A new insight on peripheral nerve repair: the technique of internal nerve splinting.

OBJECTIVE: Neuropathic pain produced by symptomatic neuromas is an important problem after peripheral nerve injury (PNI). End-to-end anastomosis of the nerve stump for PNI is well established but cannot efficiently prevent neuroma-in-continuity formation. METHODS: Sciatic nerve injury was used in the experimental model. Seventy-two rats were randomly divided into four groups: rats with nerve anastomosis sites supported with silicone tubes represented the internal nerve splinting (INS) group (n = 18); rats with end-to-end nerve anastomosis represented control group 1 (CON1) (n = 18); rats with INS and the nerve anastomosis site represented control group 2 (CON2) (n = 18); and rats that underwent the same surgical procedures for skin and muscle operations but without sciatic nerve injury represented the normal group (n = 18). RESULTS: Gross evaluations of the nerve anastomosis sites, gastrocnemius muscle atrophy, axonal regeneration and remyelination, neuropathic pain, and scar hyperplasia of the neuromas were performed, as well as motor function evaluations. Axonal regeneration, remyelination, and gastrocnemius muscle atrophy were similar between the INS group and CON1 (p > 0.05). However, neuropathic pain and scar hyperplasia-as evaluated according to the expression of anti-sigma-1 receptor antibody and anti-α-smooth muscle actin, respectively-and the weight ratios of the neuromas were reduced in the INS group compared with those of CON1 and CON2 (p < 0.05). CONCLUSIONS: Application of INS in nerve repair effectively prevented traumatic neuroma-in-continuity formation and inhibited neuropathic pain without influencing nerve regeneration in rats.