Model validation for estimating taper microgroove deformation during total hip arthroplasty head-neck assembly

Area of Science:

• Biomaterials Engineering
• Orthopedic Biomechanics
• Medical Device Design

Background:

• Total hip arthroplasty (THA) failure can stem from fretting-corrosion at head-neck taper junctions.
• Implant geometry, including microgrooves, significantly impacts damage in retrieved THA components.
• Understanding microgroove deformation is key to preventing fretting-corrosion in modular junctions.

Purpose of the Study:

• To validate microgroove deformation in THA head-neck junctions using finite element analysis (FEA).
• To compare FEA predictions with experimental measurements of microgroove changes after assembly.
• To establish a validated FEA model for optimizing THA implant design.

Main Methods:

• Experimental analysis of four CoCrMo head and four Ti6Al4V stem tapers using white light interferometry before and after assembly.
• Assembly of head-stem tapers to a 6kN reaction force, followed by precise measurement of microgroove deformation.
• Development and application of a 2D axisymmetric FEA model simulating the head-neck junction assembly and contact mechanics.

Main Results:

• Mean microgroove height change was 1.23 µm experimentally and 1.40 µm via FEA.
• FEA revealed that head-stem assembly causes high stresses and flattening of microgroove peaks.
• Significant microgroove height changes (76-100%) occurred along the stem taper contact length in both experiments and FEA.

Conclusions:

• FEA provides a validated method for assessing microgroove deformation in THA head-neck junctions.
• The study highlights the critical role of taper geometry in fretting-corrosion.
• A validated FEA model is essential for designing THA implants to minimize fretting and fretting-corrosion risks.