Association between Body Mass Index and Radiographic Severity of Knee Osteoarthritis Based on Kellgren–Lawrence Grading

Abstract

functional impairment, with excess adiposity identified as a crucial, addressable predisposing element. Even so, the precise correlation connecting body mass index (BMI) to the structural extent of joint deterioration on plain radiographs, especially along the spectrum of Kellgren–Lawrence (KL) stages, is not yet thoroughly documented among Indian cohorts. The present investigation aimed to quantify the link between anthropometric adiposity indices and radiographic grades of KOA. Materials & Methods: Within this cross-sectional observational design, 200 mature individuals presenting either suspected or confirmed KOA completed physical anthropometric measurements alongside standardized bilateral knee radiographs. Subjects were stratified into standard BMI tiers: normal weight (18.5–24.9 kg/m²), overweight status (25.0–29.9 kg/m²), and generalized obesity (?30.0 kg/m²). Radiologic involvement was staged via the classic KL classification scale (scores 0 to 4). Relationships tying BMI metrics to KL staging were determined using Spearman rank correlation analyses alongside ordinal logistic regression modeling. Multivariable adjustments controlled for chronological age, biological sex, and total duration of symptomatic joint complaints. Results: The cohort presented an average age of 59.8 ± 7.7 years, comprising a 64.5% female majority. Average BMI stood at 28.7 ± 4.6 kg/m². Average KL scoring climbed in a stepwise pattern, rising from 2.02 ± 1.01 among normal-weight subjects to 2.56 ± 1.00 in the overweight subset and reaching 2.96 ± 0.96 across individuals with obesity. Advanced joint pathology (KL stages 3–4) was identified in 30.0%, 54.2%, and 73.1% of these respective strata. A moderate direct correlation emerged between elevated BMI and worsening KL grade (?=0.38; P<0.001). Every single-unit rise in BMI (1 kg/m²) independently correlated with higher structural joint deterioration (adjusted OR 1.09, 95% CI 1.03–1.15; P=0.002). Furthermore, clinical obesity remained an autonomous predictor of heightened KL disease stages (adjusted OR 2.84, 95% CI 1.39–5.82; P=0.004). Conclusion: Elevated BMI values correlated robustly with stepwise worsening in the radiographic staging of knee osteoarthritis. These observations reinforce targeted weight reduction strategies as an essential pillar within holistic preventative and therapeutic protocols for KOA, though longitudinal prospective trials remain necessary to confirm direct causal pathways. Keywords: Body mass index; Knee osteoarthritis; Radiographic severity; Kellgren–Lawrence grading; Obesity; Overweight; Joint degeneration