Orthopaedic Nurses Certification Board (ONCB) Metabolic/Inflammatory/Tumors Practice Exam

How can a nurse differentiate rheumatoid arthritis from osteoarthritis?

1. Morning stiffness of less than 1 hour

2. Joint laxity

3. Symmetric joint swelling

4. Asymmetric joint inflammation

The correct answer is: Symmetric joint swelling

Rheumatoid arthritis (RA) and osteoarthritis (OA) are two distinct types of arthritis, each with characteristic features that can help in their differentiation. One of the hallmark signs of rheumatoid arthritis is symmetric joint swelling, which means that the inflammation affects joints on both sides of the body equally. This symmetrical pattern is a key indicator of RA and is due to the underlying autoimmune processes that lead to widespread inflammation. In RA, it is common for several joints, especially the small joints of the hands and feet, to be involved at the same time and to present with swelling and tenderness. In contrast, osteoarthritis typically leads to asymmetric joint involvement, where one side may be affected more than the other. OA is primarily a degenerative joint disease associated with wear and tear, and the resultant joint damage usually does not affect corresponding joints symmetrically. Morning stiffness in RA lasts longer, often exceeding one hour, while in OA, it typically resolves in less than half an hour. Joint laxity is more relevant in conditions related to joint hypermobility rather than distinguishing RA from OA. Overall, the presence of symmetric joint swelling strongly indicates rheumatoid arthritis, making it the distinguishing feature in this context.