Effects of Swelling on Static and Dynamic Postural Control and Patient-Reported Outcomes in Individuals With Chronic Ankle Instability

Objective: To investigate the effects of swelling on postural control and patient-reported outcomes in individuals with chronic ankle instability (CAI). Design: Cross-sectional study. Setting: Controlled laboratory. Participants: A total of 60 participants—20 CAI individuals with swelling (swelling), 20 CAI individuals without swelling (nonswelling), and 20 healthy controls (control)—were recruited. Independent Variables: Group (swelling, nonswelling, and control). Main Outcome Measures: Participants performed 3 trials of single-leg hop-to-stabilization and single-leg stance tasks, along with patient-reported outcomes. A one-way analysis of variance was used to assess group differences in dynamic and static postural control and patient-reported outcomes. Results: The swelling group exhibited worse dynamic postural control in vertical stability index and dynamic postural stability index compared with the nonswelling ( P = 0.03, P = 0.04) and control ( P < 0.01 and P < 0.01) groups. The nonswelling group showed similar dynamic postural control with the control group. Swelling ( P < 0.01 and P < 0.01) and nonswelling ( P = 0.01 and P < 0.01) groups showed worse static postural control center of pressure mediolateral velocity and center of pressure anteroposterior velocity compared with the control group. Swelling and nonswelling groups showed differences in patient-reported outcomes about ankle function and instability compared with the control group, but there was no difference in patient-reported outcomes between the swelling and nonswelling groups themselves. Conclusion: Ankle swelling contributes to altered neuromuscular control, resulting in worse dynamic postural control, but affects neither static postural control nor patient-reported outcomes in CAI individuals.