How Does THA Infection Affect Mechanical Failure Rates?

Mayo Clinic researchers have compared the long- and short-term risks of reinfection and mechanical failure in total hip arthroplasty using a contemporary 2-stage exchange protocol.

Their study, “Long-Term Results of a 2-Stage Exchange Protocol for Periprosthetic Joint Infection Following Total Hip Arthroplasty in 164 Hips,” appears in the January 2, 2019 edition of the Journal of Bone and Joint Surgery.

Matthew P. Abdel, M.D., professor of Orthopedic Surgery at the Mayo Clinic College of Medicine and co-author, described the unique nature of the study to OTW, “This study was novel since it looked at the LONG-TERM risk of BOTH reinfection and mechanical failure when patients underwent two-stage exchange arthroplasty for periprosthetic joint infection (PJI) of a primary total hip arthroplasty (THA).”

“It was also unique in that we diagnosed patients with the Musculoskeletal infection Society criteria, and stratified them via the McPherson et al. criteria. Finally, only index two-stage exchange arthroplasties were included.”

In their study, Mayo’s researchers identified 164 hips (162 patients) with infection after total hip arthroplasty between 1991 and 2006 and were treated with a two-stage exchange protocol with no prior treatment for periprosthetic joint infection.

According to the researchers, “The cumulative incidence of recurrence of infection was 10% at 1 year, 14% at 5 years, and 15% at 10 and 15 years. Seventeen patients (11%) used chronic antibiotic suppression (>6 months), with 7 (41%) of these having recurrent infection at the time of the latest follow-up. Use of chronic antibiotic suppression was the only predictive factor for reinfection.”

“The cumulative incidence of aseptic femoral and acetabular revisions was 2.6% at 5 years and 3.3% at 10 and 15 years. The cumulative incidence of all-cause revisions was 15% at 5 years and 16% at 10 and 15 years. Dislocation was the most common complication, with 28 dislocations occurring in 20 patients (12%). The mean Harris hip score improved from 52 points prior to spacer insertion to 70 points at 15 years after reimplantation.”

Dr. Abdel summarized the lessons from the study for OTW: “The most intriguing findings were that the rate of recurrence of infection at 15 years was 15% (and similar to shorter term studies) and instability after reimplantation was common. That being said, the risk of long-term aseptic loosening was small. These are also the finite take-home points for the orthopedic surgeon.”