Measures of Patellofemoral Morphology Predict the Risk of Local Cartilage Damage Progression: A Yale/MOST Collaborative Study.

BACKGROUND The relationship between patellofemoral (PF) morphology and PF cartilage damage in the general population remains unclear. PURPOSE This study aimed to determine whether 3-dimensional-based metrics of PF morphology are associated with progressive lateral PF cartilage damage. STUDY DESIGN Cross-sectional study; Level of evidence, 2. METHODS We analyzed nonweightbearing computed tomography scans of knees from a subset of participants enrolled in the community-based Multicenter Osteoarthritis Study. Baseline and 2-year magnetic resonance imaging scans of the knee were evaluated for progressive PF cartilage damage using the Magnetic Resonance Imaging Osteoarthritis Knee Score. Tibial tubercle-trochlear groove (TT-TG) distance, patellar tilt, external tibiofemoral rotation (eTFR), patellar height, entry point-trochlear groove angle, and entry point-transition point (EP-TP) angle were measured for each knee. To assess the association of each morphology measure with progressive cartilage damage, logistic regression models with generalized estimating equations were fit using continuous and natural cubic spline models. RESULTS We analyzed lateral PF cartilage damage in 389 knees (mean age, 53.79 ± 5.51 years; mean body mass index, 28.48 ± 5.13 kg/m2). TT-TG distance (β = 0.23; odds ratio, 1.26; P = .036), eTFR (β = 0.24; odds ratio, 1.27; P = .048), and EP-TP angle (Z = 2.09; P = .036) all demonstrated significant positive associations with worsening lateral PF cartilage damage. CONCLUSION The results demonstrated significant associations between 3-dimensional anatomic metrics and progressive lateral PF cartilage damage. Elevated TT-TG distance, eTFR, and EP-TP angle may be keys to understanding the mechanical cause of lateral PF osteoarthritis.