Growth hormone can decrease muscle damage complication in tibia lengthening by external fixation.

Abstract

The purpose of this study was to investigate the effects of growth hormone (GH) on muscles during limb lengthening. Sixty rats underwent tibial lengthening of approximately 30% after a latency period of 4 days, a distraction period of 30 days with a rate of 0.25 mm twice per day, and a consolidation period of 27 days. Recombinant GH was administered to 30 rats (100 g/kg/d) and the same dose of normal saline to the remaining 30 rats, between operation and sacrifice. Histopathologic, immunohistochemical, and electrophysiological studies were performed on the tibialis anterior to compare the muscle responses of GH-treated lengthened limbs, GH-treated nonlengthened limbs, saline-treated lengthened limbs, and saline-treated nonlengthened limbs at postoperative days 34 and 61. Histologic injury scores were worst in the saline-treated lengthened limbs, where vimentin expression was also highest. Cell proliferation, determined by proliferating cell nuclear antigen staining, was highest in the GH-treated lengthened limbs, where desmin expression was also highest. Electrophysiological methods that showed better muscle function was retained in the GH-treated lengthened limbs than in the saline-treated lengthened limbs. Our results suggest that GH can reduce muscle damage during limb lengthening by enhancing myogenesis and decreasing fibrogenesis.