Prevalence and clinical-radiological features of hand osteoarthritis in individuals with knee osteoarthritis

Hand osteoarthritis (HOA) frequently coexists with knee osteoarthritis (KOA), yet its clinical and radiographic burden in ageing adults with KOA remains under-recognised. To determine the prevalence and joint-specific distribution of clinical, radiographic, and symptomatic HOA in individuals with KOA; to describe associated functional characteristics; and to assess whether HOA severity is related to KOA severity. A descriptive cross-sectional study was conducted among adults ≥ 40 years with tibiofemoral KOA (KL grades 1-4). HOA was evaluated using American College of Rheumatology criteria, hand radiographs (KL ≥ 2), and symptom-based definitions. Assessments included VAS pain, WOMAC, DASH, AUSCAN, grip strength, and pinch strength. Statistical analyses used Mann-Whitney U, Kruskal-Wallis, and χ² tests (α = 0.05). Among 108 participants (mean age 62.1 ± 11.0 years; 71.3% female), 16.7% reported hand symptoms. The prevalence of clinical, radiographic, and symptomatic HOA was 9.3%, 13.0%, and 8.3%, respectively. PIP and DIP joints were most frequently affected, with no MCP involvement. Knee KL grades clustered at grades 3-4 and were associated with significantly worse WOMAC, DASH, and AUSCAN scores. Symptomatic HOA was associated with reduced grip strength, while pinch strength remained unaffected. No significant association was observed between knee and hand KL grades. HOA is a common but under-recognised comorbidity in individuals with KOA, demonstrating predominant PIP/DIP involvement and measurable functional impact. The absence of structural correlation between knee and hand OA highlights OA as a multisite, heterogeneous degenerative condition of ageing. Routine hand assessment in KOA clinics may support earlier identification and targeted management of HOA.