Journal of neurosurgery. Spine
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Spinal fusion at the L4-5 disc space alters the normal biomechanics of the spine, and the loss of motion at the fused level is compensated by increased motion and load at the other unfused segments. This may lead to deterioration of the adjacent segments of the lumbar spine, called adjacent-segment disease (ASD). In this study, the authors investigate the distracted disc height of the fused segment, caused by cage or bone insertion during surgery, as a novel risk factor for ASD after posterior lumbar interbody fusion (PLIF). ⋯ The excessive distraction of the L4-5 disc space during PLIF surgery is a significant and potentially avoidable risk factor for the development of radiographic, symptomatic ASD.
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Knowledge of the anatomy of the ligaments that unite the head with the neck is important to the clinician who treats patients with lesions in this region. Although the anatomy and function of these ligaments have been well described, those of the Barkow ligament (BL) have yet to be studied. ⋯ The BL was found in all but 1 of our specimens. This ligament appears to resist extension of the atlantooccipital joint and may be synergistic with the anterior atlantooccipital membrane. Interestingly, the function of this ligament as found in this study relies on the integrity of the transverse ligament. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal from pathological tissue using imaging modalities.