A 58-year-old woman presented with a painful left knee having previously undergone a patellectomy in association with a Maquet osteotomy at age 26, followed by a total knee arthroplasty (TKA) at age 48. The primary TKA was a posterior-stabilized design, chosen because of the absent patella, and was completed without complications ( Fig. 12.1 ). The knee had slowly developed pain and swelling over the past 4 years. The physical examination revealed an antalgic gait on the left side with a moderate to large effusion in the left knee. The range of motion of the knee was from full extension to 105 degrees. The less symptomatic right knee had also undergone a patellectomy with a Maquet osteotomy but was not painful and did not have an effusion. Radiographic studies revealed thinning of the polyethylene insert and associated polyethylene disease. There was significant cyst formation on the femoral side with less invasion of the tibial metaphyseal area ( Fig. 12.2 ). The laboratory workup included a white blood cell (WBC) count of 8500 cells/μL, an erythrocyte sedimentation rate (ESR) of 18 (normal up to 20), and a C-reactive protein (CRP) level of 4 (normal up to 5.0). The knee joint was aspirated, and the cultured fluid showed no WBCs and no bacterial growth. The patient was admitted for surgery and underwent a revision TKA using a constrained device with intramedullary stems and metal augments on the femoral side for the cystic bone loss. At the time of surgery, both components were clinically loose and had minimal underlying bone support ( Fig. 12.3 ).
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Chapter Synopsis
This chapter reviews the principles of revision total knee arthroplasty (TKA), including the preoperative workup, the history and physical examination, and the operative technique.
Important Points
The important points include a thorough history to identify any complications after the original TKA, especially evidence of infection. The physical examination should confirm the site of tenderness and any associated swelling. The balance of the collateral ligaments and the range of motion (ROM) should be evaluated to help with the choice of the revision prosthesis. The imaging techniques should include proper radiographs to see the implant. Computed tomography of the knee can help with rotation of the femoral component and in determining the true amount of bone loss. Scintigraphic studies can confirm loosening of the implant and help to differentiate loosening from infection ( Fig. 12.4 ). Laboratory tests should include at least the WBC count, ESR, and CRP. If all three are normal, the evidence for infection is very low, but the joint should always be aspirated if there is any question.
Surgical Pearls
The choice of skin incision must take into account all of the previous incisions. If there has been more than one vertical approach, the most lateral incision should be used to avoid necrosis of the lateral flap, which has the lesser blood supply. The arthrotomy must preserve the extensor mechanism at all costs. If the ROM of the knee is limited to 70 degrees or less, a modification of the approach is necessary—either a quadriceps snip, a quadriceps turndown, or a tibial tubercle osteotomy. The steps of the surgery should be completed in a methodical fashion in the following order:
- 1.
Make the skin incision
- 2.
Perform the arthrotomy
- 3.
Remove the implants
- 4.
Establish the perpendicular tibial platform
- 5.
Establish the flexion gap with proper choice of the femoral component size
- 6.
Match the extension gap to the flexion gap by augmenting the distal femoral bone where there has been loss
- 7.
Confirm the ligament balance in flexion and extension
- 8.
Address the bone defects with augments
- 9.
Choose the intramedullary stems
- 10.
Choose the tibial insert constraint
Surgical Pitfalls
The pitfalls include avulsion of the patellar tendon insertion ( Fig. 12.5 ). Placement of a fixation pin through the medial aspect of the tendon insertion to prevent lateral avulsion can be somewhat effective but may also lead to weakening of the substance of the tendon and subsequent rupture. If avulsion does occur, simple tacking of the tendon to the tibial tubercle is ineffective. At minimum, the tendon should be protected with a bolt-and-wire technique. If the patella bed has enough remaining substance, the semitendinosus tendon can be harvested, passed through the patella, and fixed on the lateral side of the tibial tubercle, serving as a modified bolt-and-wire technique.
Elevation of the joint line should be avoided, especially on the femoral side. Augments for the distal femur are almost always necessary. The flexion and extension gaps must be equalized, and if this becomes difficult, it may be necessary to implant a hinge type of device. Intraoperative fractures can occur, and proper fixation plates should always be available in the operating room for this potential problem. During removal of the patellar implant, fracture of the underlying bed may occur. Although this is certainly not desirable, it often can be ignored if the extensor mechanism is intact and the remaining fragments are firmly attached to the tendon.
Introduction
Revision total knee arthroplasty (TKA) will become increasingly common as the total number of implants increases and the total pool of TKAs ages. The techniques will continue to evolve, but the principles will remain the same. The ten steps for operative revision incorporate the three-step technique popularized by Vince and make the surgery more logical and reproducible.
Indications and Contraindications
The workup for revision TKA should include a thorough history, physical examination, imaging, and laboratory tests (especially to rule out underlying infection). Some patients may be unable to undergo any further surgery, or the success of the surgical intervention may be severely limited due to a minimal amount of remaining bone. In some cases, alternative solutions such as a reconstructive hinge knee arthroplasty or a knee fusion or bracing should be included in the preoperative considerations.
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