Sports Medicine Research: In the Lab & In the Field: Simple Balance Test Is Able To Identify Non Contact Lower Extremity Injury Risk (Sports Med Res)
Wednesday, April 19, 2017

Simple Balance Test Is Able To Identify Non Contact Lower Extremity Injury Risk

Star Excursion Balance Test Anterior Asymmetry is Associated with Injury Status in Division I Collegiate Athletes

Stiffler MR, Bell DR, Sanfilippo JL, Hetzel SJ, Pickett KA, Heiderscheit BC. J Orthop Sports Phys Ther. 2017; 29:1-27.

Take Home Message: A clinician could use Star Excursion Balance Test anterior asymmetries to possibly differentiate collegiate athletes at greater risk for non-contact knee or ankle injury.

Clinicians use the Star Excursion Balance Test (SEBT) to identify athletes at risk for lower extremity injury. However, athletes’ performance on SEBT has been inconsistent across populations. Factors such as sex and type of sport the athlete plays may contribute to this discrepancy. It is unclear if these factors affect the relationship between SEBT score and risk of injury. Therefore, the authors retrospectively evaluated whether preseason SEBT scores from 147 healthy athletes were related to who experienced a non-contact knee or ankle injury during a season, while controlling for sport, sex, and athletic exposure (starter vs. non starter). Injury was defined as any acute, non-contact, musculoskeletal condition at the knee or ankle sustained during sport participation and required the athlete to be removed for at least 1 day. Among 147 athletes 29 of them experienced an injury. The authors found that dominant limb of the injured group on average had lower reach distances in the anterior direction and a lower composite score (average of the 3 reach directions) compared with the uninjured group. All non-dominant limb reach scores were lower in injured group compared to uninjured. When the authors evaluated the side-to-side asymmetry measures they found that the anterior reach distance was different between groups. However, when accounting for sex, sport, and athletic exposure only the anterior direction asymmetry discriminated between athletes who would or would not develop an injury.

These findings are noteworthy as these authors are one of the first to determine that the SEBT, especially the anterior reach side-to-side asymmetry measure, may be a robust screening method to discriminate between athletes at risk for lower extremity injury. The author’s primary finding was that side-to-side asymmetry in the anterior reach direction (absolute or normalized limb length) was associated with non-contact knee or ankle injury independent of sport, sex, or athletic exposure. More prospective research needs to be conducted to confirm these findings and ascertain a specific cut point for high risk versus low risk athletes. Also, it should be noted that the only excluding factor related to injury history was surgical intervention. They did not exclude anyone with previous ankle sprains, which could also alter results based on previous research, which indicated the SEBT can differentiate those at risk for chronic ankle instability. Finally, it would be valuable to know if sex, sport, starting status, or chronic ankle instability modify the association between SEBT scores and injury risk. For example, the SEBT score may predict who is at risk among soccer players but not among softball players. In the meantime, medical professionals can use the SEBT as one aspect of their screening to help identify athletes at risk for non-contact lower extremity injuries.

Question for Discussion: Do you use SEBT as part of a screen to detect athletes at risk for non-contact lower extremity injuries? If so, has it been helpful? What other screening tools do you currently use?

Written by: Jane McDevitt, PhD
Reviewed by: Jeff Driban

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Anonymous said...

The model coefficient and odds ratios in the paper speak to your comment re: knowing if sex, sport, and starting status modify the association. For example, an odds ratio of 0.0 for hockey tells us that there is virtually no greater risk of non-contact injury with increasing SEBT asymmetry in that hockey. For football, on the other hand, an odds ratio of 10.6 suggests that there is a much greater risk of injury with increased asymmetry (as compared to basketball, the reference sport). You can infer from the data, then, that using the SEBT to identify those at risk for non-contact injuries in hockey is not useful, while it may be more useful in sports such as football, and to a lesser degree, soccer and wrestling.

Jeffrey Driban said...

