ICD-10 Code M05.06 – Felty’s syndrome, knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.06 – Felty’s syndrome, knee
What it is
M05.06 identifies Felty’s syndrome affecting the knee. Use it when documentation shows rheumatoid arthritis with the Felty’s syndrome component and the knee is the specified site.
Clinical signs
Clinical features vary; refer to documentation. Standard references describe Felty’s syndrome as rheumatoid arthritis with splenomegaly and neutropenia, and joint involvement may include inflammatory findings in the knee.
When to use this code
Use this code when the record clearly links Felty’s syndrome to the knee as the documented joint site. It is appropriate for encounters focused on that diagnosis, including assessment, follow-up, or problem list coding.
If the note mentions rheumatoid arthritis without Felty’s syndrome, or names a different joint, you should not assume M05.06. Check documentation for the exact diagnosis and site before assigning the code.
Do not use for
Do not use this code for generic rheumatoid arthritis, isolated knee pain, or knee disease without Felty’s syndrome. If the site or syndrome is unclear, check documentation.
Coding tip
Verify both the syndrome and the knee site in the provider note before coding M05.06.