Dynamic postural stability in subjects with braced, functionally unstable ankles

Context: Research concerning prophylactic ankle stabilizers (PASs) has focused on healthy subjects, and the results cannot be generalized to the functional ankle instability (FAI) population, a population that has an increased risk of reinjury and is likely to wear PASs. Objective: To determine whether PASs improve dynamic postural stability in FAI subjects as compared with a control (no-brace) condition. Design: A crossover design was used to determine the effects of PASs on dynamic postural stability and vertical ground reaction forces. Setting: Biomechanics laboratory. Patients or Other Participants: Twenty-eight subjects with unilateral FAI, 13 men (age = 21.5 +/- 1.2 years, height = 181.5 +/- 10.5 cm, mass = 77.6 +/- 17.2 kg) and 15 women (age = 20.5 +/- 1.1 years, height = 169.4 +/- 8.2 cm, mass = 67.9 +/- 8.8 kg). Intervention(s): A jump protocol required subjects to perform a 2-legged jump to a height equivalent to 50% of their maximum vertical leap and land on a single leg. Main Outcome Measure(s): The dynamic postural stability index, the directional components (medial-lateral, anterior-posterior, and vertical), and vertical ground reaction force after a jump landing. Results: Compared with the control condition, only the vertical component score was reduced (improved) with the application of a soft or semirigid PAS (P < .01). Conclusions: Soft and semirigid PASs did not improve dynamic postural stability as measured by the Dynamic Postural Stability Index. However, PASs may help with the attenuation of vertical forces.