California Subscriber
Answer: This procedure description presents two coding choices. First, if the orthopedist makes an incision along the vastus medialis tendon and then pulls the tendon so that it overlaps the patella, suturing it down to improve patellar alignment, you-ll report 27422 (Reconstruction of dislocating patella; with extensor realignment and/or muscle advancement or release [e.g., Campbell, Goldwaite type procedure]).
On the other hand, if he removes any bone from the tibial tuberosity, you should stick with 27420 (- [e.g., Hauser type procedure]) or 27418 (Anterior tibial tubercleplasty [e.g., Maquet type procedure]).
In either case, you should report 718.86 (Other joint derangement, not elsewhere classified; lower leg) as your diagnosis to show medical necessity for the procedure.