Do rates of femorotibial cartilage loss in Kellgren-Lawrence 2 and 3 knees differ between those with mild-moderate vs. severe patellofemoral structural damage? - Data from the FNIH and IMI-APPROACH cohorts

Abstract

[Abstract] Background: The aim was to assess whether rates of quantitative femorotibial (FT) cartilage loss are increased for knees with semiquantitatively (sq)-defined severe patellofemoral (PF) cartilage damage and/or large bone marrow lesions (BMLs) vs. those without over a period of 24 months.

Methods: 626 knees with Kellgren-Lawrence 2 and 3 from the FNIH and IMI-APPROACH studies were included. MRI assessment was performed using the MRI Osteoarthritis Knee Score (MOAKS) instrument. Baseline FT cartilage damage severity was defined as mild, moderate, or severe. PF cartilage damage was defined as mild-moderate vs. severe. A 2nd definition was based on the presence or absence of large BMLs. Quantitative cartilage thickness loss (defined as the difference from baseline to follow-up in mean cartilage thickness in the medial and in the lateral femorotibial joint, which were computed by summing the cartilage thickness measures observed in the respective cartilage plates) was derived from baseline and 24-month manual segmentations. Between-group comparisons were performed using analysis of covariance (ANCOVA) adjusting for age, sex and body mass index.

Results: 410 (65%) knees were categorized as mild, 92 (15%) as moderate, and 124 (20%) as severe medial FT cartilage damage. For almost all categories of FT cartilage damage, the difference in quantitative medial FT cartilage loss was not statistically significant. Only for the category of knees with moderate medial FT cartilage damage, statistically higher rates of FT cartilage loss were observed for those with large PF BMLs compared to those without (mean adjusted difference -0.128 mm, 95% confidence interval [-0.238, -0.018], p=0.023).

Conclusions: Screening for PF cartilage damage and BMLs does not appear to be required in a disease-modifying OA drug trial.