Studies to improve bone augmentation procedures using injectable biomaterials

椎体骨折是骨质疏松症最常见的并发症，目前尚无有效的治疗方法。据报道，与VF有关的死亡率为8%。由于预计随着人口老龄化，VF发病率将上升，因此必须找到解决办法。******骨增强术是一种治疗骨折的新方法。其中，一种自硬化胶凝性聚甲基丙烯酸甲酯PMMA，经皮注射到骨的多孔结构中。PMMA一旦硬化，就能稳定骨折。主要的好处是，患者几乎在手术后立即感受到疼痛的缓解，而费用只是其他手术治疗的一小部分。******研究计划分为3个项目，以解决该过程中的3个主要挑战。******第一个挑战是硬化PMMA水泥与骨骼的刚度不匹配，导致相邻骨骼的高应力。较高的应力会导致新的相邻损伤或PMMA的迁移。第一个目标是给粘弹性PMMA膏体充气，用无菌空气，以减少这种不匹配。具体来说，含空气的混合物产生多孔水泥，其刚度可以通过所含空气的百分比来调整。考虑到新材料面临监管挑战的问题，解决方案在于混合装置。******磷酸钙CP是最近推出的一种材料，以解决PMMA的生物学缺陷。然而，CP带来了新的注入问题。第二个目标是对CP颗粒膏体进行振动和流化，以防止悬浮液相与CP颗粒膏体分离，从而导致CP膏体挤出不均匀。由于振动流化，所述液体和膏体可保持经皮注射，所述挤出物均质。******第三个挑战是医生无法在术中评估小梁骨强度，这在很大程度上决定了椎弓根螺钉的椎体强度和稳定性，这些螺钉对于在骨质疏松的脊柱中锚定多部件机械结构至关重要。是否增加椎弓根螺钉是主观决定的。第三个目标是开发一个经皮压痕过程，其中小梁骨被认为是一个多孔的固体，并使用刚性探针客观地测量其强度。******该研究计划包括计算和实验方法，以有效地研究3个目标的物理和几何相互作用。******预期的结果将是3种新的医疗技术：压电注射器，曝气混合器和骨强度探头，以可靠地筛查骨质疏松症患者。******主要受益者是骨折患者。这些发展的社会经济影响是潜在的医疗保健储蓄和医疗行业对设备的商业利用。

There are currently no effective therapies for Vertebral Fractures VF, the most common complications of osteoporosis. The mortality rate associated with VF is reported to be 8%. Since the VF incidence is expected to escalate as the population ages, it is essential to find solutions.******Bone augmentation is a novel procedure to treat bone fractures. In it, a self-hardening cementitious polymethyl methacrylate PMMA, percutaneously injected into the porous structure of the bone. The PMMA, once hardened, stabilizes the fractured bone. The main benefit is that the patient experiences relief from pain, almost immediately after the procedure, at a fraction of the cost of other surgical treatments.******The research program is delineated in 3 projects to address 3 major challenges of the procedure.******The 1st challenge is the mismatch of the stiffness of the hardened PMMA cement and bone, causing high stresses in the adjacent bone. Higher stresses can lead to new adjacent damage or migration of the PMMA. The 1st objective is to aerate the viscoelastic PMMA paste, with sterile air, to reduce this mismatch. Specifically, the air-containing mixture produces porous cement and its stiffness can be adapted by the percentage of contained air. The solution, considering the issue of new materials facing regulatory challenges, resides in a mixing device.******Calcium phosphate CP is a material recently introduced to address the biological shortcoming of PMMA. Yet, CP comes with new injection problems. The 2nd objective is to vibrate and fluidize the CP particle paste to prevent the suspending liquid phase from separating from the CP particle paste, which results in a non-uniform CP paste extrudate. As a result of the vibrofluidization, the liquid and paste may remain percutaneously injectable and the extrudate homogeneous.******The 3rd challenge is the inability of physicians to intraoperatively evaluate the trabecular bone strength, which largely defines the vertebral strength and stability of transpedicular screws that are essential for anchoring a multi-component mechanical construct in the osteoporotic spine. The decision is made subjectively whether or not to augment the transpedicular screws. The 3rd objective is to develop a percutaneous indentation process, in which the trabecular bone is considered as a porous solid, and to use a rigid probe to objectively measure its strength.******The research program comprises both computational and experimental methods to effectively study the physical and geometric interactions in the 3 objectives.******The expected outcomes will be 3 novel medical technologies: a piezo-instrumented syringe, an aeration mixer, and a bone strength probe to reliably screen patients for osteoporosis.******The prime beneficiaries are patients suffering from bone fractures. The socioeconomic impact of these developments is potential health care savings and commercial exploitation of devices by the medical industry.