significantly different between defect groups within bending and torsional experiments respectively (intact [0%; 0%], 1.5 mm [17.8%; 17.1%], 2.0 mm [22.8%; 23.5%], 2.4 mm [27.8%; 27.6%], 2.7 mm [31.1%; 32.4%]) (p < 0.001). No significant differences in stiffness and load/torque-to-failure were noted with increasing deficit sizes in all loading conditions. Screw-hole (2.7 mm) defects up to 33% bone diameter had a maximum of 20% reduction in bending and torsional strength compared with intact bone at both loading rates. Stiffness and load/torque-to-failure in both bending and torsion were increased in bones subjected to higher loading rates (p < 0.001). CONCLUSION Screw-hole defects up to 2.7 mm did not significantly reduce feline bone failure properties in this ex vivo femoral study. These findings support current screw-size selection guidelines of up to 33% bone diameter as appropriate for use in feline fracture osteosynthesis.
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Affiliation(s)
- QiCai Jason Hoon
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, Australia
| | - Tian Wang
- Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, UNSW Sydney, Randwick, New South Wales, Australia
| | - Evelyn Hall
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, Australia
| | - William R Walsh
- Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, UNSW Sydney, Randwick, New South Wales, Australia
| | - Kenneth A Johnson
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, Australia
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Abstract
STUDY DESIGN Retrospective observational study of consecutive patients. OBJECTIVE We sought to: (1) clarify the key factors predominantly associated with the insertional torque of pedicle screws; (2) compare the optimal factors for pedicle screw insertion to obtain rigid screw fixation in patients with adult spinal deformity (ASD) and in those with adolescent idiopathic scoliosis (AIS); (3) determine the optimal screw/pedicle ratio (S/P) to obtain rigid pedicle screw fixation. SUMMARY OF BACKGROUND DATA Rigid pedicle screw fixation is mandatory to perform corrections for spinal deformities properly and to allow successful fusion after surgery. The fixation depends mainly on screw position accuracy and patient bone quality. Traditionally, spinal surgeons have decided the screw size, trajectory, and tapping size based on their intuition. Insertional torque has been indicated as useful to predict screw fixation strength, and is correlated with screw pullout strength and frequency of postoperative screw loosening. METHODS We compared insertion torque at L1-L3 levels of 324 screws in 68 patients with ASD and 58 screws in 32 patients with AIS. We assessed the association between screw/pedicle ratio and insertion torque by constructing a spline curve. RESULTS Pedicle and screw diameter correlated positively with insertion torque in patients with either ASD or AIS. The optimal screw/pedicle ratio to obtain rigid pedicle screw fixation in patients with ASD was close to, but less than one, and, by contrast, was about 1 to 1.25 in patients with AIS. CONCLUSION We propose the concept of an optimal S/P ratio for obtaining rigid pedicle screw fixation during spinal corrective surgery, which is different for patients with ASD and patients with AIS. The S/P ratio is useful for deciding the appropriate diameter screw for each case in preoperative planning.Level of Evidence: 4.
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Pinheiro RP, Zamarioli A, Chandanson T, George K, Shimano AC, Defino HLA. DIRECT PEDICLE SCREW INSERTION PULLOUT STRENGTH. ACTA ORTOPEDICA BRASILEIRA 2021; 29:203-206. [PMID: 34566479 PMCID: PMC8443012 DOI: 10.1590/1413-785220212904241648] [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: 07/30/2020] [Accepted: 09/24/2020] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Study the in vitro pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw), a screw pedicle designed to be inserted using a direct insertion technique. METHODS DSG Screws of 5.5 mm and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16 g/cm3). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. RESULTS Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared to line-to-line tapping. CONCLUSION DSG Screw showed the highest pullout strength after its insertion without pilot hole and tapping. Level of Evidence V, Expert Opinion.
