ICD-10 Code M05.77 – Rheumatoid arthritis with rheumatoid factor of ankle and foot without organ or systems involvement (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.77 – Rheumatoid arthritis with rheumatoid factor of ankle and foot without organ or systems involvement
What it is
This code identifies rheumatoid arthritis affecting the ankle and foot, with rheumatoid factor present and no documented organ or system involvement. Use it when the record specifies these joints and excludes broader complications.
Clinical signs
Typical findings include inflammatory joint pain, swelling, stiffness, and reduced motion in the ankle or foot. Clinical features vary; refer to documentation for confirmed rheumatoid factor and joint involvement.
When to use this code
Use M05.77 when the provider documents rheumatoid arthritis with rheumatoid factor involving the ankle and foot, and there is no mention of organ or systemic disease. This supports coding for localized joint disease only. If laterality or additional sites are documented, code accordingly.
Do not use for
Do not use this code if rheumatoid factor is not documented, if another joint pattern is specified, or if organ or systems involvement is present. Check documentation when the record is unclear.
Coding tip
Verify the exact joint site and the absence of systemic involvement before assigning M05.77.