Abstract
The purpose of this study was to determine test–retest reliability of knee extensor and flexor strength measurements in elderly patients after total knee replacement. Twenty men and 16 women (mean age 70 ± 4 years; mean postsurgical time 19 ± 11 months) were tested isometrically at 45 deg flexion with a hand-held dynamometer and isokinetically at 60 deg/sec angular velocity using a Kin-Com dynamometer during two test sessions within a 2-week period. All patients were independent in activities of daily living, ambulation, and stair activities, and none had previous experience with equipment-based isometric or isokinetic tests. Isometric torques at 45 deg flexion and isokinetic peak torques were reliable (intraclass correlation coefficients > 0.75) on a single test session, whereas averaging torques over two test sessions was required to produce reliable torques at 45 deg flexion during isokinetic movements. Reliability was greater during isometric than during isokinetic tests, greater during knee extension than during knee flexion, and, during the isokinetic tests, greater for peak torques than for torques at 45 deg flexion. Future studies should examine (1) reliability during the second and third test sessions when using the present and other tests protocols, and (2) means of familiarizing the patient with the test procedures in an effort to improve reliability.