Compression Strength and Porosity of Single-Antibiotic Cement Vacuum-Mixed with Vancomycin
Terence McIff, PhD
The addition of antibiotics to cement allows the theoretical benefit of providing high local drug concentrations with less risk of systemic complications. A major drawback of this combination is the detrimental effect antibiotics have on the mechanical properties of bone cement. The study was designed to determine how much Vancomysin can be added while maintaining at least 70 MPa of compressive strength. Results showed that up to 6 grams of Vancomysin can be added without have a determintal effect. Amounts larger than 6 grams could possible effect the bonds the cement needs to maintain its stiffness.
Antibiotic Delivery from PMMA/Silorane
Grahmm Funk, Terence McIff PhD
Various studies have aimed to assess the effect of incorporating antibiotics into both PMMA bone cement and a novel Silorane-based Biomaterial (SBB) for use in infection prevention and clearance in total joint arthroplasty. It has been noted that both the amount of antibiotic incorporated into the cement and the technique of incorporation have substantial effects on both the handling properties of the resultant material and the release of the antibiotic from the cement. Our studies focus on evaluating the compatibility between the cements and antibiotics by measuring their curing/handling properties, antibiotic release kinetics, efficacy of released antibiotics, and mechanical properties of the cements over time.
Development and Characterization of a New Silorane Based Bone Cement for Orthopaedic Applications
Grahmm Funk, Terence McIff PhD
A new Silorane based bone cement developed by our collaborators at UMKC has been formulated for use in orthopedics. While dental formulations containing siloranes are nontoxic and low shrink, they require an external light initiation (e.g., ultraviolet light) for curing. To allow for orthopedic applications, this new silorane bone cement has been reformulated to use a mixed chemical initiation system for polymerization. This new formulation of silorane bone cement has great potential for orthopedic use due to its low toxicity, low exothermicity, and high biocompatibility as compared to commercial bone cements. The silorane cement can be modified for kyphoplasty (less viscous) or for bone repair (putty). Due to its low exothermic characteristic, testing is underway to use the silorane cement to form antibiotic/antifungal spacers that have both load bearing capabilities and can also be used to deliver heat sensitive antimicrobials.
MRI Based Modeling to Evaluate Surgical Efficacy for Reduced OA Risk
Terence McIff, Kenneth Fischer, E. Bruce Toby
Disruption of the scapholunate interosseous link can cause a loss of normal scapholunate mechanical relationship and eventually lead to osteoarthritis. Surgical reconstruction attempts to restore the relationship and shows improvement in functional outcomes, but postoperative effectiveness in restoring normal joint mechanics still remains a question. This NIH funded study implements in vivo MRI based modeling in a human subjects study for radiocarpal contact analysis. The overall goal is to measure in vivo joint contact mechanics that occur during functional activities, as a means of evaluating the efficacy of surgical treatments for the scapholunate dissociation with regard to the risk of developing osteoarthritis (OA). We are evaluating the immediate effects of injury and repair/reconstruction on wrist contact mechanics, and follow up with subjects after 23 years, to determine differences from the early post injury/postoperative joint mechanics. Finally we are analyzing the data to determine significant differences between stages and to determine significant correlations between functional measures and contact mechanics. The resulting data (especially for normals) will help establish a statistical norm for future comparison to injured wrists, without the need for contralateral data. The data may also provide insight into potential predictive indices of OA risk.