Changes in Medial Meniscal 3D Position and Morphology Predict Knee Replacement in Rapidly Progressing Knee Osteoarthritis - Data from the Osteoarthritis Initiative (OAI)

To assess whether quantitative changes in the meniscus predict progression from early knee osteoarthritis (KOA) to knee replacement (KR). A nested case-control study was conducted among Osteoarthritis Initiative participants: All 35 case knees with baseline Kellgren-Lawrence-Grade (KLG) ≤2 that had KR between 36-60 months were matched 1:1 by age, sex, and baseline KLG to 35 control knees, without subsequent KR. Quantitative 3D medial meniscus position and morphological measures were determined from MRI at the visit just before KR (T ) and two years before (T ). Paired t-tests and case-control odds ratios (OR, standardized per SD of change in controls) were used to compare changes between groups. Cases (52% women; age 65±7y; BMI 30±4kg/m ; KLG0/1/2: 5/8/22) and controls (52% women; age 64±7y; BMI 30±5kg/m ; KLG0/1/2: 9/4/22) were similar. Compared to control knees, KR case knees displayed longitudinal changes, specifically, a decrease in tibial plateau coverage, an increase in meniscal extrusion, and a decrease in meniscal width. The odds for KR increased with greater reduction in percent tibial plateau coverage (OR: 2.28, 95%CI [1.43; 3.64]), greater increase in maximal extrusion (1.40 [1.12; 1.75]), and greater reduction of mean meniscal width (2.01 [1.23; 3.26]). The odds for KR increased with medial compartment cartilage thickness loss (OR: 2.86 [1.51; 5.41]) for comparison. Quantitative measures of meniscal position and morphology are associated with subsequent KR in knees with rapidly progressing KOA. These findings show that structural changes of the meniscus are related to an important clinical and economic outcome of KOA.