Primary Care Coding Alert

Unspecified location? Look to the M19 codes.

When ICD-9 becomes ICD-10 in October 2013, physicians will need to be more conscious of documentation when noting a patient has osteoarthritis. Current diagnosis choices (e.g., 715.xx) specify the arthritis location and whether it is primary or secondary to other conditions.

ICD-10 difference: Under ICD-10, you'll have several code families to search for the best diagnosis:

• M15 (Polyosteoarthritis)
• M16 (Osteoarthritis of hip)
• M17 (Osteoarthritis of knee)
• M18 (Osteoarthritis of first carpometacarpal joint)
• M19 (Other and unspecified osteoarthritis).

Each code is broken down into location, primary, and secondary like your ICD-9 codes, but they also sometimes specify unilateral, bilateral, and posttraumatic indications. For example, the most accurate diagnosis for a patient with primary OA of the right knee would be M17.11 (Unilateral primary osteoarthritis, right knee). The code would change to M17.12 for left knee or M17.0 for bilateral primary OA of the knee.

Documentation: To submit the most detailed diagnosis, the physician will need to expand documentation to include notes regarding unilateral, bilateral, and/or post-traumatic conditions. Some key terms to watch for include "osteoarthritis," "arthritis," "arthrosis," "DJD," "arthropathy," "post traumatic arthritis," and "traumatic arthritis."

Coding tips: You often find "unspecified" diagnoses in ICD-9 with codes representing more specific diagnoses for the same condition (as in, the .x9 choice in most

ICD-9 categories). ICD-10 changes that by listing all "unspecified" diagnoses at the end of the condition category. For example, codes M19.90--M19.93 represent unspecified locations of osteoarthritis.

In addition, traumatic osteoarthritis is now more appropriately indexed and described as post-traumatic osteoarthritis, the true condition.