Ankylosis, left knee

This code signifies the pathological fusion or stiffening of the left knee joint, resulting in significant loss of range of motion. It indicates a severe restriction in the knee's ability to bend or straighten, often leading to functional impairment.

Apply this code when documentation explicitly states ankylosis of the left knee. This diagnosis is typically supported by physical examination findings of severely limited or absent knee movement, and imaging studies (e.g., X-rays) confirming joint fusion.

• Ensure laterality is clearly documented (left knee).
• Distinguish from other knee stiffness codes (e.g., M25.662 for stiffness not elsewhere classified) which imply less severe or non-fused conditions.
• Code any underlying cause of the ankylosis (e.g., rheumatoid arthritis, trauma) as a primary or secondary diagnosis, following sequencing guidelines.