Research On Visual Representation Of Virtual Knee Arthroscopic Surgery

With the minimally invasive technology is widely used in the medical field, the traditional open surgery of knee is replaced by the minimally invasive surgery. Arthroscopic surgery is one of the minimally invasive surgeries, which was first used in the treatment of knee disease. Knee arthroscopic uses arthroscopy and micro-instruments to operate the surgery in the knee joint, the doctors need to go through a long period of training to be skilled as the surgery is difficult to operate, and the traditional training method couldn’t satisfy the huge demand of training. So it’s necessary to build a virtual knee arthroscopic surgery system to provide a convenient and reusable training method for the knee arthroscopic surgery.In the knee arthroscopic surgery, the doctor with the strong ability of hand-eye coordination is required, so the doctor’s visual need is the strongest in the training of knee arthroscopic surgery. This paper researches on the visual representation method of the virtual knee arthroscopic surgery which includes the three dimensional reconstruction of models, multi-model representation of virtual object, collision detection and soft tissues’deformation simulation. This article makes analysis and research from the following aspects:(1)Research on three dimensional reconstruction of the knee models based on medical images. By using the contour connection algorithm of surface rendering technology to reconstruct the models based on the CT medical sequence images which are preprocessed, and ensure the precision of the model while reducing the model data by decimating the surface vertexes and triangles.(2)Build Multi-model to represent the virtual object. Build visual model, collision model and behavior model for the virtual object to satisfy the visual rendering, collision detection and behavior calculation scenes of the virtual environment, and create a data structure for the object to achieve real-time data transmission among different models and ensure the synchronous update of the multi-model.(3)Research on collision detection algorithm which is suitable for the virtual knee arthroscopic surgery. By analyze the collisions of the real knee arthroscopic surgery to summarize the collision detection requirements for the virtual knee arthroscopic surgery. Select the Ray-tracing algorithm to collision detection, and build octree bounding boxes to speed up the algorithm to achieve different kinds of collision detection for the virtual knee arthroscopic surgery.(4)Build a calculation model of tetrahedral finite elements for the knee’s soft tissues. Define the material properties for the finite elements by analyzing the material properties of the knee tissues, and update the vertexes’ position by deformation calculation to simulate the deformation of the soft tissues.(5)Develop the virtual loose body removing surgery system based on the above research. The system can satisfy the demand of the knee arthroscopic surgery training by providing real time interaction and soft tissues’deformation simulation.The innovation of this paper is to use multi-model to represent the virtual object by building different models to satisfy the different virtual scenes, and achieve synchronous update of the multi-model by the data structure of the model. Analyzing the material properties of the knee tissues to define the material properties of the finite elements, and achieve real deformation simulation for the soft tissues. This paper provides a method of visual representation for the virtual knee arthroscopic surgery.