DEFINITION

• Well-fixed femoral and acetabular implants often have to be removed during revision total hip arthroplasty (THA).

• Conditions that necessitate removal of well fixed implants include:

  • Infection

  • Recurrent dislocations (malpositioned components)

  • Limb-length discrepancy

  • Severe osteolysis

  • Polyethylene wear

  • Locking mechanism failure

  • Failure of other components in the hip such as a femoral stem fracture (FIG 1)

• The key point is to determine which components should be removed and which are well fixed and can be left at the time of revision THA.

  ANATOMY

• Important anatomic considerations include the pelvic landmarks and the proximal femoral and diaphyseal anatomy.

• The pelvic landmarks that assist in component removal and positioning include the ischium, pubis, anterior and posterior acetabular columns, anterior inferior iliac spines, transverse acetabular ligament, sciatic notch, and acetabular walls.

   

   

   

   

  FIG 1 • AP radiograph of a broken T-28 femoral stem. An extended trochanteric osteotomy (ETO) is used for distal well-fixed stem removal.

• Neurologic structures at risk include the sciatic nerve, which can be identified in three distinct anatomic locations:

  • As it exits the sciatic notch

  • Lying over the ischium posterior and inferior to the posterior acetabular column

  • Beneath the femoral insertion of the gluteus maximus tendon insertion into the posterior femur.

• The superior gluteal nerve is at risk during component removal as it travels anteriorly along the ilium, approximately 4 to 5 cm superior to the tip of the greater trochanter, to innervate the gluteus medius muscle.

• The femoral nerve is well anterior to the hip for most approaches but may be at risk with further anterior dissection and retraction and with anterior supine approaches to the hip.

• The femoral artery and vein are well anterior to the dissection and usually are protected by the iliopsoas tendon and muscle belly.

• The proximal femoral anatomy includes the greater and lesser trochanter and the vastus ridge, which is a point of relatively weak bone in most revisions due to osteolysis, previous trochanteric osteotomies, or previous surgery in this area.

• The femoral diaphyseal anatomy includes the attachments of the vastus musculature at the vastus ridge and posteriorly at the linea aspera.

  • These attachments often must be reflected during extended trochanteric osteotomies to aid in removal of well-fixed femoral implants (FIG 2).

     

     

     

     

    FIG 2 • Bilateral acetabular component failure with superior displacement on the right hip and medial protrusio on the left. Both are indications for trochanteric osteotomy to facilitate exposure of the acetabulum and possible stem removal.

     

     

     

     

     

     

     

    PATHOGENESIS

     

     

    • Well-fixed implants may be removed because of polyethylene wear or in response to osteolysis that occurs as a result of particulate debris generating an inflammatory (macrophage) response and subsequent cellular activation with resulting bone resorption (FIG 3).

    • Sepsis around a THA most commonly is caused by a gram-positive organism and is best eradicated by component removal and two-stage treatment with intravenous antibiotics and a delay in reimplantation.

      • The sepsis usually progresses rather quickly to the implant interfaces despite well-fixed implants and usually cannot be treated effectively with irrigation and joint débridement alone.

      • Component removal with attention to bone preservation for subsequent reconstruction is crucial.

        NATURAL HISTORY

    • Retention of well-fixed components has been shown to lead

      to acceptable long-term performance on both the acetabular A B

      and femoral side during isolated component revision.2,5

      PHYSICAL FINDINGS

    • The physical examination of the patient undergoing revision THA includes:

      • Gait

      • Leg length

      • Distal neurovascular examination

      • Muscle strength about the hip and leg

      • Skin examination and scars over the hip

         

        IMAGING AND OTHER DIAGNOSTIC STUDIES

    • The goal of diagnostic imaging studies is to identify which implants are well fixed, confirm that there is no infection, and see what bone stock is available for the revision reconstruction.

FIG 3 • AP radiograph of severe polyethylene wear and well-fixed components with significant osteolysis in the ilium.

FIG 4 • A. AP radiographs of a well-fixed uncemented stem and acetabular component with a metal-on-metal articulation.

B. Judet oblique radiographs demonstrating anterior column deficiency and acetabular loosening with a well-fixed stem.

• Multiple plain radiographs, CT scanning with possible 3D reconstruction, scintigraphy (bone scans), and laboratory screening usually are sufficient.

• Biplanar radiographs of the entire implant and the joint above and below the prosthesis are essential.

  • These should include the entire cement mantle on cemented femoral stems.

  • Signs of ingrowth on uncemented stems have been well described3 (FIG 4A).

• Oblique, or Judet, views of the pelvis can demonstrate the anterior and posterior columns, because some defects may not be readily appreciated on routine anteroposterior (AP) radiographs (FIG 4B).