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Affiliation(s)
- Rômulo Pedroza Pinheiro
- Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Ortopedia e Anestesiologia, Ribeirão Preto, SP, Brazil
| | - Ariane Zamarioli
- Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Ortopedia e Anestesiologia, Ribeirão Preto, SP, Brazil
| | | | | | - Antonio Carlos Shimano
- Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Ortopedia e Anestesiologia, Ribeirão Preto, SP, Brazil
| | - Helton Luiz Aparecido Defino
- Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Ortopedia e Anestesiologia, Ribeirão Preto, SP, Brazil
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Stewart AJ, Miles AW, Fletcher JWA. Influence of pilot hole diameter in cancellous screw fixation in a reduced density animal bone model. Clin Biomech (Bristol, Avon) 2020; 80:105152. [PMID: 32866854 DOI: 10.1016/j.clinbiomech.2020.105152] [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: 03/23/2020] [Revised: 08/07/2020] [Accepted: 08/13/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Screw fixation in osteoporotic bone is clinically challenging. Screw failure rates are growing due to an increasing prevalence of osteoporosis. To address this, biomechanical models are needed to recreate the bone clinically encountered alongside the development of new operative techniques. The first aim of this study was to test whether the use of a smaller than recommended pilot-hole diameter improved pull-out strength for cancellous screws, with the second aim to create a model of low-density porcine bone for biomechanical testing. METHODS Thirty porcine tibiae were cut into transverse metaphyseal sections of 20 mm thickness. Bone density was altered using 0.15 M Hydrochloric acid, and measured and pre- and post-demineralisation using HRμCT. Seventy-two screw areas were randomised to either 2.5 mm or 1.5 mm pilot holes and to either be normal or reduced density. Maximum axial pull-out strength was measured. FINDINGS Demineralisation reduced bone density by 12% (p < 0.0001) and 11% (p < 0.0001) for 2.5 mm and 1.5 mm pilot hole diameters respectively. Pull-out strength reduced by 50% (p = 0.0001) and 44% (p < 0.0001) following demineralisation for both 2.5 mm and 1.5 mm pilot hole diameters. Pull-out strength increased by 51% (p = 0.0008) when inserting screws into 1.5 mm pilot holes in low density bone, and by 28% (p = 0.027) in normal bone. INTERPRETATION Porcine bone can be demineralised to model low density cancellous bone. This novel model showed that pullout force is significantly reduced in lower density screw holes, but that this reduction can be mitigated by reducing pilot hole diameter for cancellous screws.
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Affiliation(s)
| | - Anthony W Miles
- Department of Mechanical Engineering, University of Bath, UK.
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Takenaka S, Kaito T, Ishii K, Watanabe K, Watanabe K, Shinohara A, Harada T, Nakada F, Majima Y, Matsumoto M. Influence of novel design alteration of pedicle screw on pull-out strength: A finite element study. J Orthop Sci 2020; 25:66-72. [PMID: 30902538 DOI: 10.1016/j.jos.2019.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/19/2019] [Accepted: 03/01/2019] [Indexed: 02/09/2023]
Abstract
BACKGROUND We conducted a finite element study to assess the effectiveness of a novel pedicle screw design with two alterations in the distal and proximal portions. METHODS Finite element (FE) models of 24 vertebrae were constructed using computed tomographic data. Pull-out strength of 4 different pedicle screws were compared. The basic screw design was a dual threaded one (PS0), in which the proximal portion is double-threaded (cortical thread), and the distal portion is single-threaded (cancellous thread). In PS1, the inter-thread double-core shape was added to PS0 in the distal portion. Compared to PS0, in PS2, the proximal portion was elongated by 5 mm. PS3 had both PS1 and PS2 features. In addition, the 24 vertebrae were classified into 3 groups based on volumetric bone mineral density (vBMD) of the vertebral body: low <120 mg/cm3, moderate 120-170 mg/cm3, and high >170 mg/cm3. RESULTS The mean pull-out strengths (±SD) were 1137 ± 500 N, 1188 ± 520 N, 1191 ± 512 N, and 1242 ± 538 N for PS0, PS1, PS2, and PS3, respectively. In PS1, there was significant difference in the incremental ratio of pull-out strength to PS0 between the low and high vBMD groups (3.7 ± 1.6% vs. 5.0 ± 1.0%, p = 0.006). In PS2, there was a significant difference in the incremental ratio to PS0 between the moderate and high vBMD groups (7.6 ± 4.0% vs. 3.3 ± 1.8%, p < 0.001). In PS3, there was a significant difference in the incremental ratio to PS0 between the moderate and high vBMD groups (12.1 ± 4.8% vs. 8.5 ± 2.1%, p = 0.003). CONCLUSIONS The two design alterations showed the combined additive effect in the PS3 design. The moderate vBMD group has a balanced bone property to reflect the combined effects of the PS1 and PS2 design alterations.
