Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association
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We investigated the regenerative capacity of motor nerves repaired by end-to-side or end-to-end neurorrhaphy, using choline-acetyltransferase (ChAT) activity measurement or histological analysis. The right medial gastrocnemius nerves (MGNs) of 62 male Fisher strain rats were transected and divided into three groups. In group 1, the distal ends of the MGN were coapted to the side of the lateral gastrocnemius nerve, using a Y-shaped silicone tube in end-to-side neurorrhaphy. ⋯ Axonal regeneration of MGN and the recovery of MGM to nearly normal histology and weight were observed in groups 1 and 2 3 months postoperatively. Although there were no significant differences in ChAT values between groups 1 and 2, the values were significantly larger than that of group 3 3 months postoperatively. These findings suggested that end-to-side neurorrhaphy would be an alternative treatment for peripheral nerve injury in certain clinical situations.
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We made an animal model of cervical spinal cord injury in a cat and performed electrophysiological, histological, and bechavioral studies. The cervical spinal cord injury model was made by inserting a screw through the fourth cervical vertebral body of the cat. After the injury, muscle tonus of the limbs and trunk diminished. ⋯ There was demyelination and gliosis in the ventral funiculus and in part of the ventrolateral funiculus at or near the injured site. Electrophysiological and histological findings were in good agreement with the behavioral ones. Behavioral studies seem useful for evaluating the function of the spinal cord, especially for assessing the injured system in the spinal cord.
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In this experimental study, the influence of flexible nailing in the later phase of femoral fracture healing was investigated. Sixty rats were randomly assigned to three groups. In 20 rats no intervention was performed, and they served as a control group. ⋯ All values for biomechanical characteristics were reduced at 60 and 90 days in flexibly nailed bones compared with intact femurs, while in the rigid nailing group, bending load and fracture energy were similar to those in intact bones at 90 days. Bone mineral content in the callus segment and diaphysis was greater in the rigidly nailed bones than in the flexible nailing group at 60 days, while at 90 days, no differences were detected. In conclusion, this animal study indicates that: (1) flexible nailing in the later phase of fracture healing increases callus formation, while (2) the quality of bone healing is reduced.
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To investigate recent trends in the incidence of fractures in children and adolescents, we conducted a survey of distal radius fractures in 1992 and 1995 in Tottori Prefecture, Japan. Seven-hundred and forty-five patients under age 20 years were registered (562 males and 183 females). The age and sex-specific incidences of fractures in patients under 20 years of age were higher in males than in females, showing peaks at age 12-13 years for males and at age 10-11 years for females. ⋯ The age and sex-specific incidences were compared with those in the period 1986-1988, which we reported previously. The incidence in each year showed a significant increase with time for males but not for females. We conclude that the incidence of distal radius fractures in children and adolescents has a prominent peak matched by the age of the growth spurt, and the incidence of the fracture has increased in males during the past decade in Tottori Prefecture.