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Spinal biomechanics

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https://www.readbyqxmd.com/read/28323704/minimizing-pedicle-screw-pullout-risks-a-detailed-biomechanical-analysis-of-screw-design-and-placement
#1
Rohan-Jean Bianco, Pierre-Jean Arnoux, Eric Wagnac, Jean-Marc Mac-Thiong, Carl-Éric Aubin
STUDY DESIGN: Detailed biomechanical analysis of the anchorage performance provided by different pedicle screw designs and placement strategies under pullout loading. OBJECTIVE: To biomechanically characterize the specific effects of surgeon-specific pedicle screw design parameters on anchorage performance using a finite element model. SUMMARY OF BACKGROUND DATA: Pedicle screw fixation is commonly used in the treatment of spinal pathologies...
April 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28315016/biomechanics-of-the-osteoporotic-spine-pain-and-principles-of-training
#2
Guido Schröder, Andreas Knauerhase, Holger S Willenberg, Guenther Kundt, Detlef Wendig, Hans-Christof Schober
INTRODUCTION: A fracture is a clinical manifestation of osteoporosis and is one of the main causes of functional limitations and chronic pain in patients with osteoporosis. Muscle and coordination training are recommended to the patients as general measures. We inquired whether sling training is better than traditional physiotherapy in relieving pain and improving abilities of daily living. METHODS: Fifty patients with osteoporosis were divided into two groups. Group A performed conventional physiotherapy, while Group B performed sling training exercises...
March 17, 2017: Archives of Orthopaedic and Trauma Surgery
https://www.readbyqxmd.com/read/28296813/comparison-of-outcomes-between-c1-c2-screw-hook-fixation-and-c1-c2-screw-rod-fixation-for-treating-reducible-atlantoaxial-dislocation
#3
Bin Ni, Wenlong Zhao, Qunfeng Guo, Mei Zhang, Jinshui Chen, Xiang Guo, Xuhua Lu, Ning Xie
STUDY DESIGN: Retrospective comparative study OBJECTIVE.: To compare the outcomes of C1-C2 transarticular screw with C1 laminar hook (TAS+ C1H) fixation and C1 trans-arch lateral mass screw with C2 pedicle screw (C1TLMS+ C2PS) fixation in the treatment of reducible atlantoaxial dislocation(AAD). SUMMARY OF BACKGROUND DATA: TAS+ C1H is comparable to TAS with posterior wiring techniques and superior to C1 lateral mass screw combined with C2 pedicle screw (C1LMS+ C2PS) in biomechanics...
March 14, 2017: Spine
https://www.readbyqxmd.com/read/28284666/anthropometric-and-biomechanical-characteristics-of-body-segments-in-persons-with-spinal-cord-injury
#4
Y Fang, L R Morse, N Nguyen, N G Tsantes, K L Troy
People with spinal cord injury (SCI) experience bone and muscle loss in their paralyzed limbs that is most rapid and severe in the first 3years after injury. Restoration of mechanical loading through therapeutic physical activity may potentially slow or reverse post-SCI bone loss, however, therapeutic targets cannot be developed without accurate biomechanical models. Obesity is prevalent among SCI population, and it alters body composition and further affects parameters of these models. Here, clinical whole body dual-energy X-ray absorptiometry data from people with acute (n=39) and chronic (n=61) SCI were analyzed to obtain anthropometric parameters including segment masses, center of mass location, and radius of gyration for both obese and non-obese individuals...
February 3, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28279204/a-study-to-compare-the-efficacy-of-polyether-ether-ketone-rod-device-with-titanium-devices-in-posterior-spinal-fusion-in-a-canine-model
#5
Nanxiang Wang, Huanxin Xie, Chunyang Xi, Han Zhang, Jinglong Yan
BACKGROUND: The benefits of posterior lumbar fusion surgery with orthotopic paraspinal muscle-pediculated bone flaps are well established. However, the problem of non-union due to mechanical support is not completely resolved. The aim of the study was to compare the efficacy of polyether ether ketone (PEEK) rod device with conventional titanium devices in the posterior lumbar fusion surgery with orthotopic paraspinal muscle-pediculated bone flaps. METHODS: This was a randomized controlled study with an experimental animal model...
