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Pedicle screw torque

Andrea Lorenz, Carmen I Leichtle, Sandra Frantz, Marte Bumann, Ilias Tsiflikas, Thomas Shiozawa, Ulf G Leichtle
OBJECTIVE: To analyze the potential of the dual outer diameter screw and systematically evaluate the pull-out force of the dual outer diameter screw compared to the uncemented and cemented standard pedicle screws with special regard to the pedicle diameter and the vertebra level. METHODS: Sixty vertebrae of five human spines (T 6 -L 5 ) were sorted into three study groups for pairwise comparison of the uncemented dual outer diameter screw, the uncemented standard screw, and the cemented standard screw, and randomized with respect to bone mineral density (BMD) and vertebra level...
May 2017: Orthopaedic Surgery
Keitaro Matsukawa, Yoshiyuki Yato, Richard A Hynes, Hideaki Imabayashi, Naobumi Hosogane, Takashi Asazuma, Toshiyasu Matsui, Yasushi Kobayashi, Koichi Nemoto
STUDY DESIGN: A morphometric measurement of new thoracic pedicle screw trajectory using computed tomography 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 2017: Clinical Spine Surgery
Zhuo Wang, Toshihiko Sakakibara, Takamasa Yoshikawa, Tadashi Inaba, Yuichi Kasai
STUDY DESIGN: Biomechanical study of double-level pedicle screw constructs with or without crosslinks (CL) in an unstable model. OBJECTIVES: The purpose of this study is to investigate the optimal position and orientation of the CL. SUMMARY OF BACKGROUND DATA: Several reports have described biomechanical research on such CL, but no definite consensus has been reached regarding the effects. Very few studies have examined the position and orientation of the CL...
May 2017: Clinical Spine Surgery
Po-Yi Liu, Po-Liang Lai, Chun-Li Lin
BACKGROUND CONTEXT: The posterior pedicle screw-rod system, which is widely used to correct spinal deformities, achieves a good correction rate in the frontal and coronal planes but not in the axial plane. Direct vertebral derotation (DVD) was developed to correct axial plane deformities. However, the design of screw head and body connection, in terms of monoaxial, polyaxial, and uniplanar screw, may influence the efficiency of DVD. PURPOSE: This study compared the efficiency of a newly designed uniplanar screw with that of monoaxial and polyaxial screws in the DVD maneuver...
April 13, 2017: Spine Journal: Official Journal of the North American Spine Society
Hope B Pearson, Christopher J Dobbs, Eric Grantham, Glen L Niebur, James L Chappuis, Joel D Boerckel
Pedicle screw loosening has been implicated in recurrent back pain after lumbar spinal fusion, but the degree of loosening has not been systematically quantified in patients. Instrumentation removal is an option for patients with successful arthrodesis, but remains controversial. Here, we quantified pedicle screw loosening by measuring screw insertion and/or removal torque at high statistical power (β = 0.98) in N = 108 patients who experienced pain recurrence despite successful fusion after posterior instrumented lumbar fusion with anterior lumbar interbody fusion (L2-S1)...
April 7, 2017: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Vicky Varghese, Gurunathan Saravana Kumar, Venkatesh Krishnan
Pedicle screws are widely used for the treatment of spinal instability by spine fusion. Screw loosening is a major problem of spine fusion, contributing to delayed patient recovery. The present study aimed to understand the factor and interaction effects of density, insertion depth and insertion angle on pedicle screw pull out strength and insertion torque. A pull out study was carried out on rigid polyurethane foam blocks representing osteoporotic to normal bone densities according to the ASTM-1839 standard...
December 8, 2016: Medical Engineering & Physics
Sean L Borkowski, Sophia N Sangiorgio, Richard E Bowen, Anthony A Scaduto, Bo He, Kathryn L Bauer, Edward Ebramzadeh
BACKGROUND: Direct vertebral rotation (DVR) has gained increasing popularity for deformity correction surgery. Despite large moments applied intraoperatively during deformity correction and failure reports including screw plow, aortic abutment, and pedicle fracture, to our knowledge, the strength of thoracic spines has been unknown. Moreover, the rotational response of thoracic spines under such large torques has been unknown. PURPOSE: Simulate DVR surgical conditions to measure torsion to failure on thoracic spines and assess surgical forces...
March 2016: Spine Deformity
Camden B Burns, Karan Dua, Nicholas A Trasolini, David E Komatsu, James M Barsi
STUDY DESIGN: Biomechanical cadaveric study. OBJECTIVE: To compare the biomechanical properties of the iliac and S2-Alar-Iliac (S2AI) screw in a similar spinopelvic fixation construct. SUMMARY OF BACKGROUND DATA: Spinopelvic fixation is used in the correction of pelvic obliquity, high-grade spondylolisthesis, and long spinal fusions. With the development of pedicle screw fixation, the iliac screw has been used as an anchor point to the pelvis...
January 2016: Spine Deformity
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...
December 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...
July 2017: 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...
November 15, 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
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