Research And Application Of Osteotomy Guide Plate Design Based On Force Line Assisted

Knee osteoarthritis is a common disease in the elderly nowadays.The pain and disability caused by it seriously affect the normal life of the patients.Artificial total knee arthroplasty is currently the most effective method for treating knee osteoarthritis.Its purpose is to remove the bones of the worn-out joints and install artificial prostheses to restore the body’s normal lower limb line of force,thereby restoring the normal function of the knee joint.However,in traditional surgery,there are certain limitations for doctors to diagnose patients’ lower limb images preoperatively.Intraoperative positioning of lower limb lines through intramedullary surgery is of great risk,and osteotomy based on surgical experience to confirm the cutting Angle is of certain subjectivity.In order to solve the disadvantages of traditional surgery and improve the quality of surgery,preoperative planning of osteotomy process is needed.Therefore,this paper designs and develops a set of software to realize the preoperative 3D modeling of patients’ lower extremity CT images,and the lower extremity bone model of the patients is used to restore the lower extremity force line.According to the lower extremity force line combined with the characteristics of the patient’s bone surface,the osteotomy guide plate could be fitted to the patient’s bone surface.After 3D-printing,it is attached to the patient’s bone surface intraoperatively to provide osteotomy navigation.The manufacturing software of osteotomy guide plate developed in this paper is divided into three modules: CT 3D modeling module,lower limb line design module and osteotomy guide plate manufacturing module.The first module is mainly to reconstruct the CT sequence of the patient into a three-dimensional model in equal proportion,to clarify the damaged site of the knee joint and the bone surface features,and to provide a model basis for the subsequent design of the lower limb force line and the production of osteotomy guide plate.The second module mainly determines the center of the hip joint,the center of the knee joint and the center of the ankle joint that compose the lower limb force line according to the patient’s lower limb bone model.Among them,the determination of the center point of the hip joint is improved by the method of minimizing the vertical distance and fitting the quadric surface.Compared with the current method of determining the center point of the hip joint by the least square fitting ball,the accuracy of the center point of the hip joint was improved,and then the accuracy of the lower limb line was improved.The design of lower limb force line is the basis of making the cutting edge of osteotomy guide plate,and the direction of osteotomy should be perpendicular to the force line during the operation.The third module is mainly developed according to the actual needs of orthopedic surgeons.The osteotomy guide plate produced by the module can determine the Angle and position of osteotomy during operation,as well as the type and position of driving steel nails.The bottom structure of the osteotomy guide plate designed according to the characteristics of the patient’s bone surface can be stably fitted to the patient’s bone surface during the operation,which can ensure the position of the knife edge and the steel nail hole on the osteotomy guide plate as determined by the preoperative planning.The experimental results of cooperative hospitals show that the software developed in this paper can meet the actual needs of orthopedic surgeons,and the model of osteotomy guide plate is feasible and reliable in the intraoperative navigation.