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    Extensile Exposure for a Failed Revision TKA with a Metaphyseal Cone and Long Cemented Stem

    An 81-year-old man presents with an unstable knee 15 years after a revision total knee arthroplasty. He has a long cemented stem and a well fixed proximal tibial cone. What is the best way to safely revise his prosthesis?

    Authors

    Chad A Krueger, MD; Erik Zachwieja, MD; and P. Maxwell Courtney, MD

    Introduction

    Bone loss is commonly encountered in revision total knee arthroplasty (TKA). Reconstruction options largely depend on the extent of bone loss, as categorized by the Anderson Orthopaedic Research Institution classification: [1]

    • Type 1 defects do not require advanced reconstruction techniques.
    • Type 2a defects have metaphyseal damage of 1 femoral condyle or tibial plateau.
    • Type 2b defects have bilateral metaphyseal damage.
    • Type 3 defects have an extensive metaphyseal defect.

    Although some surgeons prefer cone or sleeve augments for type 2a or 2b defects, most surgeons agree that a metaphyseal augment, in the form of a sleeve or a cone, is necessary for type 3 defects. [2]

    The surgeon faces a more challenging scenario when a patient requires a re-revision TKA after undergoing a revision TKA that had addressed a metaphyseal bone defect. In the femur, a distal femoral replacement is a relatively straightforward option if removing the previous cone and cement alone will not leave enough bone to support a distal prosthesis. [3] In the tibia, however, performing a proximal tibial replacement is not an easy task, and it puts the patient at risk for substantial morbidity, including issues with the extensor mechanism.

    Therefore, it is important to know how to remove the previously implanted components without compromising the bone stock to the point that a proximal tibial replacement is necessary.

    Case Presentation

    An 81-year-old male patient presents with left knee pain and instability 15 years after undergoing bilateral revision TKA. He has difficulty going down the stairs and feels that his ability to perform daily activities is decreasing secondary to pain and instability.

    A knee brace has provided mild symptomatic improvement, but the patient feels that his knee still buckles in the brace, making him think that he is unstable on his feet. He is otherwise healthy without any neurologic symptoms.

    Physical Exam

    • Height: 6 feet, 0 inch; weight: 190 pounds; BMI: 35.8
    • Well-healed anterior midline incision
    • Range of motion: -10° to 110°
    • Significant anteroposterior laxity in flexion and extension and a recurvatum deformity in extension
    • Mild laxity with varus and valgus stress at 0° to 30° of flexion
    • Normal distal lower extremity neurovascular exam

    Laboratory Tests

    • Serum erythrocyte sedimentation rate: 17 mm/h
    • Serum C-reactive protein: 0.6 mg/L

    Imaging

    Figure 1. Preoperative anteroposterior and lateral radiographs of the left knee demonstrate a long cemented tibial stem with an asymmetric tibial cone.

    Figure 2. Weightbearing anteroposterior and lateral radiographs of the left knee.

    Figure 3. Sunrise view of the left knee.

    Diagnosis

    • Left knee instability after revision TKA

    Treatment

    There are several considerations for the management of this patient:

    • He has failed extensive non-operative treatment.
    • He has a long cemented tibial stem with a cone that appears to be well fixed. What are the best options to remove this component?
    • What is the plan for an extensile exposure of the left knee during the revision?
    • Given his instability and the amount of bone loss likely to be present after component removal, what is the plan for the definitive treatment of his knee instability?

    We discussed all treatment options with the patient and obtained his informed consent for a revision to a hinged implant, which we believed was the best option given his age, instability, and expected bone loss. Although the tibial component was well fixed, it had to be removed to accommodate the hinged bearing mechanism, as recommended by the manufacturer of the implant we planned to use.

