Nicole Bormann (Berlin, DE), Volker Eras (Berlin, DE), Aysha Schmock (Berlin, DE), Anja Hanke (Berlin, DE), Dr. Jan Brune (Berlin, DE), Prof. Dr. Britt Wildemann (Berlin, DE; Jena, DE)
Abstract text (incl. figure legends and references)
Intro: Infections are still a challenge in orthopaedic surgery and grafting materials are used, which can ideally be loaded with antibiotics if needed. This study compared different allografts with regard to the absorption and release of antibiotics. A specially designed high-absorbency, large-surface-area host graft composed of demineralized cortical fibres and granulated cancellous bone was compared with various human bone allografts. M&M: Carrier grafts: 3 typs of fibrous allografts (rehydration rate: 2.7, 4 and 8 ml/g); demineralized bone matrix (DBM); cortical granules; mineralized cancellous bone and demineralized cancellous (DIZG, Germany). Absorptive capacity: rehydration with phosphate buffered saline (PBS, final volume 0.4 cc) to determine total and matrix bound absorbent capacities separately. Release: Grafts were loaded with gentamicin (40 mg/ml, final volume 0.4 cc) and eluted in PBS. Samples were collected over 21 days and gentamicin quantified. Antimicrobial activity: eluted samples were tested by zone of inhibition (ZOI) test with S. aureus. Results: The tissue-matrix absorptive capacity and initial gentamicin release revealed the highest values for fibrous allograft. A sustained release over three days was observed for allografts with a rehydration rate of 2.7 and 4 ml/g with significantly higher levels compared to other grafts. Variation of the incubation time of 5–30 min had only a minor effect on the release kinetics. The largest ZOI occurred in samples eluted at 1 hour, regardless of graft type. The prolonged release of the fibrous grafts was confirmed by the prolonged antimicrobial activity. Discussion: The improved absorption capacity of fibrous allografts leads to a prolonged release of the antibiotic. Liquid retention facilitates handling. It can therefore serve as a suitable support graft as it provides a convenient way to store e.g. antibiotics at their intended destination and allows sustained release for septic orthopedic indications.