Related Experiment Video
Updated: Mar 7, 2026
Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position
Published on: August 17, 2017
The effects of tibia profile, distraction angle, and knee load on wedge instability and hinge fracture: A finite
Pei-Wei Weng1, Chia-Hsien Chen2, Chu-An Luo3
1Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan; Department of Orthopaedics, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Abstract:
Several plate systems for high tibial osteotomy (HTO) have been developed to stabilize the opening wedge of an osteotomized tibia. Among them, the TomoFix system, having a quasi-straight and T-shaped design, has been widely adopted in the literature. However, this system is implemented by inserting a lag (i.e., cortical) screw through the proximal combi-hole, to deform the plate and pull the distal tibia toward the plate. This process potentially induces plate springback and creates an elastic preload on the osteotomized tibia, especially at the lateral hinge of the distracted wedge. Using the finite-element method, this study aims to investigate the contoured effect of lag-screw application on the biomechanical behavior of the tibia-plate construct. Two tibial profiles (normal and more concave), three distraction angles (6°, 9°, and 12°), and three knee loads (intraoperative: contouring plate; postoperative: weight and nonweight bearing) are systematically varied in this study. The wedge instability and fracture risk at the lateral hinge are chosen as the comparison indices. The results show the necessity of preoperative planning for a precontoured procedure, rather than elastic deformation using a lag screw. Within the intraoperative period, a more concave tibial profile and/or reduced distraction angle (i.e., 6° or 9°) necessitate a higher compressive load to elastically deform the plate, thereby deteriorating the lateral-hinge fracture risk. A precontoured plate is recommended in the case that the proximal tibia is highly concave and the distraction angle is insufficient to stretch the tibial profile.
Related Concept Videos
01:24Wedges
Consider using a wedge to lift a heavy slab. Here, the wedge functions by converting the applied force into a much larger force directed almost perpendicular to the initial force. This...
01:11Deformation of Member under Multiple Loadings
In the case of a member with a variable cross-section, the strain is not constant but depends on the position. The deformation of an...
01:16Bones of the Lower Limb: Femur and Patella