Association of Body Mass Index With Radiographic Severity, Pain, Physical Function, and Knee-Related Quality of Life in Knee Osteoarthritis: A Registry-Based Pilot Study
Abstract
Background: Knee osteoarthritis (KOA) is a major cause of pain and disability, and obesity is an important potentially modifiable factor in its clinical burden. This pilot study examined the association of body mass index (BMI) with radiographic severity, pain, physical function, and knee-related quality of life among patients with KOA enrolled in an online clinical registry.
Methods: This observational, registry-based pilot study included 20 adults aged 40 years or older with clinically and/or radiographically confirmed KOA. BMI and Kellgren-Lawrence (KL) grade were obtained from the registry. Pain, physical function, and quality of life were assessed using the corresponding Knee Injury and Osteoarthritis Outcome Score (KOOS) domains. Because the data were non-normally distributed, Spearman rank correlation was used to examine associations between BMI and each outcome. Statistical significance was set at p < 0.05.
Results: Participants had a mean age of 74.55 ± 4.19 years and a mean BMI of 32.21 ± 1.57 kg/m²; all participants met BMI criteria for obesity. BMI showed a strong positive correlation with KL grade (Spearman rho = 0.7731, 95% CI 0.4919 to 0.9083; p < 0.0001). Higher BMI was also associated with lower KOOS quality-of-life scores (rho = -0.8011, 95% CI -0.9203 to -0.5456; p < 0.0001), lower KOOS pain scores (rho = -0.4909, 95% CI -0.7726 to -0.0477; p = 0.0280), and lower KOOS physical-function scores (rho = -0.4614, 95% CI -0.7568 to -0.0096; p = 0.0406). Because higher KOOS scores indicate better status, the negative correlations correspond to worse patient-reported outcomes at higher BMI.
Conclusion: Within this small cohort of patients with KOA and obesity, higher BMI was associated with greater radiographic severity and poorer pain, physical-function, and quality-of-life scores. The findings are exploratory and do not establish causality. Larger studies including a broader BMI range and adjustment for potential confounding factors are required to confirm these associations.
Keywords:
Body mass index; Knee osteoarthritis; Kellgren-Lawrence grade; KOOS; Obesity; Pain; Physical function; Quality of lifeDownloads
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Copyright (c) 2026 Riya Gurudasani, Deepak Anap (Author)
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