• In cases that demonstrate significant polyethylene wear or osteolysis, CT scanning may better demonstrate osteolytic lesion location and size.

  • These findings are helpful in guiding plans for bone grafting of lytic lesions and identifying remaining bone stock.

  • Plain radiographs usually greatly underestimate the extent of osteolysis involvement in the pelvis from polyethylene debris.

• Bone scan examination may demonstrate subtle implant loosening that may not be appreciated on plain radiographs or at the time of surgery and may help the surgeon decide whether to retain or remove implants that appear well fixed.

• Confirmation of a noninfected arthroplasty is critical prior to the revision THA.

  • Confirmation is best accomplished by laboratory evaluation, including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The combination of a normal ESR and normal CRP has been demonstrated to have a very low (<1%) likelihood of being infected.6

  • In cases of elevated ESR or CRP, aspiration of the hip is warranted, with examination of the cell count with differential and culture of the fluid.

SURGICAL MANAGEMENT

• Extended trochanteric osteotomy (ETO)

  • Most well-fixed femoral components require some form of femoral osteotomy, which offers several advantages:

    • Safe stem removal

    • Exposure

    • Deformity correction

    • Soft tissue balance

    • Bone grafting

    • Increased union rate

    • Decreased operating time

    • Safer distal cement removal

• Removal of well-fixed acetabular components may be required in the face of infection, severe polyethylene wear and need for significant acetabular bone grafting, malalignment leading to severe impingement or instability, or perhaps to change to an alternate bearing surface.

  • Care should be taken to preserve as much bone stock as possible during the removal for subsequent reconstruction.

  • Osteotomes are available that facilitate acetabular component removal.

    • These osteotomes are designed so that the rotation point is in the center of the acetabular component.

    • Small and large osteotomes are available.

      Preoperative Planning

• Appropriate removal instruments and surgical techniques are important considerations as one approaches the revision THA with well-fixed implants.

• When performing revision THA, multiple options for the implant must be on hand to match defects or needs that may be discovered intraoperatively.

   

  Positioning

• In general, patients can be positioned supine or in the lateral decubitus position.

• In the anterior supine approach, the patient is positioned in the supine position and an anterior approach to the hip is performed in the interval between the tensor fascia lata and the sartorius muscles.

• An anterior or anterolateral approach to the hip can be performed in the supine or lateral position and is extensile in both the proximal and distal directions should additional exposure be required.

• The posterior approach to the hip is performed in the lateral decubitus position.

  • At our institution, we use a pegboard positioner.

  • An axillary roll is used to provide protection for the brachial plexus during surgery.

     

     

    TECHNIQUES

     

    APPROACH

    Anterior Supine

    • The patient is positioned in the supine position and an anterior approach to the hip is performed in the interval between the tensor fascia lata and the sartorius muscles (TECH FIG 1A,B).

    • This technique is suitable for polyethylene exchange alone, in which the femoral component is well fixed and there is no significant need for bone grafting in the posterior aspect of the acetabulum (see Fig 3).

    • Bone grafting is possible through the holes in the acetabular component or through a small “trap-door” above the acetabulum (TECH FIG 1C).

       

    • This approach retains much of the posterior capsule and structures, which likely reduces the incidence of dislocation after revision.

    • The femoral head is retracted posteriorly (TECH FIG 1D), and a new liner is inserted (TECH FIG 1E).

       

      Lateral

    • A direct lateral approach to the hip involves a split in the anterior third of the gluteus medius and minimus musculature.4

       

       

       

       

       

       

       

       

      A B C

      TECH FIG 1 • A. The same patient shown in Figure 3 has been placed in the supine position for anterior approach to the hip for isolated polyethylene exchange and bone grafting behind a well-fixed component. The old incision is marked, and the central third is used. B. Acetabular exposure with retractors in place before femoral head dislocation in this hip, which shows severe polyethylene wear and osteolysis. C. Bone graft is inserted through the screw holes in the acetabular component. (continued)

       

       

       

       

       

       

      TECHNIQUES

       

      TECH FIG 1 • (continued) D. New polyethylene liner is inserted with the femoral head in view and retracted posteriorly. E. New liner in

      D E place. (Courtesy of Roger Emerson, MD.)

       

      EXTENDED TROCHANTERIC OSTEOTOMY

      • The length of the osteotomy is determined by the amount of prosthesis that is well fixed or the distal extent of the

         

        osteotomy can be performed with a high-speed burr with a thin tip (TECH FIG 2B).

        cement column that needs to be removed. Approximately a third of the lateral portion of the femoral circumference is part of the osteotomy (TECH FIG 2A).

      • The vastus lateralis remains attached to the lateral portion of the osteotomy but is reflected anteriorly to allow visualization of the lateral and posterior femoral cortex.

