Retained Antibiotic Spacers After Total Hip and Knee Arthroplasty Resections: High Complication Rates

Background: Prolonged retention of an antibiotic spacer is occasionally chosen during treatment of periprosthetic joint infections after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The purpose of our study was to evaluate the outcome of extended spacer retention. Methods: We reviewed 1106 cases of periprosthetic joint infection after THA (n = 308) and TKA (n = 798) and identified 17 (5.5%) retained hip and 34 (4.3%) retained knee spacers. Most patients (35 of 51, 69%) underwent spacer retention because they were medically unfit for further surgery. The remaining patients (16 of 51, 31%) had acceptable function and forewent further surgery. Competing risk analyses, with death as the competing risk, determined the cumulative incidence of reinfection and spacer revision. Radiographic analysis and clinical outcomes were analyzed. Results: The 2-year cumulative incidence for reinfection was 7% for retained hip and 13% for retained knee spacers. The cumulative incidence for all-cause spacer revision was 28% at 4 years for hips and 21% at 2 years for knees. The most common complications were implant migration and femoral spacer subsidence in the hip cohort, and supracondylar femur fractures and spacer dislocations in the knee cohort. The cumulative incidence for radiographic signs of mechanical failure was 72% and 87% at late follow-up for the hip and knee groups, respectively. The latest Harris Hip Score and Knee Society Score were 62 and 63, respectively. Conclusion: Antibiotic spacer retention is a rare event in the course of planned 2-stage treatment of infected THA or TKA. Failure secondary to recurrent infection is uncommon; however, failure for mechanical reasons is frequent and clinical outcomes are relatively poor.