Changes of lower-limb trabecular bone density after sciatic nerve transection in immature rats

Purpose: The changes in the bone density of immature Sprague-Dawley (SD) rats whose sciatic nerve was cut were investigated to understand the patterns of bone density deterioration and to establish the rationale for preventive managements. Materials and methods: Eighteen six-day-old SD rats were randomly divided into the right sciatic neurectomy and sham-operation group. The trabecular bone densities at the 3rd lumbar spine (L3), L4, and L5, bilateral proximal and distal femoral bones, and proximal and distal tibia at weeks 4, 8, and 12 were measured through a CT scan. Results: In both the surgery and control groups, statistically significant changes in body weight were observed at weeks 4, 8, and 12. The trabecular bone density of the surgery group at week 4 significantly decreased in the right proximal and distal tibia; and at week 8, a significant decrease was observed in the right tibia and the distal femur. At week 12, no statistically significant difference in the trabecular bone density was found between the groups. Conclusions: In immature SD rats, the reduction of trabecular BMD caused by sciatic neurectomy began in the 4th week after surgery, and proceeded from the distal part to the proximal part. The earlier reduction in the trabecular BMD of the tibia is explained by the thickness of the femur and the quadriceps femoris muscle, which are not affected by a sciatic nerve lesion. Further studies on cortical bone changes and bone metabolism markers may be needed to provide data on bone density deterioration caused by the neural damage during the growing period.