Assessment of quadriceps muscle performance by hand-held, isometric, and isokinetic dynamometry in patients with knee dysfunction.

One component of patient evaluation is muscle performance assessment. The purpose of this study was: 1) to determine the difference and correlation between hand-held, isometric, and isokinetic dynamometry test results in patients with knee dysfunction and 2) to determine the effect of pain during such testing. Bilateral quadriceps strength in 23 subjects with unilateral knee dysfunction was tested using concentric and eccentric isokinetic dynamometry at 60 degrees/sec, isometric dynamometry, and hand-held dynamometry, both at 60 degrees of knee flexion. Pain ratings were obtained before, during, and after each test. Statistical analysis revealed a significant difference between involved and uninvolved limbs for eccentric isokinetic dynamometry (p = 0.002) and hand-held dynamometry (p = 0.005); no difference was found between limbs for the concentric isokinetic and isometric dynamometry (p > 0.05). Mean percent deficits in quadriceps strength ranged from 11 to 18%, with no significant difference found between testing modes. Pearson product moment correlations ranged from 0.34 to 0.76 when comparing testing modes. No significant difference existed in pain scores before, during, and after each mode of testing. It was concluded that large variation existed between different testing modes, which results in different conclusions regarding the strength of the quadriceps in patients with knee dysfunction.