Kennedy Jim, Feerick Emer, McGarry Patrick, FitzPatrick David, Mullett Hannan
Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.
J Orthop Surg (Hong Kong). 2013 Aug;21(2):167-72. doi: 10.1177/230949901302100210.
PURPOSE. To measure the effect of void-filling calcium triphosphate cement on the loads at the implant-bone interface of a proximal humeral fracture osteosynthesis using a finite element analysis. METHODS. Finite element models of a 3-part proximal humeral fracture fixed with a plate with and without calcium triphosphate cement augmentation were generated from a quantitative computed tomography dataset of an intact proximal humerus. Material properties were assigned to bone fragments using published expressions relating Young's modulus to local Hounsfield number. Boundary conditions were then applied to the model to replicate the physiological loads. The effect of void-filling calcium triphosphate cement was analysed. RESULTS. When the void was filled with calcium triphosphate cement, the pressure gradient of the bone surrounding the screws in the medial fracture fragment decreased 97% from up to 21.41 to 0.66 MPa. Peak pressure of the fracture planes decreased 95% from 6.10 to 0.30 MPa and occurred along the medial aspect. The mean stress in the screw locking mechanisms decreased 78% from 71.23 to 15.92 MPa. The angled proximal metaphyseal screw had the highest stress. CONCLUSION. Augmentation with calcium triphosphate cement improves initial stability and reduces stress on the implant-bone interface.
目的。使用有限元分析来测量空隙填充型磷酸三钙骨水泥对肱骨近端骨折内固定时植入物-骨界面负荷的影响。方法。从完整肱骨近端的定量计算机断层扫描数据集中生成使用和不使用磷酸三钙骨水泥增强的钢板固定三部分肱骨近端骨折的有限元模型。使用已发表的将杨氏模量与局部亨氏单位相关联的表达式为骨碎片赋予材料属性。然后对模型施加边界条件以复制生理负荷。分析空隙填充型磷酸三钙骨水泥的效果。结果。当空隙用磷酸三钙骨水泥填充时，内侧骨折碎片中螺钉周围骨的压力梯度从高达21.41MPa降至0.66MPa，降低了97%。骨折平面的峰值压力从6.10MPa降至0.30MPa，降低了95%，且发生在内侧。螺钉锁定机制中的平均应力从71.23MPa降至15.92MPa，降低了78%。成角的近端干骺端螺钉应力最高。结论。磷酸三钙骨水泥增强可提高初始稳定性并降低植入物-骨界面的应力。
