Authors of section

Executive editor

Michael Baumgaertner

Authors

Michael Huo, Michael Leslie, Iain McFadyen

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Complete femoral revision with varus/valgus CCK system

1. Introduction

Isolated femoral revision without tibial revision is performed when the femoral component is unstable, or the fracture is not reconstructible. The tibial component is stable and properly aligned. It is important to select an appropriate femoral revision system that is compatible with the retained tibial component.

Femoral revision requires sufficient bone stock and functional collateral ligament integrity. If the collateral ligaments are absent, or incompetent, a hinged prosthesis is required. The hinged knee prosthesis is associated with a higher rate of failure, in particular in the younger and more active patients. Retention of the collateral ligaments origin allows for isolated femoral revision with a stemmed component.

This section focuses on the principles of revision total knee arthroplasty using a medial-lateral constrained implant system or a constrained condylar knee (CCK) system.

The tibial component should be examined for fixation stability and proper alignment during surgery and addressed if necessary.

In selected cases, a less constrained articulation and femoral component can be used for the femoral revision.

Periprosthetic distal femoral fracture

2. Preoperative planning

Femoral stem

A stem for the femoral component is often required. The stem length is generally 100 - 125 mm. Both a cemented and cementless stem can be used.

Femoral stem

Supplemental metaphyseal fixation

The surgeon may consider using supplemental metaphyseal fixation with cone or sleeve.

Different surgical techniques are involved with the use of a sleeve or a cone.

Supplemental metaphyseal fixation

Compensation for bone loss

The surgeon should have metallic augments and wedges available to compensate for any significant bone loss in the distal femur.

Femoral metallic augments

3. Patient preparation

The patient is placed in the supine position. A radiolucent table may facilitate intraoperative fluoroscopy if required.

Patient in supine position

4. Surgical approach

This procedure requires an adequate visualization of the knee joint. The most commonly used is a midline skin incision followed by a medial parapatellar arthrotomy. A proximal and distal extension may be necessary to achieve sufficient visualization and soft tissue releases.

P450 Proximal tibia replacement

5. Femur

Removal of the femoral component

The femoral component is removed, using small oscillating saw and cement osteotomes.

Removal of the femoral component

It is important to maintain the attachment of the collateral ligaments and the bony fragments of the femoral condyles.

Care must be undertaken to avoid injury to the neurovascular structures, and to the extensor mechanism of the knee.

Maintain the attachment of the collateral ligaments

Femoral preparation

Provisional stabilization of the fracture fragments will facilitate the femoral preparation.

The femoral canal is prepared with reamers of increasing size. The depth of the reaming is determined by the length of the selected stem.

Femoral preparation

If additional bone cuts are needed, then an intramedullary femoral cutting jig is used to make the appropriate bone cuts for the constrained femoral prosthesis.

Take care to rotate the cutting block in line with the transepicondylar axis and parallel to the tibial tray in order to achieve a symmetrical flexion gap.

An intramedullary femoral cutting jig is used to make the appropriate bone cuts

The diameter of the stem is determined by the reamer diameter which achieves cortical contact with the diaphyseal bone. One should allow for at least 2 mm of cement mantle around the stem if cement fixation is used.

If cementless stem fixation is selected, line to line fit of the reamer to the final stem diameter is used.

The diameter of the stem is determined by the reamer diameter which achieves cortical contact with the diaphyseal bone

If there is bone deficiency due to fracture fragmentation, additional bone cuts may be required to remove the fragments and to accommodate the use of augments behind the new femoral component to achieve the balanced extension and flexion gaps.

Use of augments behind the new femoral component

If a femoral sleeve or a cone is selected, appropriate instruments are used to prepare the distal femur.

Prepare the distal femur

6. Trial

The trial component is assembled, and a trial reduction is performed.

Trial reduction

Gap balancing and knee stability assessment is performed using the appropriate thickness of the trial polyethylene insert. The goal is to achieve symmetrical flexion and extension gaps. This is performed using tension spreaders or gap sizing blocks.

Gap balancing and knee stability assessment

Patella tracking is carefully assessed to ensure no instability or impingement throughout the entire range of knee motion.

Patella tracking is carefully assessed

7. Components insertion

Bone preparation for cementing

The femoral bone surface and the canal are lavaged to remove any debris. The bone surface and the canal are dried before proceeding.

Cement restrictors

The cement restrictor is inserted into the femoral canal to allow for a 1 cm cement mantle between the stem tip and the restrictor.

Cement restrictors

If a sleeve is used, the sleeve and the stemmed femoral component are assembled together first, then the monobloc implant is inserted into the femur.

the monobloc implant is inserted into the femur

Cementation

Cement is mixed using standard techniques and is injected into the canal with retrograde filling and pressurization, using a cement gun.

Cementation

Insertion of the femoral component

The femoral component (including any augment) is seated with 3-5° of external rotation to the mid coronal axis of the femoral shaft or in line with the trans-epicondylar axis to allow for proper patellar tracking. The femoral rotation is also aligned to the tibial component to achieve a symmetrical flexion gap.

Insertion of the femoral component

8. Final reduction

The selected polyethylene bearing component is impacted into the retained tibial tray. Additional locking screw or pin for the polyethylene bearing is inserted according to the requirements of each implant design.

Final reduction

If patellar tracking is not ideal, a lateral retinacular release and medial imbrication can be performed.

If patellar tracking is not ideal, a lateral retinacular release and medial imbrication can be performed

9. Aftercare

The patient can be mobilized with full weight-bearing and active range of motion immediately after surgery.