Validity and reliability of the measurement of the quardriceps femoris muscle strength with a hand-held dynamometer on the affected side in hemiplegic patients.

The purpose of this study was to investigate validity and reliability of measuring the quadriceps femoris muscle strength on the affected side in hemiplegic patients with a hand-held dynamometer(HHD) to prepare for a multi-center cooperative study. Measurements of the known weights(8.972 and 18.665 kg) with HHD were 8.98 +/- 0.00 kg and 18.57 +/- 0.00 kg, respectively, and measurements with HHD were almost consistent with those with KIN-COM (gold standard), because the Pearson's product-moment correlation coefficient was 0.99 (P < 0.001). There were significant differences in measurements of the quadriceps femoris muscle strength on the affected side in a hemiplegic patient between just anterior to the face of the ankle and 7 cm proximal to the ankle, and on a chair with or without a backrest (t-test, P < 0.05), but no significant difference was found between the 90 degrees and 60 degrees flexed position of the knee (t-test, 0.1 > P > 0.05). There were also no significant differences in muscle strength measured by three different examiners and on four trials, but significant differences were found among three patients (General Linear Model, P < 0.001). Therefore, by using the standardized measuring procedure, the HHD is reliable to measure strength of the quadriceps femoris muscle on the affected side in hemiplegic patients.