Three dimensional finite element analysis in the direction and amount of load applied on the fractured humerus / 中国组织工程研究

ABSTRACT

BACKGROUND: The most frequently encountered problem that an orthopedic doctor encounters in treating humerus fracture is how to choose the exact direction and amount of load applied on humerus.OBJECTIVE: To explore the clinical significance of establishing a three-dimensional model and finite element analysis in treating humerus fracture and to provide theoretical basis for applying appropriate axial stress.DESIGN: The three dimensional model of humerus was reconstructed, on which compression from different directions was applied.SETTING: Orthopedic department of an affiliated hospital and life science laboratory of a university.MATERIALS A humerus specimen received CT scanning and the trial was conducted in Shanghai Changhai Hospital and Life Science Laboratory of Tongji University from April 2002 to April 2004.METHODS: The three dimensional model of humerus was established and relevant calculation was completed with ANSYS 5.6 software. The humerus model was divided into 2 729 nodes and 49 041 units based on a three-dimensional ten-node tetrahedron as one unit. The distribution and intensity of axial compression on the fracture gap section were calculated and analyzed in the following conditions, i. e. when the humerus was fixed in X, Y and Z directions and the fracture gap section was 30°, 45°, 90° to Z axis.MAIN OUTCOME MEASURES: The axial pressure on the fracture gap section in different conditions to provide evidence for clinical treatment.RESULTS: The stress applied on the fracture gap was relatively concentrated and was 2 -3 times stronger than that in other areas, and it was generally symmetrically distributed within 10 mm around the fracture gap.CONCLUSION: The required load on humerus fracture should be calculated before a suitable implant is applied to accommodate the movement of humerus without compromising healing of the fracture.