The association between number of intercostal nerves transferred and elbow flexion: a systematic review and pooled analysis

Objective This pooled analysis evaluates the association between the number of nerves transferred and postoperative outcomes after intercostal nerve (ICN) nerve transfer for elbow flexion. Methods A systematic and pooled analysis of studies reporting individual patient demographics and outcomes after ICN-musculocutaneous nerve (MCN) transfer for traumatic brachial plexus injury was conducted. The primary outcome was the ability to attain an elbow flexion Medical Research Council (MRC) score of >= 4 at the final postoperative follow-up visit. Results Ten studies were included for a total of 128 patients. There were 43 patients who underwent two ICNT, 77 patients who underwent three ICNT, and 8 patients who underwent four ICNT. The three groups did not differ in ability to achieve MRC >= 4 (2ICNT 48.8%, 3ICNT 42.9%, 4ICNT 50.0%, p = 0.789). The number of ICNs transferred was not associated with MRC scores >= 4 on the multivariable analysis (OR: 0.55, p = 0.126). Conclusions These results indicate that two ICN transfers may be as effective as three ICN and four ICN transfers and highlight the potential for nonsurgical factors to influence postoperative outcomes. Taken together, this pooled analysis leads us to question the utility of transferring >2 ICNs for MCN neurotization.