Repair of partial lesions with nerve grafting methods in the rat tibial nerve.

A partial nerve lesion and associated neuroma can be either left alone or repaired with a graft. A by-pass graft around the undisturbed lesion with end-to-side attachments might be a good alternative. This study in rats examines these strategies using walking-track analysis, muscle weights, and histology. After a tibial nerve partial lesion (3 mm) and a 21-day delay, the reexposed lesion was either not repaired, repaired with an interposed allograft, or a by-pass allograft. Functional results showed that all three groups had a steady improvement over the 8-week period, but without significant group differences. Gastrocnemius muscle ratios reflected intermediate atrophy. Axons regenerating through the lesion were more advanced than those which regenerated through the grafts and a neuroma was absent. The partial lesion can regenerate to an intermediate level without any intervention, including a by-pass graft, although the delayed repair strategy may have counteracted any potential benefits.