Same Same but Different? 12/14 Stem and Head Tapers in Total Hip Arthroplasty

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Medical Device Engineering

Background:

• Taper corrosion is a significant issue in total hip arthroplasty (THA) modular taper junctions.
• The precise mechanisms driving taper corrosion remain incompletely understood.
• Implant taper geometry and topography are known factors influencing corrosion, with manufacturer variations.

Purpose of the Study:

• To investigate variations in design and surface characteristics of common 12/14 stem and head tapers used in THA.
• To analyze geometric and topographic parameters across different manufacturers' implants.

Main Methods:

• Analysis of commercially available 12/14 stem and head tapers.
• Measurement of geometric parameters (taper angle, diameter, length) using coordinate measuring machines.
• Determination of topographic parameters using tactile roughness measurement instruments.

Main Results:

• Significant differences in both geometry and topography were found among stem tapers from various manufacturers.
• Stem taper topography exhibited greater variation than geometric parameters.
• Head tapers showed geometric variations but not topographic differences across manufacturers.

Conclusions:

• This study highlights considerable variations in modular hip taper connections among manufacturers.
• A novel classification system for surface finish is introduced.
• Findings can inform future experimental corrosion and retrieval studies in THA.