| Infection around the knee prosthesis after total knee arthroplasty is one of the most serious complications,with an incidence of 1-5%.At present,the "gold standard" for treating the infection around the knee prosthesis is still the second revision surgery.During revision surgery,the placement of an antibiotic bone cement temporary spacer not only keeps the knee stable and mobile,but also increases the concentration of antibiotics in the joint cavity to help clear the infection.At the same time,the implantation of spacer can effectively avoid the contracture of muscle and soft tissue,which is more favorable for the second operation.At present,the manufacturing methods of all kinds of spacers are different,and there are problems such as low articular surface fitting degree,low fabrication accuracy,structural instability and low strength,which make it impossible to better fit the physiological structure of patients and prone to failure.How to design a personalized spacer and maintain postoperative stability and prevent its failure is a difficult problem in the clinical application of the spacer.In this paper,the optimization design of the individualized bone cement spacer is studied:Based on the analysis of the failure of the spacer,there are many reasons for the failure of the spacer of the knee joint.The main factors are related to the selection of the spacer model and the technical level during the operation,as well as the patient’s own factors and the range of flexion activities after the operation.In this paper,a personalized spacer was designed,and the designed femoral side spacer was improved based on the shape of the patient’s prosthesis.The concave surface of the tibial side spacer was deepened and the front end was raised.It can make the joint surface between the spacers have a certain extent,increase its mobility,make it close to the movement state of human joints,achieve the reasonable distribution of stress between the articular surfaces of the spacers,and reduce the failure of the spacers to a certain extent.In this paper,the stress distribution on the surface of tibial space occupying device in the model is obtained by finite element analysis and orthogonal test.The mechanical characteristics of knee joint spacer were analyzed as the basis for its design and improvement.Through the trend chart of the influence of factors on the analysis results,the structure size and positioning factors of the optimal spacer were obtained.The optimal combination of tibial spacer is A2B1C2,the depth of the groove is 5mm,the dip is 0°,the rotation is 0°,and the peak surface compressive stress is 3.00 MPa.The flexion and impact analysis results of the optimal design of the knee joint spacer show that the design of the knee joint spacer in this paper is reasonable and has good stability.Clinical application results showed that the silicone mold of knee joint spacer was made by 3DP technology,and the surface of the spacer was smoother and the degree of fit increased.It is convenient to make it quickly and save operation time.At the same time,the structure matching degree of the spacer is high,which is more stable after the operation,which is helpful for the postoperative recovery of patients and reduces the occurrence of the failure of the spacer.Therefore,the personalized antibiotic bone cement spacer optimized in this paper has good joint mobility and stability.It provides a new choice for the clinical application of knee joint spacer. |
