Antimicrobial Release From Prefabricated Spacers Is Variable and the Dose Is Low

Area of Science:

• Orthopaedic Surgery
• Biomaterials Science
• Infectious Disease Management

Background:

• High-dose antimicrobial-loaded bone cement (ALBC) is standard for orthopaedic infections.
• Elution characteristics of prefabricated ALBC spacers are not well understood compared to hand-mixed ALBC.

Purpose of the Study:

• Compare antimicrobial release over time between prefabricated and hand-mixed ALBC.
• Assess uniformity of release across prefabricated spacer surfaces.
• Investigate variations between different prefabricated spacer components.
• Determine if textured surfaces yield different release rates.

Main Methods:

• Comparative laboratory study of six prefabricated ALBC spacer components (hip and knee) and three hand-mixed ALBC formulations.
• Gentamicin elution measured from 41 sites on prefabricated spacers and 15 specimens of hand-mixed ALBC.
• Statistical analysis using ANOVA and Tukey's multiple-comparison test or t-test.

Main Results:

• Both prefabricated and hand-mixed ALBC showed highest gentamicin release in the first 24 hours, decreasing over 7 days.
• At Day 7, prefabricated spacers eluted more than 1g hand-mixed ALBC but less than 5g or 10g formulations.
• Release varied across spacer surfaces (2.7-9.9 µg/mm²) and between components (3.5-5.5 µg/mm²), with no significant differences found.
• Release from textured surfaces was inconsistent.

Conclusions:

• Antimicrobial release from prefabricated ALBC spacers is consistent with low-dose ALBC formulations.
• Variations in release across surfaces and between components are minimal relative to antimicrobial load.
• Prefabricated spacers offer consistent local antimicrobial delivery, similar to other low-dose ALBC methods.