The Role of Pmma Bone Cement Within Osteoporotic Bone---Thermal Injury, Permeability and Mechanical Properties (II)

Vertebroplasty, the injection of polymethylmethacrylate (PMMA) into fractured vertebral bodies, has been widely used to treat osteoporotic compression fracture. It is an emerging surgical procedure to reinforce the bone structure of osteoporotic vertebrae by filling the porous cancellous bone with bone cement. Many factors affect the reaction of polymerization of polymethylmethacrylate and, therefore, the maximal polymerization temperature, injection permeability and mechanical properties of bone cement. A surgeon may change the temperature of bone cement to enhance the clinical applicability and safety of vertebroplasty. Ideal bone cement for vertebroplasty should fit three criteria: 1) diminishing thermal damage, 2) maintaining suitable permeability and increasing working time, 3) maintaining mechanical strength. To achieve the above three criteria for bone cement in application of vertebroplasty, the results from our previous project had demonstrated that both precooling (i.e. lowering the initial temperature) and ice bath cooling (i.e. lowering the surrounding temperature) can effectively diminish thermal damage together with an extension of handling time during vertebroplasty. The results had been published in BMC Musculoskelet Disord, 13:198, 2012. Although satisfactory results were achieved, the mechanism for the optimization of cement permeability parameters and the influence on mechanical properties by cooling bone remain unknown. The aim of the present two-year study is thus, extending our previous study, designed to explore the optimization of cement permeability and the influence on mechanical properties by temperature control of bone cement. The data will reveal the influence of cooling temperature on the injection permeability and mechanical strength of bone cement. The contents of this two-year study are summarized as follows: A. The first-year study: Optimization of Cement Permeability and Establishment of Experimental Model Three types of commercially available test blocks are used to mimic different degrees of osteoporotic bone. Uniform infiltration experiments on isolated cores of osteoporotic bone (test bone block) are conducted, using a custom-built infiltration device. Bone cements are prepared by two different cooling methods. Permeability-versus-time chat during polymerization is examined. We hope to prove that optimal permeability can be achieved by temperature control of bone cement. B. The second-year study: Mechanical test and Porosity observation of Cooling Bone Cement Compression test and porosity observation of cooling bone cement will be conducted. Bone cements are prepared by two different cooling methods. The influence of cooling bone cement on mechanical properties and voids content will be investigated.

Project ID:PB10301-0507
External Project ID:NSC102-2221-E182-014-MY2