Shank-Rearfoot Joint Coupling with Chronic Ankle Instability

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.

Does the amount of lower extremity movement variability differ between injured and uninjured populations? A systematic review

“…Overall findings revealed that 73% (n = 16/22) of studies reported a statistically significant difference in at least one dependent variable used to examine movement variability between injured subjects and uninjured controls. Injured subject groups demonstrated greater variability in 64% (n = 14/22) of the studies, reduced variability in 27% (n = 6/22), and no difference between groups was evident in 27% (n = 6/22) . Table presents the percentage of studies reporting greater, less, or no difference in variability when comparing injured subjects to uninjured controls.…”

“…In the studies investigating single specific injuries, 88% (n = 14/16) reported significant between‐group differences. Of these, greater variability was evident in 75% (n = 12/16), reduced variability in 31% (n = 5/16), while 13% (n = 2/16) reported no significant differences between injured and uninjured groups . Table presents the breakdown of findings when specific injury types were group together.…”

“…The ankle was the next most commonly examined injury location with 23% (n = 5/22) of all studies . Significant between‐group findings were evident in 80% of these (n = 4/5) studies, with greater variability reported in the injured group in 60% (n = 3/5), reduced variability in 40% (n = 2/5), and no difference in 20% (n = 1/5) …”

“…Continuous measures were examined for variability in 68% (n = 15/22) of studies . Significant findings were reported in 73% (n = 11/15).…”

“…It has been postulated within the framework of dynamic systems theory that reduced variability during movement might lead to repetitive loading on a specific tissue structure resulting in excessive stress and eventual injury . Several authors have provided further support for the association between injury and reduced variability in various injured groups including chronic ankle instability and patellar tendinopathy …”