By Dean L. Winslow, MD

Professor of Medicine, Division of General Medical Disciplines, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine

Dr. Winslow reports no financial relationships relevant to this field of study.

SYNOPSIS: Researchers reviewed a case series of 51 patients who received retained “destination spacers” after resection of infected joint prostheses. The researchers noted a significant association between the presence of preoperative sinus drainage and re-infection. Long-term antimicrobial suppression after retention of a destination spacer did not result in significant prevention of re-infections.

SOURCE: Valencia JCB, Abdel MP, Virk A, et al. Destination joint spacers, reinfection, and antimicrobial suppression. Clin Infect Dis 2019; Jan 28. doi: 10.1093/cid/ciz062. [Epub ahead of print].

Researchers reviewed 51 consecutive patients from Mayo Clinic who underwent “destination joint replacement” for prosthetic joint infection (PJI). The cases included 34 with retained knee and 17 with retained hip antibiotic spacers. The median patient age was 77 years. The most common reason for choosing “destination replacement” vs. a two-stage procedure with re-implantation of a prosthetic joint was the presence of a medical comorbidity that was considered to preclude a second joint replacement in 67%. Thirty-three percent of patients had good joint function and declined a second-stage re-implantation of the prosthesis. The destination spacers all were secured to the bone surface using cement loaded with vancomycin and an aminoglycoside (tobramycin or gentamicin); amphotericin B also was included in 16% of cases. After implantation of the destination spacer, all patients received six weeks of systemic antimicrobials guided by cultures.

After the initial six weeks of systemic antibiotics, 11 patients (21%) received long-term oral antibiotic suppression for a median duration of three years. Of these 11 patients, two experienced diarrhea, one experienced renal dysfunction, and two experienced hyperpigmentation or photosensitivity after minocycline and doxycycline treatment, respectively.

During the median follow-up period of 31 months, five patients experienced re-infection, and the re-infecting pathogens were completely different from the original pathogens isolated. Four of 17 patients with preoperative draining sinus vs. only one of 34 patients without preoperative draining sinus developed re-infection.

COMMENTARY

I must confess that PJI is one of my least favorite infectious diseases. PJI complicates about 2% of primary hip and knee replacements in the United States. Although the orthopedic surgeons at our university hospital, community hospital, and affiliated VA (where I proudly receive my own healthcare) all are excellent, I have chosen to cut back running to three days per week in hopes of putting off a knee replacement during this lifetime.

Recommended management of PJI generally includes removal of all hardware, debridement of periprosthetic tissue, insertion of a temporary antibiotic-impregnated spacer, six weeks of systemic antibiotics guided by culture results, and re-insertion of a joint prosthesis after the infection is determined to be eradicated. Sometimes, our surgeons will attempt surgical debridement with “liner exchange” but leaving most of the hardware in place. We often are consulted to provide long-term “suppressive antibiotics” in these liner exchange cases, but I have been disappointed in the low success rate of this approach. These patients often have to undergo eventual removal of hardware, debridement, and insertion of an antibiotic-impregnated spacer anyway. Occasionally, these temporary antibiotic-impregnated spacers are retained permanently because of either patient comorbidities that preclude additional surgery or patient preference not to undergo a second (or third) surgery to re-implant a joint prosthesis. This case series actually is reassuring that recurrent infection is rare in patients who have a destination spacer. They often do well and, in most cases, when re-infection is encountered, it is due to new pathogens in patients who had a preoperative draining sinus.

The study also suggests that long-term antibiotic suppression in patients who undergo placement of a “destination antibiotic-impregnated spacer” likely does not improve outcomes following the usual six weeks of systemic antibiotics after initial hardware removal, debridement, and placement of the antibiotic-impregnated spacer.