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Pedicle screw torque

C I Leichtle, A Lorenz, S Rothstock, J Happel, F Walter, T Shiozawa, U G Leichtle
OBJECTIVES: Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL)...
September 2016: Bone & Joint Research
Marco T Reis, Phillip M Reyes, Bse, Idris Altun, Anna G U S Newcomb, Vaneet Singh, Steve W Chang, Brian P Kelly, Neil R Crawford
OBJECTIVE Lateral lumbar interbody fusion (LLIF) has emerged as a popular method for lumbar fusion. In this study the authors aimed to quantify the biomechanical stability of an interbody implant inserted using the LLIF approach with and without various supplemental fixation methods, including an interspinous plate (IP). METHODS Seven human cadaveric L2-5 specimens were tested intact and in 6 instrumented conditions. The interbody implant was intended to be used with supplemental fixation. In this study, however, the interbody was also tested without supplemental fixation for a relative comparison of these conditions...
July 8, 2016: Journal of Neurosurgery. Spine
Sung Joon Shin, Ji-Ho Lee, Jae Hyup Lee
STUDY DESIGN: A prospective, within-patient, left-right comparative study. OBJECTIVE: To evaluate the efficacy of hydroxyapatite (HA) stick augmentation method by comparing the insertional torque of the pedicle screw in osteoporotic and nonosteoporotic patients. SUMMARY OF BACKGROUND DATA: Unsatisfactory clinical outcomes after spine surgery in osteoporotic patients are related to pedicle screw loosening or pull-outs. HA, as a bone graft extender, has a possibility to enhance the fixation strength at the bone-screw interface...
June 27, 2016: Clinical Spine Surgery
Keitaro Matsukawa, Yoshiyuki Yato, Richard A Hynes, Hideaki Imabayashi, Naobumi Hosogane, Takashi Asazuma, Matsui Toshiyasu, Yasushi Kobayashi, Koichi Nemoto
STUDY DESIGN: A morphometric measurement of new thoracic pedicle screw trajectory using computed tomography (CT) and a biomechanical study on cadaveric thoracic vertebrae using insertional torque. OBJECTIVE: To introduce a new thoracic pedicle screw trajectory which maximizes engagement with denser bone. SUMMARY OF BACKGROUND DATA: Cortical bone trajectory (CBT) which maximizes the thread contact with cortical bone provides enhanced screw purchase...
June 20, 2016: Clinical Spine Surgery
Haibo Liu, Baocheng Zhang, Jianyin Lei, Xianhua Cai, Zhiqiang Li, Zhihua Wang
STUDY DESIGN: Finite element analysis. OBJECTIVE: To determine and compare the construct stability of occipitoatlantoaxial (C0-C1-C2) fixation provided by occipital plate, rod and screw fixation with or without C1 Lateral Mass Screw (C1LMS). SUMMARY OF BACKGROUND DATA: Occipitoatlantoaxial fixation techniques use C2 pedicle screw (C2PS) with and without C1LMS that are then incorporated into occipital plate fixation points using occipital screw...
April 23, 2016: Spine
Do-Yeon Kim, Jung-Ryul Kim, Kyu Yun Jang, Min Gu Kim, Kwang-Bok Lee
OBJECTIVE: Many studies have addressed the problem of loosening pedicle screws in spinal surgery, which is a serious concern. Titanium coating of medical implants (arthroplasty) is common, but few studies involving in vivo spine models have been reported. We evaluated the radiological, mechanical, and histological characteristics of titanium-coated pedicle screws compared with uncoated or hydroxyapatite-coated pedicle screws. METHODS: Three different types of pedicle screws, i...
July 2016: World Neurosurgery
Mark Moldavsky, Kanaan Salloum, Brandon Bucklen, Saif Khalil, Jwalant S Mehta
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...
