The spine journal : official journal of the North American Spine Society
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Cervical arthroplasty theoretically reduces the risk of adjacent level disc degeneration and segmental instability that may be seen after a cervical fusion. An essential argument in confirming the utility of cervical arthroplasty is long-term confirmation that cervical disc replacements can maintain physiological kinematics at the index and adjacent levels. ⋯ The Bryan cervical disc prosthesis provides for a durable solution for functional spinal motion at the operated level and maintained the preoperative kinematics at adjacent levels at the 5-year follow-up.
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Acute cervical spinal cord injury (SCI) has been observed in some patients after a minor trauma to the cervical spine. The discrepancy between the severity of the trauma and the clinical symptoms has been attributed to spinal canal stenosis. However, to date, there is no universally established radiological parameter for identifying critical spinal stenosis in these patients. The spinal canal-to-vertebral body ratio (Torg-Pavlov ratio) has been proposed for assessing developmental spinal canal stenosis. The relevance of the Torg-Pavlov ratio for predicting the occurrence and severity of acute cervical SCI after a minor trauma to the cervical spine has not yet been established. ⋯ Developmental cervical spinal canal stenosis assessed by the Torg-Pavlov ratio was characteristic for patients suffering from acute cervical SCI after a minor trauma to the cervical spine. Patients at risk of SCI after a minor trauma to the cervical spine can be identified by applying a Torg-Pavlov ratio cutoff value of 0.7. Other factors in addition to the spinal canal-to-vertebral body ratio affect the severity and course of symptoms as a result of cervical SCI.
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Adjacent segment degeneration (ASD) after cervical fusion is a clinical concern. Despite previous studies documenting the biomechanical effects of multilevel cervical fusion on segments immediately superior and inferior to the operative segments, the pathogenesis of the initiation of degeneration progression in neighboring segments is still poorly understood. ⋯ Biomechanical factors such as increased mechanical demand and motion that have been associated with the development of ASD progression are highest in the segment immediately superior to the fusion. These changes are even more pronounced when the fixation technique involves the addition of posterior instrumentation, thereby supporting the hypothesis of the present study. Increased degrees of stiffening of the fused segments not only may lead to degenerative changes in the disc but may also predispose the segments to premature facet degeneration. Over subsequent time period, any remaining construct micro-motion is further eliminated with fusion of the posterior facet joints and the remaining regions in the disc space also filled in with bone, which eventually results in a circumferential type of fusion. After a circumferential fusion, authors, however, speculate that the role of instrumentation in ASD progression might not be significant. In fact, sufficient evidence to support this speculation is still lacking in the literature.
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Recent years have witnessed a shift in the assessment of spine surgical outcomes with a greater focus on the patient's perspective. However, this approach has not been widely extended to the assessment of complications. ⋯ Most complications reported by the patient are perceived to be at least moderately bothersome and are, hence, not inconsequential. Surgeons reported lower complication rates than the patients did, and there was only moderate agreement between the ratings of the two. As with treatment outcome, complications and their severity should be assessed from both the patient's and the surgeon's perspectives.
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Comparative Study
Comparison of open and minimally invasive techniques for posterior lumbar instrumentation and fusion after open anterior lumbar interbody fusion.
Minimally invasive techniques for spinal fusion have theoretical advantages for the reduction of iatrogenic injury. Although this topic has been investigated previously for posterior-only interbody surgery, such as transforaminal lumbar interbody fusion, similar studies have not evaluated these techniques after anteroposterior spinal fusion, a study design that can more accurately determine the effect of pedicle screw placement and decompression via a minimally invasive technique without the confounding effect of simultaneous interbody cage placement. ⋯ Our case-control study comparing patients who underwent anterior lumbar interbody fusion followed by open posterior instrumentation with those who underwent anterior lumbar interbody fusion followed by minimally invasive posterior instrumentation demonstrated that patients undergoing MIS fusion without decompression had less blood loss, less need for transfusion in the perioperative period, and a shorter hospital stay. In contrast, most outcome measures were similar between MIS and Open groups for patients who underwent decompression.