Towards understanding mechanistic subgroups of osteoarthritis: 8‐year cartilage thickness trajectory analysis

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 OA initiative data set, this study discovers associations between the dynamics of cartilage changes and OA incidence. A fully automated cartilage segmentation and thickness measurement method were developed and validated against manual measurements: mean absolute error = 0.11–0.14 mm (n = 4129 knees) and automatic reproducibility = 0.04–0.07 mm (n = 316 knees). The 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 seven timepoints. Trajectory subgroups were defined per cartilage compartment such 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 an 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; and cLF: −2.68, 0.041. In the patella compartment, the plateaued thinning (35%) and thickening to thinning (24%) trajectories were the most common, with an average initial velocity, acceleration for each −4.17, 0.0424; 1.95, −0.0835. Knees with nonstable trajectories had higher adjusted odds of OA incidence than stable trajectories: accelerated thickening, accelerated thinning, and plateaued thinning trajectories of the MT had adjusted odds ratio (OR) of 18.9, 5.48, and 1.47, respectively; in the cMF, adjusted OR of 8.55, 10.1, and 2.61, respectively.

Uncovering associations between data-driven learned qMRI biomarkers and chronic pain

“…A previous study compared the fully automatic cartilage segmentation and thickness measurements with 4299 manual measurements publicly available on the OAI website. Pearson’s correlation coefficients ranged between 0.850 in central Lateral Femur (cLF) and 0.955 in Lateral Tibia (LT); average absolute difference ranged between 0.108 mm in Medial Tibia (MT) and 0.143 mm in cLF 23 . The bone segmentation was also previously extensively evaluated, with a stratified analysis showing no significant differences in segmentation performances at different KL gradings.…”

“…A full description of the cartilage segmentation models can be found in Supplementary Information: Cartilage Segmentation . This model was extensively validated in a previous study 23 .…”

“…The cartilage thickness was calculated for each of the three cartilage masks per sagittal slice using an Euclidean distance transform along the morphological skeleton of each mask 23 . The morphological skeleton was defined as the middle points along the length of each cartilage mask.…”

Weight Cycling and Knee Joint Degeneration in Individuals with Overweight or Obesity: Four‐Year Magnetic Resonance Imaging Data from the Osteoarthritis Initiative

“…Lateral and medial femoral compartments underwent Euclidean distance transformation and skeletonization before subsegmentation. Only the weight‐bearing region was included in the mean thickness calculation for the LF and MF (28).…”

“…A fully automatic method was developed and validated by our group for reliable cartilage segmentation and thickness measurement of knee MRI volumes as previously described (28). Three identical three-dimensional VNet architectures and three two-dimensional UNet-like architectures were trained to segment dual echo in the steady state sequence volumes.…”