The influence of PEEK acetabular shell on the mechanical stability of total hip replacements under gait loading and motion

The demand for total hip replacement surgery is increasing year by year. However, the issue of hip prosthesis failure, particularly the modular acetabular cup, still exists. The performance and functional requirements of modular acetabular cups have not yet met clinical expectations. This study focused on poly-ether-ether-ketone (PEEK) shells, using finite element methods to investigate their mechanical stability under gait loads and motion, including parameters such as deformation, micromotion, and bone strain. The results showed that a compromise was required among the mechanical performance, stability, and bone integration capabilities of the PEEK shell. As the shell rigidity increased, deformation decreased. However, increased rigidity also increased micromotion at the bone-prosthesis interface, reducing the area that promoted bone ingrowth. Additionally, potential bone absorption areas were also increased, reducing bone preservation and reconstruction capabilities. Compromises need to be made among mechanical performance, stability, and bone integration to achieve optimal mechanical stability. In this study, a 6 mm wall thickness PEEK shell was found to provide good overall mechanical stability.

Focusing only on the deformation of the shell is not sufficient to evaluate the mechanical stability of modular acetabular prostheses after implantation in the human body. The influences of shell deformation, bone-prosthesis interface micromotion, and bone strain should be fully considered simultaneously. Therefore, in this study, the CFR-PEEK shell was taken to explore the effect of shell stiffness on its mechanical stability under gait loading and motion and to evaluate whether the CFR-PEEK shells could be a suitable alternative to metal shells with better mechanical stability.