Spine
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The iliolumbar ligament is one of the three lumbopelvic ligaments. Recent study has shown that the ligament is not present at birth and is formed from metaplasia of the quadratus lumborum muscle at the end of the first decade. To study the biomechanical functions of this ligament, an apparatus was developed using linear variable differential transformers. ⋯ Flexion of L5 on S1 was mainly controlled by the posterior band and lateral bending by the anterior band of the ligament. When the L5-S1 disc was degenerated, total division of the ligaments reduced extension during loading. Its effect on torsion was not evident from this study.
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The microcapillary infusion method was evaluated in recording intramuscular pressure during isometric and concentric exercise of the erector spinae muscle. Intramuscular pressure at rest was 6.1 (SD = 1.4) mm Hg without infusion and 8.3 with an infusion rate of 1.5 ml/hour. ⋯ The erector spinae muscle was found to be heavily loaded during exercise with an average muscle contraction pressure of 175 mm Hg. Recording of intramuscular pressure in the erector spinae muscle during exercise tests can be an additional method in the study of ergonomics and biomechanics of the spine as well as in the diagnosis of chronic compartment syndrome in this muscle.
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Intramuscular pressure in the erector spinae muscle was measured during exercise with the microcapillary infusion method in 12 highly selected patients with recurrent low-back pain. The criteria for selection were low-back pain induced only by exercise, relief of symptoms at rest, and no neurologic deficits in the lower extremities. During a 4-year period, 12 patients fulfilled these criteria. ⋯ Fasciotomy of the erector spinae muscle normalized the intramuscular pressure during exercise and at rest after exercise, and relieved the pain. All the other patients with chronic low-back pain had normal intramuscular pressure findings. Chronic compartment syndrome in the erector spinae muscle seems to be an extremely uncommon cause of exercise-induced low-back pain.