Quadriceps weakness, patella alta, and structural features of patellofemoral osteoarthritis

Objective To determine the relationship between quadriceps weakness and cartilage damage and bone marrow lesions (BMLs) in the patellofemoral joint (PFJ) and if this relationship is modified by patella alta. Methods The Multicenter Osteoarthritis Study is a cohort study of persons ages 50–79 years with or at risk of knee osteoarthritis. Concentric knee extensor strength was measured using an isokinetic dynamometer. Patella alta was measured using the Insall‐Salvati ratio (ISR) on the lateral radiograph, and cartilage damage and BMLs were graded on magnetic resonance imaging in the PFJ. We determined the association between quadriceps weakness with cartilage damage and BMLs in the PFJ among knees with (ISR ≥1.2) and without (ISR