RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Principles of Revision Total Knee Replacement

P ITFALLS

  • The best results of revision TKR are achieved when the failure mechanism of the original implant is understood and rectified.

 

Principles of Revision TKR

 

Indications

  • Symptomatic patients with a failed total knee replacement (TKR) with pain and functional disability that interferes with their quality of life and who are willing to undergo a revision arthroplasty.

    Examination/Imaging

    Controversies

    • Revision TKR for pain alone and not an underlying cause often fails.

    • Revision TKR for reflex sympathetic dystrophy is ill-advised.

    • Controversy exists with one-stage versus two-stage revision knee replacements for deep sepsis. Our preference is to perform a two-stage revision procedure.

     

  • An organized approach to the revision knee is important and should include a thorough history and physical examination, review of past operative notes and implant identification stickers, and assessment of serial radiographs.

  • Physical examination of the knee should determine the location of prior incisions, the integrity of the extensor mechanism, the range of motion in the knee, the stability of the knee, and the patient’s gait pattern.

    Treatment Options

    • Nonoperative treatment of a failed TKR is sometimes indicated in elderly patients with considerable comorbidities or in patients with persistent infection or neurovascular compromise.

    • Other techniques for the failed TKR would include resection arthroplasty, arthrodesis, and amputation.

     

  • Infection should be suspected if there was prolonged drainage after the primary TKR, antibiotics were prescribed, or there is elevation of the patient’s sedimentation rate or C-reactive protein. If these indices are elevated, knee aspiration is indicated with analysis of the synovial fluid for a cell count as well as aerobic and anaerobic organisms.

  • Serial radiographs are most helpful in assessing changes in implant position or the progression of radiolucent lines.

  • Mandatory radiographs include anteroposterior (Fig. 1A), lateral (Fig. 1B), and axial patellofemoral (Fig. 1C) views of the affected knee. We also like to obtain standing hip-to-ankle radiographs to assess the joint above and below the knee implant and potential deformities that might interfere with the use of stemmed revision components.

  • Fluoroscopic-guided radiographs are often helpful in assessing bone-cement-implant interfaces.

  • Every effort should be made to identify the TKR device that is in place, both from prior operative notes and from the radiographs. It is important to know the track record of that particular implant, the modes of failure associated with that device, and any nuances with regard to the modularity of the implant.

     

     

     

     

    Principles of Revision TKR

     

     

     

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    A

     

    B

     

    C

    FIGURE 1

     

     

    Surgical Anatomy

  • The most significant blood supply to the skin courses from the medial side of the knee (Fig. 2), hence when faced with multiple incisions, it is preferential to use the most lateral incision that will adequately give exposure to the knee.

  • Since the blood supply to the skin courses deep to the adipose layer, skin flaps should be dissected off the deep fascia to protect the vascularity of the skin.

  • Preoperative assessment of bone defects is important to determine whether the femoral epicondyles are involved with the potential loss of stability afforded by the collateral ligaments, the integrity of the extensor mechanism, and what defect-filling technique (i.e., bone graft, metal augments) will be required.

     

     

    Descending branch

    of the lateral circumflex artery

     

    Lateral superior genicular artery

     

    Lateral inferior genicular artery

     

    Anterior tibial recurrent artery

     

    Anterior tibial

    artery

     

    FIGURE 2

    Highest genicular artery

     

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    Principles of Revision TKR

     

    Musculoarticular branch artery

     

    Saphenous branch artery

     

    Medial superior genicular artery

     

    Medial inferior genicular artery

     

    Medial tibial recurrent artery

     

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    P EARLS

    • Removal of hair in the operative field should be performed using electric clippers just prior to the operation.

       

    • It is helpful to mark prior incisions with an indelible ink pen.

       

    • The tourniquet should not be inflated until the last moment, to limit limb ischemia time.

       

    • The use of a sterile surgical glove over the ipsilateral foot is helpful in isolating the semisterile foot without hindering exposure to the ankle.