    Surgical Procedure

    • A standard medial parapatellar approach was made in the operative knee.
    • We sent a total of 5 specimens for culture, all of which were negative.
    • After a thorough synovial debridement, the implants were exposed. The femoral component was removed following removal of the polyethylene.
    • Our attention was then turned to the tibia. The tibial component was very well fixed and could not be removed after separating the baseplate from the underlying cement.
    • The tibial cone was also well fixed. Only a thin shell of bone remained on the periphery of the cone.
    • A tibial tubercle osteotomy was performed for better access to the cone and the tibial component (Figure 4).

    Figure 4. Intraoperative photographs showing the tibial tubercle osteotomy.

    • After the osteotomy was complete, we could clearly identify the large amount of well-fixed cement within the cone, which was providing fixation to the tibial construct.
    • We did not believe we could remove the tibial cone without creating extensive bone loss in the proximal tibia.
    • Instead, we used a metal cutting burr to remove the anterior quarter of the tibial cone. We were able to remove more cement through this window and finally free up the implant enough to remove the tibial component.
    • We then removed the remainder of the cement from the top of the tibia.
    • A hinged knee implant was placed using a combination of press fit in the diaphysis of the tibia and femur and cement fixation in the metaphysis/surface. The remaining tibial cone was left in place to provide metaphyseal support for the construct (Figure 5).

    Figure 5. Intraoperative photographs showing the tibial tubercle osteotomy after it had been secured.

    • Postoperative radiographs are shown in Figure 6.

    Figure 6. Immediate postoperative radiographs of the revised TKA.

    Postoperative Follow-up

    • The patient was placed in a hinged knee brace for 6 weeks postoperatively. He was allowed to perform weight-bearing as tolerated with his knee in extension.
    • He has done well postoperatively at 6 months. He has a range of motion from 0° to 110° in the operative knee, with no extensor lag. The osteotomy is well healed.

    Discussion

    Severe tibial bone loss and long, well-fixed cemented components are challenging circumstances to encounter during revision TKA. In these cases, deciding how to remove the components while preserving as much bone as possible is a key to success. Although tibial tubercle osteotomies may cause some surgeons to be concerned about the potential for a malunion or non-union, they are much more controlled than either fracturing the proximal tibia inadvertently or causing a patella tendon avulsion during the course of a difficult exposure. [4]

    There are no data showing the effectiveness of partial cone removal, but in this case, it was deemed the best option to avoid a proximal tibial replacement. By leaving three quarters of the cone in place, we were able to keep the remaining proximal tibia intact and securely fix the new tibial component to the cone with cement.

    Surgical Pearl

    • Performing a tibial tubercle osteotomy allows for an extensile exposure of the tibia to aid with cement removal and stem extraction in difficult cases.

    Author Information

    Chad A Kruger, MD; Erik Zachwieja, MD; and P. Maxwell Courtney, MD, are from The Rothman Institute at Thomas Jefferson University Hospital, Philadelphia, Pennsylvania. Dr. Courtney is also the Adult Reconstruction Section Editor of Rothman Institute Grand Rounds on ICJR.net.

    Disclosures: The authors have no disclosures relevant to this article.

    References

    1. Engh GA, Ammeen DJ. Bone loss with revision total knee arthroplasty: defect classification and alternatives for reconstruction. Instr Course Lect. 1999;48:167-175.
    2. Mancuso F, Beltrame A, Colombo E, Miani E, Bassini F. Management of metaphyseal bone loss in revision knee arthroplasty. Acta Biomed. 2017;88(2S):98-111. Published 2017 Jun 7. doi:10.23750/abm.v88i2-S.6520
    3. Berend KR, Lombardi AV Jr. Distal femoral replacement in nontumor cases with severe bone loss and instability. Clin Orthop Relat Res. 2009;467(2):485-492. doi:10.1007/s11999-008-0329-x
    4. Punwar SA, Fick DP, Khan RJK. Tibial Tubercle Osteotomy in Revision Knee Arthroplasty. J Arthroplasty. 2017;32(3):903-907. doi:10.1016/j.arth.2016.08.029