An alternative preparation of the acellular muscle graft for reconstruction of the injured nerve--morphological and morphometric analysis.

The application of cutaneous nerve grafts is accompanied by some disadvantages, including insufficient graft material for the reconstruction of a large mixed nerve. Recently, evacuated muscle autografts have been suggested as possible alternatives to cutaneous nerve grafts. In the present paper we have demonstrated a possible preparation of the evacuated muscle graft using an infiltration of Marcaine. The reinnervation of the distal stump of the rat median nerve was evaluated by morphological and morphometric analysis after application of the muscle acellular grafts prepared by three methods: an ordinary freeze-thawed muscle graft, a Marcaine evacuated muscle graft and a Marcaine treated graft with subsequent freezing and thawing. A comparison of the numbers and diameters of the myelinated axons in the distal nerve stumps revealed very similar conditions for axon regrowth and maturation in Marcaine evacuated and freeze-thawed muscle grafts. The best results with myelinated axon numbers and spectrum of their calibres were obtained when the Marcaine treated graft was repeatedly frozen and thawed. The pre-treatment of the muscle graft by Marcaine prevents it from shrinking and fragmenting, the main disadvantage during freeze-thawing of fresh muscle. The present results demonstrate that infiltration of striated muscles with a myotoxic compound, e.g. Marcaine, with subsequent freezing-thawing is the method of choice for the preparation of an acellular muscle graft used in peripheral nerve reconnection in the experimental model.