[Experimental study of percutaneous vertebroplasty with a novel bone void filling container system]

To investigate vertebral augmentation with a novel reticulate bone filling container system by polymethyl methacrylate (PMMA) injection in cadaveric simulated vertebral compressive fracture and explore the effect of reticulate bone filling container on cement distribution controlling within vertebral body and the restoration of biomechanical properties after augmentation.

A total of 28 freshly frozen human vertebrae specimens were randomly divided into 4 groups. After the measurements of bone mineral density (BMD) and vertebral height, each vertebra received an axle load by a MTS (material testing system) machine to test the initial strength and stiffness. Subsequently a simultaneous compressive fracture model was created to measure the stiffness and height of fractured vertebrae. Then the augmentation procedure was performed. Afterward the biomechanical properties and the vertebral height were similarly measured as pre-operatively. The expansion of bone filling container and the distribution of cement within vertebral body were morphologically observed by crossing the specimens in sagittal midline and also integrated with the radiographic results.

Stiffness was significantly restored comparing with that of fractured level (P < 0.05). And the bipedicular groups had better restoration results than the unipedicular groups. The strength and height of specimens significantly increased after the augmentation procedure but without difference among groups. In axial radiographic view, the distribution of cement in vertebral body was oval or long oval-shaped in double-layer bone filling container groups while it was irregular in single-layer groups. After crossing, the double-layer version expanded well in vertebral body and could enwrap most of injected cement. There was only a little leakage near the vessel layer. But the single-layer version had a poor expansion and a large amount of cement leakage.

This novel reticulate bone void filling container system with different layers may restore both the biomechanical properties and the height of fractured vertebrae. But, with the benefit of reducing cement leakage, a double-layer design can enwrap most of injected PMMA and has a brighter prospect of clinical application.