Analysis of the Patellofemoral Region on MRI: Association of Abnormal Trochlear Morphology With Severe Cartilage Defects

OBJECTIVE. The objective of our study was to assess patellofemoral measurements on MRI and to correlate the measurements with different grades of cartilage defect. MATERIALS AND METHODS. Axial and sagittal MR images of 100 patients with various pathologic knee conditions were analyzed. The patients were divided into two age groups: < 40 years and >= 40 years. Patellar measurements of facet asymmetry, the patella-to-patellar tendon ratio, and the amount of patellotrochlear cartilage overlap were obtained in each subject. Similarly, trochlear measurements of the ventral trochlear prominence, trochlear depth, facet asymmetry, sulcus angle, and lateral inclination were obtained. Axial and sagittal MR images were reviewed to grade the severity of focal cartilage defects in the patellofemoral region on the basis of the depth of the lesion. Measurements in knees without a chondral defect were compared with knees with mild and severe chondral defects. RESULTS. There was a statistically significant difference in the trochlear measurements of the ventral prominence (p = 0.012), trochlear depth (p = 0.001), sulcus angle (p = 0.208), and lateral inclination (p = 0.154) between normal knees and knees with severe cartilage defects in patients younger than 40 years. No significant difference was seen in the patellar measurements between normal knees and knees with severe cartilage defects. CONCLUSION. There is an association between abnormal trochlear morphology and severe patellofemoral cartilage defects in patients younger than 40 years.