ICD-10 Code M05.421 – Rheumatoid myopathy with rheumatoid arthritis of right elbow (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.421 – Rheumatoid myopathy with rheumatoid arthritis of right elbow
What it is
This code identifies rheumatoid arthritis affecting the right elbow with associated rheumatoid myopathy. Use it when the arthritis and muscle involvement are documented together in the same limb.
Clinical signs
Findings may include chronic joint pain, swelling, stiffness, and reduced range of motion in the right elbow, along with muscle weakness or wasting. Clinical features vary; refer to documentation.
When to use this code
Use M05.421 when the provider documents rheumatoid myopathy and rheumatoid arthritis in the right elbow. It applies when the right elbow is the specified site and the muscle disorder is linked to the rheumatoid condition. Check documentation if the record only states rheumatoid arthritis without myopathy.
Do not use for
Do not use this code for rheumatoid arthritis in another joint or for nonspecific myalgia without documented rheumatoid myopathy. If the side or site is unclear, check documentation.
Coding tip
Verify both the rheumatoid myopathy and the right elbow site are explicitly documented before assigning this code.