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Updated: Dec 11, 2025
09:31
Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
12.3K
Geometric Variations of Modular Head-Stem Taper Junctions of Total Hip Replacements
A Wade1, A R Beadling1, A Neville1
1University of Leeds, School of Mechanical Engineering, Institute of Functional Surfaces, Leeds, UK.
Medical Engineering & Physics
|August 19, 2020
Summary
Taper degradation in total hip replacements (THR) is a concern. This study found that taper engagement depends on both macro and micro-scale geometry variations between head and stem components, impacting implant performance.
Area of Science:
- Biomaterials Engineering
- Orthopaedic Surgery
- Mechanical Engineering
Background:
- Taper degradation in total hip replacements (THR) is a significant clinical issue, leading to adverse tissue responses and early implant failure.
- Previous research focused on global taper parameters, lacking a comprehensive understanding of factors influencing taper interface performance.
- Wear and corrosion at the taper junction are linked to adverse local tissue reactions, necessitating revision surgery.
Purpose of the Study:
- To investigate the impact of geometrical variations in as-manufactured head and stem tapers on taper engagement in THR.
- To provide deeper insights into taper engagement, a critical parameter influencing modular taper junction performance.
- To correlate local geometrical deviations with manufacturing processes and their effect on taper interface behavior.
Main Methods:
- Measurement of geometrical variations in twelve commercial male and six female tapers using a coordinate measurement machine (CMM).
- Analysis of macro-scale differences (e.g., cone angles) and micro-scale deviations from nominal geometry.
- Application of Morse taper connection theory to predict engagement based on measured geometrical parameters.
Main Results:
- Taper engagement is specific to individual head-stem couples, influenced by both macro and micro-scale geometrical deviations.
- Discrepancies in cone angles between male and female tapers often result in predominantly proximal contact.
- Some metal-on-metal head-stem couples exhibit distal mismatches, and local deviation patterns are linked to manufacturing methods.
Conclusions:
- Understanding taper engagement requires considering both global and local geometrical features of mating components.
- Manufacturing processes significantly influence local taper geometry and, consequently, implant performance.
- Further research using this measurement methodology is needed to characterize optimal modular taper junctions for THR prostheses.
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