Meniscal extrusion or subchondral damage characterize incident accelerated osteoarthritis: Data from the Osteoarthritis Initiative.

Knee osteoarthritis (KOA) is typically a slowly progressive disorder; however, a subset of knees progress with dramatic rapidity. We aimed to describe magnetic resonance imaging (MRI) findings that are associated with accelerated KOA. We conducted a longitudinal descriptive study in the Osteoarthritis Initiative cohort. We selected participants who had no radiographic KOA at baseline with one of the following in the most severe knee: (1) accelerated KOA (progressed to end-stage KOA within 48 months), (2) common KOA, and (3) no KOA at all visits. We enriched the sample by selecting knees with a self-reported or suspected knee injury. A musculoskeletal radiologist blinded to group assignments but not to time sequence performed MRI readings for the visit before and after an injury. We assessed 38 participants (knees), 66% were female, mean age 61 (9) years, and mean body mass index 28.5 (4.9) kg/m(2). Fifteen of 20 knees with no or common KOA, had no incident findings consistent with acute damage. Among the 18 knees with accelerated KOA most had incident findings: 13 (72%) had incident medial meniscal pathology with extrusion and 5 (28%) knees had subchondral damage. Incident MRI findings that are associated with incident accelerated KOA are characterized by structural damage that compromises subchondral bone or the function of the meniscus. Recognizing meniscal extrusion and/or change in shape, lateral meniscal tear, or acute subchondral damage may be vital for identifying individuals at risk for accelerated KOA.