Effect of early mobilization on healing of nerve repair: Histologic observations in a canine model

The effect of early mobilization on the healing of nerve repair was studied in a canine model. Median and ulnar nerves in the left wrist of 16 adult m ongrel dogs were transected and immediately repaired. No motion of the repa ired forelimb was allowed in the immobilized group (n = 10),while controlle d passive motion between 30 and 90 degrees of wrist flexion was begun on th e first postoperative day for 10 minutes twice daily in the mobilized group (n = 6). The pattern of revascularization and collagen formation at neuror rhaphy was examined by transillumination of India ink-injected specimen and by conventional histologic sections. Re Revascularization of nerve repair was found to occur by in growth of capillaries from proximal and distal ner ve ends, which typically crossed the neurorrhaphy by 3 weeks in the immobil ized group. Following early mobilization, there was a persistent "hypovascu lar zone" at the nerve repair site for up to 6 weeks. In addition, more sca r tissue was generated by early motion according to gross observation and q uantitative collagen analysis. Early mobilization, therefore, seems to impe de nerve regeneration by delaying revascularization and enhancing scar form ation.