Intrinsic Predictive Factors for Ankle Sprain in Active University Students: A Prospective Study

De Noronha M, Fança LC, Haupenthal A, Nunes GS. Scandinavian Journal of Medicine and Science in Sports. 2012. [Epub ahead of print]

Ankle sprains are the leading sport injury in athletic participation.  Studies have investigated whether certain intrinsic factors (e.g., balance, arch height, range of motion [ROM], previous history) could predict ankle sprains, but data from prospective study designs are limited and inconclusive.  Some emergent themes have been demonstrated suggesting that ankle history, patient demographics, ankle sagittal plane motion, and postural control may be most influential when analyzing ankle sprain risk, but need to be further examined.  Therefore, the purpose of this study was to investigate whether certain intrinsic factors (postural control, ankle ROM, motor imagery, functional instability, history of previous sprain, and body mass index [BMI]) could predict ankle sprains in healthy, active people. A total of 121 active University students participated in this study.  They were baseline tested and then tracked for 52 weeks to determine the occurrence of ankle sprain events.  The set of tests that composed the baseline assessment included a BMI calculation, the Cumberland Ankle Instability Tool (CAIT) to assess levels of functional instability at each ankle, the Foot Lift Test to assess balance, the weight-bearing lunge test to assess dorsiflexion ROM, the Star Excursion Balance Test (SEBT) to assess dynamic balance, and the side recognition task by motor imagery to identify changes of the central nervous system linked to peripheral injuries contributing to functional ankle instability perceptions.  At the end of the study, 31 (25.6%) of the participants reported an ankle sprain.  Analysis found two intrinsic variables that could significantly predict an ankle sprain: history of previous sprain and the SEBT in the postero-lateral direction (SEBT PL).  Students who had a history of previous sprain were twice as likely to suffer a subsequent sprain.  In contrast, people with better performance on the SEBT PL were less likely to suffer a sprain.

Clinically, it is advantageous to have a comprehensive understanding of what intrinsic factors are linked to higher ankle sprain risk.  This study confirms what many have found in researching chronic ankle instability: people who suffered an ankle sprain are more likely to suffer subsequent sprains.  Unfortunately, this is not a modifiable factor.  What may be more influential on practice are the results from the SEBT.  This has been a useful tool to detect functional deficits after injury, such as those with the aforementioned chronic ankle instability.  As seen in the video link, the SEBT measures how far the patient can reach in three directions (anterior, posterior-medial, and posterior-lateral).  This study suggests that those who were able to extend the furthest in the PL direction were less likely to sprain.  Extending the limb in the PL direction will require the peroneals (fibularis muscles) to activate more in order to counteract the center of gravity shift in the medial direction and remain erect.  Delays in peroneal activation during activity have been demonstrated in patients with chronic ankle instability.  However, the connection between peroneal activation and SEBT PL is only theory and needs to be further investigated.  Moreover, it is unclear whether or not the changes in SEBT PL scores simply represent balance as a whole and may be more reflective of a reduction in functional joint position sense.  Nonetheless, using the SEBT may be a useful tool for clinicians in both the treatment of an initial ankle sprain and prevention of subsequent sprains.  We may see future research that uses this tool in the rehabilitation of ankle sprains and eventually it may be included as part of a screening tool for ankle sprain risk.  However, the question remains as to whether we can we adequately identify modifiable risk factors for ankle sprain events.  Also, thinking longer-term, will any of these prospective studies lead to effective preventative programs that can be easily implemented?  Certainly clinical practice is open to strategies, but this area of research has demonstrated that the answer is not coming quickly.

Written by: Katherine Morrison, PhD, ATC
Reviewed by: Jeffrey Driban

Related Post:

de Noronha M, França LC, Haupenthal A, & Nunes GS (2012). Intrinsic predictive factors for ankle sprain in active university students: A prospective study. Scandinavian Journal of Medicine & Science in Sports PMID: 22260485