Case Study:
Coding for Patalla and Tibial Liner Replacement
Published on Sat May 01, 1999
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 [...]