Biomechanical Study On The Factors Influencing The Strength Of TKA Prosthesis Fixed With Bone Cement

Objective:At present,there are few relevant studies on bone cement fixation Technique in total knee arthroplasty in clinical research.surgeons perform the knee arthroplasty with known clinical experience about bone cement application and don’t make systematic investigation on the factors those can affect the strength of bone cement Techniques.This experiment simulates the bone cement fixation Techniques in total knee arthroplasty in vitro,to explore and evaluate the influence of bone cement application method and application period and temperature and other factors on the fixation strength of bone cement in the operation process of total knee arthroplasty,so as to providing theoretical support for clinical work.method:42 polypropylene resin base models were used for mechanical experiment.According to the principle of random grouping,the tibial and femoral prostheses and corresponding bases were divided into seven groups according to three tibial prostheses and bases and three femoral prostheses and bases in each group(see Table 1): first group(room temperature 23 ℃,dough cement added to the prosthesis surface),second groups(room temperature 23 ℃,dough cement added to the base surface),third groups(room temperature 23 ℃,dough cement added to the prosthesis and base surface),forth groups(room temperature 23 ℃,wire drawing cement added to the false surface),fifth groups(room temperature 23 ℃,hardening cement added to the false surface),sixth groups(room temperature 23 ℃,dough cement added to the false surface and water-cooled),seventh groups(room temperature 16 ℃,dough cement added to the false surface).The prosthesis and cement of 7 different groups were fixed with three different bone cement application methods: prosthesis surface,base surface and double-sided under three conditions: indoor temperature,water cooling and application period.The bond strength of bone cement between tibial and femoral prosthesis of artificial knee joint and its corresponding die base was studied by push-out test.result:In the tibial prosthesis group,the axial push-out force of single-layer fixation was not higher than that of double-layer fixation,and there was no significant difference in the maximum axial pushing force between them(P = 0.928);In the femoral prosthesis group,the strength of double-layer fixation increased by 11.6%(P = 0.012);There was no significant difference in pushing force between bone cement groups in wire drawing stage and dough stage(P = 0.734).The axial pushing force of tibia and femur decreased by 30.9%(P = 0.006)and 29.7%(P < 0.01)respectively.Temperature has an effect on the fixation strength of bone cement.The axial pushing force between the bonded prosthesis and the base after mixing bone cement at a lower indoor temperature(16 ℃)is 13.5% lower than that at normal room temperature(23 ℃)(P = 0.027).When the prosthesis and base were cooled in cold water at 5 ℃ immediately after cement fixation,the axial pushing force decreased by 19.1%(P = 0.004).Conclusion:In total knee arthroplasty,the single-layer and double-layer application of tibial prosthesis bone cement has no significant difference in the push-out force of fixation strength,and the double-layer fixation of femoral prosthesis can obtain greater fixation strength.In total knee arthroplasty,it is most appropriate to fix after the bone cement is mixed and placed to the dough stage.The lower temperature in the operating room will reduce the strength of bone cement fixation to a certain extent.After the prosthesis is fixed,soaking in cold water will also reduce the strength of bone cement fixation.