Assessing cement injection behaviour in cancellous bone: an in vitro study using flow models.

Understanding the cement injection behaviour during vertebroplasty and accurately predicting the cement placement within the vertebral body is extremely challenging. As there is no standardized methodology, we propose a novel method using reproducible and pathologically representative flow models to study the influence of cement properties on injection behaviour. The models, confined between an upper glass window and a lower aluminium plate, were filled with bone marrow substitute and then injected (4, 6 and 8 min after cement mixing) with commercially available bone cements (SimplexP, Opacity+, OsteopalV and Parallax) at a constant flow rate (3 mL/min). A load cell was used to measure the force applied on the syringe plunger and calculate the peak pressure. A camera was used to monitor the cement flow during injection and calculate the following parameters when the cement had reached the boundary of the models: the time to reach the boundary, the filled area and the roundness. The peak pressure was comparable to that reported during clinical vertebroplasty and showed a similar increase with injection time. The study highlighted the influence of cement formulations and model structure on the injection behaviour and showed that cements with similar composition/particle size had similar flow behaviour, while the introduction of defects reduced the time to reach the boundary, the filled area and the roundness. The proposed method provides a novel tool for quick, robust differentiation between various cement formulations through the visualization and quantitative analysis of the cement spreading at various time intervals

Novel methodology for assessing biomaterial-biofluid interaction in cancellous bone

Understanding the cement flow behaviour and accurately predicting the cement placement within the vertebral body is extremely challenging. Vertebral cancellous bone displays highly complex geometrical structures and architectural inhomogeneities over a range of length scales, thus making the scientific understanding of the cement injection behaviour difficult in clinical or cadaveric studies. Previous experimental studies on cement flow have used open-porous aluminum foam to represent osteoporotic bone. Although the porosity was well controlled, the geometrical structure of each of the foams was inherently unique. This paper presents novel methodology using customized, reproducible and pathologically representative three-dimensional bone surrogates to help study biomaterial-biofluid interaction. The aim was to provide a robust tool for comprehensive assessment of biomaterial injection behaviour through controlling the bone surrogate morphology and the injection parameters (i.e. needle gauge, needle placement, flow rate and injected volume), measuring the injection pressure, and allowing the visualization and quantitative analysis of the spreading distribution. This methodology provides a clinically relevant representation of cement flow patterns and a tool for validating computational simulations.</p

Novel methodology for assessing biomaterial-biofluid interaction in cancellous bone

Understanding the cement flow behaviour and accurately predicting the cement placement within the vertebral body is extremely challenging. Vertebral cancellous bone displays highly complex geometrical structures and architectural inhomogeneities over a range of length scales, thus making the scientific understanding of the cement injection behaviour difficult in clinical or cadaveric studies. Previous experimental studies on cement flow have used open-porous aluminum foam to represent osteoporotic bone. Although the porosity was well controlled, the geometrical structure of each of the foams was inherently unique. This paper presents novel methodology using customized, reproducible and pathologically representative three-dimensional bone surrogates to help study biomaterial–biofluid interaction. The aim was to provide a robust tool for comprehensive assessment of biomaterial injection behaviour through controlling the bone surrogate morphology and the injection parameters (i.e. needle gauge, needle placement, flow rate and injected volume), measuring the injection pressure, and allowing the visualization and quantitative analysis of the spreading distribution. This methodology provides a clinically relevant representation of cement flow patterns and a tool for validating computational simulations