Supratrochlear Rim is Correlated with Isolated Patellar Chondromalacia on Magnetic Resonance Imaging of the Knee.

PURPOSE: To investigate the relationship between the supratrochlear rim and isolated patellar chondromalacia (PC) using magnetic resonance imaging (MRI) scans of the knee.

METHODS: Patients without patellofemoral pain (control group) and patients with patellofemoral pain and diagnosed with stage III or IV PC based on MRI (defect group) were retrospectively identified. Patients with a history of patellar subluxation were excluded. We used patient MRI scans to perform 20 anatomical measurements of the patellofemoral joint. We also performed 2 measurements of the anterior femoral curvature. A total of 30 patients (29 ± 8.7 years) were in the control group, and 20 patients were in the defect group (29.4 ± 9.7 years).

RESULTS: The maximum curvature ( P < . 001) and mean curvature ( P < .001) of the anterior femoral condyle were found statistically significantly different between the groups. Patellotrochlear index ( P  = .03) and Insall-Salvati index ( P < .001) were also found statistically significantly different between the 2 groups. Patella type III and trochlear dysplasia grade B were found more common in the defect group.

CONCLUSIONS: In this Level III prognostic, case-control study, we have shown through MRI knee measurements that the isolated patellar chondromalacia in patients without a history of patellar subluxation and dislocation is correlated with the increased anterior femoral curvature in combination with patella alta.