Effects of fracture severity and cement viscosity on the risk of cement leakage during percutaneous vertebroplasty

Previous studies have shown the high prevalence of cement leakage and its adverse effect in vertebroplasty. Many methods have developed to reduce the risk of leakage; nevertheless, an evaluation of cement flow within the vertebrae and its correspondence to different level of vertebral injury were still less revealed. In this study, twenty human osteoporotic cadaveric vertebrae were used. Two factors, i.e., the injury level and the cement viscosity, were designed in this study. The specimens were compressed to the level of 30% (moderate fracture) and 60% (severe fracture) of original body height. A two-level cement viscosity, powder-liquid ratio with 1.6(g):1(ml) vs. 1.3(g):1(ml), was designed as the higher vs. lower viscosity of cement. During the injection, a cine CT scanning was performed to monitor the cement progression within the vertebra. After the injection, the vertebrae were sliced sagittally to find the cement infiltration within the vertebra. Results show that the injection force dropped dramatically after the cement flowing out, but gradually increased as the cement being injected afterwards. The injection force stood around 100 N when using lower-viscosity cement, and stood around 200 N when using higher-viscosity cement. It was found that fracture severity had less effect on the injection force than cement viscosity. The infiltration volume was larger at a moderate fracture level and lower viscosity. The fracture severity affects the cement leakage more than the viscosity does. The effectiveness of vertebroplasty may be enhanced by preoperative CT scans of the target vertebra.