Background/Purpose:

Despite distinct aetiologies of joint diseases, the osteoarthritic end-stage of primary osteoarthritis (OA) and rheumatoid arthritis (RA) are described using similar radiological features. However, primary and secondary osteoarthritis may be different at the cartilage-bone unit depending on the pathogenesis. Therefore, the main purpose was to investigate the histological differences in the cartilage-bone unit of the hip joint in patients with primary OA and patients with secondary OA due to RA.

Methods:

Femoral heads were obtained during arthroplasty from twelve patients with primary OA and six patients with secondary OA due to RA. The primary OA patients mean(SD) age was 62(5) years and consisted of six males and six females. The RA patients had a mean age of 63(3) years and consisted of three males and three females. The entire femoral heads were investigated, using design-based stereology methods that utilise random, systematic sampling to provide unbiased and quantitative data. The volume and thickness of the articular cartilage, calcified cartilage and subchondral bone plate were obtained. Osteophytes were, however, studied based on simple area measurements. Data were normalised if not normally distributed, and statistical significance was tested using Student’s t-test.

Results:

Conclusion:

Patients with RA had thinner articular and calcified cartilage but were otherwise not significantly different compared with OA patients. Thus, the inflammatory joint in RA was associated with a more pronounced loss of cartilage than the degenerative joint disease in primary osteoarthritis. The increased thickness of calcified cartilage in primary osteoarthritis has been attributed to endochondral ossification, which does not seem to be the case in RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/different-cartilage-bone-unit-in-patients-with-primary-osteoarthritis-and-secondary-osteoarthritis-caused-by-rheumatoid-arthritis/