Abstract
Following a lateral ankle sprain, many patients develop chronic ankle instability (CAI). CAI is a heterogeneous condition that characterizes lateral ankle sprain patients who still have decreased self-reported function, recurrent sprains and feelings of instability for greater than one year following their initial sprain. CAI is a multi-faceted condition and thus researchers have developed a rehabilitation algorithm to aid in the assessment and treatment of the most common CAI impairments. Within the ‘assess – treat – reassess’ paradigm there are four broad areas that encompass the primary clinical manifestations CAI patients exhibit. These impairment domains include deficits in range of motion, strength, postural control, and altered biomechanics during functional tasks such as walking, running, or landing from a jump. Range of motion deficits are related to arthro- or osteokinematic restrictions and joint mobilization or calf stretching are highly efficacious at restoring normal range of motion in CAI patients. Strength deficits with CAI are associated with smaller shank muscle volumes and rehabilitation is effective at improving muscle strength. However, there is currently no evidence to suggest whether improved ankle strength with rehabilitation is related to muscle hypertrophy. Therefore we aimed to analyze the effects of impairment-based rehabilitation on muscle strength and foot and ankle muscle volumes in CAI patients as part of this dissertation (Study 2).
Furthermore, it has been theorized that targeting the less functional impairments of range of motion, strength, and postural control might be a sufficient approach to rehabilitation and that gains in those impairment domains may translate into improved gait and jump landing mechanics in CAI patients. We previously demonstrated that those less functional improvements do not translate into improved gait patterns and as part of this dissertation we aimed to assess whether impairment-based rehabilitation could improve jump-landing mechanics in CAI patients (Study 1). Lastly, since impairment-based rehabilitation is insufficient at restoring normal gait mechanics, our final aim was to analyze the effects of gait training with a novel gait training device on measures of plantar pressure and surface electromyography in CAI patients (Study 3).
Following impairment-based rehabilitation, CAI patients demonstrated large and meaningful improvements in shank muscle volumes and four-way ankle strength. Unfortunately, we only identified minimal improvements in landing biomechanics and none of the improvements were prior to or during ground contact, which have been shown to be very important factors that will dictate whether or not an ankle sprain occurs. The CAI patients who received gait retraining demonstrated large and meaningful improvements in the location of their center of pressure during the stance phase of gait due to increased peroneus longus muscle activity during midstance. Furthermore, comprehensive impairment-based rehabilitation and gait training alone were both able to substantially improve self-reported outcomes for CAI patients. Based on these collective results, we recommend supplementing impairment-based rehabilitation with gait training to maximize improvements in self-reported function. Furthermore, we recommend future research analyze the effect of augmented biofeedback on jump-landing strategies in CAI patients as the improvements in range of motion, strength, and postural control seen in these same CAI patients did not manifest into meaningful improvements in landing strategies post-rehabilitation.