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Affiliation(s)
- Shota Takenaka
- Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takashi Kaito
- Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
| | - Ken Ishii
- Department of Orthopedic Surgery, School of Medicine, International University of Health and Welfare, Chiba, Japan
| | - Kota Watanabe
- Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Kei Watanabe
- Department of Orthopaedic Surgery, Niigata University Medical and Dental Hospital, Niigata, Japan
| | - Akira Shinohara
- Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan
| | - Tomohisa Harada
- Department of Spinal Surgery, Rakuwakai Marutamachi Hospital, Kyoto, Japan
| | | | | | - Morio Matsumoto
- Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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Easley J, Puttlitz CM, Seim H, Ramo N, Abjornson C, Cammisa FP, McGilvray KC. Biomechanical and histologic assessment of a novel screw retention technology in an ovine lumbar fusion model. Spine J 2018; 18:2302-2315. [PMID: 30075298 DOI: 10.1016/j.spinee.2018.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 07/24/2018] [Accepted: 07/24/2018] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Screw loosening is a prevalent failure mode in orthopedic hardware, particularly in osteoporotic bone or revision procedures where the screw-bone engagement is limited. PURPOSE The objective of this study was to evaluate the efficacy of a novel screw retention technology (SRT) in an ovine lumbar fusion model. STUDY DESIGN/SETTING This was a biomechanical, radiographic, and histologic study utilizing an ovine lumbar spine model. METHODS In total, 54 (n=54) sheep lumbar spines (L2-L3) underwent posterior lumbar fusion (PLF) via pedicle screw fixation, connecting rod, and bone graft. Following three experimental variants were investigated: positive control (ideal clinical scenario), negative control (simulation of compromised screw holes), and SRT treatments. Biomechanical and histologic analyses of the functional spinal unit (FSU) were determined as a function of healing time (0, 3, and 12 months postoperative). RESULTS Screw pull-out, screw break-out, and FSU stability of the SRT treatments were generally equivalent to the positive control group and considerably better than the negative control group. Histomorphology of the SRT treatment screw region of interest (ROI) observed an increase in bone percentage and decrease in void space during healing, consistent with ingrowth at the implant interface. The PLF ROI observed similar bone percentage throughout healing between the SRT treatment and positive control. Less bone formation was observed for the negative control. CONCLUSIONS The results of this study demonstrate that the SRT improved screw retention and afforded effective FSU stabilization to achieve solid fusion in an otherwise compromised fixation scenario in a large animal model.
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Affiliation(s)
- Jeremiah Easley
- Preclinical Surgical Research Laboratory, Colorado State University, Fort Collins, CO, USA
| | - Christian M Puttlitz
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523-1374, USA
| | - Howard Seim
- Preclinical Surgical Research Laboratory, Colorado State University, Fort Collins, CO, USA
| | - Nicole Ramo
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523-1374, USA
| | - Celeste Abjornson
- Integrated Spine Research Program, Hospital for Special Surgery, New York, NY, USA
| | - Frank P Cammisa
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA
| | - Kirk C McGilvray
- Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523-1374, USA.
