Which factor is included in the ACR criteria for knee OA?

Which factor is included in the ACR criteria for knee OA?

• A. Age >50
• B. Swelling on a hot joint
• C. ESR > 100
• D. Fever

Answer: (C)

Age over 50 is included in the ACR criteria for knee OA. OA classification uses a set of clinical features, and age greater than 50 is one of the features that helps distinguish OA when combined with knee symptoms. The other options point to inflammatory or infectious joint processes—swelling in a hot joint, a very high ESR, or fever—which are not part of OA criteria. In the classic ACR criteria, knee pain plus age over 50 (along with other noninflammatory features) supports OA diagnosis, whereas systemic inflammatory signs argue against OA.

Age over 50 is included in the ACR criteria for knee OA. OA classification uses a set of clinical features, and age greater than 50 is one of the features that helps distinguish OA when combined with knee symptoms. The other options point to inflammatory or infectious joint processes—swelling in a hot joint, a very high ESR, or fever—which are not part of OA criteria. In the classic ACR criteria, knee pain plus age over 50 (along with other noninflammatory features) supports OA diagnosis, whereas systemic inflammatory signs argue against OA.