      • An oscillating saw is used to perform the posterior portion of the osteotomy just superior to the linea aspera. The gluteus medius remains attached.

         

         

      • The distal extent of the osteotomy is beveled in the distal and anteroposterior direction. Alternatively, the

         

        {

    • The anterior portion of the osteotomy is made with a small (1⁄4-inch) osteotome perforated through the vastus musculature. Multiple perforations are made in the same plane to create the osteotomy.

    • The capsule surrounding the prosthesis below the greater trochanter is released or excised and the “shoul-der” of the prosthesis exposed.

    • The entire extended trochanteric fragment is reflected anteriorly with care not to fracture the tip of the trochanteric fragment, because this is the weakest point in the osteotomized fragment (TECH FIG 2C).

       

       

       

      Posterior osteotomy cut

      Vastus lateralis

       

      Length of osteotomy

       

      Cement column

       

      Bevel distal tip

       

      A B

       

      Oscillating saw

       

      Gluteus medius

       

      TECH FIG 2 • A. AP view of the planned femoral osteotomy demonstrating the length of the osteotomy needed to remove the prosthesis or cement (or both). About one third of the lateral portion of the femoral circumference is part of the osteotomy. B. The vastus lateralis that remains attached to the lateral portion of the osteotomy is reflected anteriorly to allow visualization of the lateral and posterior femoral cortex. An oscillating saw is used to perform the posterior portion of the osteotomy just superior to the linea aspera. The distal extent of the osteotomy is beveled in the distal and AP direction. (continued)

       

       

       

       

       

      Vastus lateralis

      Trochanteric osteotomy

      Gluteus medius

       

       

      TECHNIQUES

       

      Anterior osteotomy cut

       

      Vastus lateralis

       

      C

       

      Posterior osteotomy cut

       

      Gluteus medius

      D

       

      Prosthesis

      Vastus lateralis Gluteus medius

       

       

      E Prosthesis

      TECH FIG 2 • (continued) C. The anterior portion of the osteotomy is made with a 1⁄4-inch osteotome perforated through the vastus musculature. The entire extended trochanteric fragment is reflected anteriorly, with care not to fracture the tip of the trochanteric fragment, which is the weakest point in the osteotomized fragment.

      D. Bennett and Charnley retractors retract soft tissue and the

      trochanteric fragment to visualize the femoral prosthesis. All tissue lateral to the psoas tendon can be removed if necessary. The ce-ment–implant and cement–bone interfaces or the ingrowth interface is now accessible. E. The trial implants are inserted and a trial reduction performed before the trochanteric fragment is reattached. The osteotomy is reduced and secured with looped Luque wires.

       

      • Curved Bennett-type retractors are inserted distal to the osteotomy for soft tissue retraction and the Charnley-type hip retractor anterior arm is carefully secured to the trochanteric fragment anteriorly to expose the femoral prosthesis (TECH FIG 2D).

      • Anterior and medial capsular attachments are taken down to the level of the psoas tendon. All tissue lateral to the psoas tendon can be removed at this point if needed to allow visualization of the stem.

      • Osteotomes, ultrasonic devices, or high-speed burrs now have access to the cement–implant and cement–bone

      interfaces or the ingrowth interface, as needed for removal.

    • The femoral preparation for long-stem implant insertion is completed with flexible reamers and proximal femoral tapered reamers.

    • The trial implants are inserted and a trial reduction performed with the trochanteric fragment not attached.

    • ETO fixation is performed after the final implant is inserted. Often small amounts of trochanteric bone must be removed to facilitate appropriate osteotomy reduction and fixation with looped Luque wires (TECH FIG 2E).

       

      ACETABULAR REMOVAL

      • The goal in acetabular removal is to preserve as much of the remaining bone as possible. It is important not to gouge the acetabulum or to break off large pieces by aggressively twisting or pulling a well-secured cup.

      • Acetabular osteotome systems facilitate cup removal by using the center of the acetabular polyethylene as a reference for osteotome insertion. Osteotomes match the radius of curvature of the cup. The center of rotation of the acetabular component allows thin osteotome insertion precisely in the bone implant interface (TECH FIG 3A).

      • The osteotome blade is inserted and turned in a firm, controlled manner, maintaining its orientation to the rim of the cup.

         

    • First, a small osteotome is inserted that matches the radius of the acetabular component. It is used to enter the bone–implant interface only around the rim of the ingrown acetabular component (TECH FIG 3B,C).

    • Successively longer acetabular osteotomes are then used around the entire rim of the component to divide more medial ingrown interfaces (TECH FIG 3D).

    • A handle permits the acetabular explant chisel to be rotated around the circumference of the component to further loosen the implant and remove the cup with minimal bone loss (TECH FIG 3E).

