Meng Depeng, Ouyang Yueping, Hou Chunlin
Department of Orthopedics, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, P.R.China.
Department of Orthopedics, Changzheng Hospital, Second Military Medical University, Shanghai, 200003,
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2017 Dec 15;31(12):1456-1461. doi: 10.7507/1002-1892.201706054.
To establish the finite element model of Y-shaped patellar fracture fixed with titanium-alloy petal-shaped poly-axial locking plate and to implement the finite element mechanical analysis.
The three-dimensional model was created by software Mimics 19.0, Rhino 5.0, and 3-Matic 11.0. The finite element analysis was implemented by ANSYS Workbench 16.0 to calculate the Von-Mises stress and displacement. Before calculated, the upper and lower poles of the patella were constrained. The 2.0, 3.5, and 4.4 MPa compressive stresses were applied to the 1/3 patellofemoral joint surface of the lower, middle, and upper part of the patella respectively, and to simulated the force upon patella when knee flexion of 20, 45, and 90°.
The number of nodes and elements of the finite element model obtained was 456 839 and 245 449, respectively. The max value of Von-Mises stress of all the three conditions simulated was 151.48 MPa under condition simulating the knee flexion of 90°, which was lower than the yield strength value of the titanium-alloy and patella. The max total displacement value was 0.092 8 mm under condition simulating knee flexion of 45°, which was acceptable according to clinical criterion. The stress concentrated around the non-vertical fracture line and near the area where the screws were sparse.
The titanium-alloy petal-shaped poly-axial locking plate have enough biomechanical stiffness to fix the Y-shaped patellar fracture, but the result need to be proved in future.
建立钛合金花瓣形多轴锁定钢板固定Y形髌骨骨折的有限元模型并进行有限元力学分析。
采用Mimics 19.0、Rhino 5.0和3-Matic 11.0软件建立三维模型。通过ANSYS Workbench 16.0进行有限元分析，计算Von-Mises应力和位移。计算前，对髌骨的上下极进行约束。分别在髌骨下、中、上部分的1/3髌股关节面施加2.0、3.5和4.4 MPa的压应力，模拟膝关节屈曲20°、45°和90°时作用于髌骨的力。
所获得的有限元模型的节点数和单元数分别为456 839和245 449。在模拟膝关节屈曲90°的工况下，三种模拟工况下的Von-Mises应力最大值为151.48 MPa，低于钛合金和髌骨的屈服强度值。在模拟膝关节屈曲45°的工况下，最大总位移值为0.092 8 mm, 根据临床标准是可以接受的。应力集中在非垂直骨折线周围和螺钉稀疏区域附近。
钛合金花瓣形多轴锁定钢板对Y形髌骨骨折具有足够的生物力学固定强度，但结果有待进一步验证。
