Revision Total Hip Arthroplasty

CHAPTER 45 Revision Total Hip Arthroplasty


Megaprosthesis Proximal Femoral Replacement and Total Femur Replacement



Javad Parvizi, Franklin H. Sim



CHAPTER OUTLINE



Key Points 336

Indications 337

Contraindications 337

Preoperative Planning 338

Surgical Technique 338
Anesthesia and Patient Positioning 338

Surgical Approach 339

Femoral Reconstruction 339

Acetabular Reconstruction 341

Closure 341

Postoperative Management 341

Results 341

Complications 342

Summary 342



KEY POINTS



image Examine patients thoroughly. Note scars fro previous surgeries, status of abductors, and the limb length.

image Communicate with the patient, and help make his or her expectations realistic.

image Perform detailed preoperative templating. Have the company representative available to review your templating and to ensure that correct components, and neighboring sizes, are available on the day of surgery.

image Ensure that thorough medical optimization of the patient’s status has been carried out.

image Ask for experienced scrub and anesthetic team members.

image Minimize soft-tissue dissection off the native bone, and retain as much of the host bone as possible.

image Restore appropriate leg length and soft-tissue tension.

image Have a low threshold for the use of constrained liners.

image Ensure good hemostasis, and perform meticulous wound closure.

During the past decade, remarkable advances in the field of revision hip reconstruction have been made. One such improvement was the introduction of second-generation modular prosthetic components (Fig. 45-1) that allow better ability to restore limb length and to achieve optimal soft-tissue tension, which may reduce the incidence of instability that frequently occurred after insertion of a monolithic megaprosthesis. The new generation of megaprostheses also provides a better environment for soft-tissue reattachment and the ability to reapproximate the retained host bone to the prosthesis. However, with current improvements in alternative reconstruction methods and increased use of cortical strut grafts to augment host bone, the indications for the use of the megaprostheses have narrowed.


image

FIGURE 45-1 Photograph shows new generation of modular proximal femoral and total femoral replacement prosthesis.



INDICATIONS


We currently reserve the use of the megaprosthesis (proximal femoral replacement and total femoral replacement) to expedite recovery for elderly or sedentary patients with massive bone loss that may have occurred after failed total hip arthroplasty (THA) deep infection (Fig. 45-2), periprosthetic fracture (Fig. 45-3), fracture nonunion with failed multiple attempts at osteosynthesis, and hip salvage after a failed resection arthroplasty. In younger patients in whom bone loss of high magnitude is encountered and the bone cannot be reconstructed by conventional means, an allograft prosthetic composite would be preferred over femoral prosthetic replacement. An important prerequisite for the use of prosthetic femoral replacement and allograft prosthetic composite is the availability of sufficient distal femoral length (>10 cm) for secure fixation of the cemented or uncemented femoral stem. When distal bone is severely deficient, total femoral replacement may be considered.


image

FIGURE 45-2 The anteroposterior radiograph of a patient with multiple previous surgeries for deep infection that had resulted in massive proximal femoral bone loss (A) that necessitated the use of a megaprosthesis for reconstruction (B).


image

FIGURE 45-3 A 72-year-old patient with periprosthetic fracture (A). Because of severe bone loss, reconstruction with a megaprosthesis was carried out (B).



CONTRAINDICATIONS


The presence of superficial or deep infection around the hip is considered an absolute contraindication to insertion of a megaprosthesis. In addition, an uncooperative patient, vascular insufficiency that may prevent healing, and the presence of significant medical comorbidities precluding administration of anesthesia also are considered contraindications.



PREOPERATIVE PLANNING


The importance of preoperative planning in hip arthroplasty in general and in megaprosthesis reconstruction in particular cannot be overstated. These cases can be technically demanding, requiring meticulous attention to detail if success is to be achieved.


Most patients undergoing megaprosthesis reconstruction have had multiple previous procedures. Therefore it is imperative to examine the incision site carefully for the presence of skin lesions that may predispose to infection and to determine the appropriate previous scar to be used. A new incision may occasionally have to be used if the previous scars are inappropriately placed to access the hip. On occasion, involvement of plastic surgeons may be necessary to evaluate the status of the soft tissue in case a local or free flap may be required for reconstruction. Thorough examination of the hip with particular attention to the status of the abductors and the limb length should be carried out. Preoperative clinical and radiographic (standing films) assessment of the limb length is carried out, and the findings recorded. Patients should be counseled about the possibility of limb length discrepancy that may result from surgery. In our opinion lengthening of the limb up to 4 cm can be carried out safely. Any lengthening beyond this point is likely to place the neurovascular structures at risk. Intraoperative monitoring of the sciatic and femoral nerves may need to be performed in patients in whom extensive (>4 cm) limb lengthening is anticipated.


All patients (other than those undergoing tumor resection) needing a megaprosthesis have undergone multiple previous surgeries of the hip. We always order a white blood cell count with differential, C-reactive protein, and erythrocyte sedimentation rate to rule out infection. Based on clinical and radiographic examinations and the result of serology, hips with a high index of suspicion also undergo preoperative aspiration to rule out deep infection. All patients should also receive a thorough medical examination with appropriate laboratory investigation. Revision hip arthroplasty with a megaprosthesis, with extensive soft-tissue dissection, usually a long operative time, and a large volume of blood loss, is immensely physiologically demanding for the patient.


Preoperative templating to select the appropriate stem length and diameter is essential. Problems with removal of existing hardware, specific needs for acetabular reconstruction and for potential insertion of constrained liners, and the need to ensure the absence of prior infection should be anticipated and addressed appropriately. Despite the most accurate preoperative measurements, a variety of prosthesis sizes should be available in the operating room, because intraoperative adjustments with change in size of prosthesis are common. The megaprosthesis manufacturing company representative should be contacted to be present in the operating room. Experienced operating room personnel, particularly the scrub person, should assist with this procedure. An experienced anesthesia team should administer anesthesia because invasive monitoring in these often elderly and frail patients is warranted.



SURGICAL TECHNIQUE



Anesthesia and Patient Positioning


Regional anesthesia is preferred in these patients. Intraoperative blood salvage (cell-saver equipment) should be used in these patients. The anesthesia team should be warned about possible large volume loss and encouraged to monitor this closely. Invasive monitoring with the use of arterial lines or pulmonary catheters may be necessary in some patients. We place the patient in the lateral decubitus position and use hip rests to secure the patient (Fig. 45-4). Impermeable U-drapes are used to isolate the groin. The distal third of the extremity is also isolated from the field using impermeable drapes. It is very important to include the knee in the operative field in all of these patients—even in those undergoing proximal femoral replacement. Extension of the incision and arthrotomy of the knee to address intraoperative problems such as fractures extending distally are not uncommon. The skin is scrubbed with Betadine solution for at least 10 minutes and DuraPrep is applied before the application of Ioband to the skin.

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Mar 10, 2016 | Posted by in Reconstructive surgery | Comments Off on Revision Total Hip Arthroplasty

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