Accelerated knee osteoarthritis is associated with pre-radiographic degeneration of the extensor mechanism and cruciate ligaments: data from the Osteoarthritis Initiative

BackgroundTo determine if adults with incident accelerated knee osteoarthritis (KOA) are more likely to have degenerative knee ligaments or tendons compared to individuals with typical or no KOA.MethodsWe identified 3 sex-matched groups among Osteoarthritis Initiative participants who had a knee without radiographic KOA at baseline (Kellgren-Lawrence [KL]<2): 1) accelerated KOA: at least 1 knee had KL grade3 in 48months, 2) typical KOA: at least 1 knee increased in radiographic scoring within 48months, 3) no KOA: both knees had the same KL grade at baseline and 48months. We evaluated knee magnetic resonance images up to 2years before and after a visit when the accelerated or typical KOA criteria were met (index visit). Radiologists reported degenerative signal changes for cruciate and collateral ligaments, and extensor mechanism and proximal gastrocnemius tendons. We used generalized linear mixed models with 2 independent variables: group and time.ResultsStarting at least 2years before onset, adults with accelerated KOA were twice as likely to have degenerative cruciate ligaments than no KOA (odds ratio=2.10, 95% CI=1.18, 3.74). A weaker association (not statistically significant) was detected for adults with accelerated versus typical KOA (OR=1.72, 95%CI=0.99, 3.02). Regardless of time, adults with accelerated (odds ratio=2.13) or typical KOA (odds ratio=2.16) were twice as likely to have a degenerative extensor mechanism than no KOA. No other structural features were statistically significant.ConclusionsDegenerative cruciate ligaments or extensor mechanism antedate radiographic onset of accelerated KOA. Hence, knee instability may precede accelerated KOA, which might help identify patients at high-risk for accelerated KOA and novel prevention strategies.