Articulating antibiotic spacer: 89% of infected hips free of reinfection at five years

Design

Retrospective single-centre cohort

Population

298 patients (302 hips) with two-stage exchange for chronic PJI using an articulating spacer

Primary outcome

Survival free of reinfection and rerevision at 5 years

Effect

Reinfection-free 89% (85.2 to 93.1); any reoperation-free 80%; spacer dislocation HR 6.2 for later dislocation

This single-centre series, published in The Bone & Joint Journal in September, followed 298 patients (302 hips) treated with two-stage exchange for chronic periprosthetic joint infection using a commercially available, partly intraoperatively fabricated articulating high-dose antibiotic spacer between 2005 and 2022. Forty per cent had already had infection-related surgery. Mean follow-up was six years.

Five years after reimplantation, survival free of reinfection was 89% (95% CI 85.2 to 93.1), free of aseptic rerevision 93%, free of any rerevision 86% and free of any reoperation 80%. Dislocation caused most aseptic rerevisions (15 of 20). McPherson host C (HR 3.7) and limb grade 3 (HR 3.3) raised reinfection risk. Spacer fracture and spacer dislocation each occurred in about 5%, and spacer dislocation strongly predicted dislocation after reimplantation (HR 6.2, 2.3 to 16.9).

This gives surgeons a reference figure for consent and a specific warning: a hip that dislocates on its spacer is at high risk of dislocating again. The authors suggest higher-stability bearings at reimplantation for these patients. It is a single high-volume centre and one spacer design, without a comparison group.

• Quote about 9 in 10 hips free of reinfection at five years after two-stage exchange with an articulating spacer, adjusted for host grade.
• Record McPherson host and limb grade before the first stage; host C and limb grade 3 roughly tripled reinfection risk.
• Plan a higher-stability bearing at reimplantation if the spacer dislocated.
• Warn patients that about 1 in 20 will have a spacer fracture or dislocation during the interval.

Why it matters

Spacer behaviour during the interval predicts the most common mechanical failure after reimplantation.

Don't overread it

Single centre and one spacer design without a control group; results may not transfer to other spacers or settings.

The statistics, in plain English

Five-year survival of 89% (85 to 93%) is estimated from Kaplan-Meier curves, which account for patients followed for different lengths of time. The hazard ratio of 6.2 for dislocation has a wide interval (2.3 to 16.9) because events were few, but even the low end is a strong association.

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