Effects of Immobilization on Plantar-Flexion Torque, Fatigue Resistance, and Functional Ability Following an Ankle Fracture

Open Access
Publisher Website
Google Scholar
Abstract
Background and Purpose. The goal of this investigation was to study the recovery of ankle plantar-flexor peak torque, fatigue resistance, and functional ability (stair climbing, walking) following cast immobilization in patients with ankle fractures. Subjects. The participants were 10 patients who underwent open reduction-internal fixation and 8 weeks of cast immobilization following a fracture of the ankle mortise and 10 age- and sex-matched, noninjured comparison subjects. Methods. Plantar-flexor torque and fatigue resistance were measured at 1, 5, and 10 weeks of rehabilitation using an isokinetic dynamometer. Ankle plantar-flexor peak torque and fatigue resistance were correlated to timed ambulation, timed stair climbing, and unilateral heel-rises. Results. Following immobilization, plantar-flexor peak torque was decreased at all angular speeds and positions. The decrease in peak torque was associated with an increase in fatigue resistance. With rehabilitation, ankle plantar-flexor torque and fatigue resistance normalized. Regression analysis revealed a strong relationship between plantar-flexor peak torque and functional measures. By 10 weeks post-immobilization, peak torque, fatigue resistance, and all measures of functional performance had returned to control levels. Conclusion and Discussion. The decrease in muscle performance, functional ability, and fatigue resistance induced by 8 weeks of cast immobilization can be reversed with 10 weeks of supervised physical therapy. In addition, this study demonstrated that ankle-plantar flexor torque is a good predictor of stair-climbing and walking performance in patients with ankle fractures.