ICD-10 Code M05.862 – Other rheumatoid arthritis with rheumatoid factor of left knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.862 – Other rheumatoid arthritis with rheumatoid factor of left knee
What it is
M05.862 identifies rheumatoid arthritis with rheumatoid factor affecting the left knee, with the “other” category indicating a specified rheumatoid arthritis type not described by a more exact code.
Clinical signs
Look for documented inflammatory arthritis in the left knee, such as pain, swelling, stiffness, or reduced range of motion. Rheumatoid factor positivity should be supported in the record; clinical features vary, so refer to documentation.
When to use this code
Use this code when the provider documents rheumatoid arthritis with rheumatoid factor and clearly identifies the left knee as the involved site. It fits cases where the diagnosis is more specific than general rheumatoid arthritis but not another named subtype. If laterality or rheumatoid factor status is unclear, check documentation.
Do not use for
Do not use it for rheumatoid arthritis without rheumatoid factor, unspecified joint involvement, or disease in another joint. Check documentation if the record only states knee pain, effusion, or arthritis without confirming rheumatoid arthritis.
Coding tip
Verify both the rheumatoid factor association and left-knee laterality before assigning M05.862.