A prospective randomised controlled trial comparing endoscopic decompression of the ulnar nerve with open decompression in the surgical management of cubital tunnel syndrome (UNDER study)
Surgeons will train on cadavers to learn a newer, less invasive technique for treating a trapped nerve in the elbow, then test it against the standard operation in a trial of 334 patients. Cubital tunnel syndrome—where the ulnar nerve is compressed at the elbow—causes numbness, tingling, and weakness in the hand. When symptoms persist, surgery is needed. The standard open decompression works well but recovery can be slow. The alternative, endoscopic decompression, uses a tiny camera and smaller cuts, which may speed recovery, but it is rarely used because surgeons lack training and data on its safety and effectiveness are weak. If the trial shows endoscopic surgery is as good as or better than open surgery, more surgeons could adopt the technique. Patients might return to work and daily activities sooner, with smaller scars and fewer complications. The study also includes a cost-effectiveness analysis, so the NHS could decide whether the newer method is worth funding. Results will be published in journals and shared through press releases and social media, potentially shaping future clinical guidelines for this common nerve condition.
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Research question: What is the clinical efficacy and cost-effectiveness of endoscopic decompression in the management of cubital tunnel syndrome (CuTS) measured using the Patient Rated Ulnar Nerve Evaluation (PRUNE) disease specific PROM at 3 months. Background: Cubital tunnel syndrome is a compression neuropathy of the ulnar nerve at the elbow. Surgical decompression is recommended for persistent and severe symptoms, using either open (OD) or endoscopic (ED) techniques. The open technique is widely used and has a low rate of complications and symptom recurrence. Patients may recover more quickly after ED, however this technique is used infrequently and has a higher rate of complications. Data on comparative efficacy and relative failure rates for both techniques is limited. A comparative study is needed, and endoscopic surgical training required to enable wider adoption. Aim: To train surgeons in endoscopic cubital tunnel surgery and conduct a randomised controlled trial (RCT) comparing OD and ED in the surgical management of CuTS. Objectives: To ascertain the relative patient reported clinical efficacy of OD and ED at 3 months measured by the PRUNE score using a two arm RCT with a parallel economic evaluation determining cost effectiveness. Methods: The study has 2 Phases. In Phase 1, 30 hand and upper limb surgeons from up to 20 hospitals will be trained in ED by cadaveric training workshops. Satisfactory completion of simulation training (Phase 1a) will allow progression to the training evaluation cohort whereby patients with CuTS considered for primary decompression surgery will be recruited for a pilot cohort study (Phase 1b). Each surgeon will perform up to 5 ED procedures and be eligible for transition to Phase 2 depending on previous experience, satisfactory attainment of defined competencies and 6 week follow up outcome data. Phase 1 study data will be used to evaluate the endoscopic technique, explore the learning curve, determine complication profiles, and estimate complication rates. In Phase 2, 334 eligible participants will be recruited at up to 20 UK hospitals and randomised to ED or OD. The primary outcome measure is the PRUNE at 3 months. Secondary outcome measures include motor function in ulnar nerve innervated muscles by British Medical Research Council (BMRC) scale, elbow range of motion, scar cosmesis by POSAS v2, return to work, complications and EuroQol EQ-5D-5L. Remote 6 month follow up will assess early symptom recurrence. Timelines: Estimated study duration 54 months. Months 1-8 study set up; Months 9-15 staggered site opening (up to 30 surgeons across 20 sites); Months 9-20 recruitment of up to 150 participants for endoscopic training cohort study with minimum 6 week follow up; Months 12-40 recruitment of 334 participants (10 per surgeon per annum) to Phase 2 RCT; Months 24-28 review of internal pilot and STOP/GO criteria; interim analysis of 6 month follow up data for Phase 1b and for first 6 months recruitment Phase 2; Month 46 end of primary outcome data collection Phase 2; Months 47-54 study close, data analysis, dissemination. Anticipated impact and dissemination: Clinicians and patients to know whether OD or ED is superior and understand harm and benefits of each. The results will be presented in high impact journals and at international meetings. The results will be disseminated through press releases and social media, and may be used to inform evidence-based guidelines on the management of CuTS.
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