In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours

Reference:

Kwon, Y.-M., Mellon, S., Monk, A. P., Murray, D. and Gill, H.S., 2012. In vivo evaluation of edge-loading in metal-on-metal hip resurfacing patients with pseudotumours. Bone & Joint Research, 1, pp. 42-49.

Related documents:

Official URL:

http://dx.doi.org/10.1302/2046-3758.14.2000019

Related URLs:

• http://www.bjr.boneandjoint.org.uk/content/1/4/42.full
• http://dx.doi.org/10.1302/2046-3758.14.2000019

Abstract

Objectives: Pseudotumours (abnormal peri-prosthetic soft-tissue reactions) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated metal ion levels, suggesting that excessive wear may occur due to edge-loading of these MoM implants. This study aimed to quantify in vivo edge-loading in MoMHRA patients with and without pseudotumours during functional activities. Methods: The duration and magnitude of edge-loading in vivo was quantified during functional activities by combining the dynamic hip joint segment contact force calculated from the three-dimensional (3D) motion analysis system with the 3D reconstruction of orientation of the acetabular component and each patient’s specific hip joint centre, based on CT scans. Results: Edge-loading in the hips with pseudotumours occurred with a four-fold increase in duration and magnitude of force compared with the hips without pseudotumours (p = 0.02). Conclusions: The study provides the first in vivo evidence to support that edge-loading is an important mechanism that leads to localised excessive wear (edge-wear), with subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours.

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