Biomechanical behavior of novel composite PMMA-CaP bone cements in an anatomically accurate cadaveric vertebroplasty model

Vertebral compression fractures are caused by many factors including trauma and osteoporosis. Osteoporosis induced fractures are a result of loss in bone mass and quality that weaken the vertebral body. Vertebroplasty and kyphoplasty, involving cement augmentation of fractured vertebrae, show promise in restoring vertebral mechanical properties. Some complications however, are reported due to the performance characteristics of commercially available bone cements. In this study, the biomechanical performance characteristics of two novel composite (PMMA-CaP) bone cements were studied using an anatomically accurate human cadaveric vertebroplasty model. The study involves mechanical testing on two functional cadaveric spinal unit (2FSU) segments which include monotonic compression and cyclical fatigue tests, treatment by direct cement injection, and microscopic visualization of sectioned vertebrae. The 2FSU segments were fractured, treated, and mechanically tested to investigate the stability provided by two novel bone cements; using readily available commercial acrylic cement as a control. Segment height and stiffness were tracked during the study to establish biomechanical performance. The 2FSU segments were successfully stabilized with all three cement groups. Stiffness values were restored to initial levels following fatigue loading. Cement interdigitation was observed with all cement groups. This study demonstrates efficient reinforcement of the fractured vertebrae through stiffness restoration. The pre-mixed composite cements were comparable to the commercial cement in their performance and interdigitative ability, thus holding promise for future clinical use.