INTRODUCTION: Functional recovery following nerve transection still remains unsatisfactory. Aberrant reinnervation of target organs caused by misdirected axonal growth at the repair site is regarded as one reason for a poor functional outcome. Two studies were performed to compare different methods for preventing aberrant reinnervation between transected and repaired nerves in adjacency.

MATERIAL AND METHODS: In two different experiments rat sciatic nerve was transected and repaired as follows: epineural sutures of the sciatic nerve (Ax6, A1x10); separate fascicular repair of tibial and peroneal nerves (Bx8, B1x10); as in B separating both nerves using a pedicle fat flap as barrier (Cx8); as in C using Integra"-sheets as barrier (Dx8); and as in C using non-vascularized autologous fascia as barrier (E1x10). As control solely the tibial nerve was transected and repaired (Fx5, F1x8).

RESULTS: Muscle contraction force was significant higher in group C compared to groups A and B after four months. Group D showed clear and consistent, but not significantly higher values than groups A and B. Histology at the coaptation site showed multiple axons crossing from the tibial to the peroneal nerve and vice versa in groups A, A1 and B, B1. In group C isolated axonal growth of axons from the tibial to the peroneal nerve and vice versa was observed when gaps between the fat cells were evident. No axonal crossing was visible in groups D, E1 and F, F1. These findings were confirmed by a significant higher rate of correct directed axonal growth of groups C, D, and F using sequential retrograde double labeling technique of the soleus motoneuron pool. When fascia was used as barrier (group E1), muscle contraction force was significant lower than in group B1, although group E1 demonstrated a higher rate of specificity than groups A1 and B1. The reason for this inferior result in group E1 was nerve compression due to a capsule formation at the site of the fascia.

CONCLUSION: A barrier between two transected and repaired nerve fascicles in adjacency significantly prevents aberrant reinnervation between both nerves. Owing to its simplicity and its superiority, interposition of vascularized tissue such as a pedicle fat flap is recommended as excellent option for improving motor recovery in brachial plexus, sciatic nerve, and facial nerve repair. (Experiment 1 includes groups A, B, C, D, F. Experiment 2 includes groups A1, B1, C1, F1)