Bilateral primary osteoarth of first carpometacarp joints

This code signifies the presence of degenerative joint disease affecting both first carpometacarpal (CMC) joints, specifically the articulation between the trapezium and the first metacarpal bone. It indicates that the osteoarthritis is primary, meaning it is not secondary to trauma, inflammation, or another underlying condition.

Apply this code when documentation clearly states bilateral primary osteoarthritis of the first CMC joints. This is commonly seen in patients presenting with pain, stiffness, and reduced range of motion at the base of both thumbs, often confirmed by imaging studies showing characteristic degenerative changes.

• Ensure documentation specifies "bilateral" involvement; otherwise, a unilateral code (M18.1- or M18.2-) would be more appropriate.
• Verify that the osteoarthritis is explicitly stated as "primary" to differentiate it from secondary forms (M18.3- or M18.4-).
• Look for supporting diagnostic imaging reports (e.g., X-rays) that confirm degenerative changes at both first CMC joints.