March 2016: Indian Journal of Orthopaedics
Koshi Ninomiya, Koichi Iwatsuki, Yu-Ichiro Ohnishi, Toshika Ohkawa, Toshiki Yoshimine
STUDY DESIGN: Retrospective study. PURPOSE: To evaluate the initial fixation using the cortical bone trajectory (CBT) technique for posterior lumbar fusion through assessment of the clear zones around the screws and the risk factors involved. OVERVIEW OF LITERATURE: Postoperative radiolucent zones (clear zones) are an indicator of poor conventional pedicle screw fixation. METHODS: Between January 2013 and April 2014, 19 patients (8 men and 11 women) underwent posterior lumbar interbody fusion or posterior lumbar fusion using the CBT technique...
December 2015: Asian Spine Journal
BaoCheng Zhang, HaiBo Liu, XianHua Cai, ZhiHua Wang, Feng Xu, XiMing Liu, HuaSong Wang, Hui Kang, Ran Ding
STUDY DESIGN: A finite element analysis. OBJECTIVE: The aim of this study was to determine the biomechanical differences between atlantoaxial fusion cage combined with transoral atlantoaxial reduction plate fixation (TARP + Cage, modified TARP technique) and that combined with C1 lateral mass screw and C2 pedicle screw fixation (C1LS + C2PS + Cage, modified Goel technique) in the treatment of basilar invagination (BI) by finite element analysis. SUMMARY OF BACKGROUND DATA: Clinical studies have shown that transoral anterior atlantoaxial release followed by TARP fixation can achieve reduction, decompression, fixation, and fusion of C1-C2 through a transoral-only approach...
April 2016: Spine
Yan Zhuang, Xiaojian Cao
OBJECTIVE: To compare the fixation strength of optimum placed pedicle screw (OS) with redirectionally correctly placed pedicle screw (RS) following a violation of lateral pedicle. METHODS: Thirty fresh lumbar vertebrae (L1-5) were obtained from 6 pigs weighing 95-105 kg, male or female. Each vertebra was instrumented with a monoaxial pedicle screw into each pedicle using two different techniques. On one side, a perfect screw path was created using direct visualization and fluoroscopy...
February 2015: Chinese Journal of Reparative and Reconstructive Surgery
Hiroki Oshino, Toshihiko Sakakibara, Tadashi Inaba, Takamasa Yoshikawa, Takaya Kato, Yuichi Kasai
PURPOSE: There have been several reports on the pullout strength of cortical bone trajectory (CBT) screws, but only one study has reviewed the stability of functional spine units using the CBT method. The purpose of this study was to compare vertebral stability after CBT fixation with that after pedicle screw (PS) fixation. METHODS: In this study, 20 lumbar spine (L5-6) specimens were assigned to two groups: the CBT model group that underwent CBT screw fixation (n = 10) and the PS model group that underwent pedicle screw fixation (n = 10)...
2015: Journal of Orthopaedic Surgery and Research
Keitaro Matsukawa, Eiko Taguchi, Yoshiyuki Yato, Hideaki Imabayashi, Naobumi Hosogane, Takashi Asazuma, Koichi Nemoto
STUDY DESIGN: In vivo analysis of insertional torque of pedicle screws using cortical bone trajectory (CBT) technique. OBJECTIVE: To investigate factors contributing to the fixation strength of CBT screws and to clarify the ideal cortical trajectory for lumbar fusion. SUMMARY OF BACKGROUND DATA: CBT has developed as a new minimally invasive technique of lumbar instrumentation. Despite biomechanical studies demonstrating the superior characteristics of CBT, no study has elucidated the most suitable path for optimal fixation or compared the fixation within variations of trajectory...
August 1, 2015: Spine
K Wiendieck, H Müller, M Buchfelder, B Sommer
AIM: We investigated mechanical pull-out behavior and tightening torque of a novel dual core pedicle "6T screw" (6T). The aim of this study was to test if these changes in screw geometry are increasing the strength of the pedicle screw fixation after repeated insertion. METHODS: Three different types of pedicle screws were inserted in rigid foam blocks. Tightening torque and pull-out strength were measured during two repetitive insertions of a standard 6.5x45mm conical screw...