March 9, 2017: Journal of Orthopaedic Surgery and Research
https://www.readbyqxmd.com/read/28262607/biomechanics-of-the-human-intervertebral-disc-a-review-of-testing-techniques-and-results
#6
REVIEW
N Newell, J P Little, A Christou, M A Adams, C J Adam, S D Masouros
Many experimental testing techniques have been adopted in order to provide an understanding of the biomechanics of the human intervertebral disc (IVD). The aim of this review article is to amalgamate results from these studies to provide readers with an overview of the studies conducted and their contribution to our current understanding of the biomechanics and function of the IVD. The overview is presented in a way that should prove useful to experimentalists and computational modellers. Mechanical properties of whole IVDs can be assessed conveniently by testing 'motion segments' comprising two vertebrae and the intervening IVD and ligaments...
January 31, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28259461/spinal-biomechanical-properties-are-significantly-altered-with-a-novel-embalming-method
#7
Roderick M Holewijn, Sayf S A Faraj, Idsart Kingma, Barend J van Royen, Marinus de Kleuver, Albert J van der Veen
In vitro tests on the biomechanical properties of human spines are often performed using fresh frozen specimens. However, this carries the risk of pathogen transfer from specimen to the worker and the specimens can only be used for a limited amount of time. Human spinal specimens embalmed with formaldehyde carry an almost absent risk of transfer of pathogens and can be stored and used for a long time, but the tissue properties are strongly affected making this method inapplicable for biomechanical testing. In this study, a new embalming technique called Fix for Life (F4L), which claims to preserve the tissue properties, was tested...
February 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28259005/removal-of-fixation-construct-could-mitigate-adjacent-segment-stress-after-lumbosacral-fusion-a-finite-element-analysis
#8
Yueh-Ying Hsieh, Chia-Hsien Chen, Fon-Yih Tsuang, Lien-Chen Wu, Shang-Chih Lin, Chang-Jung Chiang
BACKGROUND DATA: Combined usage of posterior lumbar interbody fusion and transpedicular fixation has been extensively used to treat the various lumbar degenerative disc diseases. The transpedicular fixator aims to increase stability and enhance the fusion rate. However, how the fused disc and bridged vertebrae respectively affect adjacent-segment diseases progression is not yet clear. METHODS: Using a validated lumbosacral finite-element model, three variations at the L4-L5 segment were analyzed: 1) moderate disc degeneration, 2) instrumented with a stand-alone cage and pedicle screw fixators, and 3) with the cage only after fusion...
February 23, 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/28250641/traumatic-high-grade-spondylolisthesis-at-c7-t1-with-no-neurological-deficits-case-series-literature-review-and-biomechanical-implications
#9
Ha Son Nguyen, Hesham Soliman, Shekar Kurpad
Traumatic high-grade spondylolisthesis in subaxial cervical spine is frequently associated with acute spinal cord injury and quadriparesis. There have been rare cases where such pathology demonstrates minimal to no neurological deficits. Assessment of the underlying biomechanics may provide insight into the mechanism of injury and associated neurological preservation. Patient 1 is a 63-year-old female presenting after a motor vehicle collision with significant right arm pain without neurological deficits. Imaging demonstrated C7/T1 spondyloptosis, associated with a locked facet on the left at C6/7 and a locked facet on the right at C7/T1, with a fracture of the left C7 pedicle and right C7 lamina...
January 2017: Journal of Craniovertebral Junction and Spine
https://www.readbyqxmd.com/read/28244135/spinal-loading-patterns-from-biomechanical-modeling-explain-the-high-incidence-of-vertebral-fractures-in-the-thoracolumbar-region
#10
Alexander G Bruno, Katelyn Burkhart, Brett Allaire, Dennis E Anderson, Mary L Bouxsein
Vertebral fractures occur most frequently in the mid-thoracic and thoracolumbar regions of the spine, yet the reasons for this site-specific occurrence are not known. Our working hypothesis is that the locations of vertebral fracture may be explained by the pattern of spine loading, such that during daily activities the mid-thoracic and thoracolumbar regions experience preferentially higher mechanical loading compared to other spine regions. To test this hypothesis, we used a female musculoskeletal model of the full thoracolumbar spine and rib cage to estimate the variation in vertebral compressive loads and associated factor-of-risk (load-to-strength ratio) throughout the spine for 119 activities of daily living, while also parametrically varying spine curvature (high, average, low, and zero thoracic kyphosis models)...
