Introduction

Lateral ankle sprains are common injuries and occur more frequently in active sporting individuals. The recurrence rate is high, which is thought to result from the lack of definite return to sports (RTS) criteria. As such, many individuals return too early and may experience another instability episode. If accumulated too often, it can lead to chronic ankle instability. Therefore, this study wanted to develop a tool to objectively predict RTS after lateral ankle sprain. This would help in the decision-making for determining who is ready for RTS after an acute lateral ankle sprain.

Methods

This was a prospective study that included participants who had suffered an acute lateral ankle sprain. It didn’t matter whether this was their first or a recurrent ankle sprain but they were only eligible when they practiced a sport at least once a week. They were included in this study within one month after the sprain occurred. All the participants had to have the desire to re-participate in their usual sporting activities.

Their ankle was examined clinically to confirm no syndesmosis injury was coexisting. In case the patient was suspected to have a syndesmosis injury, they were excluded. Only participants with an acute lateral ankle sprain were thus included. They all received a prescription for physiotherapy rehabilitation for 4 months.

To Predict RTS after lateral ankle sprain, the authors developed the Ankle-Go composite score based on existing evidence. They consulted the literature to define the main deficits associated with a lateral ankle sprain or chronic ankle instability and the risk of re-injury. Four functional tests and two patient-reported outcomes were selected.

• Single-leg stance test (SLS) on a firm surface
• Modified star excursion balance test (mSEBT)
• Side hop test (SHT)
• Figure-of-8 test (F8T)
• Foot and Ankle Ability Measure involving 2 subscales evaluating activities of daily living (FAAM-adl) and sports (FAAM-sport)
• Ankle Ligament Reconstruction-Return to Sport after Injury (ALR-RSI): This measures psychological readiness to RTS in patients with an injured ankle.

At 2 and 4 months after inclusion, the Ankle-Go test was administered and the participants were asked whether they had returned to their preinjury sport. They were compared against 30 control participants who were also regularly participating in sports and who had no history of lower limb injuries.

The primary objective of this study was to evaluate the psychometric properties of the Ankle-Go score and its predictive ability for RTS at the same level of play after an acute lateral ankle sprain. Therefore, the authors assessed:

• The floor or ceiling effects
• The internal consistency
• The construct validity
• The test-retest reliability and sensitivity to change
• The discriminant validity
• The predictive validity

Results

Sixty-four participants were included in this study. The patients with an ankle sprain and the healthy controls had a similar baseline age. There were slightly more males compared to females in the control group. The patients with the ankle injury were more active and achieved more hours of intensive sports per week.

At 2 and 4 months, the participants with the ankle sprain and the control group underwent the Ankle-Go testing.

Half of the participants who sustained an ankle sprain returned to their preinjury level of sport at 4 months. The Ankle-Go score measured at 2 months had a good predictive value to predict RTS after lateral ankle sprain at 4 months. The area under the curve (AUC) was 0.77 (95% CI, 0.64-0.88). The authors found 8 points to be the cut-off point since it corresponds to a sensitivity of 72% and a specificity of 66%.

Nearly twenty percent of the ankle-injured participants did not return to their pre-injury sport level at 4 months. The Ankle-Go score at two months had a good predictive capacity to predict no RTS after lateral ankle sprain at 4 months. The AUC was also 0.77 (95% CI, 0.65-0.89). Seven points were considered the cut-off score since it corresponded to a sensitivity of 67% and a specificity of 92%.

Questions and thoughts

There is a high recurrence rate of ankle sprains. A study by Medina McKeon found that approximately 90% of athletes who suffered from a first or recurrent ankle sprain returned to participation within a week. Probably this is one of the reasons for a high recurrence rate since we know that it takes 6 to 12 weeks for the ligaments to heal.

Only participants who desired to return to their sporting activities were included in the study. In this prospective study, I think that this led to an excellent completion rate, as all participants were 100% compliant. It seems as if this population was extremely motivated to participate in their usual sporting activities again after they sustained a lateral ankle sprain. Therefore, you could probably better use it with participants who consult you with the same desire.

The physiotherapy sessions were not described in this study. There was no “standardized” protocol, which is good as this led to a case-by-case rehabilitation plan with individualized sessions. But at the same time, we don’t know what type of physiotherapy was administered. The same remark can be made for the severity of the lateral ankle sprain. We don’t know what grade of ankle sprain occurred, nor what exact ligaments were affected. The only thing we know here is that someone with a syndesmosis injury was excluded from participating in the trial.

