Rates of change and sensitivity to change in cartilage morphology in healthy knees and in knees with mild, moderate, and end‐stage radiographic osteoarthritis: Results from 831 participants from the osteoarthritis initiative

Abstract

Objective To study the longitudinal rate of (and sensitivity to) change of knee cartilage thickness across defined stages of radiographic osteoarthritis (ROA), specifically healthy knees and knees with end-stage ROA. Methods One knee of 831 Osteoarthritis Initiative (OAI) participants was examined: 112 healthy, without ROA or risk factors for knee OA, and 719 ROA knees: 310 calculated Kellgren Lawrence [cKLG] grade 2, 300 cKLG3, and 109 cKLG4. Subregional change in thickness was assessed after segmentation of weight-bearing femorotibial cartilage at baseline and at one year from coronal MRI. Regional and ordered values (OV) of change were compared by baseline ROA status. Results Healthy knees displayed small changes in plates and subregions (±0.7%; standardized response mean [SRM] ±0.15), with OVs being symmetrically distributed around zero. In cKLG2 knees, changes in cartilage thickness were small (≤1%; minimal SRM -0.22) and not significantly different from healthy knees. Knees with cKLG3 showed substantial loss of cartilage thickness (up to -2.5%; minimal SRM -0.35), with OV changes being significantly (p<0.05) greater than those in healthy knees. cKLG4 knees displayed the largest rate of loss across ROA grades (up to -3.9%; minimal SRM -0.51), with OV changes also significantly (p<0.05) greater than in healthy knees. Conclusion MRI-based cartilage thickness showed high rates of loss in knees with moderate and end-stage ROA, and small rates (indistinguishable from healthy knees) in mild ROA. From the perspective of sensitivity to change, end-stage ROA knees need not be excluded from longitudinal studies using MRI cartilage morphology as an endpoint.

A relationship between mechanically-induced changes in serum cartilage oligomeric matrix protein (COMP) and changes in cartilage thickness after 5 years

“…While the sample size in this early investigation was small, the fact that for all time points and all cartilage regions with a statistically significant association greater cartilage thinning was associated with higher COMP concentration as a percent of pre-activity levels suggests that the results describe a real phenomenon. Moreover, the regions with statistically significant correlations are consistent with regions identified in large cohort studies as being more prone to thickness alterations with OA 41,42 . COMP levels were measured in serum rather than in synovial fluid, and serum levels of COMP may have originated from tissues other than articular cartilage at the knee, such as ligaments, tendon, and menisci 43 or from other joints.…”

Patterns of Femoral Cartilage Thickness are Different in Asymptomatic and Osteoarthritic Knees and Can be Used to Detect Disease-Related Differences Between Samples

“…Although increasing the number of knees per subgroup would certainly strengthen the differences among subgroups and the correlations between the thickness measurements and the KLG, this increase should not affect the conclusions of the study that asymptomatic knees have similar thickness patterns, that thickness pattern alterations increase with OA severity, and that mean thickness measurements are less sensitive than thickness pattern alterations. Furthermore, the modest differences in mean thickness measurements between subgroups generally agree with prior literature [14,37,38]. As a first step toward the analysis of the shape of the cartilage thickness, this study considered anterior-posterior and medial-lateral thickness patterns.…”

Use of imaging techniques to predict progression in osteoarthritis

“…K/L ¼ 4: loss at 3.9% pa at eMT; K/L ¼ 3: loss at 2.5% pa at ccMF; K/L ¼ 2: loss at 1% pa at ccMF [14] Increase in cartilage defects 20% over 2 years in middle-aged adults [2] Medial TFJ: 46%, lateral TFJ: 22% over 30 months in symptomatic OA [2] OA progression a : 16% in those with knee pain [15] Increase in BMLs 27% over 30 months in symptomatic OA [16] 24% progression and 25% regression over 2.7 years [17] Change in composition Change in T2: mean T2, T2 contrast, and T2 variance increased over 36 months at medial femur…”