Spine
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A model of the lumbar back muscles was constructed incorporating 49 fascicles of the lumbar erector spinae and multifidus. The attachment sites and sizes of fascicles were based on previous anatomic studies, and the fascicles were modeled on radiographs of nine normal volunteers in the upright position. Calculations revealed that the thoracic fibers of the lumbar erector spinae contribute 50% of the total extensor moment exerted on L4 and L5; multifidus contributes some 20%; and the remainder is exerted by the lumbar fibers of erector spinae. ⋯ Collectively, all the back muscles exert large compression forces on all segments. A force coefficient of 46 Ncm-2 was determined to apply for the back muscles. These results have a bearing on the appreciation of the effects on the back muscles of surgery and physiotherapy.
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To avoid homologous transfusion in spinal fusion surgery, acute normovolemic hemodilution was combined with controlled hypotensive anesthesia. Patients were kept hemodiluted, not only during surgery, but also after surgery by delaying transfusion until the next morning or later. ⋯ Only 4 of 119 patients (3.4%) required homologous blood, compared to 25 of 29 patients (86%) in 1982, at which time none of these techniques were used. The average hemoglobin on the seventh postoperative day was similar in both groups; 11.5 g/dl in the current series compared to 11.1 g/dl in the 1982 series.
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A prospective study of 12 patients with sagittal plane imbalance after multiple surgeries for scoliosis is reported. Reconstruction was attempted by posterior thoracolumbar junction osteotomy. Eighty-seven degrees of thoracic kyphosis (ending at L3) was improved to forty-one degrees (ending at T12). ⋯ No permanent complications ensued. The procedure, without anterior surgery, corrects the deformity at the apical area. Cotrel-Dubousset instrumentation secured correction and fixation.
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Twenty-two patients with neurologic deficit due to delayed posttraumatic vertebral collapse after osteoporotic compression fractures of the thoracolumbar spine underwent anterior decompression and reconstruction with bioactive Apatite-Wollastonite containing glass ceramic vertebral prosthesis and Kaneda instrumentation. Eighteen patients previously had minor trauma that resulted in a mild vertebral compression fracture without any neurologic involvement and were either conservatively treated or not treated at all. Four had no history of back injury. ⋯ The average follow-up was 34 (20-58) months after surgery. All patients had returned to their daily living with neurologic recovery and stable spine. This type of anterior procedure is effective in the osteoporotic patients and there was a very low incidence of instrumentation failure and very low morbidity.