Objective Analysis of long-term mechanical properties of the proximal tibia after UKA and TKA, exploring the causes of UKA and TKA failure. Methods Establishment of a healthy, UKA, TKA proximal tibial finite element model Predicting the density distribution and stress distribution of the proximal tibia using Wolff"s bone reconstruction theory combined with the finite element method. Results The mean stress in the lateral ankle of UKA is essentially constant, but tends to increase, 2% increase in average density, Average medial ankle density reduced by 13% and average, stresses both reduced by 11%. 1.5% reduction in average density and 14% reduction in average stress in TKA lateral ankle, Average medial ankle density reduced by 1.4 %, and average stress reduced by 19 %, 10% increase in average prosthetic end density, 15% increase in average stress. Conclusions Implantation of UKA and TKA prostheses can cause stress masking, this may be the main cause of post-operative loosening of the prosthesis. Increased stress at the end of the TKA prosthesis, this may lead to the failure of the TKA. The average stress on the non-replacement side of the UKA increases as the bone is reconstructed, which may lead to worsening osteoarthritis on the contralateral side of the UKA in the medium to long term. The results of the study may provide data to support the reduction of the probability of complications of UKA and TKA.