| dc.description.abstract | In the most severe cases of longitudinal bone fractures such as femur, tibias, humerus, etc., the bone can be completely separated into two fragments. In order to guarantee the re-ossification of the bone, it is required to reposition the bone fragments together. This process requires a delicate surgery called “bone reduction surgery”. It consists of relocating the different pieces of the same bone in their original position. In manual bone reduction surgery (both opened and minimally invasive), the surgeons have to use a considerable amount of physical strength to relocate to bones because of the natural recall force applied by the patient’s anatomy (muscular tissues and tendons). Another problem is the hazardous environment of image-guided surgery. Indeed, while surgeons must perform these mechanism adjustments, both surgeons and patients are subject to excessive X-ray exposure during the procedure. Unlike patients, surgeons will suffer from repeated exposures to the radiation generated by the medical imaging system. In order to solve these problems, a technique based on the use of robotic-assisted fixation systems has become one of the best choices. The most advanced technique relies on robotic manipulators providing higher precision and stability.
With the objective of developing a robotic manipulator for this application, a series of mechanism concepts are studied in the present report. Two new 6-DoF hybrid parallel manipulators are firstly proposed based on a 3-RPS tripod parallel mechanism combined with a double triangular planar parallel mechanism. Then, two 6-DoF parallel manipulators with three limbs were investigated. For each mechanism, the kinematic and velocity models are calculated. In order to validate the analytical solutions of kinematic and velocity analysis, a series of the simulations are carried out on two software: Matlab and Msc Adams View. The workspace they can generate is compared to the Stewart manipulator, which is a classical mechanism for the targeted application.
The use of a robotic manipulator is due to be part of an entire surgical procedure involving a pre-operative simulation software dedicated to pre-planning reduction surgery, namely PhysiGuide. In this study, it is used to measure the kinematic associated with bone fragments manipulation and to transfer these data to the robot during a simulated intra-operative phase. Simulations are then performed based on a real patient’s fracture images showing the suitability of the proposed mechanisms with bone reduction surgery. A series of prototypes are fabricated and tested on a femur bone model. | en_US |