       

       

       

       

       

       

       

       

       

       

      TECHNIQUES

       

      A B C

       

       

       

       

       

      TECH FIG 3 • A. The acetabular osteotome used to remove cups allows thin osteotome insertion precisely in the bone implant interface. B. A small osteotome is first used to enter the bone–implant interface around the rim of the acetabular component. C. Osteotome shown with the implant removed. D. A longer acetabular osteotome removes the medial ingrown interfaces. E. Using the acetabular explant chisel on a handle, the implant is removed with minimal bone loss. (Courtesy of

      D E Zimmer, Inc., Warsaw, IN.)

       

       

      PEARLS AND PITFALLS

      Acetabular deficiencies ■ Osteolysis and bone loss behind well-fixed acetabular components is underestimated on

      plain radiographs. A simple polyethylene exchange may become a much more extensive revision if proper preoperative evaluation such as CT scanning has not been completed.

      Extended trochanteric osteotomy ■ Bevel the distal transverse arm of the osteotomy to prevent distal fracture propagation.

      • Pass a cerclage wire distal to the osteotomy before femoral preparation and trial and final implant insertion.

      • Pay careful attention to trochanteric osteolysis and fracture risk at the vastus ridge at the junction of the vastus lateralis and the abductor attachment into the trochanter.

      • Have adequate bone graft available, including morselized cancellous graft and cortical struts for contained and uncontained defects.

      • With distally fixed stems combined with an ETO, a tight distal diaphyseal fit must be obtained, achieving three-point fixation.

      • Postoperative radiographs are needed, because the intraoperative fracture rates are higher for revision THA and ETO cases.

      • An ETO can be combined with a proximal reduction or angular osteotomy.

      • Leave vastus muscle attached to the trochanteric fragment to provide adequate blood supply for osseous healing and implant stability.

       

       

      Acetabular removal

      • Thin osteotomes based on the cup and head size reduce bone loss during removal of well-fixed acetabular components.

      • The polyethylene should be removed from the acetabular component to allow screw removal, then replaced for a guide or reference for removal instruments.

      • Cementing an acetabular polyethylene shell is an option if the locking mechanism is not functional after polyethylene component removal.

       

       

      POSTOPERATIVE CARE

    • Weight bearing is restricted to about 50% for 6 to 8 weeks if an implant has been reinserted and bone graft has been used.

    • With polyethylene exchanges and component retention of osseointegrated implants, weight bearing as tolerated is recommended.

    • When an implant is removed and an antibiotic-impregnated static spacer is inserted, foot-flat (essentially non–weight bearing) weight bearing is recommended. We combine this with a hinged knee brace locked in extension, which allows wound care but limits motion and provides additional support while allowing mobilization during the time of IV antibiotic therapy.

      COMPLICATIONS

    • Femoral fractures are common about the trochanteric region and in the diaphysis during removal of well-fixed femoral implants.

    • Isolated component revision has a higher dislocation rate than primary revision THA.

    • Acetabular deficiencies may be extensive in the face of polyethylene wear and osteolysis.

      OUTCOMES

    • Aribindi et al1 reported on the outcomes associated with THA revision with an extended trochanteric osteotomy in

122 cases with a minimum of 1 year of follow-up (average, 2.6 years).

• No non-unions, no migration greater than 2 mm

• All healed by 3 months

• 92% bone ingrowth, one stem revised for loosening

• Dislocation rate 10% (three required revision)

• 20% intraoperative fracture rate

REFERENCES

1. Aribindi R, Paprosky W, Nourbash P, et al. Extended proximal femoral osteotomy. Instr Course Lect 1999;48:19–26.

2. Berger RA, Quigley LR, Jacobs JJ, et al. The fate of stable cemented acetabular components retained during revision of a femoral component of a total hip arthroplasty. J Bone Joint Surg Am 1999;81A:1682–1691.

3. Engh CA Jr, Hopper RH Jr, Engh CA Sr. Distal ingrowth components. Clin Orthop Relat Res 2004;420:135–141.

4. Frndak PA, Mallory TH, Lombardi AV Jr. Translateral surgical approach to the hip. The abductor muscle “split.” Clin Orthop Relat Res 1993;(295):135–141.

5. Moskal JT, Shen FH, Brown TE. The fate of stable femoral components retained during isolated acetabular revision: a six-to-twelve-year follow-up study. J Bone Joint Surg Am 2002;84A:250–255.

6. Spangehl MJ, Masri BA, O’Connell JX, et al. Prospective analysis of preoperative and intraoperative investigations for the diagnosis of infection at the sites of two hundred and two revision total hip arthroplasties. J Bone Joint Surg Am 1999;81A:672–683.