Data collection and analysis A minimum of two review authors independently reviewed search results to select studies for inclusion by using pre-specified criteria, assessed risk of bias of included studies and extracted data from included studies. We grouped outcomes into the following categories: (1) hand function, (2) other patient-reported outcomes (e.g. satisfaction, pain), (3) early objective outcomes (e.g. correction of angular deformity), (4) late objective outcomes (e.g. recurrence) and (5) adverse effects. Main results We included 14 articles describing 13 studies, comprising 11 single-centre studies and two multi-centre studies. These studies involved 944 hands of 940 participants; of these, 93 participants were reported twice in separate articles describing early and late outcomes of one trial. Three papers reported the outcomes of two trials comparing different procedures. One trial compared needle fasciotomy versus fasciectomy (125 hands, 121 participants), and the other compared interposition firebreak skin grafting versus z-plasty closure of fasciectomy (79 participants). The other 11 studies reported trials of technical refinements of procedures or rehabilitation adjuncts. Of these, three investigated effects of postoperative splinting on surgical outcomes. Ten studies (11 articles) were randomised controlled trials (RCTs) of varying methodological quality; one was a controlled clinical trial. Trial design was unclear in two studies awaiting classification. All trials had high or unclear risk of at least one type of bias. High risks of performance and detection bias were particularly common. We downgraded the quality of evidence (Grades of Recommendation, Assessment, Development and Evaluation-GRADE) of outcomes to low because of concerns about risk of bias and imprecision. Outcomes measured varied between studies. Five articles assessed recurrence; two defined this as reappearance of palpable disease and two as deterioration in angular deformity; one did not explicitly define recurrence. Hand function on the Disabilities of the Arm, Shoulder and Hand (DASH) Scale (scores between 0 and 100, with higher scores indicating greater impairment) was 5 points lower after needle fasciotomy than after fasciectomy at five weeks. Patient satisfaction was better after fasciotomy at six weeks, but the magnitude of effect was not specified. Fasciectomy improved contractures more effectively in severe disease: Mean percentage reduction in total passive extension deficit at six weeks for Tubiana grades I and II was 11% lower after needle fasciotomy than after fasciectomy, whereas for grades III and IV disease, it was 29% and 32% lower. Paraesthesia (defined as subjective tingling sensation without objective evidence of altered sensation) was more common than needle fasciotomy at one week after fasciectomy (228/1000 vs 67/1000), but reporting of complications was variable. By five years, satisfaction (on a scale from 0 to 10, with higher scores showing greater satisfaction) was 2.1/10 points higher in the fasciect...