Revision THA using an antibiotic-loaded spacer in two stages: The new standard

Investigators found a 4% to 5% rate of infection persistence in patients at long-term follow-up.

Issue: September 2007

Now that orthopedic surgeons have an established standard of care for infected total hip arthroplasty, one expert is advocating they now focus on finding a cure for the 4% to 5% of cases that become reinfected.

According to Clive P. Duncan, MD, FRCS(C), two-stage revision using a temporary prosthesis made of antibiotic-loaded acrylic cement (PROSTALAC) has become the standard of care for infected total hip arthroplasties (THAs) in most centers across North America.

Surgeons can expect an initial 90% success rate with this technique, he said.

“From the experience we’ve had over the past 20 years, the use of an antibiotic-loaded spacer does not compromise the final result. It does definitely expedite the mobilization and rehabilitation of these patients and it does facilitate the second stage,” Duncan said.

“We should now focus on the cause and cure of infection in the remaining 4% who are resistant to contemporary treatment, looking at the host, the organism and treatment factors to reduce this final rate of failure.”

Duncan and his colleagues reviewed the technique and experience with two-stage revision using the PROSTALAC Hip [DePuy Orthopaedics, a Johnson & Johnson Company] at the 8th Annual Current Concepts in Joint Replacement Spring 2007 Meeting.

Treatment options

This patient experienced a deep-seated infection around an extensively porous-coated stem.

Images: Duncan CP

To diagnose infection in THA cases, Duncan suggested obtaining a wound history, synovial biopsy and erythrocyte sedimentation rate and C-reactive protein tests in every exploration. Joint aspiration and intraoperative frozen section are also required in select cases, Duncan wrote in the presentation abstract.

Treatment options for infected THA cases – besides one- or two-staged revision – also include debridement and implant retention, suppression with antibiotics, excision arthroplasty, arthrodesis or hip disarticulation, Duncan said.

“But we do have convincing evidence that revision hip replacement is the treatment of choice in most cases,” he said.

Duncan noted that while most centers in North America favor a two-staged approach, typically about 10% of infected cases are still considered suitable for one-stage revision.

A two-staged approach is most important in cases with multiple organisms, gram-negative organisms, an immune-compromised patient or when dealing with major anatomical defects, Duncan wrote in the abstract.

Using PROSTALAC

Introduced about 20 years ago, the PROSTALAC Hip and modifications of this concept allowed surgeons to “produce an antibiotic-loaded facsimile of the joint to preserve normal leg length, early mobilization, antibiotic elution at a very high rate in the periprosthetic space, and ease of revision at the second stage,” Duncan said.

“We first introduced it in 1986 for complex cases and a few years later (1991) in more straightforward cases, such as where there is a late onset of a deep-seated infection around an extensively porous-coated stem.”

Over the years, results with PROSTALAC have revealed a 90% to 95% rate of infection control, an 85% to 90% rate of implant security, and an 80% to 85% rate of satisfactory outcomes, Duncan said.

Long-term results

However, long-term results have not been published on this technique, according to Duncan. He and his colleagues obtained a 10-year to 15-year follow-up on 92 patients treated from 1989 to 1996.

They primarily evaluated the reinfection rate of this group. “It has been suggested by some that with time there would be a drop-off in success and survivorship, due to recurrent infection, and that would be disappointing,” Duncan said.

Forty-four patients from this group were deceased. Based on hospital records, office records and interviews with next of kin, investigators found that none of these patients died with evidence of ongoing reinfection,” Duncan said.

Overall, investigators found that 11 of the 92 patients had early recurrences of infection, and surgeons cured seven with repeat surgery.

“Four failed despite surgery, giving us a final infection persistence of only 4% in this group,” Duncan said. “Aseptic revision was required in surprisingly few patients: aseptic loosening in three cases and recurrent dislocation in two cases.”

Patient-reported quality of life results were also encouraging. Duncan and his colleagues compared the patients’ WOMAC, SF-12, Oxford Hip and UCLA Activity scores to those of an aseptic revision cohort. Investigators matched the cohorts for gender, age and comorbidities.

“There basically was no difference between the revisions done for septic vs. aseptic failure,” Duncan said. “Similar outcomes were noted in the study of two-stage revision for infected knee replacements, with little difference when compared with revisions for aseptic failure.”

Here is an intraoperative view of the same patient’s infection.	Surgeons treated this patient with an extended trochanteric osteotomy, taking care not to devascularize the bone.
In another intraoperative image, Duncan demonstrated surgeons’ removal of the distal metal fragment.	Surgeons then inserted an antibiotic facsimile of the stem. Duncan said surgeons can use their own discretion in the type and dosing of antibiotics.
Shown here is a postoperative image. Duncan said that surgeons typically allow patients to leave the hospital within 3 days, and then have them return 8 weeks to 12 weeks later for revision.

For more information:
Clive P. Duncan, MD, FRCS(C), can be reached at the University of British Columbia, 3114-910 W. 10th Ave., Vancouver, BC V5Z 4E3; 604-875-4272; e-mail: clive.duncan@vch.ca. He has no direct financial interest in the products discussed in this article. He is a paid consultant for Zimmer Inc.
Reference:
Duncan CP. When infection happens: Out, out damn bugs! #86. Presented at the 8th Annual Current Concepts in Joint Replacement Spring 2007 Meeting. May 20-23, 2007. Las Vegas.