Orthop Traumatol Surg Res. 2021 Mar 28:102908. doi: 10.1016/j.otsr.2021.102908. Online ahead of print.
INTRODUCTION: Antibiotic-loaded bone cements (ALBCs) are used as spacers in two-stage revision arthroplasty for periprosthetic joint infection. We previously described a new technique applying vancomycin powder coating to custom-made cements (superficial vancomycin coating (SVC)) but, to our knowledge, this method has not been assessed. We therefore performed an in-vitro study to determine: 1) whether manually applied SVC strengthened the cements' antibiotic effect; and 2) whether the mechanical requirements for the cements were fulfilled.
HYPOTHESIS: SVC increases the antibiotic effect of cement within the first 24 hours.
METHODS: Cuboid blocks were produced from two commercially available acrylic ALBCs (Palacos R+G and Copal G+V) with and without SVC. Each block was eluted in phosphate-buffered saline at 37°C. Eluates obtained at 1, 2, 3, 4, 5, 10, 15, 30 and 60 minutes and 3, 6 and 24 hours were evaluated against Staphylococcus aureus (Palacos, Copal) and Methicillin-resistant Staphylococcus aureus (MRSA) (Copal) using zone of inhibition tests. Mechanical test results (bending modulus, bending strength) were compared to ISO requirements (≥1,800 MPa, ≥50 MPa).
RESULTS: Palacos with SVC produced significantly greater zones of inhibition against Staphylococcus aureus than Palacos without SVC (p=0.002). Copal with SVC showed greater zones of inhibition against both Staphylococcus aureus and MRSA (p=0.002). The antibiotic effect was enhanced by SVC in both cements at every time point within 24 hours. The bending modulus and bending strength of Palacos with SVC (2,089± 166 MPa, 60.8±2.6 MPA) and Copal with SVC (2,283±195 MPa, 56.9±2.4 MPa) were significantly above ISO requirements.
CONCLUSION: SVC boosts the antibiotic effect of ALBCs in the first 24 hours, while maintaining sufficient stability. These findings endorse SVC as a promising additive in septic revision surgery.
LEVEL OF EVIDENCE: III; case control study.