TITLE:
Impact of Biomechanical Forces on Antibiotics Release Kinetics from Hydroxyapatite Coated Surgical Fixation Pins
AUTHORS:
Mirjam Lilja, Jan H. Sörensen, Torben C. Sörensen, Maria Åstrand, Philip Procter, Hartwig Steckel, Maria Strømme
KEYWORDS:
Hydroxyapatite; Fixation Pin; Tobramycin; Coating Wear; Drug Release; Gamma Sterilization
JOURNAL NAME:
Journal of Biomaterials and Nanobiotechnology,
Vol.4 No.4,
September
23,
2013
ABSTRACT: This work investigates the impact of
biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapatite
(HA) coated fixation pins during their insertion into synthetic bone. Stainless
steel fixation pins are coated with crystalline TiO2 by cathodic arc
evaporation forming the bioactive layer for biomimetic deposition of Tobramycin
containing HA. Tobramycin is either introduced by co-precipitation during HA
formation or by adsorption-loading after HA deposition. The samples containing
antibiotics are inserted into bone mimicking polyethylene foam after which the
drug release is monitored using high performance liquid chromatography. This
analysis shows that HA coating wear and delamination significantly decrease the
amount of drug released during initial burst, but only marginally influence the sustained release period. Spalled coating fragments
are found to remain within the synthetic bone material structure. The presence
of HA within this structure supports the assumption that the local release of
Tobramycin is not only expected to eliminate bacteria growth directly at the
pin interface but as well at some distance from the implant. Furthermore, no
negative effect of gamma sterilization could be observed on the drug release
profile. Overall, the observed results demonstrate the feasibility of a
multifunctional implant coating that is simultaneously able to locally deliver
clinically relevant doses of antibiotics and an HA coating capable of promoting
osteoconduction. This is a potentially promising step toward orthopaedic
devices that combine good fixation with the ability to treat and prevent
post-surgical infections.