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Case Reports in Orthopedics
Volume 2015 (2015), Article ID 738671, 5 pages
http://dx.doi.org/10.1155/2015/738671
Case Report

Late Nontraumatic Dissociation of the Femoral Head and Trunnion in a Total Hip Arthroplasty

1Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
2Royal Free London NHS Foundation Trust, Barnet Hospital, Wellhouse Lane, Barnet, Hertfordshire EN5 3DJ, UK

Received 23 February 2015; Revised 16 April 2015; Accepted 18 April 2015

Academic Editor: Paul E. Di Cesare

Copyright © 2015 Simon J. M. Parker et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Modular total hip arthroplasties are increasingly popular because customisation allows optimal restoration of patient biomechanics. However, the introduction of component interfaces provides greater opportunities for failure. We present a case of late nontraumatic dissociation of the head-neck interface, more than 10 years after insertion. Case Description. A 58-year-old woman had a left metal-on-metal total hip arthroplasty in 2002 for hip dysplasia. Following an uneventful 10-year period, she presented to hospital in severe pain after standing from a seated position, and radiographs demonstrated complete dissociation of the modular femoral head from the stem, with the femoral head remaining in its cup. There was no prior trauma or infection. Mild wear and metallosis were present on the articulating surface between the femoral head and trunnion. Soft tissues were unaffected. Discussion and Conclusions. This is the latest occurrence reported to date for nontraumatic component failure in such an implant by more than 7 years. The majority of cases occur in the context of dislocation and attempted closed reduction. We analyse and discuss possible mechanisms for failure, aiming to raise awareness of this potential complication and encouraging utmost care in component handling and insertion, as well as the long term follow-up of such patients.