Numerical Simulation And Experimental Study Of Unicompartmental Knee Arthroplasty

According to the principles of minimally invasive and knee-preserving unicondylar replacement,it has become an important solution for the treatment of knee osteoarthritis.However,due to its high postoperative revision rate and poor long-term efficacy,many scholars are skeptical about its clinical effect.Therefore,the biomechanical research before and after unicondylar replacement of the knee joint is of great value to improve the level of unicondylar replacement.In this paper,the biomechanical changes of the knee joint before and after unicondylar replacement were analyzed from the perspectives of simulation and experiment.Mainly include: dynamic simulation based on(Adams/Life MOD),establishment and verification of 3D model of human knee joint,biomechanical analysis of human knee joint before and after unicondylar replacement,experimental study before and after unicondylar replacement,interface stress of knee joint unicondylar replacement Failure analysis.The details are as follows:1.Use the human body dynamics simulation software to establish a multi-rigid body model of the human body,simulate the walking process,and obtain the changes of mechanical parameters such as the transverse force and sagittal angle of the knee joint with time.The results showed that the force and angle of the knee joint changed periodically in the absence of weight-bearing,and the time of one cycle was about1.3s.At about 0.1s,the left knee joint was in a straight state,and the maximum peak force of the left knee joint was at this time.About 760 N.2.Use Mimics,Geomagic Studio,3-matic and other medical software to extract the left lower extremity model from the CT and MRI of the volunteer,materialize it in Solidworks,and finally establish model of the knee joint.In the finite element software Abaqus,a 1000 N vertical load was applied to the three-dimensional model of the knee joint,and it was found that the simulation results were consistent with the simulation results and experimental results in the existing literature,indicating that the established three-dimensional model of the knee joint was effective.3.On the basis of a healthy knee joint model,the No.3 Oxford knee unicondylar prosthesis was used to simulate the osteotomy and assembly process of the knee joint unicondylar replacement surgery,and a three-dimensional model of the knee joint unicondylar replacement was established.The simulation results are loading analysis of the boundary,and the biomechanical changes of the knee joint before and after replacement are analyzed and compared.The results showed that the maximum stress of tibial cortical bone increased after replacement compared with that before replacement.It is generally believed that postoperative tibial prosthesis fractures and medial tibial pain are related to the increased stress of tibial cortical bone;the proportion of total load on the medial compartment of knee joint increased after replacement.The stress of the lateral compartment of the femoral cartilage,tibial cartilage and meniscus increased by 12.98% compared with pre-replacement,indicating that even if the load of the lateral compartment is reduced and the original joint level is maintained,the soft tissue of the lateral compartment after surgery There is still a risk of degenerative disease and progressive arthritis.4.The electrical measurement experiment scheme of knee unicondylar replacement corresponding to the finite element simulation was designed,and the No.3 Oxford knee unicondylar prosthesis was used to simulate the osteotomy and assembly process of knee unicondylar replacement surgery.The experimental results showed that there were significant changes in biomechanics before and after knee unicondylar replacement.At the same time,the results of the numerical simulation and the results of the electrical test have a high consistency,which shows that the results of the previous simulation analysis have strong reliability.5.Based on the knee joint unicondylar replacement model established above,by changing the prosthesis material,the stress failure analysis of the weakest position of the knee joint unicondylar replacement structure(tibial prosthesis platform interface)was further carried out,and the implantation of different prosthesis materials was studied.The effect of posterior on the interfacial stress of the tibial plateau prosthesis.The reduction of the elastic modulus of the prosthesis can reduce the maximum principal stress of the interface.Considering the interface stress,the titanium alloy prosthesis is better than the stainless steel prosthesis;the interface damage areas of the tibial prosthesis platform are mainly at the medial anterior and posterior corners and the lateral mid-end.Therefore,improving the prosthesis-bone cement bonding ability in this area can prevent the loosening of the tibial prosthesis platform of the unicondylar knee joint.The results have clinical value in the prevention of tibial prosthesis platform loosening after unicondylar surgery.