Other unilateral secondary osteoarthritis of knee

This code signifies osteoarthritis affecting only one knee, which has developed as a consequence of another underlying condition or injury, rather than primary age-related degeneration. It indicates a secondary form of unilateral knee joint wear and tear.

Apply this code when documentation specifies secondary osteoarthritis impacting a single knee, and the laterality is clearly identified as unilateral. This is appropriate when the etiology is attributed to trauma, infection, or another systemic disease affecting only one knee.

• Ensure documentation explicitly states "secondary" and "unilateral" for the knee affected.
• Always code the underlying cause of the secondary osteoarthritis first, if known and applicable.
• Differentiate carefully from primary osteoarthritis (M17.1-) and bilateral secondary osteoarthritis (M17.4).