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Matsukawa K, Yato Y. Lumbar pedicle screw fixation with cortical bone trajectory: A review from anatomical and biomechanical standpoints. Spine Surg Relat Res 2017; 1:164-173. [PMID: 31440629 PMCID: PMC6698564 DOI: 10.22603/ssrr.1.2017-0006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/06/2017] [Indexed: 12/14/2022] Open
Abstract
Over the past few decades, many attempts to enhance the integrity of the bone-screw interface have been made to prevent pedicle screw failure and to achieve a better clinical outcome when treating a variety of spinal disorders. Cortical bone trajectory (CBT) has been developed as an alternative to the traditional lumbar pedicle screw trajectory. Contrary to the traditional trajectory, which follows the anatomical axis of the pedicle from a lateral starting point, CBT starts at the lateral part of the pars interarticularis and follows a mediolateral and caudocranial screw path through the pedicle. By markedly altering the screw path, CBT has the advantage of achieving a higher level of thread contact with the cortical bone from the dorsal entry point to the vertebral body. Biomechanical studies demonstrated the superior anchoring ability of CBT over the traditional trajectory, even with a shorter and smaller CBT screw. Furthermore, screw insertion from a more medial and caudal starting point requires less exposure and minimizes the procedure-related morbidity, such as reducing damage to the paraspinal muscles, avoiding iatrogenic injury to the cranial facet joint, and maintaining neurovascular supply to the fused segment. Thus, the features of CBT, which enhance screw fixation with limited surgical exposure, have attracted the interest of surgeons as a new minimally invasive method for spinal fusion. The purpose of this study was: 1) to identify the features of the CBT technique by reviewing previous anatomical and biomechanical literature, and 2) to describe its clinical application with a focus on the indications, limitations, surgical technique, and clinical evidence.
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Affiliation(s)
- Keitaro Matsukawa
- Department of Orthopaedic Surgery, Self Defense Force Central Hospital, Tokyo, Japan
| | - Yoshiyuki Yato
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Tokyo, Japan
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Comparison of Pedicle Screw Fixation Strength Among Different Transpedicular Trajectories: A Finite Element Study. Clin Spine Surg 2017; 30:301-307. [PMID: 28746125 DOI: 10.1097/bsd.0000000000000258] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
STUDY DESIGN Comparative biomechanical study by finite element (FE) method. OBJECTIVE To investigate the pullout strength of pedicle screws using different insertional trajectories. SUMMARY OF BACKGROUND DATA Pedicle screw fixation has become the gold standard for spinal fusion, however, not much has been done to clarify how the fixation strength of pedicle screws are affected by insertional trajectories and bone properties. MATERIALS AND METHODS Three-dimensional FE models of 20 L4 vertebrae were constructed from the computed tomographic data. Five different transpedicular trajectories were compared: the traditional trajectory, the vertical trajectory, and the 3 lateral trajectories with different sagittal directions (caudal, parallel, cranial). For a valid comparison, screws of the same shape and size were inserted into the same pedicle in each subject, and the pullout strength were compared with nonlinear FE analyses. In addition, the pullout strength was correlated with bone mineral density (BMD). RESULTS The mean pullout strength showed a 3.9% increase for the vertical trajectory relative to the traditional trajectory, 6.1% for the lateral-caudal trajectory, 21.1% for the lateral-parallel trajectory, and 34.7% for the lateral-cranial trajectory. The lateral-cranial trajectory demonstrated the highest value among all trajectories (P<0.001). In each trajectory, the correlation coefficient between the pullout strength and BMD of the femoral neck (r=0.74-0.83, P<0.01) was higher than the mean BMD of all the lumbar vertebrae (r=0.49-0.75, P<0.01), BMD of the L4 vertebra (r=0.39-0.64, P<0.01), and regional BMD of the L4 pedicle (r=0.53-0.76, P<0.01). CONCLUSIONS Regional variation in the vertebral bone density and the amount of denser bone-screw interface contribute to the differences of stiffness among different screw trajectories. BMD of the femoral neck is considered to be a better objective predictor of pedicle screw stability than that of the lumbar vertebra.
