Relationship Between Body Mass Index (BMI) and Degree of Knee Osteoarthritis Based on the Kellgren-Lawrence Classification in Patients at Royal Prima Hospital Medan, March–May 2025

Abstract

Knee osteoarthritis is a progressive degenerative joint disease characterized by pain, reduced mobility, and decreased quality of life. Excess body weight may accelerate structural joint deterioration through increased mechanical loading and obesity-related inflammatory processes. This study aimed to determine the relationship between body mass index (BMI) and the radiographic severity of knee osteoarthritis based on the Kellgren–Lawrence classification among patients at Royal Prima Hospital Medan. This analytical observational study employed a cross-sectional design using secondary data obtained from medical records of 71 patients selected through consecutive sampling. BMI was categorized as normal weight, overweight, or obese, while knee osteoarthritis severity was classified according to Kellgren–Lawrence Grades 1–4. Data were analyzed using Spearman’s rank correlation test. Most participants were women (93%), with a mean age of 62.18 ± 8.67 years. Overweight was the most prevalent BMI category (47.9%), followed by obesity (29.6%). Grade 4 osteoarthritis was the most common radiographic finding (45.1%), followed by Grade 3 (38.0%). Obese patients were predominantly classified as Grade 4 (71.4%), whereas overweight patients were predominantly classified as Grade 3 (52.9%). BMI was significantly and positively correlated with osteoarthritis severity (r = 0.333; p = 0.005). In conclusion, higher BMI was associated with greater radiographic severity of knee osteoarthritis, although the strength of the correlation was relatively weak.