Orthopedic Coding Alert

Case Description

A patient previously had total knee replacement, including a metal-backed in-growth patella that had failed and required revision. The operative report states he undergoes a revision of left total knee replacement.

Coding and Procedural Background

To analyze this case correctly, its helpful to understand the CPT description of a total knee replacement as well as its revision.

Total knee replacement, or 27447: This procedure replaces severely damaged or worn cartilage in the medial, lateral, and patellofemoral compartments of the knee. Heres how: The surgeon makes a midline incision over the knee and dissects down to expose the knee joint. In order to improve range of motion, he or she may release ligaments or soft tissues. With a cutting-alignment tool called a jig, the orthopedist removes both the femoral condyles and the medial and lateral compartments of the tibial joint surface. He or she also may remove damaged cartilage on the joint surface of the patella by cutting the under-surface and replacing it with a prosthesis. After the rest of the components for the tibia and femur are secured with glue and/or bone screws, the incision is repaired.

Total knee revisions, or 27486 and 27487: In 27486, one of the femoral or tibial components are removed. An osteotome or saw is used to loosen the cement or bone and the prosthesis is then popped out with a mallet. The surgeon then makes bone cuts to accommodate the new component. (Donor bone, or allograft, may or may not be packed into the defect, depending on the severity of the defect.) The component is then placed and cemented. In 27487, the same procedure occurs except the femoral and entire tibial components are replaced.

Operative Report Notes

After making an incision and identifying the extensor mechanism, performing a medial parapatellar arthrotomy, and elevating the medial soft tissue off the medial tibia, the surgeon took a gram stain which was negative. Then he divided the patellofemoral ligaments and circumferentially dissected the patella.

A visual inspection of the metal-backed in-growth patella component showed signs of wear, so the surgeon removed it using osteotomes. The surgeon also found marked destruction of the tibial polyethylene and removed all flakes of polyethylene from the knee in addition to performing a radical synovectomy.

The posterior cruciate ligament was recessed slightly to allow me to go up to a bigger polyethylene insert. I placed a size 11 polyethylene insert into the knee and I went from 0 to 100 in 20 degrees without varus or valgus instability. At this point, a Howmedica PCA size large11 mm polytheythlene was placed. The knee was reduced, taken through range of motion, stable through the previously mentioned parameters.

The patella cutting guide was placed and the patella was cut leaving 13 mm patella. A Howmedica small patella component, all polyethylene was now placed slightly medial.

The patient tolerated procedure well and arrived in recovery room in stable condition.

Coding Challenges

Its difficult to find the right code that describes this procedureas is the case with many orthopedic surgeries.

The patients femoral and tibial components were found to be stable but he had tibial polyethylene debris within the knee. So along with the revision of the patella component, the liner was revised as well, says Leslie A. Follebout, coding analyst at Peninsula Orthopaedic Associates in Salisbury, MD.

Yet 27487 would only be appropriate if the femoral and entire tibula component had been replaced. In this case, although the surgeon called the procedure a knee revision, neither the femoral nor the entire tibula component was replaced; therefore, 27487 would not be the best code.

In fact, with 27487 having the highest RVU (60.07) of the knee replacement or revision codes, it would be considered upcoding if you selected this code. Just because the tibial liner was replaced does not justify using this code. Sources point out that the 1999 revised edition of CPTs definition of this code included the entire tibial component.

Likewise 27486 (revision of total knee arthroplasty, with one component) is not entirely appropriate either because it was the patella, not the femoral or tibula component that was replaced. (This procedures RVU is 45.61.)

One option is to use 27486 and reduce it by appending a -52 modifier (reduced services) to indicate that the physician had elected to reduce or eliminate a portion of the procedure. (You cannot charge for a partial or complete synovectomy because it is considered bundled into both total knee revision codes.)