Thanks for the comment. Was the model set up as injury = football + SEBT data; If so, doesn't the odds ratio for hockey and football indicate the odds of athletes in those sports having the outcome (injury) after controlling for balance data? Jane and I were thinking of a traditional moderation analysis in which the analyses are performed stratified by sport (e.g., relationship btwen SEBT and injury within football).

Hot Shots said...

Ah, I see what you were getting at - analyzing sports separately. Based on injury numbers and sample size, I don't think the data set presented in the paper would have been statistically powered to predict injury within a single sport. To get enough power to do that analyses, multiple years of data would need to be pulled, which could present other issues of differing exposure between seasons (e.g. making post-season one year but not the next), different strength and conditioning programs, and potentially a few coaching changes which could all influence the injury outcomes year to year. The data presented in the paper does make it easier to account for sport with "all other things equal", but also to account for asymmetry with "all other things equal" e.g. if you have 2 starters on the football team, the one with more asymmetry will be more likely to be injured.

Tyler Keith said...

This article provides for an interesting outcome associated to the SEBT. Due to the retrospective nature of this study it can be difficult to associate increased injury prevalence with diminished anterior reach distance, but obviously the relationship is there. The main thought that I have, is the biomechanical discrepancies between those with a further anterior reach that make them less likely (according to these results) to suffer an injury compared to those with decreased reach lengths.

Previous literature has suggested that their are different balancing techniques/strategies associated with the different reach directions of the SEBT. For example, it seems as though the anterior reach is mostly associated with the distal movers, specifically the ankle, as well as the knee. The posterior reaches are more associated with proximal segments such as the hip. Previous research also suggests that the weight bearing lunge test (WBLT) is correlated with anterior reach of the SEBT, where decreased WBLT is correlated with decreased anterior reach. It may be that the SEBT can serve as a screening for athletes as suggested by the article, however it may be overlooking something. Simply put, these same athletes may have morphological differences, or may have different functional ranges of motion (such as decreased WBLT) that is manifesting itself as decreased anterior reaches. Perhaps these athletes simply have decreased weight bearing dorsiflexion range of motion, and that is what is leading to their increased injury risk.

Although this article provides some important/interesting results, they do not fully explain the differences between groups. To be used as an effective screening tool, clinicians must identify where the differences between groups are coming from, and the discrepancies must be addressed to effectively help prevent injuries in our athletes.

Jane McDevitt said...

Hot Shot,
I agree they need a larger prospective cohort, and there are plenty of other factors that could alter the SEBT. However, I do think they provided the platform to have these conversations.

Tyler Keith,
I think you brought up a great point. Range of motion should also be considered because the lack of anterior or posterior reach may be decreased due to that and I think given the SEBT score and ROM they would end up giving us some more solid ground on whether they are at risk of injury. It would lead to a much longer test, but I think would be helpful in discerning group differences.

Abbis Haider said...

This looks like an interesting study where SEBT is used for identifying risk of injury in athletes. I think I agree with the above comment of Tyler where he has mentioned the use of Knee-to-Wall test to see the functional ROM of the athletes and see if we see any deficits in knee-to-wall test. The other thing I will bring to spotlight is what if you find lower anterior reach scores of athletes before the season starts. What will you do about it? will you do emphasize more on balance training or will just work on gaining the ROM. So we need to identify what is missing? and then gear our rehabilitation towards it. It has been reported previously (Pionner et al.2016) that CAI subjects who showed lower reach distances also had lower ROM`s. So I think we need to really understand that from where these deficits are coming from to really focus on the rehabilitation plan that we devise to target these athletes.

Jane McDevitt said...

I agree this test should be used to determine the athlete's asymmetries and adjust rehabilitation protocols as necessary. I think a study that identifies asymmetries and implements a rehab protocol could help us determine the effectiveness of the SEBT as well as the best approach to addressing these issues. This could also help educate athletes on the need to go through screening such as SEBT and the need to stick to the rehab protocol.

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