Measurement Method Of Soft Tissue Tension Of Knee Joint Based On Prosthesis Sensor

Total knee arthroplasty(TKA)is a standard treatment for patients with severe osteoarthritis.Main procedures of TKA include preoperative planning,osteotomy,prosthesis installation,and soft tissue balance.The purpose of soft tissue balance is to ensure the correct joint force line and keep the joint contact point in the normal physiological position.But in TKA,the traditional soft tissue balance method is to judge the joint space,but this method depends on the experience of doctors and has certain subjectivity.In order to help surgeons evaluate the soft tissue balance more easily and accurately,this paper designs a soft tissue tension evaluation method based on joint implanted prosthesis sensor.In this paper,a strategy of automatic diagnosis and processing of knee joint X-ray image is proposed in the pre-operative planning.The osteotomy plane is automatically planned on the image.And a dynamic model aiming at solving the ligament tension is established in this paper.In this dynamic model,the ligament is not described by any material model.Then,the stress and joint angle of the prosthesis and ligament were analyzed by finite element method.The prosthesis sensor is designed based on the point cloud data of standard prosthesis,flexible pressure film is used as measuring element and genetic algorithm is used to optimize the layout of sensing element,data acquisition card is used for signal acquisition,and corresponding software interface is designed on QT software.The performance of the sensor was tested by weight.The results show that the sensor has linearity ?2.2%and repeatability ?4.4%,which can meet the needs of application.In order to verify the feasibility of the soft tissue tension detection method proposed in this paper,a simplified lower limb model is designed.A force / position hybrid control scheme with variable admittance parameters is used on the parallel platform to simulate the movement and stress of the lower limb.The experimental results show that the method can qualitatively show the relationship between joint force and soft tissue tension,but due to the difference of knee joint environment and real knee joint,the numerical precision in of this method needs to be verified.