Evaluating the C-Score from Weight-Bearing CT as a Quantitative Imaging Biomarker for Worsening Knee Osteoarthritis Structure and Pain in the Multicenter Osteoarthritis Study

Osteoarthritis Cartilage. 2026 Sep 29:S1063-4584(26)01055-1. doi: 10.1016/j.joca.2026.09.015. Online ahead of print.

ABSTRACT

OBJECTIVE: Investigate a novel “C-score” metric of femoral bone shape, derived from weight-bearing-CT (WBCT), as an imaging biomarker for knee osteoarthritis (OA) structural progression and pain worsening in men and women with, and at increased risk for, symptomatic knee OA.

DESIGN: Images were acquired for 649 knees (56.3% females, mean±SD age 63.8±9.6 years, BMI 28.5±5.0 kg/m²). Statistical shape models (SSM) were constructed from segmented distal femurs. C-score was the distance along the femur shape vector from KL0/1 to KL2/3 mean shapes, standardized to 1SD of KL0/1 variation in the SSM. Generalized estimating equations, adjusted for sex, age, >1 knee per participant, and BMI, determined associations between 2-year-worsening of OARSI Joint-Space-Narrowing (JSN) grade in the medial-tibiofemoral compartment and baseline C-score or minimally clinically important worsening (MCIW) of pain (2 points on the WOMAC-pain-subscore).

RESULTS: 70 knees had medial-tibiofemoral JSN worsening. In adjusted models, C-score was associated with JSN progression (OR: 1.43 (1.07, 1.92); p=0.01). Baseline C-score was also associated with 2-year MCIW pain (OR: 1.27 (1.00-1.62); p=0.047). The association of C-score with progression of JSN was more pronounced in men, and the association with pain progression was more pronounced in women, but these sex differences were not statistically significant (p >0.05).

CONCLUSION: In individuals with or at risk of knee OA, higher C-scores are moderately associated with medial-tibiofemoral JSN progression and worsening knee pain over 2-year-follow-up. The C-score is a promising imaging biomarker for knee OA structural progression and pain worsening.

PMID:42810573 | DOI:10.1016/j.joca.2026.09.015