Are Corrosion and Material Loss a Threat for Titanium-Titanium Tapers in Total Hip Arthroplasty Modular Acetabular Components?

BACKGROUND: Extensive research has reported on fretting corrosion and material loss for a variety of metal taper interfaces in orthopaedic devices. For modular acetabular shell-liner constructs, the interfaces studied thus far have consisted of mixed metal pairings, and the risk of fretting corrosion and material loss for the all-titanium shell-liner taper junction in one ceramic-on-ceramic (COC) design remains poorly understood. We asked: do titanium shell-liner taper interfaces in COC total hip arthroplasty devices show in vivo evidence of (1) fretting and/or corrosion and (2) quantifiable potential material loss?

METHODS: We examined 22 shell-liner pairs and 22 single liners from retrieved COC components. The taper interface surfaces were assessed for fretting corrosion using a semiquantitative scoring method and imaged with scanning electron microscopy. A subcohort of components were measured with a coordinate measuring machine, and volumetric material loss and maximum wear depth were calculated.

RESULTS: Fretting corrosion at the taper interfaces was minimal-to-mild for 95% of liners, and 100% of shells. Imaging revealed fretting marks within a band of corrosion on some implants, and evidence of corrosion not in the proximity of mechanical damage. Estimated material loss ranged from 0.2 to 1.3 mm3 for liners and 0.5 to 1.1 mm3 for shells. Maximum wear depth for all components was 0.03 mm or less.

CONCLUSIONS: Our results indicate that, compared to other taper junctions in total joint arthroplasty, the risk of corrosion and material loss may be minimal for titanium shell-liner interfaces.