Spine
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The relationship between epidural pressure and lumbar posture was assessed in patients with lumbar spinal stenosis. ⋯ Epidural pressure was significantly related to posture. These pressure changes correlated with the development of cauda equina symptoms. The increase of epidural pressure by posture may induce compression of the cauda equina. These pressure changes may explain the postural dependency in eliciting symptoms.
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This study analyzed interlaminar shear stresses across the laminae of a ligamentous L3-L4 motion segment. A three-dimensional finite element model of the motion segment was developed and its response in axial compression mode was predicted. ⋯ The interlaminar shear stresses being higher in the posterolateral regions of the intact disc reinforces that, from clinical studies, tears originate in the posterolateral portion of the disc. The large interlaminar shear stresses, caused by asymmetry in the disc structure due to injury, along with chemical and structural changes in the disc with age, may be an important cause of further degeneration through laminae separation. This is the case for traditional composite laminates. This study points out the importance of interlaminar shear stresses to gain further understanding of the role of mechanical factors in producing disc degeneration, especially delamination of the anulus. Clinical relevance of the findings and possible relationship to the aging process are explored.
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Prospective histologic comparison of perineural tissues from patients requiring decompression surgery for herniated intervertebral disc with those from cadaveric controls. ⋯ The vascular abnormalities detected in patients may represent an important etiopathologic factor predisposing to intraneural and perineural fibrosis, and hence to chronic pain symptoms, after disc herniation. It seems important to preserve the perineural microcirculation following disc herniation.
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Comparative Study
Development of degenerative spondylosis of the lumbar spine after partial discectomy. Comparison of laminotomy, discectomy, and posterolateral discectomy.
The development of degenerative spondylosis after successful operative decompression of the affected nerve root was prospectively evaluated in a comparative case series of 100 patients with a herniated lumbar nucleus pulposus. ⋯ The increased incidence of spondyloarthrosis with the posterior approach suggests that minimally invasive posterolateral extradural procedures should be considered for the decompression of a compromised lumbar nerve root.