An in Vivo Study of the Dynamic Q Angle of the Knee Joint during Flexion

Abstract

The quadriceps (Q) angle between the rectus femoris and the patella tendon, measured in laying or standing, is an important reference to value a healthy or abnormal knee joint. The purpose of the present study was to measure a dynamic Q angle, which was defined as the Q angles during the flexion of the knee joint. Skin maker-based motion tracking technique was applied. The dynamic Q angle was calculated based on the cluster of markers attached to the skin. 30 normal subjects (15 male, 15 female) participated in the test. The results indicated that the Q angle was similar between the male and female during the knee flexion from 0° to 100°, but significant difference was observed from 105° to 120°. We observed this new phenomenon and reported the data in order to help understand the knee joint mechanism and the function of the patella. As a reference, our results proved more information for the diagnosis of an abnormal knee joint.