Study of Antibiotic Spacer Design to Treat Infection After Hip Replacement
Condition: Osteoarthritis; Hip Infection; Prosthetic Joint Infection; Complications; Arthroplasty, Infection or Inflammation; Complications; Arthroplasty
MeSH terms: Infections; Communicable Diseases; Osteoarthritis; Inflammation
Study type: Interventional

Summary: 
      Infection remains one of the most difficult-to-treat complications of total hip arthroplasty.
      The gold standard treatment is two-stage removal of the prosthesis with later replacement of
      permanent implants.The first stage consists of removal of the infected arthroplasty
      components and the surrounding devitalized tissue, copious pulsed irrigation, and placement
      of a temporary antibiotic-impregnated cement spacer. This spacer is typically left in place
      six weeks, during which time the patient receives intravenous antibiotics. After the surgeon
      feels that the infection has been eradicated, or if a second debridement is required, a
      second operative procedure is performed. While the use of an antibiotic spacer is well
      accepted, whether the spacer should immobilize the hip (a so-called "static" spacer) or allow
      for range of motion (a so-called "articulating" spacer) is controversial. Proponents of
      static spacers argue that immobilization of the periarticular soft tissues aids in clearance
      of the infection and that these spacers are simpler to fashion intraoperatively. Proponents
      of articulating spacers argue that they improve hip function, prevent damage to the
      musculature surrounding the hip, allow easier reimplantation, improve hip function, and
      prevent dislocation following hip reimplantation. While good results have been described with
      both methods, comparative trials have been conflicting as to whether spacer design alters hip
      function, operative time, and dislocation rates. Equipoise exists within the literature, and
      no randomized clinical trial has been conducted to evaluate this issue.

      The purpose of this study is to compare articulating and static antibiotic-impregnated
      spacers for the treatment of chronic periprosthetic infection complicating total hip
      arthroplasty through a prospective, randomized clinical trial. The goals of this trial are to
      determine the effect of spacer design upon eradication of infection, hip function, ease of
      reimplantation, and dislocation rates. The investigators hypothesize that articulating
      spacers will provide shorter operative times at replantation while improving hip function and
      hip dislocation rates following hip reimplantation.
    

Detailed description: 
      After diagnosis of infection and informed consent, patients will be taken to the operating
      room. After anesthetization, patients will be randomized to either an articulating spacer or
      static spacer. Randomization will be performed by prepared opaque envelopes administered by a
      nonparticipant in the study. After a complete debridement of devitalized tissue, explantation
      of infected components and any associated cement, either an articulating or static spacer
      will be placed. All spacers will be formed using 3.0 g of Vancomycin and 1.0 g of Tobramycin
      for each 40 g packet of cement. Articulating spacers will be formed of antibiotic-impregnated
      cement using the Stage One system (Biomet, Warsaw, IN) sized to fit the endosteal and
      acetabular bone defect. Static spacers will be hand-made with a rod of antibiotic-impregnated
      cement and cement beads of sufficient quantity to fill the acetabulum.

      Post-operatively, all patients will be made touch-down weight bearing protected with a walker
      or crutches. At the time of reimplantation, the joint will be aspirated and multiple cultures
      obtained along with intraoperative histopathological analysis to evaluate for persistent
      infection.

      Data collected preoperatively will include age, gender, laterality, etiology of hip
      degeneration, comorbidities, Harris Hip score, infecting organisms and Paprosky femoral and
      acetabular bone loss classification. The Harris Hip score has been used extensively in the
      study of revision hip arthroplasty and has been found to be reliable and valid and will be
      determined preoperatively and at all follow-up visits.

      Data collected at the time of implant removal and reimplantation will include operative time,
      blood loss, surgical approach, and need for an extended trochanteric osteotomy. Radiographs
      performed immediately following and just prior to reimplantation will be reviewed to
      determine if the spacer utilized has caused bone loss; bone loss to the cut bony surfaces
      will be confirmed intraoperatively. At each follow-up visits radiographic appearance, the
      Harris Hip Score, dislocation events, recurrence of infection, and the need for revision or
      reoperation of any kind on the hip will be determined.

      All portions of this study will be part of conventional care except for randomization and
      collection of the Harris Hip Score. Which type of spacer is used currently depends upon the
      judgment of the attending surgeons and both are used routinely.

      The primary outcome variable will be Harris Hip Score. A power analysis was conducted with
      the assistance of Dr. Mario Moric at Rush. Using the standard deviation of Harris Hip Scores
      from Hsieh and colleagues (2004) and Fehring and colleagues (1999), the largest previous
      studies reporting such data, Dr. Moric estimated 56 patients, 28 patients per group, would be
      needed to detect a clinically relevant difference of ten points. To account for attrition,
      our target total sample size will be 80 patients.
    

Intervention name(s): Implantation of a static, non-articulating cement spacer.; Implantation of an articulating spacer.
Intervention type(s): Procedure; Procedure
Intervention description(s): After diagnosis of infection and informed consent, patients will be taken to the operating room. After anesthetization, patients will be randomized to either an articulating spacer or static spacer. Randomization will be performed by prepared opaque envelopes administered by a nonparticipant in the study. After a complete debridement of devitalized tissue, explantation of infected components and any associated cement, either an articulating or static spacer will be placed. All spacers will be formed using 3.0 g of Vancomycin and 1.0 g of Tobramycin for each 40 g packet of cement. Static spacers will be hand-made with a rod of antibiotic-impregnated cement and cement beads of sufficient quantity to fill the acetabulum.; After diagnosis of infection and informed consent, patients will be taken to the operating room. After anesthetization, patients will be randomized to either an articulating spacer or static spacer. Randomization will be performed by prepared opaque envelopes administered by a nonparticipant in the study. After a complete debridement of devitalized tissue, explantation of infected components and any associated cement, either an articulating or static spacer will be placed. All spacers will be formed using 3.0 g of Vancomycin and 1.0 g of Tobramycin for each 40 g packet of cement. Articulating spacers will be formed of antibiotic-impregnated cement using the Stage One system (Biomet, Warsaw, IN) sized to fit the endosteal and acetabular bone defect.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: arthroplasty; hip replacement; Osteoarthritis; knee Infection; Prosthetic Joint Infection; Complications; Arthroplasty, Infection or Inflammation; Complications; Arthroplasty