Axonal regeneration through muscle autografts submitted to local anaesthetic pretreatment

Freeze-thawed muscle grafts (FTMG) have been used as an alternative to nerve grafts for the reconstruction of peripheral nerve defects, although their use has some disadvantages. For instance, FTMG may fragment easily after freeze-thawing, a fact impairing their use for surgery. In this study we describe a method to obtain muscle autografts based on the myotoxic properties of local anaesthetics. Fifteen adult rats had their left tibialis anterior muscles injected transcutaneously with 0.3 ml of 2% lidocaine hydrochloride. Twenty-four hours later the injected muscle was removed and a lidocaine muscle graft (LMG) was obtained by trimming the muscle to a rectangular block of approximately 1.0 cm in length. The left sciatic nerve was exposed in the mid-thigh region and a segment removed so that a final 1.0 cm-long gap was produced. The LMG was coaxially autografted to the epineurium between the proximal and distal nerve stumps. In another 15 rats, the sciatic nerve gap was repaired with FTMG obtained from the tibialis anterior muscle. Surgical procedures were similar in both groups. Axonal regeneration and muscle reinnervation were studied quantitatively and ultrastructurally 60 days after the insertion of LMG and FTMG. The results showed that axonal regeneration with the LMG was qualitatively similar to that observed with the FTMG, with no significant differences between groups. We conclude that LMG was a successful muscle graft and a suitable alternative to other denaturing methods, without the disadvantages of FTMG.