Comparison of muscle histology and generated pressures of two types of dynamic graciloplasties in rabbits.

Abstract

To compare the muscle histology and the generated pressures of the conventional spiral graciloplasty with those of the split sling graciloplasty in rabbits. Six rabbits underwent a split sling graciloplasty in the left leg and a conventional graciloplasty in the right leg around polyurethane tubes. Beforehand muscle biopsy specimens were taken at several locations in both legs. After chronic stimulation once again biopsies were performed. Comparisons were made with regard to histology and pressures. The same level of global changes occurred in both legs. The type II fiber diameter increased significantly in both legs. The amount of connective tissue increased significantly in both legs, but the resulting percentages were comparable. The changes at the distal site of the split sling graciloplasty were comparable to other biopsy specimens. The mean pressures in the conventional graciloplasty were 42 and 52 cm H2O without and with stimulation, respectively. In the split sling graciloplasty these pressures were 48 and 76 cm H2O, respectively. The ability to sustain long-lasting contractions was the same using both techniques. 25 Hz was the optimal frequency for muscle stimulation. Histologically the conventional graciloplasty is comparable with a split sling graciloplasty. The achieved pressures are the same or slightly higher with the split sling graciloplasty as compared with the conventional graciloplasty.