Weakness and MRI Knee Cartilage loss

Objective. To determine whether baseline quadriceps weakness predicts cartilage loss on magnetic resonance imaging (MRI). Methods. Subjects aged 40-79 with knee pain (n=163) were recruited from a random population sample and examined for quadriceps weakness with manual isometric strength testing, using a 3-point scoring system (0=poor resistance, 1=moderate resistance, 2=full resistance), which was dichotomized as normal (grade 2) vs weak (grade 0/1). MRI of the more symptomatic knee was obtained at baseline and at mean of 3.3-years. Cartilage was graded 0-4 on MRI. Exponential regression analysis was used to evaluate whether quadriceps weakness was associated with whole knee cartilage loss and, in secondary analyses with compartment specific cartilage loss, adjusted for age, sex, body mass index, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) pain and baseline MRI cartilage score. Results. Of 163 subjects, 54% were female, mean age 57.7 years. Quadriceps weakness was seen in 11.9% of the subjects. Weakness was a predictor of whole knee cartilage loss (hazard ratio [HR] 3.48, 95% confidence interval [CI] 1.30-9.35). Quadriceps weakness was associated with cartilage loss in the medial tibiofemoral (TF) compartment (HR 4.60, 95% CI 1.25-17.02), while no significant association was found with lateral TF (HR 1.53, 95% CI 0.24-9.78) or patellofemoral compartment (HR 2.76, 95% CI 0.46-16.44). Conclusion. In this symptomatic, population-based cohort, quadriceps weakness predicted whole knee and medial TF cartilage loss after 3 years. This is the first study to show that a simple clinical examination of quadriceps strength can predict the risk of knee cartilage loss.Medicine, Faculty ofNon UBCMedicine, Department ofPopulation and Public Health (SPPH), School ofRheumatology, Division ofReviewedFacult