Does Cement Viscosity Impact Antibiotic Elution and In Vitro Efficacy Against Common Prosthetic Joint Infection...

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Infectious Disease

Background:

• Polymethylmethacrylate (PMMA) antibiotic-laden bone cement (ALBC) is crucial for preventing prosthetic joint infections (PJIs) in total joint arthroplasty.
• Cement viscosity is a key factor influencing antibiotic elution, yet its specific impact on medium-viscosity formulations remains unclear.
• Understanding comparative elution and efficacy of different ALBC products against common PJI pathogens is essential.

Purpose of the Study:

• To determine if cement viscosity impacts in vitro antibiotic elution characteristics when comparing medium- and high-viscosity ALBC from the same manufacturer.
• To assess if ALBC manufacturer and aminoglycoside type (gentamicin vs. tobramycin) affect in vitro antibiotic elution against common PJI pathogens.

Main Methods:

• Three PMMA-based ALBC products were tested: Palacos® R (high viscosity) + gentamicin, Palacos (medium viscosity) + gentamicin, and Simplex™ P (low viscosity) + tobramycin.
• Elution was studied over 5 days against four common PJI pathogens: S. aureus (methicillin-sensitive and resistant) and S. epidermidis (methicillin-sensitive and resistant).
• Kirby-Bauer assays determined zones of inhibition, and eluted antibiotic concentrations were extrapolated to assess efficacy and area under the curve (AUC).

Main Results:

• Cement viscosity did not significantly impact antibiotic elution when comparing medium- and high-viscosity Palacos formulations.
• Palacos ALBC (both medium and high viscosity) demonstrated significantly greater in vitro antibiotic elution and activity than Simplex™ P over 5 days.
• All tested ALBC products initially exceeded the minimum inhibitory concentration (MIC) for all pathogens, but only Palacos formulations maintained concentrations above MIC for MRSA and MSSE beyond Day 1.

Conclusions:

• Medium-viscosity ALBC exhibits comparable elution properties to high-viscosity ALBC from the same manufacturer.
• Palacos medium- and high-viscosity ALBC demonstrated superior in vitro antibiotic elution and activity against three of four common PJI pathogens compared to Simplex low-viscosity ALBC.
• Further in vivo research is needed to confirm the clinical efficacy of these ALBC products in preventing PJIs.