Q&A: Proper ICD-10-CM reporting for OA

Q: We have an elderly patient admitted to our hospital who is also presenting with osteoarthritis (OA) of the right knee. Since we don’t report OA very often, we are having trouble determining if we should code primary or secondary OA. How can we determine primary versus secondary OA, and how would it be reported in ICD-10-CM?

A: OA, or degenerative joint disease, is identified in categories M15-M19 of the ICD-10-CM manual. This is the most common type of arthritis in the elderly. If the arthritis is ever in the spine, refer to category M47, Spondylosis.

When coding OA, review the medical records to determine whether the OA is localized or generalized and if it’s primary or secondary. Bilateral OA of the same site is considered localized, where generalized OA affects multiple joints. Code the joints affected separately.

Primary OA is caused by aging and secondary OA is caused by other conditions such as avascular necrosis. Per Coding Clinic, Fourth Quarter 2016, when the type of OA is not specified, “primary” is the default, as it is the most common form.

For example, ICD-10-CM codes for unilateral, primary OA of the knees can be identified with the following:

• M17.10, unilateral primary osteoarthritis, unspecified knee
• M17.11, unilateral primary osteoarthritis, right knee
• M17.12, unilateral primary osteoarthritis, left knee

Editor’s note: Adrienne Commeree, CPC, CPMA, CCS, CEMC, CPIP, RHIA, lead medical coding specialist at the Washington State Health Care Authority located in Olympia, Washington, and adjunct coding instructor at Tacoma Community College located in Tacoma, Washington, answered this question. Opinions expressed are that of the author and do not necessarily represent HCPro, ACDIS, or any of its subsidiaries.

This answer was provided based on limited information. Be sure to review all documentation specific to your own individual scenario before determining appropriate code assignment.