Intertester reliability and concurrent validity of fluid-based and universal goniometers for active knee flexion.

This study was designed 1) to determine the intertester reliability of the universal goniometer and the fluid-based goniometer and 2) to establish the concurrent validity of the fluid-based goniometer. Two testers measured active knee flexion of 20 healthy subjects (15 women, 5 men) using both instruments. The subjects had a mean age of 24.