Determining Ankle Stability in Collegiate Athletes Using the Biodex Balance System

DeLayne Rotolo, Georgia College & State University


Context: An ankle injury is the most common lower extremity injury in sports because of the amount of force that goes through the ankle. Understanding the athlete’s ankle stability can better inform a medical team on the probability of an ankle injury occurring and help to mitigate the risk. Objective: The Biodex Balance System (BBS) was used to investigate potential fluctuations in ankle stability over an athlete’s season. Design: Experimental study Patients/Participants: A total of 30 Division II college athletes (25 female, 5 male; ages 18-22) volunteered as subjects. Methods: Athlete single leg test and the Clinical Test of Sensory Interaction and Balance test were analyzed using the BBS. Stability factors examined with the BBS included: overall stability index, anterior/posterior stability index, medial/lateral stability index, eyes open/closed on a firm surface, and eyes open/closed on a foam surface. The BBS used degrees from level to determine ankle stability (higher degrees meant less stability). Baseline measures were established during the pre-season. Mid-season and post-season assessments were completed by repeating the test again at later time points (5 and 10 weeks, respectively). Data were analyzed with SPSS (general linear models, one-way ANOVAs, and Repeated ANOVAs). Results: Overall stability of the right leg increased by 1 degree at mid-season, with the left leg increasing by .6 degrees at mid-season. No significant difference was found on any of the following trials: eyes open firm surface: F(3,26)=.338, p=.798; eyes closed firm surface: F(3,26)=.352, p=.788; eyes open foam surface: F(3,26)=1.895, p=.155; eyes closed foam surface: F(3,26)=1.901, p=.154. Conclusion: There was an increase in bilateral ankle stability by mid-season, regardless of sport or sex. Discussion: Further investigation is needed to determine the cause of increased ankle stability over time.