Indications for removal of well-fixed total knee arthroplasty components include all circumstances in which an implant must be removed to optimize the results of the subsequent revision. As implant removal techniques have evolved and improved, surgeons have become more willing to remove well-fixed implants to optimize the subsequent reconstruction. That is, surgeons have become less fearful of the drawbacks of removing well-fixed implants and at the same time, have become more conscious of the value of starting with fresh implants that do not compromise options available for the subsequent reconstruction.

Indications for removal of well-fixed implants include the following:

Removal of well-fixed implants is relatively contraindicated when the implant can be preserved at revision surgery without compromising the reconstruction results. In some cases, a well-fixed, well-positioned tibial component that has parts compatible with modern femoral components may be preserved. A well-fixed femoral component may also be preserved in special circumstances; however, it is important to understand that preserving the well-fixed femoral component limits the surgeon’s ability to adjust the position of the joint line, and therefore the flexion and extension balance. A well-fixed femoral component can be preserved less frequently than a well-fixed tibial component.

A well-fixed patellar component can often be preserved even when tibial and femoral revision are required. To be retained, the patellar component should not demonstrate severe polyethylene damage and should be reasonably compatible with the geometry of the trochlear groove of the planned new femoral component. Most dome-shaped patellar components articulate sufficiently well with the trochlear groove of most femoral implants to be considered compatible (4).

When the surgeon considers removing any implant, the risks and benefits of the decision must be weighed carefully. The surgeon must consider the following questions: How important is it to remove the implant for the subsequent reconstruction? How much bone is likely to be lost at the time of implant removal? If the anticipated amount of bone is lost, how much will this affect the subsequent revision options and success? What is the likelihood of more bone than expected being lost during implant removal? What is the likelihood of a catastrophic problem occurring during implant removal such as fracture of the major supportive portion of the bone? If major bone loss or a fracture occurs during implant removal, how much will this affect the results of the proposed reconstruction? How much time is implant removal likely to take, and what risk does the extra operative time pose to the individual patient? What benefits are likely to be realized by an implant removal? Are these benefits important enough to justify the risks previously mentioned?

The preoperative plan should take into account the diagnosis for which the patient is being revised and should include careful consideration of the specific interventions necessary to solve the existing problems with the knee arthroplasty. Before surgery, anticipate which implants will require removal to accomplish the surgical plan, and in turn, have appropriate tools available to accomplish the anticipated implant removal.

Before the surgery, make every effort to identify the specific implants already in place by manufacturer and design. Familiarize yourself with the design of the implants to be removed and methods of implant disassembly. Some implants can be removed much more easily if proper implant disassembly tools or implant-specific removal instruments are on hand, and in such cases, when possible, make arrangements in advance to have these instruments available.

Consider the tools needed for implant removal, including osteotomes, oscillating saws, punches, and universal tibial and femoral implant extraction devices. Also, have available specialized instruments such as high-speed metal cutting instruments and ultrasonic devices for cement removal. When necessary, have available specialized intramedullary cement column removal instruments when cemented stemmed implants must be removed.

As part of the preoperative plan, consider the order in which implants will be removed and have back-up plans available should the initial plan for implant removal fail. Also consider alternative plans if more bone loss than expected occurs during implant removal.

Effective implant removal is based on using specific instruments for specific tasks. The following is a list of commonly used instruments with a discussion of strengths and weaknesses of each.