RELIABILITY AND VALIDITY OF KNEE JOINT ANGLE MEASUREMENT BY ELECTROGONIOMETRIC AND ELECTRO-OPTICAL SYSTEMS.

The paper presents the results of a reliability and validity study of sagittal plane knee joint angles measured by electrogoniometer and Selspot systems. The electrogoniometer results, as expected were less valid than the Selspot results but both systems provided angles that were a linear function of the true joint angle. The inaccuracies in the measured joint angles are obviously caused by soft tissue deformation and movement over the skeleton.