Effects of immobilization on plantar-flexion torque, fatigue resistance, and functional ability following an ankle fracture.
OBJECTIVE
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.


METHODS
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.


CONCLUSIONS
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.
Occuptional and Physical Therapy Department, Hospital of the University of Pennsylvania, Philadelphia, USA. mshaffer@iastate.edu.
M A
MA
Shaffer
E
E
Okereke
J L
JL
Esterhai
M A
MA
Elliott
G A
GA
Walker
S H
SH
Yim
K
K
Vandenborne
D000328:Adult; D016512:Ankle Injuries / Q000534:rehabilitation* / Q000601:surgery; D001696:Biomechanical Phenomena; D002370:Casts, Surgical / Q000009:adverse effects; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods; D050723:Fractures, Bone / Q000534:rehabilitation* / Q000601:surgery; D005684:Gait / Q000502:physiology*; D006801:Humans; D007103:Immobilization / Q000009:adverse effects*; D007537:Isometric Contraction; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010147:Pain Measurement; D026741:Physical Therapy Modalities / Q000379:methods*; D016059:Range of Motion, Articular; D012016:Reference Values; D012044:Regression Analysis