A new bone cement to minimize thermally-induced tissue necrosis

Osteoporosis and low bone mass affect more thanmillion people in the USwith vertebral compression fractures as the major source of morbidity and health care costsFor patients with mild or minimal painand initially even for patients with severe painconservative therapy is usually the first choiceSuch treatment including opiatesbraces and bedrest have their own risk profileFor patients with severe painminimally invasive fluoroscopy guided proceduresvertebroplasty and kyphoplastythat involve injection of cement bone into the vertebral body are typically considered to stabilize fractures and provide mobilityCement leakage is the most common complication of vertebroplasty and kyphoplastyThe high heat of polymerization of the implant cement can cause thermal damage to surrounding tissuenerves and spinal cordAdditionallycurrent cements with high modulusstiffnesscan also result in stress to adjacent vertebrae and spinal structureNo current cement formulation simultaneously addresses the issues of high temperature and modulusIn this proposalwe hypothesize that a phase change additive can decrease the peak polymerization temperature of acrylic bone cement to below the cell necrosis temperature while simultaneously decreasing its modulus of elasticityThis idea is based on the scientific premise that a suitable phase change additivewhich undergoes endothermic melting during exothermic polymerization of the cementwill absorb sufficient heat to maintain a low peak temperatureAs our pilot data showsa fatty acid based acrylic polymeric additive was able to substantially decrease the peak polymerization temperature while simultaneously decreasing its modulus and provides a pathway to address both these problemsThe Specific Aims arefirstto test the hypothesis that a suitable phase change polymer can decrease the peak polymerization temperature of acrylic bone cement to a temperature below the cell necrosis temperature by formulating the polymer and measuring cement setting temperaturessecondto test the hypothesis that the phase change polymer will decrease the modulus of elasticity of acrylic bone cement by mechanically testing cements of various formulations containing the phase change polymerthirdto compare the cytotoxicity of a control acrylic cement with a cement containing the phase change polymerSuccessful completion of this project will provide guidance to develop cement formulations that will not cause thermally induce tissue damage and thereby improve fixation of the cement not just for vertebral augmentation but easily translatable to improve anchoring for joint replacementsdental implantsand fixation in craniomaxillofacial and other trauma applicationsIt will also allow incorporation of heat sensitive biomoleculessuch as bone morphogenetic proteinsgrowth factorsas well as heat sensitive antibiotics to be incorporated into the cementLastlyit willin the futureallow formulations that could be used for rapid cast formation without burning skinWe therefore believe that this patent protected platform technology has far reaching value for a variety of applicationsand serving several unmet clinical needs Bone cements meet a clinical need in fixation of fractured spinal cord vertebrae for patients with osteoporosis who have undergone vertebral compression fractureoccurring inpatients each year in the USA drawback associated with implantation of bone cements by vertebroplasty or balloon kyphoplastyis that they can leak into the spinal canal risking thermal damage due to the high heat of polymerizationThis proposal aims to provide guidance to develop new bone cements with a significantly low temperature of polymerization to allay any concerns of thermal tissue damage occurring both within the vertebrae as well as in the surrounding tissue in cases of cement leakage