Osteoarthritis ICD-10-CM codes

Osteoarthritis coding is site-driven across categories M15 through M19: M15 covers polyosteoarthritis, M16 the hip, M17 the knee, M18 the first carpometacarpal joint, and M19 other and unspecified sites. M19.90 (unspecified osteoarthritis, unspecified site) applies when the joint is not documented.

Where applicable, the fourth or fifth character distinguishes primary osteoarthritis from secondary and post-traumatic forms, so code selection depends on whether the provider documents a cause.

Assign codes for each involved joint separately when multiple joints are affected, and follow any applicable instructional notes for combination coding with related musculoskeletal conditions.