The patellar tilt angle: correlation of MRI evaluation with anterior knee pain.

The purpose of this study was to analyze the degree of patella tilt and its correlation with the symptoms of anterior knee pain. We used magnetic resonance imaging (MRI) to measure the angle of patella tilt. The patients (n = 128) were classified into two groups. Group 1 (n = 78) included patients who had never had symptoms of anterior knee pain but had MRI for evaluation of the menisci and the ligaments. Group 2 (n = 50) included patients who had MRI for evaluation of anterior knee pain syndrome. Patients who had gross deformities like patellar dislocation, tricompartmental osteoarthritis, or inflammatory arthritis were excluded. The average patella tilt angle was 6.3 (SD = 3.9) and 12.8 (SD = 8.4) degrees, respectively, for the two groups of patients. Twenty-three patients in group 2 underwent arthroscopy because of failure of conservative treatment, and the average patella tilt angle in this subgroup was 16.4 degrees. Our study suggests that patella tilt angle is correlated with the symptoms of anterior knee pain, and indicated that the cause of pain came from the tight lateral retinaculum. In addition, MRI was found to be an accurate and reproducible method of measurement of the patellar tilt angle.