End-to-side anterior interosseous nerve transfer augmentation of ulnar nerve function in moderate and severe cubital...

The anterior interosseous nerve (AIN) end-to-side (ETS) nerve transfer is a relatively recent treatment innovation in managing cubital tunnel syndrome (CuTS). Potential benefits must be balanced against the risks associated with the adoption of an innovative technique, evaluating procedure-specific risks, and considering additional costs in the safe delivery of care. The ETS technique has been proposed as a method of improving intrinsic muscle function in the hand in the setting of ulnar nerve compression at the elbow. The technique is controversial with emerging evidence from retrospective cohort and single-arm interventional studies to support its use. However, there is persisting uncertainty regarding the relative contributions of the decompression, collateral sprouting from intact terminal axons, and neo-innervation from the ETS transfer to any functional recovery. Given this lack of equipoise regarding the efficacy of ETS nerve transfers, a randomised controlled trial is proposed to assess recruitment, protocol compliance, subject retention, and define the sample size for a future multicentre study.

This randomised controlled trial (RCT) protocol defines a prospective, single centre study of 20 patients randomised to ulnar nerve decompression with or without ETS nerve transfer, with participant blinding to treatment allocation. Anticipated follow up period is up to 24 months.

Data from this study will be used to calculate the sample size for a future multicentre RCT evaluating SETs transfer in CuTS. It would also inform on the willingness of clinicians to randomise their patient given the current uncertainty surrounding this technique and the retention rates anticipated. Should the RCT demonstrate significant functional benefits of combining ETS nerve transfer with decompression, it could shift clinical practice toward using this dual approach, especially in patients with moderate or severe ulnar neuropathy. The findings would likely influence treatment algorithms, optimising patient outcomes, and could also spur further studies into ETS applications in peripheral nerve injuries.

ISRCTN ID Number: ISRCTN18379703, Date of Registration: 14th May 2024.