Women who were overweight and demonstrated evidence of joint inflammation on magnetic resonance imaging (MRI) were at increased risk for developing knee osteoarthritis (OA), while women who were obese exhibited increased risk for OA without inflammatory markers, according to study findings published in Arthritis Care and Research.

Researchers compared the knees of 355 patients with radiographic evidence of OA with 355 matched controls. They classified the patients by body mass index (BMI), with 178 (25.1%) participants in the normal range (BMI <25 kg/m2), 283 (39.9%) in the overweight range (BMI ≥25 kg/m2 and <30 kg/m2), and 249 (35.1%) in the obese range (BMI ≥30 kg/m2).

The researchers retrospectively examined consecutive annual MRIs for inflammatory markers (effusion-synovitis and Hoffa-synovitis) up to 4 years prior to onset of radiographic OA. Not only did they compare BMI classifications, but they also analyzed differences in BMI and inflammatory markers between men and women.


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At year 2, women who were overweight had higher likelihoods of developing incident radiographic OA if they had Hoffa-synovitis (odds ratio [OR], 3.26; 95% CI, 1.39-7.65) or effusion-synovitis (OR 3.56; 95% CI, 1.45-8.75). Increased risk for effusion correlated with BMI greater than 25 kg/m2 at year 2 (OR 2.21; 95% CI, 1.11-4.43), and, although not statistically significant, year 1 (OR 1.68; 95% CI, 0.98-2.88).

Conversely, at year 2, women who were obese were more likely to develop incident radiographic OA if they did not have synovitis (OR 2.87; 95% CI, 1.21-6.83). The researchers speculated that increased mechanical loading of the joints and bony structural changes contributed more to OA development than inflammatory markers.

Men did not show any combination of BMI or synovitis, indicating women who were obese or overweight were are at increased risk for radiographic OA with effusions.

The study had several limitations. Firstly, the researchers did not analyze patients diagnosed with metabolic syndrome. They also did not collect information on symptomatic OA to determine whether these symptoms developed prior to or after radiographic imaging. They also did not use MRI with contrast, which detects synovitis better than MRI without contrast. This may have interfered with evaluator agreement on synovitis diagnosis based on suboptimal imaging.

The study authors concluded, ““Both mechanical load and inflammation have a role in OA incidence for [women who are] overweight and obese, while for men, the role of inflammation in conjunction with high BMI appears to be less relevant.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Roemer FW, Guermazi A, Hannon MJ, et al. Presence of magnetic resonance imaging-defined inflammation particularly in overweight and obese women increases risk of radiographic knee osteoarthritis: The POMA study.  Arthritis Care Res (Hoboken). Published online February 2, 2021. doi:10.1002/acr.24568