February 27, 2017: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/28224297/fracture-reduction-by-postoperative-mobilisation-for-the-treatment-of-hyperextension-injuries-of-the-thoracolumbar-spine-in-patients-with-ankylosing-spinal-disorders
#11
Richard A Lindtner, Christian Kammerlander, Michael Goetzen, Alexander Keiler, Davud Malekzadeh, Dietmar Krappinger, Rene Schmid
INTRODUCTION: The aim of this study was to evaluate results of surgical stabilisation of hyperextension injuries of the thoracolumbar spine in patients with ankylosing spinal disorders using two different treatment strategies: the conventional open rigid posterior instrumentation and percutaneous less rigid posterior instrumentation. Surgical and non-surgical complications, the postoperative radiological course, and clinical outcome at final follow-up were comparatively assessed. Moreover, we sought to discuss important biomechanical and surgical aspects specific to posterior instrumentation of the ankylosed thoracolumbar spine as well as to elaborate on the advantages and limitations of the proposed new treatment strategy involving percutaneous less rigid stabilisation and fracture reduction by postoperative mobilisation...
February 21, 2017: Archives of Orthopaedic and Trauma Surgery
https://www.readbyqxmd.com/read/28222402/impact-of-anchor-type-on-porcine-lumbar-biomechanics-finite-element-modelling-and-in-vitro-validation
#12
Martin Brummund, Vladimir Brailovski, Yvan Petit, Yann Facchinello, Jean-Marc Mac-Thiong
BACKGROUND: Rigid posterior implants used for spinal stabilization can be anchored to the vertebrae using pedicle screws or screws combined with transverse process hooks. In the present study, a finite element model of a porcine lumbar spine instrumented with screws and hooks is presented and validated. METHODS: The porcine lumbar spine model was validated using in-vitro measurements on six porcine specimens. Validation metrics included intervertebral rotations (L1 to L6) and nucleus pressure in the topmost cranial instrumented disc...
February 14, 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/28215399/restoring-standing-capabilities-with-feedback-control-of-functional-neuromuscular-stimulation-following-spinal-cord-injury
#13
REVIEW
Raviraj Nataraj, Musa L Audu, Ronald J Triolo
This paper reviews the field of feedback control for neuroprosthesis systems that restore advanced standing function to individuals with spinal cord injury. Investigations into closed-loop control of standing by functional neuromuscular stimulation (FNS) have spanned three decades. The ultimate goal for FNS standing control systems is to facilitate hands free standing and enabling the user to perform manual functions at self-selected leaning positions. However, most clinical systems for home usage currently only provide basic upright standing using preprogrammed stimulation patterns...
February 15, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28207656/biomechanical-evaluation-of-transpedicular-nucleotomy-with-intact-annulus-fibrosus
#14
Fabrizio Russo, Robert A Hartman, Kevin M Bell, Nam Vo, Gwendolyn A Sowa, James D Kang, Gianluca Vadalà, Vincenzo Denaro
STUDY DESIGN: Biomechanical testing of partially nucleotomized ovine cadaveric spines. OBJECTIVE: To explore how the nucleus pulposus (NP) affects the biomechanical behavior of the intervertebral disc (IVD) by performing a partial nucleotomy via the transpedicular approach. SUMMARY OF BACKGROUND DATA: Mechanical loading represents a crucial part of IVD homeostasis. However, traditional regenerative strategies require violation of the annulus fibrosus (AF) resulting in significant alteration of joint mechanics...
February 15, 2017: Spine
https://www.readbyqxmd.com/read/28195302/testing-biomechanical-models-of-human-lumbar-lordosis-variability
#15
Eric R Castillo, Connie Hsu, Ross W Mair, Daniel E Lieberman
OBJECTIVES: Lumbar lordosis (LL) is a key adaptation for bipedalism, but factors underlying curvature variations remain unclear. This study tests three biomechanical models to explain LL variability. MATERIALS AND METHODS: Thirty adults (15 male, 15 female) were scanned using magnetic resonance imaging (MRI), a standing posture analysis was conducted, and lumbar range of motion (ROM) was assessed. Three measures of LL were compared. The trunk's center of mass was estimated from external markers to calculate hip moments (Mhip ) and lumbar flexion moments...
