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Two-Stage Revision Total Hip Arthroplasty
CASE STUDY
A 67-year-old man underwent a primary, uncemented, left total hip arthroplasty (THA) 11 years earlier for osteoarthritis ( Fig. 76.1 ). His postoperative course was uneventful, and he was followed by his surgeon on a yearly basis. He presented to the surgeon’s office complaining of a 3-week history of increasing left hip pain, swelling, and discomfort with weight bearing and range of motion. There was an area of swelling around his old incision. Laboratory evaluation showed an erythrocyte sedimentation rate (ESR) of 74 mm/hr (normal range, 0 to 17 mm/hr) and a C-reactive protein (CRP ) value that was 171 μg/L (normal range, 0 to 5 μg/L). A fluoroscopically guided hip aspiration yielded 12 mL of cloudy fluid. Analysis of the aspirate found a white blood cell (WBC) count of 110,000 cells/μL with 98% segmented polymorphonuclear cells (PMNs).
The patient was taken to the operating room for a two-stage revision THA. An extended trochanteric osteotomy (ETO) was used to remove the well-fixed femoral stem. Intraoperative samples were taken for culture along with intraoperative frozen section analysis; results were consistent with acute inflammation and infection. An antibiotic-loaded cement spacer was placed, and the ETO was closed using cables ( Fig. 76.2 ). Postoperative consultation with an infectious disease specialist led to long-term placement of a peripherally inserted central catheter (PICC) for intravenous antibiotic therapy for 6 weeks.
Two weeks after the cessation of antibiotics, the patient was seen in the clinic. No drainage or erythema was observed from the patient’s wound, and his radiographs showed no interval change. ESR and CRP values showed downward trends throughout his postoperative course. Nine weeks after the insertion of the antibiotic spacer, the ESR was 5 mm/hr, and the CRP value was 0.3 μg/L. He was scheduled for a left hip reimplantation with the possibility of a repeat débridement, depending on the intraoperative synovial fluid WBC count, differential, and frozen section results.
At the time of reoperation, after insertion of the Charnley retractor, the hip was aspirated under direct visualization ( Fig. 76.3 ). The synovial fluid obtained intraoperatively was sent for a WBC count and differential. The WBC count was 126 cells/μL, and the differential showed 56% PMNs. Intraoperative frozen section analysis showed fewer than five PMNs per high-power field, with no evidence of acute inflammation. Samples were sent for culture of aerobic, anaerobic, fungal, and acid-fast organisms. Based on the intraoperative cell count, the low suspicion of infection based on frozen section results, and a lack of gross purulence, the decision was made to proceed with the revision THA. The previous ETO had healed in the interim. The cement spacer was removed, and a fully porous-coated, diaphyseal-engaging femoral stem was implanted, as was a cementless cup with multiple screws for adjunctive fixation ( Fig. 76.4 ). All cultures were negative, and antibiotics were discontinued on the third postoperative day.
Introduction
Despite advances in almost every aspect of management, periprosthetic joint infection (PJI) continues to plague the joint replacement surgeon. Large published studies report infection rates for patients undergoing primary hip replacements between 0.5% and 2%. PJI is associated with worse outcomes when compared in terms of range of motion, postoperative mobility, and patient satisfaction. Although major efforts have been made to prevent infection, the surgeon who performs hip arthroplasties must understand the key elements of diagnosing and treating this condition.
The initial workup and diagnosis of PJI is covered in Chapter 74 . We think that any patient with complaints about a joint replacement should be evaluated for infection. The workup begins with a thorough history and physical examination, followed by obtaining the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level, which are highly sensitive for ruling out infection. If both results are negative, the diagnosis of PJI is unlikely, and further testing usually is not required. If results are abnormal or the history and physical examination suggest PJI, the hip is aspirated.
Hip aspiration is performed with fluoroscopic guidance using a large-diameter (typically 18-gauge) spinal needle to ensure proper sample collection. The aspirate is sent for a synovial fluid white blood cell (WBC) count, percentage of polymorphonuclear cells (PMNs), and bacterial culture. A crystal analysis can also be performed, because this is a rare cause of pain postoperatively. The patient should be off antibiotics for a minimum of 2 weeks to ensure accurate culture results. Combined with elevated ESR and CRP values, a WBC count of more than 3000 cells/μL or a PMN level greater than 80% is consistent with a diagnosis of PJI.
