Is there a relationship between anterior knee pain and femoral trochlear dysplasia? Assessment of lateral trochlear inclination by magnetic resonance imaging

It may be very difficult to diagnose the pathology in patients with anterior knee pain. Patients with chronic anterior knee pain have been reviewed for the study. Our aim was to delineate the presence of subtle trochlear dysplasia by measuring lateral trochlear inclination (LTI) in axial magnetic resonance imaging (MRI) scans. While there were 109 knees in the study group with anterior knee pain (AKP), control group consisted of 74 knees without AKP. The LTI measurements were performed at the level of proximal cartilaginous area of trochlear groove in axial scans. The condition was termed to be trochlear dysplasia when LTI was below 11º. Parameters in both groups were statistically analyzed and compared for their association with LTI. There was no significant difference between LTI values of male and female subjects in each group. The mean LTI values in anterior knee pain and control groups were 17.32º and 21.5º, respectively, and the difference was statistically significant (P < 0.05). The ratio of knees with trochlear dysplasia was 16.5% in AKP group, which was only 2.7% in control. In the AKP group, the ratio of trochlear dysplasia was significantly high (P < 0.05). Although trochlear dysplasia has been generally detected in cases with patellar instability, this study revealed that the frequency of this finding in patients with other causes of anterior knee pain was also considerably high. Measurement of lateral trochlear inclination in axial MRI scans with radiologic assessment seems to be a valuable diagnostic criterion, especially in patients in whom etiology of anterior knee pain could not be identified.