ICD-10 Code M05.462 – Rheumatoid myopathy with rheumatoid arthritis of left knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.462 – Rheumatoid myopathy with rheumatoid arthritis of left knee
What it is
This code identifies rheumatoid arthritis affecting the left knee, with associated rheumatoid myopathy. Use it when the record shows both inflammatory joint disease and muscle involvement linked to rheumatoid disease.
Clinical signs
Typical findings include chronic inflammatory joint pain, swelling, stiffness, and reduced range of motion in the left knee. Rheumatoid myopathy may also present with muscle weakness or wasting; clinical features vary, so refer to documentation.
When to use this code
Use this code when the provider documents rheumatoid arthritis with rheumatoid myopathy in the left knee specifically. It is appropriate when the left knee is the involved joint and the muscle disorder is clearly linked to rheumatoid disease.
Check documentation if the note only says rheumatoid arthritis, generalized myopathy, or knee pain without a clear rheumatoid connection. Do not assume laterality or muscle involvement unless both are stated.
Do not use for
Do not use this code for rheumatoid arthritis without myopathy, or for myopathy unrelated to rheumatoid disease. Check documentation if the left knee is not specified.
Coding tip
Confirm both the rheumatoid myopathy and the left-knee laterality are documented before assigning M05.462.