       

      P ITFALLS

    • If the contralateral limb is not well padded, there is a risk of contusion during the operative procedure.

     

    Principles of Revision TKR

     

    Positioning

    • Supine positioning of the patient

    • Use of a tourniquet high on the thigh of the operated leg

    • Use of a foot support to hold the knee in 75–80° of flexion

    • Use of a lateral bolster over the greater trochanter to prevent the limb from falling sideways

    • Use of a self-adhering impervious drape to prevent pooling of iodine under the tourniquet

       

      Equipment

      • A well-padded operating room table

      • A foot positioner

      • A lateral bolster

       

       

      Controversies

      • Other methods to position the operative leg include the use of a sterile foot holder that fits in a track that sits on the operative table, or the use of a computerized robotic arm to position the leg.

       

       

       

      P EARLS

      • Portals

        • Small incisions should be avoided in revision TKR. It is best to utilize an incision that extends one handbreadth proximal to the patella to just distal to the tibial tubercle.

           

        • Prior transverse incisions can be safely crossed at right angles.

           

        • It is helpful to make the skin incision and develop the skin flap with the knee flexed. In compromised skin, a sham incision is sometimes advisable.

       

      Portals/Exposures

      Portals

    • A longitudinal midline incision is usually preferred, deviating just medial to the tibial tubercle distally.

    • When faced with multiple incisions, it is advisable to use the most lateral incision that will give adequate exposure, thereby preserving as much of the rich medial blood supply as possible.

    • If only part of a preexisting incision is utilized, any additional incisions should intersect an old incision at a right angle.

    • All incisions should extend vertically to the underlying fascia, and any skin flaps that are developed should be elevated from the underlying fascia to minimize the disruption of blood supply to the skin.

    • Five intraoperative aerobic/anaerobic cultures for culture and sensitivity are recommended.

       

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      P EARLS — cont’d

      • With a history of recurrent wound breakdown or draining sinus, the surgeon may well want to consider a medial head of the gastrocnemius transfer with skin grafting before the revision procedure. For example, in Figure 4, a chronic infection in a total knee arthroplasty patient was successfully treated with a

      two-stage revision procedure in which skin coverage was achieved between stages with a medial head of the gastrocnemius flap and split-thickness skin grafting. Early involvement of a plastic surgeon prior to the actual surgery is recommended.

      • Exposures

         

        • Release of the scar tissue from the anterior aspect of the lateral tibial plateau can greatly facilitate mobilization of the patella.

           

        • The patella does not have to be everted, but can simply be subluxed off the femur until exposure is completed.

       

      Principles of Revision TKR

       

      Exposures

  • The surgeon should have a “tight knee protocol” in order to gain adequate exposure. This should include maximizing the longitudinal incision through the extensor mechanism, elevating the fat pad/patellar tendon and anterolateral capsule from the anterior tibial metaphysis, reestablishing the lateral gutters, removing the tibial polyethylene insert, placing a pin in the tibial tubercle to prevent “peel off” of the patellar tendon, and having a low index before performing a quadriceps snip.

  • If exposure is still difficult, we prefer to perform a

    tibial tubercle osteotomy (Fig. 3). Occasionally, the tibial tubercle is compromised by osteolysis, and in these cases, a quadriceps turndown might be preferable.

     

     

    P EARLS — cont’d

    • Release of the medial capsular structures from the medial tibial plateau to at least the midpoint of the medial tibial plateau and external rotation of the lower leg can greatly facilitate exposure.

       

    • The use of a pin through the patellar tendon at its insertion to the tibial tubercle can greatly aid in preventing patellar tendon peel off.

       

    • Synovectomy and release of scar tissue can greatly improve exposure.

     

     

     

     

    FIGURE 3 FIGURE 4

     

     

    P ITFALLS

    • Not elevating skin flaps at the fascial level.

       

    • Avoid elevating flaps through the underlying adipose tissue, which might disrupt the skin’s blood supply.

    • Too short of an incision.

