Postdysenteric arthropathy, left knee

This diagnosis code signifies an inflammatory joint condition affecting the left knee that develops as a sequela to a previous dysenteric infection. It represents a reactive arthritis where the immune system, triggered by the gastrointestinal infection, mistakenly attacks the synovial lining of the joint.

Apply this code when documentation clearly indicates a diagnosis of reactive arthritis of the left knee following a confirmed or suspected dysenteric episode. The patient's history should include a prior diarrheal illness, and current symptoms should localize to the left knee.

• Ensure documentation specifies "left knee" and a clear link to a preceding dysenteric infection.
• Do not confuse with other forms of reactive arthritis (e.g., Reiter's syndrome) or infectious arthritis.
• Consider coding the underlying dysenteric infection (if still active or recently resolved) as a primary diagnosis, with this code as a secondary condition.