Outpatient Facility Coding Alert

Question: Which ICD-10 codes support medical necessity for knee arthroplasties?

Oregon Subscriber

Answer: Although TKA codes 27437 (Arthroplasty, patella; without prosthesis) through 27447 (Arthroplasty, knee, condyle and plateau; medial AND lateral compartments with or without patella resurfacing (total knee arthroplasty)) share a common root, they do not share a common list of acceptable diagnoses across procedures and payers.

Don't worry:  If the operative report isn't clear, you can ask your provider to confirm the patient's diagnosis. You can also check out this list of ICD-10 codes that might indicate the provider performed a knee arthroplasty. Experts agree that most of the knee arthroplasty claims orthopedic coders see will involve some sort of arthritis, most likely osteoarthritis.

Some knee-related ICD-10 codes include:

• M17.0- (Bilateral primary osteoarthritis of knee)
• M17.1- (Unilateral primary osteoarthritis of knee)
• M17.2- (Bilateral post-traumatic osteoarthritis of knee)
• M17.3- (Unilateral post-traumatic osteoarthritis of knee)
• M17.4- (Other bilateral secondary osteoarthritis of knee)
• M17.5- (Other unilateral secondary osteoarthritis of knee)
• M17.9- (Osteoarthritis of knee, unspecified).

Another patient population that often requires knee arthroplasties are those with rheumatoid arthritis (RA). Some knee-related RA ICD-10 codes include:

• M05.06- (Felty's syndrome, knee)
• M05.16- (Rheumatoid lung disease with rheumatoid arthritis of knee)
• M05.26- (Rheumatoid vasculitis with rheumatoid arthritis of knee)
• M05.36- (Rheumatoid heart disease with rheumatoid arthritis of knee)
• M05.46- (Rheumatoid myopathy with rheumatoid arthritis of knee)
• M05.56- (Rheumatoid polyneuropathy with rheumatoid arthritis of knee)
• M05.66- (Rheumatoid arthritis of knee with involvement of other organs and systems).

In addition to the M05.06- code set, ICD-10 also lists several more diagnosis categories for different types of rheumatoid arthritis (RA): RA with involvement of other organs or systems, RA with rheumatoid factor, etc. Each of these RA code sets includes a diagnosis for RA of the knee. 

---