Correlations between isokinetic knee muscle strength, postural and functional parameters in knee osteoarthritis patients

Abstract

The aim of the study was to investigate the relations between isokinetic muscle strength of the knee, postural profile and physical function in knee osteoarthritis patients. We included patients with advanced unilateral osteoarthritis (grades III or IV graded radiographically by Lawrence classification). We assessed functional impairment by the WOMAC score in its Arabic version, the strength of the knee muscles by isokinetic dynamometry and postural profile via the Satel ® platform in bipodal and monopodal conditions in open and closed eyes. The parameters were monitored: mediolateral (Long X) and anterior-posterior deviations (Long Y) of plantar center of pressure. Twenty patients with the mean age of 55.9 ± 13.0 years were evaluated. We objectified the decrease rating of isokinetic strength parameters of symptomatically knee compared to the healthy side. The mean of peak torque of the knee flexor was 46.3 ± 29.3 Nm on the symptomatic side, against 49.1 ± 34.9 on the healthy side ( P = 0.2). The mean of peak torque of the knee extensor was 61.8 ± 33.8 Nm on the symptomatic side, against 76.4 ± 47.0 Nm on the healthy side ( P = 0.04). We objectified increased postural parameters in monopodal stance on the symptomatic side compared to the healthy side in two conditions open and closed eyes. The average of the Long X in monopodal were respectively 917.1 ± 192.9 and 1472.4 ± 485.2 mm in open and closed eyes conditions of the symptomatic side and 886.8 ± 195.6 and 1303.9 ± 423.0 mm on the healthy side ( P = 0.2). The mean of The WOMAC score was 11.2 ± 3.9. A moderate correlation ( r = −0.54, P = 0.03) between the peak torque of the extensor at 60°/s and long X in monopodal stance in the symptomatic side was objectified. The correlations found between isokinetic strength and functional parameters were low. A deficit of the symptomatic knee muscles was objectified in our patients. The relations between the muscular and postural parameters were found. The one with the functional capacity was low.