Biomechanical study of hybrid-fixed femoral prosthesis in total knee arthroplasty

Cemented prostheses provide superior initial stability but are associated with a higher incidence of postoperative radiolucent lines in the posterior femoral condyle, which are critical predictors of loosening. Cementless prostheses rarely lead to the development of radiolucent lines but demonstrate weaker initial stability. To address these limitations, i.e., to extend prosthesis longevity while providing optimal initial stability, in this study, we developed a hybrid prosthesis design and explored whether it could achieve the same initial fixation stability as that of conventional cemented prostheses.

We developed a hybrid prosthesis with a cementless posterior condylar interface covered with biological coating. Using synthetic bone models, we created three femoral prosthesis fixation models: fully cemented, non-cemented posterior condyle, and hybrid. We analyzed in vitro force-displacement data to evaluate the impact of different fixation methods on the initial stability of the femoral component.

The hybrid prosthesis achieved initial stability comparable to that of fully cemented prostheses. Furthermore, the biological coating may enhance long-term stability by promoting bone ingrowth in the posterior condylar area, potentially surpassing the durability of fully cemented designs and mitigating the risk of prosthetic loosening.

The hybrid design maintained initial stability and may allow for potential long-term improvements through bone ingrowth.