Wang Jincheng

Comparison of three different surgical approaches for treatment of thoracolumbar burst fracture

Objective: The main treatment method used for thoracolumbar fractures is open reduction and internal fixation. Commonly there are three surgical approaches: anterior, posterior and paraspinal. We attempt to compare the three approaches based on our clinical data analysis. Methods: A group of 94 patients with Denis type A or B thoracolumbar burst fracture between March 2008 and September 2010 were recruited in this study. These patients were treated by anterior‐, posterior‐ or paraspinal‐approach reduction with or without decompression. The fracture was fixed with titanium mesh and Z‐plate via anterior approach (24 patients), screw and rod system via posterior approach (38 patients) or paraspinal approach (32 patients). Clinical evaluations included operation duration, blood loss, incision length, preoperative and postoperative Oswestry disability index (ODI). Results: The average operation duration (94.1 min±13.7 min), blood loss (86.7 ml±20.0 ml), length of incision (9.3 mm± 0.7 mm) and postoperative ODI (6±0.5) were significantly lower (P<0.05) in paraspinal approach group than in traditional posterior approach group (operation duration 94.1 min±13.7 min, blood loss 143.3 ml±28.3 ml, length of incision 15.4 cm±2.1 cm and ODI 12±0.7) and anterior approach group (operation duration 176.3 min±20.7 min, blood loss 255.1 ml±38.4 ml, length of incision 18.6 cm±2.4 cm and ODI 13±2.4). There was not statistical difference in terms of Cobb angle on radiographs among the three approaches. Conclusion: The anterior approach surgery is convenient for resection of the vertebrae and reconstruction of vertebral height, but it is more complicated and traumatic. Hence it is mostly used for severe Denis type B fracture. The posterior approach is commonly applied to most thoracolumbar fractures and has fewer complications compared with the anterior approach, but it has some shortcomings as well. The paraspinal approach has great advantages compared with the other two approaches. It is in accordance with the concept of minimally invasive surgery and can replace most posterior approach operations.

A finite element analysis of the flange earrings of strong anisotropic sheet metals in deep-drawing processes

Flange earrings of strong anisotropic sheet metals in deep-drawing process are numerically analyzed by the elastic-plastic large deformation finite element formulation based on a discrete Kirchhoff triangle plate shell element model. A Barlat-Lian anisotropic yield function and a quasi-flow corner theory are used in the present formulation. The numerical results are compared with the experimental ones of cylindrical cup drawing process. The focus of the present researches is on the numerical analysis and the constraining scheme of the flange earring of circular sheets with strong anisotropy in square cup drawing process.