Spine
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The effects of human trunk extensor muscle fatigue on the estimated trunk muscle forces and spinal loading were investigated during the performance of repetitive dynamic trunk extension. ⋯ The results of the study do not suggest that an increase in the muscular loading of the spine occurs as a result of changing trunk muscular recruitment patterns. Therefore, future studies should focus on injury mechanisms that may occur as a result of a change in the viscoelastic passive tissue responses, muscular insufficiency, or a decline in neuromuscular control and coordination.
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An experimental study to elucidate the initial factors in the pathogenesis of lumbar pain caused by disc herniation. ⋯ Application of nucleus pulposus to nerve root increased endoneurial fluid pressure and decreased blood flow in the dorsal root ganglia. This study's acute observations in the dorsal root ganglia may thus help to explain why disc herniations without compression of neural tissue are sometimes painful because similar pathologic findings are observed after only nucleus pulposus application to the nerve root. The authors further suggest that exposure of nerve roots to nucleus pulposus may establish a "compartment syndrome" in the dorsal root ganglia.
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An experimental porcine study in which functional lumbar spinal units were tested in compression to failure. Biomechanical, radiographic, magnetic resonance imaging, and histological characteristics are described. ⋯ This study shows that the weakest part of the lumbar spine of the juvenile pig, when compressed, is the growth zone and the junction between the point of insertion of the anulus fibrosus and the vertebra. This location of weakness may explain the high frequency of disc degeneration and "persisting apophysis" seen in the spine of athletes.
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A prospective study was conducted in 37 patients with cervical spondylosis with incomplete cord injury to assess the role of decompression in these patients. ⋯ Although neurologic improvement after an incomplete spinal cord injury when no bony lesion was present was slow during the first few months after trauma, more than 60% of the patients showed neurologic recovery with a muscle grade higher than 3 at 2-year follow-up. Surgical decompression, however, was associated with immediate neurologic improvement, faster recovery of neurologic function, early mobilization, better long-term neurologic outcome, briefer hospital stays, and fewer complications related to long confinements in bed than was nonoperative treatment.
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The psychometric properties and clinical use of a battery of physical performance measures were tested on 44 patients with low back pain and 48 healthy, pain-free control subjects. ⋯ The results provide support for the use of these physical performance measures as a complement to patient self-report.