       

    • Maintain an 8-cm skin bridge between longitudinal skin incisions.

       

    • The patellar tendon is vulnerable during the exposure of a revision TKR and should be protected at all costs.

     

    Procedure

    Step 1: Preoperative Planning

    • Preoperative planning in terms of the incision, exposure, prosthesis removal technique, bone defect reconstruction, and implant selection is fundamental.

       

      Instrumentation

      • Incisions are best made with a sharp scalpel with gentle retraction with rake retractors.

       

       

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      Controversies

      • Occasionally, revision arthroplasty is performed through a lateral parapatellar approach (i.e., to facilitate hardware removal), but this is a more difficult approach to perform a revision TKR.

      • Osteotomy of the medial femoral epicondyle with later reattachment has been advocated to enhance exposure in tight knees, but is not widely used.

       

      Principles of Revision TKR

       

      FIGURE 5

       

       

      P EARLS

      • Preoperative planning rounds at least 1 week prior to the surgery involving the surgical team and representatives from the ward (i.e., nurses and physiotherapists) greatly facilitate not only the operative procedure, but also the postoperative care of the patient (Fig. 5).

         

      • In difficult revision TKRs, it is advisable for the surgical team to be ready with plans A, B, and C.

         

        P ITFALLS

      • Poor preparation can lead to prolonged surgical time, second-best implant selection, and poorer outcomes.

       

       

      228

       

       

      P EARLS

      • Adequate exposure of the implant-bone interface greatly facilitates implant removal.

         

      • “Stacked” osteotomes are useful to lift loosened implants while protecting the underlying bone.

         

        P ITFALLS

      • Gigli saws occasionally remove excessive bone and probably should be avoided.

         

      • Avoid the use of rigid extractors before breaking down all fixation interfaces.

       

      Principles of Revision TKR

       

      Step 2: Implant Removal

  • The goal of component removal is to minimize host bone loss. The use of micro-oscillating saws, flexible chisels, and osteotomes are usually adequate.

  • Extraction devices should only be used once the interfaces have been broken.

    Step 3: Instrumentation

  • Intramedullary “endosteal” referencing is preferred during revision TKR (Fig. 6).

  • Once the old implants have been removed, it is advisable to restore the flexion space by releasing scar tissue from the posterior femoral condyles.

  • Start with tibial preparation. This minimizes damage to femoral bone and provides a platform to reconstruct the knee.

  • The use of low-profile instrumentation that locks onto intramedullary reamers of trial component stems adds stability and accuracy to bone cuts.

     

    P EARLS

    • Use of offset couplers helps optimize femoral and tibial component positioning and taking advantage of remaining host bone support.

     

  • Offset couplers are very helpful in revision TKR to optimize femoral and tibial component positioning.

     

     

     

     

     

    FIGURE 6

     

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    P EARLS

    • Cavitary defects are usually best treated with impaction cancellous allograft bone and cementing of the prosthesis on and into the impacted bone.

       

    • Most contemporary revision systems enable the surgeon to screw metal augments onto the revision components.

       

    • Wherever possible, we prefer rectangular metal augments over wedge-shaped metal augments.

       

      P ITFALLS

    • The use of structural allografts in revision TKR requires special expertise and, in most instances, should only be considered by an experienced revision knee arthroplasty surgeon.

       

    • When faced with massive bone loss, it can be difficult to obtain proper rotational alignment of revision hinge arthroplasties.

     

    Principles of Revision TKR

     

    Step 4: Bone Defects

    • Bone defects may be dealt with using metal augments, allograft, or cement.

    • AORI bone defect classification is helpful.

      • Minimum metaphyseal defects (F1, T1) usually can be handled with bone cement, which is no more than 5 mm in thickness.

      • When there is loss of a medial or lateral condyle or plateau (F2, T2), 5- or 10-mm metal augments or allograft can be utilized. In the failed unicompartmental knee arthroplasty shown in Figure 7A, a metal tibial augment (Fig. 7B) was used to replace lost bone.

