Q-angle: an invaluable parameter for evaluation of anterior knee pain.

BACKGROUND Patellofemoral pain syndrome is a descriptive term applied to patients with nonspecific anterior knee pain, and is the most common knee problem. The pain in most patellofemoral disorders is generalized to the anterior part of the knee. One important concept in patellofemoral joint function is the quadriceps angle (Q-angle). Theoretically, a higher Q-angle increases the lateral pull of the quadriceps femoris muscle on the patella and potentiates patellofemoral disorders. This study was undertaken to evaluate the relationship between the anterior knee pain and Q-angle. METHODS This prospective study was performed on two groups; the case group consisted of 100 outpatients (44 men, and 56 women) aged between 15 and 35 years, with anterior knee pain. The control group consisted of 100 outpatients (50 men, and 50 women) with the same age distribution, who presented with different problems in the upper extremities and no knee problems. The Q-angle of each knee was measured in all participants, using a universal goniometer. RESULTS The mean Q-angle for men, women, and all participants in the case group was 15.2, 20.1, and 18.0 degrees, respectively. In the normal control group the angles were 12.1, 16.7, and 14.9 degrees, respectively. All these differences were statistically significant (P < 0.001). CONCLUSION These results substantiate the fact that patients with anterior knee pain have larger Q-angles than healthy individuals.