Design And Analysis Of Ankle External Fixation System Based On Ilizarov Technology

The ankle and foot deformities not only affect the normal function of foot and inference patients’ daily lives, but also brings enormous psychic trauma to them. In the medical field, Podiatric surgery is an emerging department of surgery, and it is still at the starting stage. Since the Ilizarov technology was introduced to China in 90 s, the development of malformed correction has been made a jump step. However, national application of Ilizarov has not made any significant progress, nor the advancement and innovation.Based on the anatomic properties, the three dimensional bony reconstruction of ankle and foot is built by the medical software MIMICS. Besides, this research project studies deeply about the remodeling regulation and biomechanical characteristics of ankle and foot bone under loading stimulation after osteotomy. Moreover, focus on ankle and foot deformities in sagittal plane, parallel mechanism is applied in the design of the external fixator, and its kinematics and singularity is studied. Additionally, this project has made a deep research in the orthopedic principle of surgery osteotomy, and provides the strategy to avoid angular and shifted deformities in sagittal plane of ankle and foot. Finally, the kinematical characteristics of the designed parallel external fixator are verified through the simulation of ADAMS.In this study, two main outstanding contributions were made in the correction of ankle and foot bony deformities. First of all, the Wolff’s law and Ilizarov technology were innovatively combined during the research process, and a new algorithm of bony remodeling under the application of external fixators after osteotomy was proposed. This algorithm not only took into consideration of the material characteristics of bone skeleton, but also considered the effect of “dead zone” to bone remodeling during this process. Besides, screw theory was used in the design of the external fixator in this study. Orthopedic principle and mechanical engineering were combined, and a singularity-free workspace was obtained by proposing an algorithm to avoid singularity points in the application of the designed external fixator.