Relationship between Peak Torque and Angle-specific Torques in an Isokinetic Contraction of Normal and Laterally Unstable Knees.

This study assessed the relationship between the isokinetic peak torque (PT) (speed of movement, 60 degrees /sec and 180 degrees /sec) and the angle-specific torques (ASTs) at 15 and 75 degrees of knee flexion in multiple contractions of the quadriceps and hamstrings in 21 subjects having a chronic lateral collateral ligament (LCL) insufficiency in one knee. At every test speed, the Pearson product moment (r) correlation coefficients between the PT and ASTs were highly significant (p < 0.001) in the uninjured (r = 0.66-0.92) as well as in the LCL insufficient (r = 0.78-0.88) knees. In both extremities, the majority of the correlation coefficients exceeded 0.80, which was the threshold set before the study for the coefficients to be exceeded before the relationship could be considered clinically important. Using regression analysis, both extremities showed completely nonsystematic distribution of the residuals. In conclusion, concerning healthy or LCL-insufficient knees, the correlations between PT and ASTs were high and consistent. Therefore, AST analyses may offer little additional information about thigh muscle function to that obtained through a simpler and more commonly used measurement, the PT analysis. J Orthop Sports Phys Ther 1991;13(2):89-94.