Predictors of Patellofemoral Pain Applying Full Weight Bearing Kinematic MRI

Purpose. To determine the associations among PFM, trochlea groove morphology, femoral and patellar rotation and to determine which measures best predict patellofemoral pain (PFP). Material & Methods. Knees of 51 female patients with PFP and 26 healthy female volunteers as control group were analysed with kinematic magnetic resonance imaging and full weight-bearing. The bisect offset (BSO), patellar tilt angle (PTA), femoral rotation angle (FRA), patellar rotation angle (PRA) were measured in steps of 10° between 0° to 50° of knee flexion. Static measures of Insall-Salvati ratio (ISR), sulcus angle (SAB & SAC) and lateral trochlear inclination at bone and cartilage levels (LTIB & LTIC) were performed and compared. Results. The SAB & SAC were higher and the LTIB & LTIC were lower in patients compared to volunteers. BSO, PTA, PRA and medial FRA were higher in the PFP group at all flexion angles. A multiple logistic regression analysis demonstrated that increase of FRA and SAB by 1° increased the likelihood of PFP 5.6 times and 1.6 times respectively, decrease of PRA by 1° decrease PFP likelihood by 1.7 times. Conclusion. These results revealed FRA, SAB and PRA to have best predictive value for patellofemoral pain. Current findings can help to assess the complexity of predisposing factors for PFP in practice.