Unil post-trauma osteoarth of 1st carpometacarp jt,unsp hand

This code describes degenerative joint disease affecting the base of the thumb on one side, specifically resulting from a prior injury. It indicates that the exact hand (left or right) affected by this post-traumatic arthritis is not specified in the medical record.

Use this code when documentation clearly states unilateral osteoarthritis of the first carpometacarpal joint and explicitly links it to a previous trauma, but the laterality of the affected hand is not documented. Supporting documentation should include a history of injury to the thumb or hand, along with clinical findings consistent with osteoarthritis.

• Only use this code when laterality is truly unspecified; if laterality is known, use the more specific codes (M18.31 or M18.32).
• Ensure the documentation explicitly states "post-traumatic" to differentiate from primary or secondary osteoarthritis.
• Look for a documented history of trauma to the affected joint that predates the onset of osteoarthritis symptoms.