ICD-10 Code M05.479 – Rheumatoid myopathy with rheumatoid arthritis of unspecified ankle and foot (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.479 – Rheumatoid myopathy with rheumatoid arthritis of unspecified ankle and foot
What it is
This code identifies rheumatoid arthritis affecting an unspecified ankle and foot, with associated rheumatoid myopathy. Use it when documentation links the joint disease and muscle involvement together.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include inflammatory ankle or foot pain, swelling, stiffness, and muscle weakness consistent with rheumatoid myopathy.
When to use this code
Use this code when the provider documents rheumatoid arthritis with rheumatoid myopathy involving an unspecified ankle and foot. It fits records that confirm the ankle or foot site but do not specify laterality. If the note names a more specific ankle or foot location, code that documented site instead.
Do not use for
Do not use this code if the record describes rheumatoid arthritis without myopathy, or if the ankle or foot site is specified differently. Check documentation when the muscle involvement is unclear.
Coding tip
Confirm both the rheumatoid myopathy and the unspecified ankle or foot site are documented before assigning M05.479.