Background High shoe-surface friction is a proposed risk factor for ‘non-contact’ lateral ankle sprain (LAS) injuries. Spraino® is a novel product that minimizes friction at the lateral edge of the shoe, thereby potentially mitigating the risk.
Objective To determine preliminary effect and safety of Spraino® when used to prevent LAS injury among indoor sport athletes.
Design A double-blinded, prospective, two-arm pilot randomised controlled trial (RCT). Participants were allocated (1:1) to Spraino® or to a ‘do-as-usual’ control group. The random allocation was concealed for investigators and participants. Group allocations were outcome-assessor-blinded.
Setting Indoor sports clubs competing at divisional- or league level in handball, badminton and basketball in Denmark.
Participants 510 elite- and sub-elite indoor sport athletes with at least one previous LAS injury within the preceding 24 months were enrolled; 480 completed the trial.
Intervention Spraino®; a low-friction patch applied to the lateral side of the shoe.
Main Outcome Measurements The trial was explorative with evenly-valued outcome measures related to incidence and severity of self-reported LAS injuries, pain in the ankle, fear of injury and intervention-related adverse events.
Results A total of 151 LAS injuries were reported within the trial period, of which 96 were categorized as non-contact injuries. A total of 50 injuries were severe. All metrics favoured Spraino® with computed incidence rate ratios of 0.87 (95% CI, 0.62–1.23) for any LAS injury, 0.64 (95% CI, 0.42–0.97) for non-contact LAS injuries, and 0.41 (95% CI, 0.19–0.89) for severe non-contact LAS injuries. The relative time-loss for the total number of injuries was 0.65 (95% CI, 0.45–0.93). Fear-of-injury and ankle pain was also lower in the Spraino® group. Six participants reported minor harms due to slipping on the floor because of Spraino®.
Conclusions Spraino® was found to be effective and safe when used to prevent LAS injuries in indoor sports. Findings should be replicated in a confirmatory RCT.
Trial registration ClinicalTrials. gov: NCT03311490
Funding Innovation Fund Denmark (7038–00087A)
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