Cement mantle fatigue failure in total hip replacement: experimental and computational testing

Area of Science:

• Biomedical Engineering
• Materials Science
• Orthopedic Surgery

Background:

• Loosening of the femoral component in total hip replacement can occur due to fatigue cracking of the cement mantle.
• Computational simulation offers a potential tool for preclinical evaluation of implant designs and failure mechanisms.

Purpose of the Study:

• To investigate the predictive capability of a computational method for fatigue cracking in experimental models of implanted femur constructs.
• To compare computational predictions with experimental results for different femoral implant surface finishes.

Main Methods:

• Experimental specimens with visible cement mantles were subjected to two million cycles of simulated level gait loading.
• Computational (finite element) models were created mirroring the experimental geometries, incorporating simulated residual stress and porosity.
• Cement fatigue and creep were modeled over two million cycles.

Main Results:

• For polished stem surfaces, predicted fracture locations and stem displacements closely matched experimental findings.
• For grit-blasted stem surfaces, the computational method correctly predicted no cement mantle fractures, aligning with experimental outcomes.

Conclusions:

• The computational method demonstrated capability in predicting cement mantle fracture and subsequent stem displacement.
• This simulation approach can be a valuable tool for preclinical assessment of total hip replacement components.