No abstract

Chronic ankle instability (CAI) results in longstanding symptoms and subjective feelings of "giving way" following initial ankle sprain. Our purpose was to identify differences in joint coupling and variability between shank internal/external rotation and rearfoot inversion/eversion throughout the gait cycle of CAI subjects and healthy controls. Twenty-eight young adults participated (CAI, n = 15, control, n = 13). Kinematics were collected while walking and jogging on a treadmill. A vector coding method in which direction (θ) and magnitude of the angle-angle relationship and stride-to-stride variability (VCV) in shank-rearfoot coupling were calculated. In walking, the CAI group demonstrated lower θ, indicating a greater proportion of rearfoot-to-shank motion, compared with the control group in early and late swing. The CAI group had higher magnitude, indicating greater combined motion between the two segments, in early swing, but lower magnitude, indicating less combined motion, during late swing. The CAI group also had lower VCV measures, indicating less stride-to-stride variability during stance. In jogging, the CAI group had lower θ measures than the control group during stance and swing. Differences in shank-rearfoot coupling of the CAI group may be related to changes in sensorimotor control and lead to further instances of instability.

In those with chronic ankle instability, taping resulted in a more neutral ankle position during walking and jogging in shoes on a treadmill. This change in foot positioning and the mechanical properties of the tape may explain the protective aspect of taping in preventing lateral ankle sprains.

Foot and ankle injuries are extremely common among athletes and other physically active individuals. Rehabilitation programs that emphasize the use of therapeutic exercise to restore joint range of motion, muscle strength, neuromuscular coordination, and gait mechanics have been shown to have clinical success for patients suffering various foot and ankle pathologies. Rehabilitation programs are discussed for ankle sprains, plantar fasciitis, Achilles tendonitis, and turf toe.

Context: Chronic ankle instability (CAI) occurs in some people after a lateral ankle sprain and often results in residual feelings of instability and episodes of the ankle's giving way. Compared with healthy people, patients with CAI demonstrated poor postural control and used a more anteriorly and laterally positioned center of pressure (COP) during a single-limb staticbalance task on a force plate. Balance training is an effective means of altering traditional COP measures; however, whether the overall location of the COP distribution under the foot also changes is unknown.Objective: To determine if the spatial locations of COP data points in participants with CAI change after a 4-week balancetraining program.Design: Randomized controlled trial. Setting: Laboratory.Patients or Other Participants: Thirty-one persons with self-reported CAI.Intervention(s): Participants were randomly assigned to a 4-week balance-training program or no balance training.Main Outcome Measure(s): We collected a total of 500 COP data points while participants balanced using a single limb on a force plate during a 10-second trial. The location of each COP data point relative to the geometric center of the foot was determined, and the frequency count in 4 sections (anteromedial, anterolateral, posteromedial, posterolateral) was analyzed for differences between groups.Results: Overall, COP position in the balance-training group shifted from being more anterior to less anterior in both eyes-open trials (before trial ¼ 319.1 6 165.4, after trial ¼ 160.5 6 149.5; P ¼ .006) and eyes-closed trials (before trial ¼ 387.9 6 123.8, after trial ¼ 189.4 6 102.9; P , .001). The COP for the group that did not perform balance training remained the same in the eyes-open trials (before trial ¼ 214.1 6 193.3, after trial ¼ 230.0 6 176.3; P ¼ .54) and eyes-closed trials (before trial ¼ 326.9 6 134.3, after trial ¼ 338.2 6 126.1; P ¼ .69).Conclusions: In participants with CAI, the balance-training program shifted the COP location from anterolateral to posterolateral. The program may have repaired some of the damaged sensorimotor system pathways, resulting in a more optimally functioning and less constrained system. Key Words: sprains, rehabilitation, postural control Key PointsA 4-week progressive balance-training program effectively altered the spatial locations of center-of-pressure data points in participants with chronic ankle instability. The alteration in the spatial locations of center-of-pressure data points may indicate a more optimally functioning sensorimotor system.