Towards Understanding Mechanistic Subgroups of Osteoarthritis: 8 Year Cartilage Thickness Trajectory Analysis.

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Abstract

Many studies have validated cartilage thickness as a biomarker for knee osteoarthritis (OA), however, few studies investigate beyond cross-sectional observations or comparisons across two timepoints. By characterizing the trajectory of cartilage thickness changes over 8 years in healthy individuals from the Osteoarthritis Initiative Dataset, this study discovers associations between the dynamics of cartilage changes and OA incidence. A fully automated cartilage segmentation and thickness measurement method was developed and validated against manual measurements: mean absolute error 0.11-0.14mm (n=4129 knees) and automatic reproducibility 0.04-0.07mm (n=316 knees). Mean thickness for the medial and lateral tibia (MT, LT), central weight-bearing medial and lateral femur (cMF, cLF), and patella (P) cartilage compartments were quantified for 1453 knees at 7 timepoints. Trajectory subgroups were defined per cartilage compartment as: stable, thinning to thickening, accelerated thickening, plateaued thickening, thickening to thinning, accelerated thinning, or plateaued thinning. For tibiofemoral compartments, the stable (22-36%) and plateaued thinning (22-37%) trajectories were the most common, with average initial velocity [μm/month], acceleration [μm/month2 ] for the plateaued thinning trajectories LT -2.66, 0.0326; MT -2.49, 0.0365; cMF -3.51, 0.0509; cLF -2.68, 0.041. In the patella compartment, the plateaued thinning (35%) and thickening to thinning (24%) trajectories were the most common, average initial velocity, acceleration for each -4.17, 0.0424; 1.95, -0.0835. Knees with non-stable trajectories had higher adjusted odds of OA incidence than stable trajectories: accelerated thickening, accelerated thinning, and plateaued thinning trajectories of the MT had adjusted OR of 18.9, 5.48, and 1.47 respectively; in the cMF, adjusted OR of 8.55, 10.1, and 2.61. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.