Outpatient parenteral antibiotic therapy in primary hip and knee arthroplasty infection managed with debridement and retention of prosthesis: a retrospective cohort study.

Background: Attempted joint salvage of infected primary arthroplasty traditionally has utilized joint washouts in combination with costly long-term inpatient parenteral antibiotic regimens. Outpatient and home parenteral antibiotic therapy (OHPAT) represents a potential alternative. However, there is a lack of published data on its value for primary deep arthroplasty infection. This paper describes the surgical and microbiologic outcomes of a cohort of patients with deep arthroplasty infections treated with OHPAT after surgical washout and debridement. Methods: Local OHPAT records identified all patients who underwent attempted joint salvage of a primary hip or knee replacement complicated by a deep post-operative infection between February 2006 and February 2009. Minimum follow-up for all patients was 24 mos. For each patient, hospital records were reviewed to ascertain the effectiveness of treatment. Results: In total, 14 patients (10 total knee replacements; four total hip replacements) were identified from the records. Eleven joints (79%) were salvaged. There was a trend toward a higher salvage rate with early infection (< 6 mos after primary surgery), with eight of nine joints (89%) being salvaged, versus 60% (three of five) for later presentation. Methicillin-sensitive Staphylococcus aureus was the most common organism identified (43% of cases), and 57% of infections were polymicrobial. The average duration of OHPAT was 58 days. Two patients were readmitted because of clinical deterioration, both of whom later required revision. All patients, regardless of their outcomes, stated they were satisfied with the OHPAT service and believed it was more convenient than inpatient treatment. We estimate OHPAT saved approximately 13,000 pound per patient episode. Conclusions: Use of OHPAT for deep infection after primary arthroplasty has a high success rate. It is effective at identifying patients failing treatment, is cost-effective, and has a high level of patient satisfaction.