The participants who returned to their sport at the same preinjury level or higher at 4 months had scores that were significantly lower than those of the control group, meaning that they may not have fully recovered at that time point. The item leading to this difference is the ALR-RSI, measuring psychological readiness. This score was markedly lower than in controls (80.9% vs 96.1%). Therefore, assessing the psychological readiness for RTS during rehabilitation in patients suffering from a lateral ankle sprain seems very important.

The composite modified Star Excursion Balance test score and the score on the FAAM-sport questionnaire were also lower in those who RTS after lateral ankle sprain compared to healthy controls. This means that there are ongoing difficulties when the athletes return to their pre-injury level of sport. In this light, a lengthy physiotherapy follow-up evaluation may be necessary after 4 months.

Talk nerdy to me

The main objective of this study was to examine the psychometric properties of the Ankle-Go score and this resulted in:

• A good internal consistency of the Ankle-Go
• An excellent test-retest reliability
• A standard error of 0.41 points and an MDC of 1.2 points
• No floor or ceiling effects

The authors indicate that the test has a good predictive value for predicting 4-month RTS after lateral ankle sprain and no RTS. However, the Youden index, which is the indicator of the performance (the larger the better) of the Ankle-Go prediction at a given cutoff, was low.

• With 0.38 for 8 points being predictive for RTS at 4 months and 0.44 for predicting no RTS at 4 months with a score of 7, the Youden index was closer to the null value, meaning that it was closer to having no predictive value.
• This Youden index ranges from 0-1, and clearly, a score below 0.5 indicates an overall lack of the test to discriminate between those who RTS and those not.
• As such, the cut-off point for having an acceptable Youden index is 50% or 0.5.

The Ankle-Go score was developed according to available evidence regarding their ability to detect differences among patients with ankle sprains. The scoring items were given a particular weight, based on the level of evidence that existed in a certain item. Therefore, the mSEBT was assigned a higher number of points. This also means that the Ankle-Go score might still change as evidence of the other items might change in the future.

A limitation of this study is that the severity of ligament injuries was not considered. However, this information is not always accessible to the clinician. We do not know the exact injury characteristics of the studied sample and the outcomes might change when another population is studied. Possibly, this tool can be used along a different spectrum of injuries, but it remains uncertain up to now.

The return to the pre-injury level of sport was predicted, however, the study did not assess parameters on the performance of the athlete. How well did the athlete perform under fatigue for example? In this light, the Ankle-Go score might be useful to make evidence-based decisions about RTS but possibly isn’t assessing the criteria for return to performance.

The scope of this study was to provide an evidence-based tool to predict RTS after lateral ankle sprain. The authors indicated that this was necessary since there are many recurrences of lateral ankle sprains and many develop chronic ankle instability. They stated that no validated criteria for RTS were available. The only evidence here exists in the PAASS criteria, which were derived from consensus by the International Ankle Consortium. We published a blog earlier, describing this consensus statement. Read it here.

In this first step, it became clear that the tool had good psychometric properties. The use of this tool should be further examined to determine its predictive capability since this requires a validation study in a different sample. When the results are results are reproducible, ideally, this should be followed by an impact analysis to determine if this prediction model improves patient outcomes and then, it can finally be implemented in real-life practice.

Take home messages

When someone performs the Ankle-Go test battery at 2 months after they sustained a sprained ankle, a score of 8 has a specificity of 0.66 for RTS at 4 months. Clinically, this means that patients who do not reach a score of 8 points at 2 months are unlikely to return to their preinjury level of sport at 4 months. When patients achieve a score of 7 or less at two months, their probability of RTS after lateral ankle sprain at 4 months is low. You can use this target score to adjust the rehabilitation process. When your patient scores below 7 at two months, the rehab should be adapted to address the specific functional difficulties leading to the lower Ankle-Go score. This can further lead your decision-making process in the clearance of athletes to RTS. Importantly, the current study did not test return-to-performance. You can use the Ankle-Go tool at anklego.com

Reference

Picot B, Lopes R, Rauline G, Fourchet F, Hardy A. Development and Validation of the Ankle-GO Score for Discriminating and Predicting Return-to-Sport Outcomes After Lateral Ankle Sprain. Sports Health. 2024 Jan-Feb;16(1):47-57. doi: 10.1177/19417381231183647. Epub 2023 Jul 11. PMID: 37434508; PMCID: PMC10732116.