Superficial cartilage transverse relaxation time is associated with osteoarthritis disease progression - data from the FNIH biomarker study of the osteoarthritis initiative.

Objective To study whether layer-specific cartilage transverse relaxation time (T2), and/or longitudinal change is associated with clinically relevant knee osteoarthritis (OA) disease progression. Methods The FNIH biomarker consortium was a nested case-control study on 600 knees from 600 Osteoarthritis Initiative participants. Progressor knees had both medial tibiofemoral radiographic joint space width (JSW) loss (≥0.7 mm) and a persistent increase in WOMAC pain (≥9 on a 0-100 scale) at 24-48 month from baseline (n=194). Multi-echo spin-echo (MESE) MRIs for cartilage T2 analysis had been acquired in the right knees only (97 progressor knees). These were compared to 104 control knees without JSW or pain progression. 53 knees had JSW progression, and 57 pain progression only. Cartilage thickness segmentations obtained from DESS MRI were matched to MESE MRI, to extract superficial and deep femorotibial cartilage T2. Superficial medial femorotibial compartment (MFTC) T2 at baseline was the primary, and change in deep MFTC T2 between baseline and 12 months the secondary analytic outcome of this post-hoc exploratory study. Results Baseline superficial MFTC T2 was significantly elevated in progressor knees (adjusted mean 47.2ms [95% confidence interval [CI] 46.5, 48.0]) and JSW progression only knees (adjusted mean 47.3ms [95% confidence interval [CI] 46.3, 48.3]), respectively, vs non-progressor knees (45.8ms [95% CI 45.0, 46.5]) after adjustment for age, sex, BMI, WOMAC pain, and medial JSN grade (ANCOVA). Change in T2 was not significantly associated with case status. Conclusions Baseline superficial, but not deep, medial cartilage T2 is associated with clinically relevant disease progression in knee OA.