July 22, 2015: Journal of Neurosurgical Sciences
Hsin-Chang Chen, Yu-Shu Lai, Wen-Chuan Chen, Jou-Wen Chen, Chia-Ming Chang, Yi-Long Chen, Shih-Tien Wang, Cheng-Kung Cheng
Cannulated pedicle screws are designed for bone cement injection to enhance fixation strength in severely osteoporotic spines. However, the screws commonly fracture during insertion. This study aims to evaluate how different positions/designs of radial holes may affect the pullout and structural strength of cannulated pedicle screws using finite element analysis. Three different screw hole designs were evaluated under torsion and bending conditions. The pullout strength for each screw was determined by axial pullout failure testing...
August 2015: Medical Engineering & Physics
D-Y Kim, J-R Kim, K Y Jang, K-B Lee
Many attempts have been made to reduce complications of bone implant, such as pedicle screw loosening. To address this problem, the authors suggest a new concept of bone-to-bone biologic fixation using recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded cannulated pedicle screws. Recombinant human bone morphogenetic protein-2 is an osteoinductive cytokine. Four types of titanium pedicle screws were tested (uncannulated, cannulated with no loading, beta-tricalcium phosphate (TCP)-loaded, and TCP/BMP2 loaded) using 16 miniature pigs...
2015: European Cells & Materials
Yaoyao Liu, Jianzhong Xu, Dong Sun, Fei Luo, Zehua Zhang, Fei Dai
The objectives of this study were to investigate the safety and biomechanical stability of a polymethylmethacrylate (PMMA)-augmented bone cement-injectable cannulated pedicle screw (CICPS) in cancellous bone model, and to analyze the stress distribution at the screw-cement-bone interface. The OMEGA cannulated pedicle screw (OPS) and conventional pedicle screw (CPS) were used as control groups. Safety of the CICPS was evaluated by the static bending and bending fatigue tests. Biomechanical stability was analyzed by the maximum axial pullout strength and maximum torque tests...
July 2016: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Benjamin D Elder, Sheng-Fu L Lo, Christina Holmes, Courtney R Goodwin, Thomas A Kosztowski, Ioan A Lina, John E Locke, Timothy F Witham
BACKGROUND CONTEXT: A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a promising approach. PURPOSE: The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. STUDY DESIGN/SETTING: This is a systematic literature review...
June 1, 2015: Spine Journal: Official Journal of the North American Spine Society
Seong Yi, Dae-Cheol Rim, Seoung Woo Park, Judith A Murovic, Jesse Lim, Jon Park
OBJECTIVE: In vertebrae with low bone mineral densities pull out strength is often poor, thus various substances have been used to fill screw holes before screw placement for corrective spine surgery. We performed biomechanical cadaveric studies to compare nonaugmented pedicle screws versus hydroxyapatite, calcium phosphate, or polymethylmethacrylate augmented pedicle screws for screw tightening torques and pull out strengths in spine procedures requiring bone screw insertion. METHODS: Seven human cadaveric T10-L1 spines with 28 vertebral bodies were examined by x-ray to exclude bony abnormalities...
June 2015: World Neurosurgery
James J Doulgeris, Kamran Aghayev, Sabrina A Gonzalez-Blohm, William E Lee, Frank D Vrionis
BACKGROUND: This investigation compares an interspinous fusion device with posterior pedicle screw system in a lateral lumbar interbody lumbar fusion. METHODS: We biomechanically tested six cadaveric lumbar segments (L1-L2) under an axial preload of 50N and torque of 5Nm in flexion-extension, lateral bending and axial rotation directions. We quantified range of motion, neutral zone/elastic zone stiffness in the following conditions: intact, lateral discectomy, lateral cage, cage with interspinous fusion, and cage with pedicle screws...
February 2015: Clinical Biomechanics
H N Mehmanparast, J M Mac-Thiong, Y Petit
Posterior pedicle screw fixation is commonly used for patients with spinal disorders. However, failure of fixation is reported in many cases and surgeons have only little information. The objective of this study was to assess the correlation between the probe indentation force, screw insertion torque and the pullout force using bone surrogates of different densities. The indentation force and insertion torque were measured using a custom made test bench during screw insertion into polyurethane foam blocks. The two variables were significantly correlated to pullout force and to density...
2014: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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