Effect of activity level after TKA on the relative bone mineral density measured on standard radiographs in periprosthetic tibial bone: a five-year follow-up study

Abstract

Background To suggest the best activity level to guide clinical rehabilitation by evaluating the effect of activity level on BMD in the proximal tibia 5 years after TKA. Methods In 121 patients, the UCLA activity rating was evaluated, and the relative BMD in periprosthetic tibial bone was measured by ImageJ software on anteroposterior X-ray images. ANOVA, chi-squared test, paired t test and nonlinear regression were used for data analysis. Results Activity level significantly affected rBMD in the proximal tibia, with the smallest reduction in rBMD observed with moderate activity. The difference in rBMD% between the lateral and medial metaphysis was significant. The regions with a significant difference in rBMD% between the lateral and medial metaphysis were closest to the base plate of the prosthesis. The lateral and medial regions closest to the stem of the prosthesis showed no significant difference in rBMD%. Conclusions Moderate-intensity functional exercise is recommended within 3 years after TKA.