COMPARISON OF MUSCLE HISTOLOGY AND GENERATED PRESSURES OF 2 TYPES OF DYNAMIC GRACILOPLASTIES IN RABBITS

Objective: To compare the muscle histology and the generated pressures of the conventional spiral graciloplasty with those of the split slin g graciloplasty in rabbits. Methods: Six rabbits underwent a split sli ng graciloplasty in the left leg and a conventional graciloplasty in t he right leg around polyurethane tubes. Beforehand muscle biopsy speci mens were taken at several locations in both legs. After chronic stimu lation once again biopsies were performed. Comparisons were made with regard to histology and pressures. Results: The same level of global c hanges occurred in both legs. The type II fiber diameter increased sig nificantly in both legs. The amount of connective tissue increased sig nificantly 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 conve ntional graciloplasty were 42 and 52 cm H2O without and with stimulati on, respectively. In the split sling graciloplasty these pressures wer e 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. Conclusions: Histologically the con ventional graciloplasty is comparable with a split sling graciloplasty . The achieved pressures are the same or slightly higher with the spli t sling graciloplasty as compared with the conventional graciloplasty.