Rheumatoid arthritis without rheumatoid factor, unsp knee

This diagnosis code signifies a chronic inflammatory autoimmune disease primarily affecting the synovial lining of the knee joint, characterized by the absence of rheumatoid factor in laboratory testing. It indicates an inflammatory arthropathy leading to joint pain, swelling, and potential damage, specifically impacting an unspecified knee.

Apply this code when documentation confirms a diagnosis of seronegative rheumatoid arthritis affecting the knee, without specifying laterality. This code is appropriate when the provider explicitly states "rheumatoid arthritis without rheumatoid factor" or "seronegative rheumatoid arthritis" and the affected joint is the knee, but the specific knee (left or right) is not documented.

• Ensure the medical record explicitly states "without rheumatoid factor" or "seronegative" to differentiate from seropositive forms.
• Avoid using this code if laterality (left or right knee) is documented; instead, use the more specific M06.061 or M06.062.
• Query the provider for laterality if "unspecified knee" is documented to allow for more precise coding.