Regularity of Postural Control in Young Adults with Lateral Ankle Instability: Comparison with Healthy Individuals and Effects of a Rehabilitation Protocol

Research Type: Level 1 - Randomized controlled trial (RCT), Meta-analysis of randomized trials with homogeneous results Introduction/Purpose: Despite the frequent use of linear variables to assess postural control, there are still disagreements about the suitability of these variables to identify lateral ankle instability (LAI), document the progression of this condition, or distinguish these individuals from those without this injury. Since numerous factors contribute to adequate postural balance, non-linear analyses may be an alternative to provide more information about the postural control of individuals with LAI. Objectives: To compare the regularity of the postural control between individuals with and without LAI and between pre-post rehabilitation. Methods: Forty-two individuals participated in the study: twenty-one in the group without LAI (control) and twenty-one with LAI (intervention). Data from the intervention group were used from the clinical trial entitled “Effect of a global rehabilitation program on static postural control, dynamic stability and functionality in individuals with LAI”. Three assessments of postural control were performed using a force platform over eight weeks following the same time intervals as the cited study. The mean velocity, area, standard deviation of the displacement amplitude, and regularity (sampling entropy) of the center of pressure (COP) were calculated. Results: The intervention group showed greater COP regularity at baseline than the control group (p=0.021). After four weeks of treatment, the regularity of the intervention group decreased (p=0.018) and approached the control values, remaining the same after eight weeks (p=0.001). In the linear analysis of COP, only the mean velocity distinguished the groups (p=0.016), with a reduction after four weeks (p=0.001) and maintained in the eighth week (p=0.001) of rehabilitation. The COP area was reduced over time in the intervention (four weeks p=0.012 and eight weeks p=0.034), but the standard deviation showed no differences. Conclusion: The mean velocity and regularity distinguished the postural control of individuals with and without LAI, being greater in the LAI group. After rehabilitation, the LAI group improved postural stability, which was demonstrated by the velocity and sway area reduction. The regularity analysis highlighted that rehabilitation in the LAI group expanded the motor repertoire to deal with postural demands, indicating increased adaptability, reaching patterns similar to those without injury.