Association between high-resolution CT quantitative features of the knee and radiological structural progression in patients with rheumatoid knee arthritis

Conventional radiographic assessment has limitations in predicting structural progression in rheumatoid arthritis (RA). This study aimed to investigate whether baseline quantitative features of the knee on high-resolution computed tomography (HR-CT) are associated with subsequent radiological progression in patients with RA. The cohort study retrospectively encompassed 500 individuals diagnosed with RA affecting the knee treated from January 2020 to January 2024. We classified them into progression (n = 126) or non-progression (n = 374) groups based on an increase in the modified Larsen score at 6-month follow-up vs. baseline. Serological tests (Rheumatoid Factor RF, Anti-Cyclic Citrullinated Peptide Antibody ACPA, Matrix Metalloproteinase-3 MMP-3, C-Reactive Protein CRP, Erythrocyte Sedimentation Rate ESR), HR-CT quantitative features (Bone Mineral Density BMD, Joint Space Width JSW, Osteophyte Volume, Subchondral Bone Sclerosis thickness, Index of Articular Surface Irregularity), disease activity scores (Disease Activity Score in 28 joints using ESR DAS28-ESR, Tender Joint Count TJC28, Swollen Joint Count SJC28), and patient-reported outcomes (Health Assessment Questionnaire Disability Index HAQ-DI, Rheumatoid Arthritis Quality of Life RAQoL) were evaluated before and at 6 months after treatment initiation. In 500 individuals, 126 (25.2%) exhibited radiological progression. The progression group had longer disease duration (15.18 ± 4.87 vs. 12.34 ± 3.25 years, p < 0.001), higher baseline DAS28-ESR (4.60 ± 1.21 vs. 4.07 ± 1.01, p < 0.001), CRP (15.21 ± 6.11 vs. 13.11 ± 5.91 mg/L, p < 0.001), lower BMD (295.18 ± 46.33 vs. 315.42 ± 48.25 mg/cm 3 , p < 0.001), and narrower JSW (3.40 ± 0.65 vs. 3.80 ± 0.75 mm, p < 0.001) compared to the non-progression group. Key HR-CT features correlated with progression. Multivariate regression identified lower baseline BMD (OR = 0.992), narrower JSW (OR = 0.375), greater Osteophyte Volume (OR = 1.052), thicker Subchondral Bone Sclerosis (OR = 2.648), and higher Surface Irregularity Index (OR = 2.206) as independent predictors of progression (all p < 0.05). Baseline HR-CT quantitative features, specifically lower BMD, narrower JSW, greater osteophyte volume, thicker subchondral bone sclerosis, and higher articular surface irregularity, independently predict radiological structural progression in knee arthritis associated with RA.