Carpal tunnel syndrome (CTS) is the commonest hand condition referred for elective surgery in the UK with approximately 50 000 carpal tunnel decompressions per year. This incidence of both the condition and surgery is increasing, with consequent concerns over the funding available for this.

It is generally accepted that severe CTS with a neurological deficit is best treated by surgical decompression while steroid injections and night splints are proven treatments for mild symptoms. However for moderate CTS, it is not clear which of these treatments is best. Steroid injections usually work well but there is concern over the longevity of effect.

Two previous randomised trials included all severities of CTS apart from those with thenar wasting. One small trial showed better outcomes for surgery after 20 weeks but included patients who had previously had steroid injections, introducing bias in favour of surgery. The other trial reported only a slight advantage in favour of surgery but did not use a validated outcome measure.

We intend to perform a multicentre randomised trial of surgical decompression versus steroid injection for moderate CTS. Outcome measurements at up to 2 years will include Carpal Tunnel Syndrome Assessment Questionnaire, patient satisfaction, scar pain and complications.