Missouri Subscriber
Answer: You can report both codes on your claim based on the fact that the surgeon addressed conditions in separate compartments, although not all insurers will honor the charges.
You should report 27446 (Arthroplasty, knee, condyle and plateau; medial OR lateral compartment) for the unicondylar knee replacement.
In addition, you should report 27599 (Unlisted procedure, femur or knee) for the microfracture.
You should send your operative report with the claim, along with a letter from the physician explaining that the conditions were in separate compartments.