A quantitative study of muscle fiber survival and regeneration in normal, predenervated, and Marcaine-treated free muscle grafts in the rat.

Free grafts were performed on the rat extensor digitorum longus muscle after no pretreatment, 14-day predenervation, or two or one preinjections of Marcaine. Numbers of surviving muscle fibers were counted in 4-day grafts, and the total number of muscle fibers was counted in 60-day grafts. Mean numbers of surviving muscle fibers in 4-day grafts were 132 for untreated muscles, 1166 for predenervated muscles, and eight and two for muscles treated with two and one Marcaine injections, respectively. In all four groups, the numbers of muscle fibers in 60-day grafts did not differ significantly from the mean number of muscle fibers (3880) in the normal extensor digitorum longus. It was concluded that most of the muscle fibers found in a mature free graft are newly regenerated rather than surviving original muscle fibers.