Prospectively Observational Evaluation of Clinical Outcomes in Two-stage Reimplantation for Infected Knee Arthroplasty Patients

*Background and study aims: Total knee arthroplasty (TKA) infection is a devastating complication requiring multiple hospitalizations, operations, and outpatient visits placing a significant burden on both patients and treating surgeons. The incidence of prosthetic joint infection after primary hip or knee arthroplasty is about 2% among the Medicare population. When revision surgery is needed, two kinds of treatment include one-stage and two-stage re-implantation procedure can be applied. Bengtsonet al., in an earlier report, evaluated 107 patients with a 75.7% success rate after one-stage revision. In the case of two-stage TKA revision success rates of 89% to 100% are noted with follow-up periods of 2 to 7.5 years. Delayed re-implantation after administration of intravenous antibiotics appears to offer better success rates than direct-exchange techniques. Therefore, the two-stage re-implantation procedure is considered the gold standard for treatment of subacute and chronic deep prosthetic joint infections (PJI). However, the protocols of the antibiotic therapy after resection arthroplasty have varied in different reports. The purpose of this study will be to evaluate the clinical outcomes of two-stage re-implantation for infected knee arthroplasty using the standardized protocol of combined parenteral and oral antibiotic therapy and the criterion for re-implantation.

*Study participants

Study period: from March 2011 to June 2019.

*Procedures and operations

-The first stage The first stage consisted of the removal of the prosthesis and all hardware, debridement of all infected and devitalized tissues, removal of all biofilms, and aqueous povidone iodine irrigation. For primary joint arthroplasty with cement, all the bone cement was removed. Samples for culture and histology were performed at the time of removal of prosthesis (ROP). The Long-leg splint was applied to the limb until the next replacement procedure. The first stage was using antibiotic-impregnated bone cement as a static spacer block. The types of antibiotic regimens were determined according to the results of cultures form the preoperative joint aspirations. In this study, 1 to 2 g of vancomycin (for gram-positive bacteria) and/or 1 to 2 g of ceftazidime (for gram-negative bacteria) per 40g package of cement would be hand-mixed according to the previous culture. Any past history of adverse events of the antibiotics used in the cement would be clarified to avoid any possible allergic reactions to the antibiotic-loaded cement. If the patient had allergic reactions to vancomycin or ceftazidime, daptomycin or gentamicin 1 to 2 g will be used for alternative antibiotic cement.