Indications and Contraindications
A two-stage exchange revision hip arthroplasty with interval implantation of an antibiotic-laden spacer is indicated in patients with evidence of an infected total hip arthroplasty (THA), and it is our treatment of choice for chronic PJI. A careful history should be taken to evaluate the patient for antibiotic allergies that may alter the composition of the antibiotics in the cement spacer. Contraindications to reimplantation of prosthetic components at the second stage include continued infection or medical comorbidities that preclude a surgical procedure.
One-stage exchange has been employed predominantly in Europe. It can be considered in cases in which the bacteria and sensitivities have been identified preoperatively, although we have no experience with this technique for managing chronic PJI.
Equipment and Personnel
Treatment of PJI requires a multidisciplinary team composed of the orthopedic surgeon working closely with an infectious disease specialist, the patient’s primary care physician, and a nutritionist to optimize outcomes. Access to a musculoskeletal pathologist with experience in PJI is important to ensure that the frozen section result is properly evaluated. These procedures are also often associated with blood loss that is higher than seen in primary hip procedures, and proper management intraoperatively and in the immediate postoperative period is essential for avoiding complications. Communication with the anesthesia team can ensure availability of blood products and proper fluid resuscitation and monitoring.
The original operative report should be obtained to determine the component manufacturer, models, and sizes. Representatives from the implant companies can be valuable in supplying proprietary instruments for implant removal and the trial components that may be required. A tool to remove the femoral head should be requested ( Fig. 76.5 ), and a plan should be in place to remove the acetabular liner. Specialized curved acetabular osteotomes that precisely match the outer diameter of the shell can rapidly remove well-fixed shells with minimal bone loss, but they require the surgeon to know the diameter of the device in place and to have a trial liner in place or reinsert the old liner after screws (if present) have been removed.
The surgeon should anticipate how difficult the stem will be to remove and whether an extended trochanteric osteotomy (ETO) will be required. Cemented stems with a smooth or satin finish can be easily disimpacted from the cement mantle, whereas precoated and roughened stems often require an ETO for removal. Similarly, extraction of well-fixed, cementless stems presents a range of difficulty. Flat-wedge tapered stems or those with limited proximal coating can often be removed easily from above, whereas even metaphyseal-engaging stems with a bioactive surface that extends more distally often have extensive bone ongrowth past the metadiaphyseal junction and are most safely removed with an ETO. Fully porous-coated, diaphyseal-engaging stems always require an ETO, and removal typically includes cutting the stem in the cylindrical portion and using trephines to remove the distal portion.
If an ETO is planned, burs with appropriate tips should be available, including those that can cut metal. Flexible osteotomes can be used to disrupt the implant–bone interface proximally. Cables or cerclage wires are required to repair the ETO. Cement drills and taps are effective at distal cement removal, and an assortment of other hand-held instruments can be used to remove more proximal cement ( Fig. 76.6 ). Ultrasonic cement removal devices can also help in this endeavor.
Construction of an antibiotic spacer can proceed along several different pathways, but it always requires several packages of bone cement and heat-stable powdered antibiotics. Typically, a combination of 3 g of vancomycin and 1.2 g of tobramycin is used per package of cement in our practice. This ratio should be tailored to individual patient considerations and the sensitivities of the organism if known preoperatively. We have found that a metal sifter helps in breaking up and mixing the antibiotics into the bone cement.
Commercially available preformed molds can be used to shape an articulating, antibiotic-loaded spacer (see Fig. 76.8 ). Advantages of an articulating spacer include maintenance of leg length and soft tissue tension, which can facilitate the second-stage procedure, although the spacers can dislocate. Advantages of the commercially available molds include the ability to use trials, because custom-made spacers sometimes do not fit as expected intraoperatively.
Several techniques have been described for making antibiotic-loaded spacers by hand, and they can work well at a lower cost. Although we prefer to use articulating spacers, nonarticulating spacers are used in patients with acetabular or femoral bone loss that may not support the articulating spacer or may lead to additional bone loss with weight bearing. If a nonarticulating spacer is chosen, we prefer to use a chain of beads threaded onto 16-gauge wire to facilitate removal and a dowel of cement built onto a threaded Steinmann pin. If a threaded Steinmann pin is not used, the cement dowel can fracture during attempted extraction, leaving cement in the femoral canal that can be challenging and frustrating to remove.
Surgical Technique
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