Background It is widely accepted by many adolescent basketball players and their coaches that wearing a lace-up ankle brace will reduce the incidence of acute ankle injuries. To date there have been no prospective studies to determine if lace-up ankle braces reduce the incidence of ankle injuries in adolescent basketball players.

Objectives To determine whether a lace-up ankle brace reduces the incidence and severity of acute ankle injuries sustained by adolescent basketball players during one season.

Design Prospective randomised controlled study using stratified cluster (school) randomisation.

Participants 1460 adolescent male and female (age 13–18) basketball players from 46 USA high schools.

Intervention Lace-up ankle brace.

Main outcome measures (1) Rate and incidence of acute ankle injuries, (2) Ankle injury severity (days lost from participation). Injury rates were estimated using Kaplan-Meier survival analysis and compared between the intervention and control group using a log-rank test. The Cox Proportional Hazards model was utilised to examine the relationship between injury rate and ankle bracing while controlling for covariate. Injury severity was compared using the Wilcoxon Rank-Sum test.

Results The acute ankle injury rate (per 1000 exposures) was 1.41 in the control group, compared to 0.47 in the braced group. 75 controls (10.4%) sustained an acute ankle injury, compared to 26 athletes (3.5%) in the braced group (Cox HR 0.31, 95% CI 0.20 to 0.49). Lace-up ankle braces reduced the number of injuries in athletes with (HR 0.35, 95% CI 0.17 to 0.71) and without (HR 0.30, 95% CI 0.17 to 0.53) history of previous ankle injury. There was no difference (p=0.223) in the median number of days lost (braced group=5, controls=6).

Conclusion Lace-up ankle braces reduced the incidence of acute ankle injuries in male and female adolescent basketball players, independent of previous injury status.