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The effect of insertion technique and surgeon experience on the pullout strength of orthopaedic screws. CURRENT ORTHOPAEDIC PRACTICE 2016. [DOI: 10.1097/bco.0000000000000313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Moldavsky M, Salloum K, Bucklen B, Khalil S, Mehta JS. In vitro biomechanical study of pedicle screw pull-out strength based on different screw path preparation techniques. Indian J Orthop 2016; 50:177-82. [PMID: 27053808 PMCID: PMC4800961 DOI: 10.4103/0019-5413.177572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Poor screw-to-bone fixation is a clinical problem that can lead to screw loosening. Under-tapping (UT) the pedicle screw has been evaluated biomechanically in the past. The objective of the study was to determine if pedicle preparation with a sequential tapping technique will alter the screw-to-bone fixation strength using a stress relaxation testing loading protocol. MATERIALS AND METHODS Three thoracolumbar calf spines were instrumented with pedicle screws that were either probed, UT, standard-tapped (ST), or sequential tapped to prepare the pedicle screw track and a stress relaxation protocol was used to determine pull-out strength. The maximum torque required for pedicle screw insertion and pull-out strength was reported. A one-way ANOVA and Tukeys post-hoc test were used to determine statistical significance. RESULTS The pedicle screw insertion torques for the probed, UT, ST and sequentially tapped (SQT) techniques were 5.09 (±1.08) Nm, 5.39 (±1.61) Nm, 2.93 (±0.43) Nm, and 3.54 (±0.67) Nm, respectively. There is a significant difference between probed compared to ST (P ≤ 0.05), as well as UT compared to both ST and SQT (P ≤ 0.05). The pull-out strength for pedicle screws for the probed, UT, ST and SQT techniques was 2443 (±782) N, 2353(±918) N, 2474 (±521) N, and 2146 (±582) N, respectively, with no significant difference (P ≥ 0.05) between techniques. CONCLUSIONS The ST technique resulted in the highest pull-out strength while the SQT technique resulted in the lowest. However, there was no significant difference in the pull-out strength for the various preparation techniques and there was no correlation between insertion torque and pull-out strength. This suggests that other factors such as bone density may have a greater influence on pull-out strength.
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Affiliation(s)
- Mark Moldavsky
- Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical, Inc., Audubon, PA 19403, USA,Address for correspondence: Mr. Mark Moldavsky, Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical, Inc. 2560 General Armistead Ave., Audubon, PA 19403, USA. E-mail:
| | - Kanaan Salloum
- Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical, Inc., Audubon, PA 19403, USA
| | - Brandon Bucklen
- Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical, Inc., Audubon, PA 19403, USA
| | - Saif Khalil
- Musculoskeletal Education and Research Center (MERC), A Division of Globus Medical, Inc., Audubon, PA 19403, USA
| | - Jwalant S Mehta
- Royal Orthopedic Hospital, Birmingham Spinal Surgery, West Midlands, UK
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Matsukawa K, Yato Y, Imabayashi H, Hosogane N, Asazuma T, Nemoto K. Biomechanical evaluation of the fixation strength of lumbar pedicle screws using cortical bone trajectory: a finite element study. J Neurosurg Spine 2015; 23:471-8. [DOI: 10.3171/2015.1.spine141103] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
Cortical bone trajectory (CBT) maximizes thread contact with the cortical bone surface and provides increased fixation strength. Even though the superior stability of axial screw fixation has been demonstrated, little is known about the biomechanical stiffness against multidirectional loading or its characteristics within a unit construct. The purpose of the present study was to quantitatively evaluate the anchorage performance of CBT by the finite element (FE) method.
METHODS
Thirty FE models of L-4 vertebrae from human spines (mean age [± SD] 60.9 ± 18.7 years, 14 men and 16 women) were computationally created and pedicle screws were placed using the traditional trajectory (TT) and CBT. The TT screw was 6.5 mm in diameter and 40 mm in length, and the CBT screw was 5.5 mm in diameter and 35 mm in length. To make a valid comparison, the same shape of screw was inserted into the same pedicle in each subject. First, the fixation strength of a single pedicle screw was compared by axial pullout and multidirectional loading tests. Next, vertebral fixation strength within a construct was examined by simulating the motions of flexion, extension, lateral bending, and axial rotation.
RESULTS
CBT demonstrated a 26.4% greater mean pullout strength (POS; p = 0.003) than TT, and also showed a mean 27.8% stronger stiffness (p < 0.05) during cephalocaudal loading and 140.2% stronger stiffness (p < 0.001) during mediolateral loading. The CBT construct had superior resistance to flexion and extension loading and inferior resistance to lateral bending and axial rotation. The vertebral fixation strength of the construct was significantly correlated with bone mineral density of the femoral neck and the POS of a single screw.
