Stems are indicated in almost all revision total knee arthroplasty (TKA). Data show that routine use of stems in revision TKA leads to fewer failures than discretionary use of stems.

Stems provide the benefit of enhanced mechanical fixation while distributing the load over a greater area, which is important in total knee arthroplasty revision (TKAR) because bone quality and quantity usually are compromised by failure of the previous implant, stress shielding, or bone loss related to implant removal.

Conceptually, there are 3 main areas for implant fixation in TKAR: (1) the bone surfaces of the femur and tibia, (2) the metaphyses of the femur and tibia, and (3) the diaphysis of the femur and tibia. The bone surfaces typically are fixed with cement. Metaphyseal fixation may be with cement or with uncemented sleeves or cones. Diaphyseal fixation is with stems, which may be cemented or uncemented.

Both cemented and uncemented stems can provide reliable, stable fixation in revision TKA. Each has advantages and disadvantages.

Stem choice should be based on available implants, remaining bone stock, presence of bony deformity, and ease of extraction.

Most uncemented stems obtain a press fit in the diaphysis but do not provide true biologic fixation because most do not have bone ingrowth or ongrowth surfaces. Uncemented stems may be easier to insert and extract than cemented stems. Final implant position is dictated by the diaphysis. This can sometimes be modified with offset stems. When bone deformity is present, uncemented stems allow less latitude to compensate than cemented stems. Pain at the stem tip has been reported in some patients with uncemented stems.

Cemented stems provide immediate and long-term fixation. They provide more versatility in the presence of bone deformity than uncemented stems but in the presence of normal anatomy provide less alignment guidance. Cemented stems allow for local antibiotic delivery from the cement. Cemented stems typically are more difficult to extract than uncemented stems.

Despite advantages and disadvantages of each method, cemented or uncemented stems can be used in most cases, depending on surgeon preference (Figures 62.1 and 62.2).

Suggested indications for uncemented stems:

Suggested indications for cemented stems:

Revision TKA: femoral and tibial implants

Supine

Nonsterile tourniquet

Standard, midline approach with median parapatellar arthrotomy is preferred. Considerations should be made for previous skin incisions or soft tissue defects.

Extensile knee approaches such as quadriceps snip or tibial tubercle osteotomy may be required. See Section IV-B, Chapter 2 for details.

Obtain previous operative reports and implant records.

Obtain full-length hip-to-ankle radiograph. Determine the desired mechanical alignment and determine which stem configurations can help achieve this.

If the tibial or femoral component will be retained, review the manufacturer’s revision instrumentation options. Custom or seldom used implants may require shipment from the device company.

Template femoral and tibial stem length, diameter, and component position. Anticipate use of uncemented or cemented stems.

Perform the desired approach to the knee, employing an extensile approach if needed. If possible, it is preferable to use the previous incision. If multiple incisions are present, utilizing the most lateral incision possible is desirable.

Remove implants, being careful to preserve as much bone as possible (see Section IV-B, Chapter 3).