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Postural Control Before And After Unexpected Inversion Perturbation In Chronic Ankle Instability, Coper, And Control

2022; Lippincott Williams & Wilkins; Volume: 54; Issue: 9S Linguagem: Inglês

10.1249/01.mss.0000877656.46420.87

1530-0315

Minsub Oh, Seunguk Han, Hyunwook Lee, J. Ty Hopkins,

Orthopedic Surgery and Rehabilitation

Context: Chronic ankle instability (CAI) patients have reduced postural control. They also may show an inability to develop successful neuromuscular control due to an unexpected perturbation. Little is known about the effect of unexpected inversion perturbations on static and dynamic balance. Purpose: To examine the effects of unexpected inversion perturbation on static and dynamic balance in CAI patients, copers, and controls. Method: Nineteen CAI patients (M = 8, F = 11; 22 ± 2 yrs, 173 ± 8 cm, 69.5 ± 10 kg), 19 copers (M = 8, F = 11; 22 ± 2 yrs, 173 ± 9 cm, 70.2 ± 10 kg), and 19 controls (M = 8, F = 11; 22 ± 2 yrs, 172 ± 10 cm, 69.4 ± 10 kg) participated. Subjects performed 3 static and dynamic balance tasks before and after unexpected inversion perturbation during single-leg drop landings onto a 25° tilted platform from a height of 30 cm. The main outcome measures were the center of pressure (COP) velocity and range from the single-leg stance and dynamic postural stability index from the jump-landing. One-way randomized block ANOVAs were used to assess differences in posttest-pretest mean differences between groups. Effect sizes were calculated as Cohen's D. Results: Relative to controls, the CAI group showed no differences in anterior-posterior and vertical stability indices (-0.01 ± 0.02 vs. 0.00 ± 0.01, p = 0.10; 0.05 ± 0.07 vs. 0.00 ± 0.07, p = 0.08, respectively), while they showed medium effect sizes for both variables (d = -0.71 and 0.73, respectively). In the static balance, the CAI group showed higher differences in COP velocity and range in the sagittal plane (0.17 ± 0.19 vs. 0.01 ± 0.15, p < 0.05; 0.03 ± 0.05 vs. -0.03 ± 0.09, p < 0.05, respectively) than the copers with large effects (d = 0.83 and 0.83, respectively). Conclusions: The CAI group displayed decreased static and dynamic balance after unexpected perturbation. The current data suggest that the decreased balance in CAI patients may reflect a decreased ability for neuromuscular adaptation to unanticipated inversion perturbation compared to copers and controls.