February 13, 2017: American Journal of Physical Anthropology
https://www.readbyqxmd.com/read/28190488/effect-of-a-titanium-cage-as-a-stand-alone-device-on-biomechanical-stability-in-the-lumbosacral-spine-of-canine-cadavers
#16
M Teunissen, A J van der Veen, T H Smit, M A Tryfonidou, B P Meij
Degenerative lumbosacral stenosis is a common disease in dogs characterised by intervertebral disc herniation, loss of disc height and stenosis. Decompressive dorsal laminectomy and partial discectomy can cause spinal instability and worsen foraminal stenosis. Pedicle screw and rod fixation (PSRF) with an intervertebral body cage allows for distraction and restoration of disc height and restores foraminal apertures. The aim of this study was to evaluate the ex vivo biomechanical properties of a titanium intervertebral cage alone and in combination with PSRF in the lumbosacral spine of dogs...
February 2017: Veterinary Journal
https://www.readbyqxmd.com/read/28185981/analysis-of-the-s2-alar-iliac-screw-as-compared-with-the-traditional-iliac-screw-does-it-increase-stability-with-sacroiliac-fixation-of-the-spine
#17
Daniel G Hoernschemeyer, Troy D Pashuck, Ferris M Pfeiffer
BACKGROUND CONTEXT: Arthrodesis of the lumbosacral junction continues to be a challenge in pediatric and adult spinal deformity surgery. PURPOSE: To evaluate the biomechanical rigidity of two types of lumbosacral fixation. Our hypothesis was that the use of S2 alar-iliac (S2AI) fixation will result in statistically similar biomechanical fixation as compared with use of an iliac screw with a 95% confidence interval. STUDY SETTING: Controlled biomechanical laboratory METHODS: Ten human cadaveric lumbosacral specimens were separated into two test groups: (1) S2AI (n=5) and (2) iliac screw (n=5)...
February 6, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28167249/how-are-adjacent-spinal-levels-affected-by-vertebral-fracture-and-by-vertebroplasty-a-biomechanical-study-on-cadaveric-spines
#18
Jin Luo, Deborah J Annesley-Williams, Michael A Adams, Patricia Dolan
BACKGROUND CONTEXT: Spinal injuries and surgery may have important effects at neighbouring spinal levels, but previous investigations of adjacent-level biomechanics have produced conflicting results. We use 'stress profilometry' and non-contact strain measurements to investigate thoroughly this long-standing problem. PURPOSE: To determine how vertebral fracture and vertebroplasty affect compressive load-sharing and vertebral deformations at adjacent spinal levels...
February 3, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28158961/people-with-chronic-neck-pain-walk-with-a-stiffer-spine
#19
Deborah Falla, Leonardo Gizzi, Hesam Parsa, Angela Dieterich, Frank Petzke
Study Design Case-control. Background People with chronic neck pain present a number of sensorimotor and biomechanical alterations, yet little is known about the influence of neck pain on gait and motions of the spine during gait. Objective To evaluate the spine kinematics and gait characteristics in people with non-specific chronic neck pain. Methods People with chronic non-specific neck pain and age and gender matched asymptomatic controls walked on a treadmill at three different speeds (self-selected, 3km/h, 5km/h) either with their head in a neutral position or rotated 30º...
February 3, 2017: Journal of Orthopaedic and Sports Physical Therapy
https://www.readbyqxmd.com/read/28156207/is-lumbar-facet-fusion-biomechanically-equivalent-to-lumbar-posterolateral-onlay-fusion
#20
Jeffrey M Toth, Kevin T Foley, Mei Wang, Howard B Seim, A Simon Turner
OBJECTIVE This study was designed with the following research objectives: 1) to determine the efficacy of facet fusion with recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) in an ovine lumbar facet fusion model; 2) to radiographically and histologically compare the efficacy of lumbar facet fusion with rhBMP-2/ACS to facet fusion with an iliac crest bone graft (ICBG); and 3) to biomechanically compare lumbar facet fusion with rhBMP-2/ACS to lumbar posterolateral fusion (PLF) with ICBG...
February 3, 2017: Journal of Neurosurgery. Spine
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