Modular taper degradation remains a concern in Total Hip Arthroplasty (THA), first
reported in the 1980s, it is responsible for over 3% of THA primary revisions [1, 2]. Wear
and corrosion of the taper interface can result in mechanical failure; however, a more
common consequence is biological complications such as Adverse Reactions to Metal
Debris (ARMD) can result from the degradation products [3-6]. Despite the growing
interest in taper degradation and wear debris, current regulatory methods, ISO 17853
[7] and ASTM F1875 [8], do not capture the current state of the art in either debris
generation or isolation and imaging.
Research into fretting crevice corrosion at the taper interface often isolates one
degradation aspect, such as wear, metallurgical changes, or corrosion, limiting the
understanding of combined effects and often failing to represent real-world usage. The
aim of this thesis was to investigate the factors affecting degradation and debris
generation at the modular taper interface, such as lubricant, geometry and loading.
This thesis presents a multiscale approach to investigating the degradation occurring
at the modular taper. Experiments quantified corrosion, wear and debris generation in
Ringer’s solution, acidified Ringer’s solution and calf serum buffered with Ringer’s
solution, from: simple Hertzian fretting contacts, clinical component testing per ASTM
F1875 [8], and complex loading comparing simulated implant usage from elderly
sedentary and young active patient strata.
Key findings show that nanosized metallic debris is generated from fretting contacts,
including clinical components, with the smallest debris measuring 3 nm and largest 67
µm. Larger slip amplitudes increased corrosion and debris size (2.33 C and 0.04 C
charge transfer at �� = 150 µm and 25 µm, respectively). In serum, over 40% of debris
was smaller than 500 nm, regardless of fretting amplitude. Additionally, implant loading
affected degradation, more dynamic loading resulted in increased debris size and taper
roughness (average Feret diameter = 7.05 µm and Sa = 0.90 µm from young active
patient profile, average Feret diameter 5.20 µm and Sa = 0.67 µm from elderly sedentary
patient profile). These findings suggest that current standards may not be suitable for
assessing degradation of the interface, and that there is increased degradation and
proportion of pro-inflammatory debris from more advanced testing and more active
patient profiles.
