Investigating the interaction of design factors on fretting and corrosion resistance in modular femoral head tapers

Mechanically assisted crevice corrosion (MACC) at the modular femoral head taper junction in total hip arthroplasty (THA) is a significant concern, influenced by a combination of design factors such as taper length, diameter, surface finish, and neck shaft angle. While each factor individually affects corrosion resistance, their interactions play a critical role in determining overall implant performance. This study aimed to systematically evaluate the interaction of key design factors on fretting and corrosion performance in modular femoral head tapers. A full-factorial Design of Experiments (DOE) approach was utilized, testing 16 unique taper configurations under cyclic loading conditions. Fretting currents were measured at various intervals, and post-test analysis included Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) to qualitatively assess surface damage and corrosion byproducts. Surface finish emerged as the most influential factor, with rough finishes significantly reducing fretting currents compared to smooth finishes. The combination of larger taper diameters and longer lengths, which enhance structural rigidity, also contributed to lower fretting currents. SEM and EDS analyses corroborated these findings, showing less deformation and corrosion product accumulation in configurations with rough surface finishes and enhanced rigidity. This study highlights the importance of accounting for interactions among design factors when evaluating modular taper performance. Increased structural rigidity and roughened surface finishes were associated with reduced fretting currents and corrosion under the conditions tested (Ti-CoCr pairing), suggesting that these design characteristics may help mitigate mechanically assisted crevice corrosion and extend implant longevity in total hip arthroplasty.