Supercharged End-to-Side Anterior Interosseous Nerve Transfer Versus Subcutaneous Ulnar Nerve Transposition for Severe Cubital Tunnel Syndrome: A Comparative Clinical Study.

BACKGROUND

To compare the clinical and electrophysiological outcomes of subcutaneous ulnar nerve transposition (SCT) alone versus SCT combined with supercharge end-to-side anterior interosseous nerve transfer (SETS) for the treatment of severe cubital tunnel syndrome (CuTS).

METHODS

This retrospective cohort study included 48 patients with severe CuTS who underwent surgery between 2016 and 2024. Patients were divided into the SETS group (SCT+SETS, n=24) and the control group (SCT alone, n=24). The primary outcome was the rate of recovery of intrinsic hand muscle strength at 12 months postoperatively. Secondary outcomes included compound muscle action potential (CMAP) amplitude, MCV, Quick-DASH scores, SETS-specific near-nerve stimulation positivity rates, and complication rates.

RESULTS

At 12 months postoperatively, 75.0% (18/24) of patients in the SETS group achieved MRC grade 4 first dorsal interosseous (FDI) muscle strength, whereas no control group patient reached grade 4 (P<0.001). SETS group FDI-CMAP amplitude improved from 0.58±0.12 mV preoperatively to 2.45±0.85 mV postoperatively, with a mean improvement of 1.87±0.79 mV, significantly greater than the 0.70±0.78 mV improvement in the control group (P<0.001). The near-nerve stimulation positivity rate in the SETS group was 71.4%. Complication rates did not differ significantly between groups (P>0.05). Multivariate logistic regression identified disease duration <12 months (OR=4.2, 95% CI: 1.6-11.0), preoperative FDI strength ≥MRC grade 2 (OR=3.5, 95% CI: 1.3-9.4), and age <60 years (OR=2.7, 95% CI: 1.0-7.2) as independent predictors of favorable functional recovery after SETS.

CONCLUSIONS

In patients with severe CuTS, adding SETS to SCT significantly improves intrinsic hand muscle strength recovery and electrophysiological outcomes without increasing the risk of complications. Patients with disease duration <12 months, age <60 years, and mild-to-moderate preoperative muscle atrophy derive the greatest benefit.