ICD-10 Code M05.662 – Rheumatoid arthritis of left knee with involvement of other organs and systems (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.662 – Rheumatoid arthritis of left knee with involvement of other organs and systems
What it is
This code identifies rheumatoid arthritis affecting the left knee, with documented involvement of other organs or systems. It is used when the knee joint is part of a systemic rheumatoid disease process.
Clinical signs
Typical findings include chronic inflammatory joint pain, swelling, stiffness, and reduced range of motion in the left knee. Clinical features vary; refer to documentation for extra-articular involvement.
When to use this code
Use this code when the provider documents rheumatoid arthritis in the left knee and also states involvement of other organs or systems. The record should support both the joint site and systemic disease involvement. If the extra-articular manifestation is not documented, check documentation before assigning this code.
Do not use for
Do not use it for rheumatoid arthritis limited to the knee without other organ or system involvement. It is also incorrect for degenerative, traumatic, or unspecified knee arthritis.
Coding tip
Verify laterality and systemic involvement in the assessment, problem list, or specialist note before coding.