Development of a hybrid finite element model for individual simulation of intertrochanteric osteotomies.
Intertrochanteric osteotomies of the proximal femur are used to improve the anatomy and function of the hip joint in a number of orthopaedic diseases. To investigate the geometrical and biomechanical aspects of pre-operative planning we created a set of programs to automatically perform a simulation of intertrochanteric osteotomies on a three-dimensional finite element model of the human proximal femur based on computed tomography (CT) data and using uniform brick-shaped elements. To eliminate artefacts resulting from the rough surface of the brick elements, the femoral head was represented by a tetrahedron-based head that included a cartilage layer and a subchondral cortical zone. Applicability of the procedure was tested by performing a parametric study using a model created from CT scans taken in vivo, by applying individually calculated force conditions for the one-leg stance situation. We found a large influence of osteotomy angle on the observed stress in the femoral head cartilage, especially in a situation with insufficient containment of the femoral head. The model presented here is a biomechanical tool to simulate intertrochanteric osteotomies patient-specifically for a better understanding of the effects of such operations in the individual case. The open design of the described programs allows future interfacing with surgical navigation and robot systems.
Schmitt
J
J
Department of Orthopaedic Surgery, Philipps-University of Marburg, Baldingerstrasse, D-35033 Marburg/Lahn, Germany. schmitt2@mailer.uni-marburg.de
Meiforth
J
J
Lengsfeld
M
M
D000368:Aged; D000465:Algorithms; D001847:Bone Diseases / Q000628:therapy; D002356:Cartilage / Q000473:pathology; D005260:Female; D005269:Femur / Q000601:surgery*; D006615:Hip / Q000473:pathology; D006801:Humans; D008953:Models, Anatomic; D009985:Orthopedics / Q000379:methods; D010027:Osteotomy / Q000379:methods*; D012984:Software; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed