Does quadriceps strength modify the association between patella alta and structural features of osteoarthritis on MRI? The MOST Study

Abstract

Patella alta (PA), a high riding patella, is associated with cartilage damage and bone marrow lesions (BMLs) in the lateral patellofemoral joint (PFJ). Quadriceps strength has been shown to decrease cartilage loss in the lateral PFJ. In subjects with PA, the patella is not stabilized by the trochlea; we hypothesized that stronger quadriceps, a dynamic stabilizer, would lead to less PFJ cartilage damage and BMLs, especially in those with PA. We measured the Insall‐Salvati ratio (ISR) [patellar tendon length/patellar length] in 896 knees from a cohort of persons aged 50–79 years. Knees in the highest quartile of ISR were considered to have PA. Quadriceps strength was measured using an isokinetic dynamometer. Lateral PFJ cartilage damage and BMLs were graded on MRI and dichotomized into presence or absence. Using separate logistic regression models, we determined the association between sex specific tertiles of quadriceps strength and cartilage damage and BMLs, among those with and without PA, adjusting for age, sex, and BMI. Among those with PA, subjects in the highest strength tertile were 0.73 (0.4, 1.3) and 0.65 (0.35, 1.2) times less likely to have cartilage damage and BMLs compared to those in the lowest strength tertile. Similar results were seen in subjects without PA. Our results suggest that quadriceps strength may protect against cartilage loss and BMLs but is no more protective for those with than those without PA.Grant Funding Source: NIH/Arthritis Foundation