Orthopaedics Which one of the following is not a diagnostic criterion for rheumatoid arthritis according to the American Rheumatism Association? A Raised rheumatoid factor. B Symmetric swelling (arthritis) for at least 6 weeks. C Symmetrical muscle weakness. D Rheumatoid nodules. 💡 Explanation Which one of the following is not a diagnostic criterion for rheumatoid arthritis according to the American Rheumatism Association? ✓ Correct Answer: C. Symmetrical muscle weakness.