      • When faced with more severe bone loss that affects ligamentous stability, an allograft with the use of a constrained implant or the use of hinge arthroplasty might be indicated.

 

 

 

A B

FIGURE 7

 

 

 

230

 

Principles of Revision TKR

 

A B

FIGURE 8

 

Step 5: Implant Selection

  • Most revision knee arthroplasties utilize stemmed tibial and femoral components. A Legion (Smith & Nephew, Memphis, TN) revision arthroplasty was used to revise the patient illustrated in Figure 1, as seen in anteroposterior (Fig. 8A) and lateral (Fig. 8B) radiographs.

  • Preoperative templating not only allows the surgeon

    to assess the size of the femoral and tibial components, but also the diameter and length of the stems required.

  • Most revision TKRs are performed with a posterior cruciate ligament–sacrificing implant.

  • Constrained varus/valgus tibial inserts should only be used when faced with varus/valgus ligamentous instability.

  • Hinged knee replacements should be used sparingly only in gross multidirectional instability.

     

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    Principles of Revision TKR

     

    Step 6: Implant Fixation

     

    P EARLS

    • The surgeon needs to assess varus/valgus stability of the limb, both in extension and flexion.

       

    • As much as possible, the surgeon should attempt to restore the joint line to help reconstruct normal joint biomechanics. If the opposite joint is not affected by arthritis, it can be a useful comparator. Otherwise, the surgeon can reference the distance from the medial collateral ligament to the joint line (usually about 22 mm) or the position of the inferior pole of the patella to the joint line (usually one finger breadth).

     

    • Our preference is to use hybrid fixation, cementing the femoral and tibial components as well as the metaphyseal portions of the stems, but press-fitting the stems (Fig. 9A and 9B).

 

 

P EARLS

  • Use of antibiotic cement is advisable in revision TKR, especially in the second stage of a two-stage revision for deep sepsis.

 

 

Controversies

  • Controversy exists as to whether femoral and tibial stems should be cemented or press-fit.

 

 

 

 

A B

FIGURE 9

 

 

 

 

P EARLS

  • Use of thicker revision patellar components can help restore patellar thickness.

 

Principles of Revision TKR

 

FIGURE 10

 

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Step 7: Patellar Implant

Controversies

  • Many surgeons prefer onlay, cemented patellar components.

  • Trabecular metal and cemented onlay patellar implants and morsellized bone grafting secured within a soft tissue pouch have also been advocated for dealing with thin patellas (10 mm thick).

 

  • Revision TKR outcomes are better when the patella is resurfaced, in terms of both reducing anterior knee pain and restoring extensor mechanism biomechanics (i.e., patellar height).

  • Our preference is to use cemented, inset, bioconvex polyethylene patellar components (Fig. 10), which deal with patellar cavitary defects and allow patellar resurfacing with less than 10 mm of patellar bone.

     

    P EARLS

    • If the patient is developing a knee flexion contracture, the use of a knee extension splint at night is helpful.

       

    • If the patient is developing a stiff knee, insertion of a continuous epidural, gentle manipulation, and intense physiotherapy within the first 6 weeks are beneficial.

     

    Postoperative Care and Expected Outcomes

  • Usually, revision TKR patients may bear weight as tolerated. Exceptions would include patients with a tibial tubercle osteotomy or extensive allograft reconstruction, who would be kept on partial weight bearing for 6–8 weeks.

  • Parenteral antibiotics are usually continued for 3–5 days, when the results of intraoperative cultures will be received.

  • Early physiotherapy is beneficial to maximize postoperative range of motion and restore knee strength.

    Controversies

    • Debate exists as to the optimal deep venous thrombosis agent and the duration of use.

     

  • Deep venous thrombosis prophylaxis for 10–42 days is recommended.

  • Skin staples or sutures are usually removed 2 weeks after surgery.

  • Early follow-up at 4–6 weeks and 3 months after surgery is recommended.