Does Radiographic Severity Reflect Clinical Burden? Insights from a Cross-sectional Study in Knee Osteoarthritis

Abstract Background: Knee osteoarthritis (OA) is a leading cause of pain and disability in older adults. The Kellgren–Lawrence (KL) grading system is commonly used to classify radiographic severity, but its correlation with clinical burden remains unclear. Objective: To assess the association between KL Grades (1–3) and various clinical, functional and muscular parameters in patients with primary knee OA. Methodology: This cross-sectional observational study included 72 patients (aged 40–75 years) with KL Grade 1–3 knee OA. Clinical assessments included pain (Visual Analogue Scale [VAS]), knee range of motion (ROM), quadriceps thickness (ultrasound), thigh circumference and hamstring: quadriceps (H:Q) strength ratio. Functional status was evaluated using the timed up and go (TUG) and 30-s chair stand test. Categorical variables included crepitus, knee effusion, body mass index (BMI) grade and knee alignment. Statistical analyses included ANOVA, Kruskal–Wallis, post hoc Dwass–Steel–Critchlow–Fligner test, Chi-square and correlation tests. Results: VAS pain scores and ROM restrictions increased significantly with KL grade ( P < 0.001). The H:Q ratio and chair stand test performance declined markedly across grades ( P < 0.001), with large effect sizes (ε 2 > 0.84). KL grade showed a strong positive correlation with pain ( r = 0.843) and a negative correlation with flexion ROM ( r = −0.929) and H:Q ratio (ρ = −0.932). Crepitus and effusion were significantly associated with higher KL grades, while BMI, age and gender were not. Quadriceps thickness and TUG showed non-significant trends. Conclusion: KL grading correlates significantly with key clinical indicators of knee OA severity, particularly pain, ROM, muscle imbalance and lower limb function. However, radiographic evaluation alone may underestimate individual variation, underscoring the need for multidimensional assessment in OA management.