Biomechanical Study On Reconstruction Method For Proximal Tibia Bone Tumors After Excision

[Objective]1.Analyzed the stress status of the model with various size,level and location cortical defect of proximal tibia and explore the relationship between bone defect in the proximal tibia and fracture risk.2.Analyzed the stress and displacement of the model with various intramedullary stem lengths,and provide theoretical basis was provided for selecting length of intramedullary stem for custom tumorours proximal tibia prosthesis.3.Analyzed the limb function and gait characteristics of patients with primary tibial bone tumors that treated by limb salvage and explore biomechanical characteristics of the patients with different reconstruction method.[Methods]1.A model three-dimensional model was reconstructed by digital medical software and various size,level,location of circle bone defect of the proximal tibia were established to analyzed the stress of various bone defect model.2.A model three-dimensional model was reconstructed by digital medical software and tumor prosthesis-tibia model with various stem length was reconstructed to analyzed the stress level and distribution characteristic3.Three-dimensional gait of patients with proximal tibial bone tumors were collected by a novel joint kinematics measurement syste-opti_Knee(?).then,the The gait difference was compared between involved knee and contralateral knee,the knee joint 6 degrees of freedom and 5 kinematic parameters was analyzed.[Results]1.The stress of each bone defect model was higher than that 45.38MPa of the complete tibial model under the walking condition.the stress of the lateral wall defect defect ?50mm model was 186.2MPa,the stress of model with posterior wall defect ?40mm,?50mm were:133.5-144.7MPa;stress of residual defect model is less than the tibial yield stress(ay)125MPa.2.Proximal tibia tumorours prosthesis-tibial model with osteotomy 12cm,prosthesis with various handle length can produce different stress and displacement under the walking condition,stress range is 34.34-95.22MPa,the length of prosthetic intramedullary stem were positively correlated with the stress of prosthesis and PAMA(R2=0.97 and R2=0.82),meanwhile,the length of prosthetic intramedullary stem were negatively correlated the displacement of model the maximum stress appears in the prosthetic intramedullary stem(R2=0.95)3.1.Patients with proximal tibial bone tumor prosthesis replacement,MaxLRS of involve knee was less than conlateral knee in stance phase and he displacement of the knee joint was slightly changed<0.05);3.2.Patients with proximal tibial bone tumor treated by microwave ablation,the motion freedom of the flexion and extension of involved knee was less than conlateral knee in swing phase,the internal and external and the adduction-abduction rotation were greater than those of the conlateral knee(P<0.05).MaxRSW of the tibia was greater than that of the knee(P<0.05).[Conclusion]1.The degree of defects and the location is an important factor of tibial fractures,defects that more than ?20mm will increase the risk of fracture.Defect that more than 30mm was significantly fracture risk;anteromedial wall of the defect has a higher safety factor than other walls;2.When osteotomy length of the proximal tibia is about 120mm,the length of the prosthetic intramedullary stem with 120mm may be a better choice.3.1.Bone tumor in proximal tibia with prosthesis reconstruction after surgery can obtain good knee function and stable gait.degree of freedom of the knee was adapted the prosthes during walking;3.2.Bone tumor in proximal tibia with microwave ablation after surgery of can obtain good knee function and approximately normal stable gait,but degree of flexion and extension was less than contralateral knee.