Thesis: Ankle sprain prevention - from evidence, via practice, to the athlete

On Wednesday September 7th, Kasper Janssen will defend his PhD thesis "Brace versus Balance Board", on the cost-effectiveness of preventive measures against secondary ankle ligament injuries. Prevention of ankle sprains could preserve health in people who participate in high-risk sports and in those who have suffered a previous ankle ligament injury. Chapter 2 of this thesis summarizes all the available evidence on the effectiveness of measures to prevent ankle sprains in athletes. Based on the available evidence, neuromuscular (NM) training and bracing were considered the two main secondary preventive interventions for further research. Subsequently, chapter 3 to 5 present the design and results of the first RCT that evaluated, following usual care, the (cost-)effectiveness of combined bracing and NM training, versus stand-alone bracing, versus the use of NM training, with recurrences of ankle sprain as the primary outcome. Chapter 6 provides a secondary analysis of the compliance with these interventions to reveal potential predictors of this compliance. In chapter 7 a user survey of three different ankle braces in soccer, volleyball and running describes subjective factors that can influence the acceptability of ankle brace use by athletes.  

Recommendations and implications for athletes and practitioners

The present thesis showed that bracing is superior to NM training in reducing the incidence of self-reported recurrences, but not the severity. Bracing is associated with an added 47% reduction in risk of recurrence, versus NM training. Although the current clinical guidelines are vague on the prescription of NM training and bracing, our study results support the prescription of bracing as single secondary preventive measure for the prevention of self-reported recurrences. In addition, bracing provides not only a more effective measure as a single intervention, but also a less expensive one. As in our study bracing was shown to be effective when prescribed during sports for 12 months, the prescription period of brace use in athletes needs to be extended, instead of being phased out. In the first 2 months full compliance to NM training and bracing as individual home-based interventions was 45% and 48%, respectively. However, when the interventions were combined the compliance dropped to 28%. Combined prescription of these interventions is therefore discouraged, unless carefully considered by the treating practitioner for ‘additional’ purposes other than prevention of recurrences, like persisting pain, feeling of giving way, return to sport and performance in sport, or chronic ankle instability (CAI). It is important to remark that the superiority of bracing over NM training with respect to prevention of recurrences does not imply that NM training is obsolete for ankle sprain prevention. Firstly, the superiority of bracing over NM training is only valid on a population level. When it comes to preventive advise to an individual athlete, intrinsic, extrinsic, situational and psychological factors are to be incorporated. Secondly, the mentioned ‘additional’ purposes also apply to NM training prescription and should be valued individually.

The current work demonstrated that a major factor to account for when prescribing measures for ankle sprain prevention is compliance. Having had a previous ankle sprain, i.e. before the index ankle sprain, increases the likelihood of a higher compliance with any of the interventions. Athletes without a history of previous ankle sprain and athletes who did not previously perform NM training are substantially less likely to comply with NM training. In contrast, athletes who participate in a sport that is high-risk for sustaining an ankle sprain, like soccer, basketball, and volleyball, are substantially more likely to comply with wearing a brace during sports. For these reasons, practitioners prescribing preventive NM training or bracing should take into account “history of previous ankle sprains”, “history of experience with NM training”, and “high- or low-risk sport participation” for sustaining an ankle sprain, to optimize compliance with these interventions.

Finally, it was shown that modern ankle braces-types all score high on perceived ease of use and perceived quality. However, the brace types significantly differ with respect to subjective evaluation of comfort, stability, hindrance, overall satisfaction and willingness to buy the brace. Soccer players and runners prefer a compression brace over a sem-rigid brace, while volleyball players prefer a lace-up brace over a semi-rigid brace. These results need to be disseminated in athletes, sporting clubs, coaches and practitioners, thus promoting selection of an optimal ankle brace for individual ankle sprain prevention. Other studies have shown that prescribing an App-based preventive NM training program is a valid option, when compared to written advice. If brace advise is also efficacious if given via an App remains to be proven.

Following the current trend for patient centered-care, preventive advice should take in account individual needs and preferences of the athlete. Athletes should have the opportunity to make informed decisions about their treatment and preventive interventions, if applicable, in partnership with their (sports medicine) practitioner or coach. Introducing the knowledge transfer scheme for use in ankle sprain prevention by the Dutch Association of Sports Medicine created a compact, but comprehensive and integrated, advice on treatment and prevention of ankle sprains in sport, for use by individual athletes. In a focus group meeting athletes concluded that preventive advise needs to be linked to treatment advise for ankle sprains to create a window of opportunity for initiation of preventive behaviour. An ankle SPRain INtervention Timeline (SPRINT) infographic was developed to present this integrated preventive advice to athletes via social and other media. GP’s, sports medicine practitioners, coaches and sporting clubs can use this timeline to inform and guide an informed decision for preventive bracing, NM  training, or even taping.

Challenges for future research

The results of this thesis create new insights in the effectiveness and cost-effectiveness of bracing, versus NM training, versus a combination of these two interventions. Furthermore, this thesis presents new potential predictors for compliance with NM training and brace use and quantifies subjective factors that may help to enhance adoption of bracing. Nevertheless, this thesis also displays new challenges for future research. Based on the outcomes of this thesis the following is recommended for future research:

  • To perform more randomized controlled trials on bracing versus NM training for prevention of ankle sprain recurrences to support our findings, including clinical and athlete consequences of ankle sprains, like persisting pain, feeling of giving way, return to sport and performance in sport, chronic ankle instability (CAI) and osteoarthritis.
  • To design a practitioner-centred App to guide brace, tape and NM training prescription, and to evaluate effects on preventive ankle sprain advice, linked to initial treatment of the index sprain.
  • To adequately monitor and report compliance in future investigations on NM training and bracing.
  • To perform an implementation study on interventions preventing ankle sprains (bracing, NM training and taping) with an athlete-centered approach, wherein the informed athlete is allowed to select the intervention.
  • To determine optimal duration of ankle bracing for secondary prevention of ankle sprains in sport. Specifically, long term follow-up is necessary to determine of life-long preventive bracing is necessary in high-risk sports.
  • To establish the pathway through which bracing reduces the risk of ankle sprain occurrence and recurrence.
  • To confirm the value of potential predictors of compliance to bracing and NM training in different sports.
  • To evaluate the effect of a compression & figure-of-eight strap brace on the risk of ankle sprain recurrences in different sports (for example soccer and running).
  • To perform a RE-AIM analyses of the reach of educational material on ankle sprain prevention (like the Ankle SPRINT infographic), for example testing the influence of the material on the misbelieve of ‘weakening ankle ligaments by bracing’.