Influence of Absorbable Calcium Sulfate-Based Bone Substitute Materials on Human Haemostasis-In Vitro Biological Behavior of Antibiotic Loaded Implants.

Dominik Pförringer,Rainer Burgkart,Moritz Crönlein,Andreas Obermeier,Martijn Van Griensven,Marc Beirer,Norbert Harrasser,Martin Lucke,Axel Stemberger

doi:10.3390/ma11060935

Abstract

Calcium sulfate (CS) formulations are frequently implanted as antibiotically impregnated bone substitutes in orthopedic and trauma surgery to prevent or treat bone infections. Calcium ions have been discussed as candidates to accelerate blood coagulation. The goal of this study is to evaluate substance-specific influences of CS formulations on blood coagulation. Specific ELISAs were conducted to determine markers of activated blood coagulation after incubation of human blood with CS beads. Additionally, wettability with freshly drawn human blood was measured. Three different types of CS bone substitute beads were compared (CS dihydrate with tripalmitin, containing Gentamicin (Herafill®-G: Group A) or Vancomycin (CaSO4-V: Group B); and a CS hemihydrate with Tobramycin (Osteoset®: Group C)). Examinations were performed by ELISA assays for F1+2, FXIIa and C3a. Our results prove that none of the CS preparations accelerated single specific assays for activated coagulation markers. This allows the conclusion that neither Herafill®-G (CaSO4-G) nor CaSO4-V alter haemostasis negatively. Blood samples incubated with Osteoset® display an elevated F1+2-activity. The addition of tripalmitin in Herafill®-G shifts the original into a significantly hydrophobic formulation. This was additionally proven by contact angle examination of the three substances with freshly drawn human blood, showing that acceleration of plasmatic coagulation is hindered by lipids and induced by surface effects caused by presence of rapidly soluble calcium ions in the Osteoset® preparation.

Highlights

Infected bone defects are frequently addressed through implantation of various bone grafts, often based on calcium sulfate preparations containing antibiotics
The addition of tripalmitin in Herafill® -G shifts the original into a significantly hydrophobic formulation. This was proven by contact angle examination of the three substances with freshly drawn human blood, showing that acceleration of plasmatic coagulation is hindered by lipids and induced by surface effects caused by presence of rapidly soluble calcium ions in the Osteoset® preparation
For this controlled clinical trial, resorbable bone substitute materials consisting of Calcium Sulfate (CS) dihydrate, gentamicin and tripalmitin (Herafill® -G, Heraeus, Wehrheim, Germany), CS dihydrate, vancomycin, and tripalmitin, as well as commercially available CS hemihydrate with tobramycin (Osteoset®, Wright Medical Group Inc., Memphis, Tennessee, USA), were compared

Summary

Introduction

Infected bone defects are frequently addressed through implantation of various bone grafts, often based on calcium sulfate preparations containing antibiotics. Two formulations which are commercially available in Germany, as well as a third, prospective formulation containing vancomycin to address MRSA-infections, were compared, regarding their specific effects on blood coagulation after implantation [1]. The blood coagulation cascade requires calcium ions, and efficiently acts on the activation of platelets [2]. Three antibiotically loaded [3] calcium-based formulations were compared for this experiment: Calcium Sulfate (CS). CS is an inexpensive material known for its high biocompatibility [4], and functions as a carrier material [5,6] by incorporation of therapeutic substances. Calcium preparations are known to influence blood coagulation, rendering it meaningful to compare the substances’ effects on human blood coagulation. A comparison of the wettability of the substances using contact angle measurements allows conclusions to be drawn regarding superficial material-blood interaction

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