- Two-stage exchange arthroplasty failed in more than one-quarter of patients who developed periprosthetic joint infection following total hip or total knee arthroplasty
- Important predictors of failure were preoperative synovial fluid WBC count, synovial fluid WBC neutrophil percentage and serum erythrocyte sedimentation rate
- Patients at high risk of failure should be identified prior to two-stage exchange arthroplasty and be counseled about realistic expectations for controlling infection
In North America, two-stage exchange (resection arthroplasty followed by reimplantation) is the intervention of choice when periprosthetic joint infection (PJI) develops after total hip or total knee arthroplasty. However, in recent studies the success rate for this procedure was typically under 85%.
Researchers at Massachusetts General Hospital have determined that certain laboratory tests routinely conducted prior to two-stage exchange arthroplasty can help predict which patients with PJI are at high risk of failure. Hany Bedair, MD, orthopedic surgeon at the Center for Hip & Knee Replacement, Maureen K. Dwyer, PhD, assistant research scientist, and colleagues published their results in the Journal of Bone and Joint Surgery.
The researchers reviewed the records of 205 patients at four institutions who had a diagnosis of PJI after primary total knee arthroplasty (n=132) or primary total hip arthroplasty (n=73). All patients completed both stages of a two-stage exchange, performed by one of 30 surgeons between 2000 and 2014. They received microbe-specific intravenous antibiotics for at least six weeks.
Only patients who had follow-up data available for at least two years after reimplantation were included in the final analysis. The average follow-up was 5.2 years (range, 2.0–16.2 years).
Two-stage exchange was considered a failure if the patient required revision surgery for recurrent infection (same or different organism) in the joint of interest, or if the patient was on chronic suppressive antibiotics at the most recent follow-up. The overall failure rate was 27.3%, with a similar prevalence observed for patients who had undergone hip arthroplasty (23.3%) and knee arthroplasty (29.5%).
The researchers compared demographic, surgical and laboratory variables between the patients with treatment failure and those with treatment success.
Preoperative synovial fluid white blood cell count (WBC) (P = .008), synovial fluid WBC neutrophil percentage (P = .04) and serum erythrocyte sedimentation rate (ESR) (P = .035) were greater in patients with recurrent infection than in those without.
Failure of two-stage exchange was 2.5 times more likely for patients with an elevated preoperative synovial fluid WBC count, two times more likely for those with an elevated preoperative synovial fluid WBC neutrophil percentage, and 1.8 times more likely for those with an elevated preoperative serum ESR.
Patients at high risk of failure should be identified prior to two-stage exchange arthroplasty and be counseled about realistic expectations for controlling infection. The authors caution that it is unclear whether altering the treatment strategy for such patients might improve infection control.
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