CONCLUSIONS
CBT demonstrated superior fixation strength for each individual screw and sufficient stiffness in flexion and extension within a construct. The TT construct was superior to the CBT construct during lateral bending and axial rotation.
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Affiliation(s)
- Keitaro Matsukawa
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Yoshiyuki Yato
- 2Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Hideaki Imabayashi
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Naobumi Hosogane
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Takashi Asazuma
- 2Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Koichi Nemoto
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
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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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Chatzistergos PE, Magnissalis EA, Kourkoulis SK. Numerical simulation of bone screw induced pretension: The cases of under-tapping and conical profile. Med Eng Phys 2014; 36:378-86. [DOI: 10.1016/j.medengphy.2013.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 11/25/2013] [Accepted: 12/08/2013] [Indexed: 10/25/2022]
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Uruc V, Ozden R, Dogramacı Y, Kalacı A, Hallaceli H, Küçükdurmaz F. A new anchor augmentation technique with a cancellous screw in osteoporotic rotator cuff repair: an in vitro biomechanical study on sheep humerus specimens. Arthroscopy 2014; 30:16-21. [PMID: 24183107 DOI: 10.1016/j.arthro.2013.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 08/29/2013] [Accepted: 09/03/2013] [Indexed: 02/02/2023]
Abstract
PURPOSE The aim of this study was to test a simple technique to augment the pullout resistance of an anchor in an over-drilled sheep humerus model. METHODS Sixty-four paired sheep humeri were harvested from 32 male sheep aged 18 months. Specimens were divided into an augmented group and non-augmented group. FASTIN RC 5-mm titanium screw anchors (DePuy Mitek, Raynham, MA) double loaded with suture material (braided polyester, nonabsorbable USP No. 2) were used in both groups. Osteoporosis was simulated by over-drilling with a 4.5-mm drill. Augmentation was performed by fixing 1 of the sutures 1.5 cm inferior to the anchor insertion site with a washer screw. This was followed by a pull-to-failure test at 50 mm/min. The ultimate load (the highest value of strength before anchor pullout) was recorded. A paired t test was used to compare the biomechanical properties of the augmented and non-augmented groups. RESULTS In all specimens the failure mode was pullout of the anchor. The ultimate failure loads were statistically significantly higher in the augmented group (P < .0001). The mean pullout strength was 121.1 ± 10.17 N in the non-augmented group and 176.1 ± 10.34 N in the augmented group. CONCLUSIONS The described augmentation technique, which is achieved by inferior-lateral fixation of 1 of the sutures of the double-loaded anchor to a fully threaded 6.5-mm cancellous screw with a washer, significantly increases the ultimate failure loads in the over-drilled sheep humerus model. CLINICAL RELEVANCE Our technique is simple, safe, and inexpensive. It can be easily used in all osteoporotic patients and will contribute to the reduction of anchor failure. This technique might be difficult to apply arthroscopically. Cannulated smaller screws would probably be more practical for arthroscopic use. Further clinical studies are needed.
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Affiliation(s)
- Vedat Uruc
- Department of Orthopedics and Traumatology, Medicine Faculty of Mustafa Kemal University, Antakya, Turkey.
| | - Raif Ozden
- Department of Orthopedics and Traumatology, Medicine Faculty of Mustafa Kemal University, Antakya, Turkey
| | - Yunus Dogramacı
- Department of Orthopedics and Traumatology, Medicine Faculty of Mustafa Kemal University, Antakya, Turkey
| | - Aydıner Kalacı
- Department of Orthopedics and Traumatology, Medicine Faculty of Mustafa Kemal University, Antakya, Turkey
| | - Hasan Hallaceli
- Department of Orthopedics and Traumatology, Medicine Faculty of Mustafa Kemal University, Antakya, Turkey
| | - Fatih Küçükdurmaz
- Department of Orthopedics and Traumatology, Faculty of Medicine, Bezmialem Vakıf University, Istanbul, Turkey
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