Lateral cartilage defects and medial subchondral surface ratio are associated with knee-related disability

We sought to determine the relationship between (i) full-thickness cartilage defects and tibiofemoral subchondral surface ratio (SSR) and (ii) disability and quality of life in patients with mild radiographic osteoarthritis (OA) (Kellgren-Lawrence grade 2) or without radiographic OA (Kellgren-Lawrence grades 0 or 1)? A total of 642 participants from the Osteoarthritis Initiative (OAI) with baseline knee MRIs and a Kellgren-Lawrence grade 2 or less on both bilateral screening radiographs were included. The independent relationship was assessed between (i) full-thickness cartilage defect presence and tibiofemoral SSR and (ii) Knee Injury and Osteoarthritis Outcome Score (KOOS) quality of life (QOL), KOOS function in sports and recreation (KOOS-sport/rec), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) disability score after adjustment for relevant confounders with multivariate regression modeling. The prevalence of medial full-thickness defects was 10.4% (67/642) and lateral was 18.1% (116/642). Lateral defect presence was associated with worse KOOS-QOL (beta -3.61 SE 1.04; p = 0.001), KOOS-sport/rec (beta -4.70 SE 1.38; p = 0.001) and WOMAC-disability scores (beta 0.02 SE 0.01; p = 0.001); these associations were not influenced by defect size. A larger medial compartment SSR was associated with worse KOOS-QOL (beta -27.20 SE 6.80; p < 0.001), KOOS-sports/rec (beta -22.30 SE 9.01; p = 0.01) and WOMAC-disability scores (beta 0.16 SE 0.04; p < 0.001). In older adults with little to no radiographic osteoarthritis, lateral full-thickness cartilage defects, irrespective of size, and a larger medial compartment tibiofemoral SSR are potential sources of knee-related symptoms that are not appreciated on standard radiographs. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:378-385, 2019.