Side-to-side nerve bridges reduce muscle atrophy after peripheral nerve injury in a rodent model

Background Peripheral nerve injury can result in muscle atrophy and long-term disability. We hypothesize that creating a side-to-side bridge to link an injured nerve with a healthy nerve will reduce muscle atrophy and improve muscle function. Methods Sprague-Dawley rats were divided into four groups (n = 7 per group). Group 1: transection only - a 10-mm gap was created in the proximal tibial nerve; group 2: transected plus repaired - the transected tibial nerve was repaired; group 3: transected plus repaired plus nerve bridge - transected nerve repaired with a distal nerve bridge between the tibial and peroneal nerves via epineurial windows; and group 4: transected plus nerve bridge - transected tibial nerve left unrepaired and distal bridge added. Gait was assessed every 2 wk. At 90 d the following measures were determined: gastrocnemius mass, muscle and nerve nuclear density, and axonal infiltration into the nerve bridge. Results Groups 3 and 4 had greater improvements in walking track recovery than groups 1 and 2. Group 3's gastrocnemius muscles exhibited the least amount of atrophy. Groups 1, 2, and 4 exhibited greater histologic appearance of muscle breakdown compared with group 3 and control muscle. Finally, most bridges in groups 3 and 4 had neuronal sprouting via the epineurial windows. Conclusions Our study demonstrated reduced muscle atrophy with a side-to-side nerve bridge in the setting of peripheral nerve injury. These results support the application of novel side-to-side bridges in combination with traditional end-to-end neurorrhaphy to preserve muscle viability after peripheral nerve injuries.