The influence of low concentrations of a water soluble poragen on the material properties, antibiotic release, and biofilm inhibition of an acrylic bone cement Josh A. Slane a,b, ⁎, Juan F. Vivanco b,e , Warren E. Rose c , Matthew W. Squire d , Heidi-Lynn Ploeg a,b a Materials Science Program, University of Wisconsin-Madison, Madison, WI, USA b Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA c Pharmacy Practice Division, School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA d Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA e Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibañez, Viña del Mar, Chile abstract article info Article history: Received 23 January 2014 Received in revised form 26 March 2014 Accepted 6 May 2014 Available online 22 May 2014 Keywords: Bone cement Infection Drug release Mechanical properties Biofilm Soluble particulate fillers can be incorporated into antibiotic-loaded acrylic bone cement in an effort to enhance antibiotic elution. Xylitol is a material that shows potential for use as a filler due to its high solubility and potential to inhibit biofilm formation. The objective of this work, therefore, was to investigate the usage of low concentra- tions of xylitol in a gentamicin-loaded cement. Five different cements were prepared with various xylitol loadings (0, 1, 2.5, 5 or 10 g) per cement unit, and the resulting impact on the mechanical properties, cumulative antibiotic release, biofilm inhibition, and thermal characteristics were quantified. Xylitol significantly increased cement porosity and a sustained increase in gentamicin elution was observed in all samples containing xylitol with a maximum cumulative release of 41.3%. Xylitol had no significant inhibitory effect on biofilm formation. All measured mechanical properties tended to decrease with increasing xylitol concentration; however, these effects were not always significant. Polymerization characteristics were consistent among all groups with no significant differences found. The results from this study indicate that xylitol-modified bone cement may not be appropriate for implant fixation but could be used in instances where sustained, increased antibiotic elution is warranted, such as in cement spacers or beads. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Prosthetic joint infection is one of the most devastating complica- tions that can occur following total joint replacement with a prevalence rate of approximately 2.2% for both hip and knee implants [1]. Often times, these infections are attributable to bacterial colonization through biofilm formation on the implant’s surface, which makes treatment with traditional systemic antibiotics exceedingly difficult [2]. As a pro- phylactic measure against infection, antibiotics are often incorporated into bone cement in order to provide local drug administration at the implant site and avoid systemic toxicity concerns. Despite some positive outcomes with this technique [3], the relative hydrophobic nature of bone cement limits the amount of antibiotic that can be released and typically only ~10% of the total incorporated drug is eluted from the cement [4]. Moreover, the antibiotic release profile normally observed is characterized by a high initial burst release followed by a low, non-therapeutically effective phase [5] wherein biofilm formation may still persist. In an effort to enhance antibiotic elution, inert soluble poragens can be added to bone cement. As the poragen dissolves in vivo, an intercon- nected porous network is left behind which increases fluid infiltration into the cement, theoretically leading to increased, prolonged antibiotic diffusion [4,6]. A wide variety of materials have been studied including soluble sugars [7–11], chitosan [12,13], tricalcium phosphate [14], and glycine [15]. These materials are typically employed in high poragen/ cement loading ratios (e.g. 22 g xylitol per 40 g cement [16]) which have a significant adverse impact on the cement’s mechanical proper- ties rendering them unsuitable for prosthesis fixation in primary arthroplasty. Therefore, there is a necessity to investigate alternative ce- ment formulations that utilize lower poragen concentrations in hopes of achieving high antibiotic release levels without inducing deleterious effects on the cement’s mechanical properties. Xylitol is a material that shows high potential as a filler within bone cement. It is a highly water-soluble crystalline powder that is non- immunogenic, inexpensive and widely available. Xylitol has demonstrat- ed in animal models to affect bone metabolism and lead to increased bone density [17] and improved structural/mechanical properties [18]. Materials Science and Engineering C 42 (2014) 168–176 ⁎ Corresponding author at: Materials Science Program, University of Wisconsin- Madison, 1513 University Avenue, Room 3046, Madison, WI 53706, USA. Tel.: +1 608 263 6692; fax: +1 608 265 2316. E-mail address: jaslane@wisc.edu (J.A. Slane). http://dx.doi.org/10.1016/j.msec.2014.05.026 0928-4931/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec