A Cochrane review included 4 studies comparing surgery to either splinting or a steroid injection, with a total of 317 subjects. The pooled estimate favoured surgery for the primary outcome, improvement at three months of follow-up (RR 1.23, 95% CI 1.04 to 1.46; 3 trials, n=295). The outcome was favourable for surgery also at six months (RR 1.19, 95% CI 1.02 to 1.39; 2 trials, n=245) and at one year (RR 1.27, 95% CI 1.05 to 1.53; 2 trials, n= 198). Neurophysiological parameters also favoured surgery (RR 1.44, 95% CI 1.05 to 1.97; 1 trial, n=50). A significant proportion of people treated medically will require surgery while the risk of re-operation in surgically treated people is low (RR 0.04 favouring surgery, 95% CI 0.01 to 0.17; 2 trials, n=198). Complications were significantly more common in the surgical arm (RR 1.38, 95% CI 1.08 to 1.76; 2 trials, n=226).
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in participants, interventions and outcomes).