Coding Scenario: Infected knee prosthesis, morbid obesity

A morbidly obese man had bilateral knee replacements six years ago. His right knee developed recurrent infections, which were treated. The knee joint replacement was revised twice, but he still developed MRSA infections. A decision was made to remove the joint and insert an antibiotic cement spacer while he receives ongoing IV antibiotics at home via PICC.

Rationale:

• Capture the infection through coding T84.53XA (Infection and inflammatory reaction due to internal right knee prosthesis, initial encounter). Because the infection is being actively treated, use the seventh character “A.”
• Code the infection identified as MRSA with B95.62 (Methcillin resistant Syaphylococcus aureus infection as the cause of diseases classified elsewhere).
• The patient is documented as being morbidly obese, so you’ll also list E66.01 (Morbid (severe) obesity due to excess calories).
• Code the absence of the right knee from the original knee replacement with Z89.521 (Acquired absence of right knee).
• Assign Z45.2 (Encounter for adjustment and management of vascular access device).*
• To capture the patient’s ongoing IV antibiotics usage, assign Z79.2 (Long term (current) use of antibiotics).
• You could also add Z96.652 for the uninfected left knee prosthesis.

Correction:

*The code Z45.2 (Encounter for adjustment and management of vascular access device) was assigned in the scenario above. This was a coding error. Per Q3 2018 Coding Clinic guidance, Z45.2 should not be reported if the only service provided is administration of intravenous therapy.