Background
The incidence of medial patellofemoral articular cartilage injuries was significantly higher than that of the lateral, although many studies have suggested that lateral patellofemoral intercompartmental pressure is higher than that of the medial. The mechanism of medial patellofemoral cartilage injury remains unknown. The objective of this investigation is to explore the factors that may influence the development of medial compartment osteoarthritis in the patellofemoral joint.
Methods
This study included imaging of 246 knees from 235 patients. These patients were divided into medial more severe patellofemoral compartment osteoarthritis group(MPFOA), lateral more severe patellofemoral compartment osteoarthritis group(LPFOA) by the Whole-Organ Magnetic Resonance Imaging Score (WORMS). The development of MPFOA or LPFOA was analyzed by logistic regression equations about these factors: hip-knee-ankle angle (HKA), Suleus angle (SA), Congruence angle (CA), Lateral Patellofemoral angle (LPTA), Patellar Tilt angle (PTA), Patellofemoral index (PFI), Insall-Salvati index (I-S), Femorotibial rotation angle (FTR), Tibial tubercle-trochlear groove distance (TT-TG), Patella Wiberg type, Dejour classification of femoral trochlea, and Kellgren-Lawrence (K-L) grade.
Results
123 cases had a more severe osteoarthritis in the medial patellofemoral compartment compared to the other 123 cases. The results of binomial multivariate logistic regression analysis showed that having a Wiberg type I patella (OR = 4.364, 95%CI:1.910 ~ 9.969, P = 0.000), and having a FTR > 10° (OR = 3.497, 95%CI:1.370 ~ 8.926, P = 0.009) were high-risk factors for MPFOA. 70 cases had a more severe osteoarthritis in the lateral patellofemoral compartment compared to 176 other cases. The results of binomial multivariate logistic regression analysis showed that having a Wiberg type III patella (OR = 2.916, 95%CI: 1.267 ~ 6.712, P = 0.012), and having a FTR < 0° (OR = 4.601, 95%CI: 1.416 ~ 14.946, P = 0.011) were all high-risk factors for LPFOA.
Conclusions
FTR angle and patellar Wiberg type have a strong influence on the severity and incidence of medial and lateral osteoarthritis of the patellofemoral joint. The prevalence of MPFOA may not be related to varus and vaglus of the lower limb. The dynamic factors of the weight-bearing position of the patellofemoral joint are important when studying the pathogenesis of medial patellofemoral osteoarthritis.
