Does the Addition of Low-Dose Antibiotics Compromise the Mechanical Properties of Polymethylmethacrylate (PMMA)?

The increasing numbers of total joint replacements and related implant-associated infections demand solutions, which can provide a high-dose local delivery of antibiotics. Antibiotic-loaded bone cement (ALBC) is an accepted treatment method for infected joint arthroplasties. The mechanical properties of low-dose gentamicin-loaded bone cement (BC) in medium- and high-viscosity versions were compared to unloaded BC using a vacuum mixing system. As an additional control group, manual mixed unloaded BC was used. In a uniaxial compression test, ultimate compressive strength, compressive yield strength, and compression modulus of elasticity, as well as ultimate and yield strain, were determined according to ISO 5833-2022 guidelines. All groups exceeded the minimum compressive strength (70 MPa) specified in the ISO 5833 guidelines. Both ALBC groups showed a similar ultimate compressive and yield strength to the unloaded BC. The results showed that vacuum mixing increased the compression strength of BC. ALBC showed similar compressive strength to their non-antibiotic counterparts when vacuum mixing was performed. Added low-dose gentamicin acted as a plasticizer on bone cement. From a biomechanical point of view, the usage of gentamicin-based ALBC formulations is viable.