Optimization Technique and FE Simulation for Lag Screw Placement in Anterior Column of the Acetabulum

  • Ruo-feng Tong
  • Sheng-hui Liao
  • Jin-xiang Dong
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3994)


This paper presents an optimization technique for determining the lag screw placement in the anterior column of the acetabulum, and investigates new method for generating accurate finite-element (FE) model for biomechanics analysis. For prepare once measure, an accurate hemi-pelvis model is reconstructed from the volume-of-interest extracted from computed-tomography (CT) data, and the initial position of the lag screw is determined by traditional manual like method. Then, an objective function, for improving the placement of lag screw, is build by adaptive sampling the weighted distance of screw to the acetabulum boundary according to surgical requirement, and the two end points of the lag screw are modified iteratively to reduce the objective value. 30 hemi-pelvis models are tested by the optimization technique, and the statistical measure data are provided according to new anatomic reference landmarks for clinical use. In the second part, FE method is employed to evaluate the optimization result. To generate accurate and high quality FE model, a semi-automatic FE preprocessor specifically adapted to the pelvis anatomy is developed. The produced volume mesh has a very regular mesh structure and achieves a smooth change of element size transition. The final simulation stress distribution pattern justifies the placement of the lag screw in the anterior column of the acetabulum.


  1. 1.
    Schopfer, A., Willett, K., Powell, J., Tile, M.: Cerclage wiring in internal fixation of acetabular fractures. J. Orthop. Trauma. 7, 236–241 (1993)CrossRefGoogle Scholar
  2. 2.
    Anglen, J.O., DiPasquale, T.: The reliability of detecting screw penetration of the acetabulum by intraoperative auscultation. J. Orthop. Trauma. 8, 404–408 (1994)CrossRefGoogle Scholar
  3. 3.
    Mears, D.C., Rubash, H.E.: Techiques of Internal Fixation. In: Mears, D.C., Rubash, H.E. (eds.) Pelvic and Acetabular Fractures, Thorofare, NJ, Slack, pp. 299–318 (1986)Google Scholar
  4. 4.
    Letournel, E., Judet, R.: Operative Treatment of Specific Type of Fractures. In: Letournel, E., Judet, R. (eds.) Fractures of the Acetabulum, 2nd edn., pp. 442–447. Springer, Berlin (1993)Google Scholar
  5. 5.
    Ebraheim, N.A., Xu, R., Biyani, A., Benedetti, J.A.: Anatomic basis of lag screw placement in the anterior column of the acetabulum. Clin. Orthop. Relat. Res. (339), 200–205 (1997)Google Scholar
  6. 6.
    Shephard, M.S., Georges, M.K.: Three-Dimensional Mesh Generation by Finite Octree Technique. International Journal for Numerical Methods in Engineering 32, 709–749 (1991)MATHCrossRefGoogle Scholar
  7. 7.
    Borouchaki, H., Hecht, F., Saltel, E., George, P.L.: Reasonably Efficient Delaunay Based Mesh Generator in 3 Dimensions. In: Proceedings 4th International Meshing Roundtable, October 1995, pp. 3–14 (1995)Google Scholar
  8. 8.
    Weatherill, N.P., Hassan, O.: Efficient Three-dimensional Delaunay Triangulation with Automatic Point Creation and Imposed Boundary Constraints. International Journal for Numerical Methods in Engineering 37, 2005–2039 (1994)MATHCrossRefGoogle Scholar
  9. 9.
    Rebay, S.: Efficient Unstructured Mesh Generation by Means of Delaunay Triangulation and Bowyer-Watson Algorithm. Journal of Computational Physics 106, 125–138 (1993)MATHCrossRefGoogle Scholar
  10. 10.
    Marcum, D.L., Weatherill, N.P.: Unstructured Grid Generation Using Iterative Point Insertion and Local Reconnection. AIAA Journal 33(9), 1619–1625 (1995)MATHCrossRefGoogle Scholar
  11. 11.
    Lohner, R.: Progress in Grid Generation via the Advancing Front Technique. Engineering with Computers 12, 186–210 (1996)CrossRefMathSciNetGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Ruo-feng Tong
    • 1
  • Sheng-hui Liao
    • 1
  • Jin-xiang Dong
    • 1
  1. 1.State Key Laboratory of CAD and CG, Department of Computer Science and EngineeringZhejiang UniversityChina

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