Reiter's disease, unspecified knee

This code describes an inflammatory arthropathy, specifically Reiter's disease (now often referred to as reactive arthritis), affecting an unspecified knee. Reiter's disease is characterized by a triad of arthritis, urethritis, and conjunctivitis, though not all components may be present. The "unspecified" nature indicates that the laterality (right or left knee) is not documented.

Use this code when the physician's documentation clearly diagnoses Reiter's disease with involvement of the knee, but the specific knee (right or left) is not specified. This code is appropriate for initial encounters or follow-up visits where the laterality remains undetermined. Documentation should support the diagnosis of reactive arthritis and knee involvement.

• Avoid using this code if the laterality of the affected knee is documented; instead, choose a more specific code (M02.361 for right, M02.362 for left).
• Ensure documentation supports the diagnosis of Reiter's disease/reactive arthritis, not just general knee pain or arthritis.
• Consider sequencing this code with codes for associated conditions such as conjunctivitis (H10.-) or urethritis (N34.-) if present and documented.