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

Abstract Background Prolonged retention of an antibiotic spacer is occasionally chosen during treatment of periprosthetic joint infections (PJIs) after THA and TKA. The purpose of our study was to evaluate the outcome of extended spacer retention. Methods We reviewed 1106 cases of PJI following 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 re-infection and spacer revision. Radiographic analysis and clinical outcomes were analyzed. Results The 2-year cumulative incidence for re-infection 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 HHS and KSS were 62 and 63, respectively. Conclusion Antibiotic spacer retention is a rare event in the course of planned two-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.