Antibiotic-Loaded Cement Spacer — SCE Infectious Diseases MCQ

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ModerateBone & Joint InfectionAntibiotic-Loaded Cement SpacerSCE Infectious Diseases

A 45-year-old man develops a prosthetic joint infection of his right hip. Two-stage revision is planned. At stage 1, the prosthesis is removed and an antibiotic-loaded cement spacer is inserted. What antibiotic is most commonly loaded into the spacer cement?

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Correct answer: D — Gentamicin (alone or combined with Vancomycin) — thermostable aminoglycosides maintain activity through cement polymerisation

Antibiotic-loaded bone cement (ALBC) spacers in two-stage PJI revision typically contain Gentamicin (most commonly) ± Vancomycin. These antibiotics are chosen because they are: (1) thermostable (surviving the exothermic cement polymerisation reaction at ~70°C), (2) available in powder form for mixing, (3) broad-spectrum (covering common PJI organisms — staphylococci, streptococci, Gram-negatives), and (4) elute effectively from PMMA cement over weeks. High-dose loading (≥3.6 g Gentamicin per 40 g cement) achieves local concentrations far exceeding systemic MICs. Rifampicin, Meropenem, and Flucloxacillin are heat-labile or poorly compatible with cement.

Reference: BSAC 2023 – PJI guidelines; NICE NG157 2024