Effectiveness of Spraino for preventing lateral ankle sprain injuries in indoor sports: a pilot randomised controlled trial with 510 athletes

Background: Lateral ankle sprains (LASs) are common in indoor sports and high shoe-surface friction is considered a risk factor for non-contact LASs. Spraino is a novel Teflon-patch that is attached to the outside of sports shoes to minimise friction at the lateral edge, which could mitigate the risk of LAS. We aimed to determine preliminary effectiveness (incidence rate and severity) and safety (harms) of Spraino when used to prevent LAS injury among indoor sport athletes.

Methods: In this exploratory, parallel-group, two-arm pilot RCT, 510 sub-elite indoor sport athletes with a previous LAS injury were randomly allocated (1:1) to Spraino or “do-as-usual”. Allocation was concealed and the trial was outcome-assessor-blinded. Match and training exposure, LASs and associated time-loss were captured weekly via text messages. Information on harms, fear-of-injury and ankle pain were also documented.

Results: 480 participants completed the trial, reporting a total of 151 LASs, of which 96 were categorised as non-contact, and 50 as severe. All outcomes favoured Spraino with incidence rate ratios of 0,87 (95% CI: 0,62-1,23) for all LASs; 0,64 (95% CI: 0,42-0,98) for non-contact LASs; and 0,47 (95% CI: 0,25-0,88) for severe LASs. Time-loss per LAS was also lower in the Spraino group (1,8 vs 2,8 weeks, p=0,014). Six participants reported minor harms because of Spraino.

Conclusion: Compared to usual care, athletes allocated to Spraino had a reduced risk of LAS injury and reduced time-loss, with only few reports of minor harms. The next step is to test these promising risk reductions in a confirmatory RCT.

Trial registration: NCT03311490

Funding: Copenhagen Center for Health Technology (grant RFH-15-00013), Innovation Fund Denmark (grant 7038-00087A)