The spine journal : official journal of the North American Spine Society
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Comparative Study
Biomechanical evaluation and comparison of polyetheretherketone rod system to traditional titanium rod fixation.
Polyetheretherketone (PEEK) has been increasingly used as a biomaterial for spinal implants. PEEK lumbar fusion rods have recently become available for use in posterior lumbar fusion procedures. ⋯ PEEK rods provide comparable stability to titanium rods of equivalent diameter in cadaveric testing. Mechanical testing suggests PEEK rods can withstand far beyond the angular displacements suggested by cadaveric testing and that of normal physiologic range of motion. Potential advantages to PEEK rods include better anterior column load sharing, reduced stress at bone-to-screw interface, and reduced computed tomography and magnetic resonance imaging scatter and artifact.
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Lumbar discectomy is the most common type of back surgery performed in the United States. Outcomes after this procedure can be variable and it appears that Workers' Compensation patients might be at increased risk for poor outcomes. ⋯ Results of this study suggest that compensated back surgery patients are at greater risk for poor lumbar discectomy outcomes than noncompensation patients. Presurgery correlates of poor outcomes may be useful in identifying high-risk compensation patients.
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C2 laminar screws are becoming an increasingly used method of fixation. They allow for avoidance of fixation through the C2 pedicle, eliminating the risk of vertebral artery injury. Recent studies have described the anatomic considerations of this technique in a large cadaveric population. In clinical practice, however, direct measurement is impractical and preoperative imaging must be relied upon to determine whether or not this technique can be safely used. ⋯ Given the high degree of correlation between CT measurements and direct anatomic measurements, we conclude that CT scan can accurately determine laminar thickness, a measurement critical to safe placement of intralaminar screws. It appears that longer screw lengths that were previously reported may be safely used while remaining intra-osseous. We continue to advocate preoperative planning using CT to identify patients whose lamina may be unable to accommodate safe screw placement using this technique.
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Thoracic spinal cord injury (SCI) without fractures or discoligamentary injuries in adults is extremely uncommon. This is because of the inherent stability of the thoracic spine provided by the structure of the ribcage, and the increasing stiffness of the overall spine with rising age. Till date, the pathogenesis of this disorder in adults is still unclear. ⋯ Multiple rib fractures including the 4th rib resulted in violent avulsion of nerve root T4, possibly causing focal myelum contusion. This is an unusual mechanism of neurologic injury in adults, which has not been described before.
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There is conflicting evidence regarding erector spinae muscle fatigability because previous studies have not considered the thoracic and lumbar components separately. These muscles have very different mechanical responses and, therefore, would be recruited differentially for the chosen task. ⋯ The results of this study suggested that subjects with LBP demonstrated higher fatigability of the erector spinae muscles at the thoracic part than at the lumbar part. The increased fatigability of the thoracic part needs to be emphasized in rehabilitation strategies for subjects with LBP. In addition, as age increased, the median frequency of the lumbar part of the erector spinae muscles significantly decreased. Understanding the anatomical and biomechanical characteristics of the erector spinae muscle may enhance clinical outcomes and rehabilitation strategies for subjects with LBP.