Morphologic characteristics of muscles grafted in rabbits with neurovascular repair.

In 34 female white rabbits, rectus femoris (RFM) muscles were grafted with immediate anastomoses of the vasculature (VA) and with nerves either left intact (NI-VA) or with nerves repaired (NR-VA). The purpose of the study was to compare the morphologic changes that occur in NI-VA grafts and NR-VA grafts from 8 to 120 days after grafting. After 8 days, nearly complete survival of all muscle fibers was found. The muscle mass and single fiber cross-sectional area (CSA) of the NI-VA group remained near control values for the first 30 days and then declined to 82 percent and 62 percent of the control values, respectively. Little evidence of morphologic disruption was observed. The NR-VA grafts displayed a significant denervation atrophy within the first 15 days, with relative values 67 percent of the control value for mean mass and 53 percent for single fiber CSA. By 120 days, mass and CSA recovered to 80 percent and 62 percent of control values. Although the similarity of the deficits in the nerve-intact and nerve-repaired grafts suggest that tenotomy and repair, rather than innervation, were the major limitations, the mechanism was not resolved.