Open Journal of Orthopedics, 2018, 8, 381-412 http://www.scirp.org/journal/ojo ISSN Online: 2164-3016 ISSN Print: 2164-3008 DOI: 10.4236/ojo.2018.810041 Oct. 16, 2018 381 Open Journal of Orthopedics Adverse Wear in MOM Hip-Arthroplasty Related to the Production of Metal Fragments at Impingement Sites T. K. Donaldson 1 , E. J. Smith 2 , A. Koutalos 3 , A. John 4 , J. Y. Lazennec 5 , I. C. Clarke 6* 1 Empire Orthopedics, Colton, CA, USA 2 Department of Orthopaedics, University of Bristol, Bristol, England 3 Department of Orthopaedics, University Hospital of Larissa, Larissa, Greece 4 Department of Orthopaedics, University of Cardiff and Vale NHS Trust, Wales, England 5 Department of Orthopedic and Trauma Surgery, La Pitié-Salpêtrière Hospital, University of Paris, Paris, France 6 Department of Orthopaedics, Loma Linda University Medical Center, Loma Linda, CA, USA Abstract Metal on metal (MOM) bearings were reintroduced as resurfacing arthrop- lasty (RA) for the younger, more active patient and were later incorporated into total hip arthroplasty (THA). Early results were encouraging. However, recent publications identified adverse tissue responses to metal debris, such that the majority of MOM designs have been abandoned due to the increase in cobalt-chromium (CoCr) debris and associated metal ions. Reports of MOM THA cited risks that included acetabular cups with high-inclination angles, i.e. “edge-loading”, and “trunnionosis”. Hip impingement was also a cited risk in one MOM study, with “type-IV” wear noted to be a slid- ing/impaction type of wear, characterized by deep scratches. Sliding/impaction wear mechanisms produced at impingement are not well represented in cur- rent MOM literature. Therefore, our objective in this review was to consoli- date evidence for impingement risks. We hypothesize that hip impingement and subluxation with metal-backed acetabular cups can trigger wear mechan- isms that result in, 1) femoral-neck notching, 2) release of large metal par- ticles, 3) production of uniquely large scratches, defined as “microgrooves” on heads and cups, 4) formation of “polar” and “basal” microgrooves pre- cisely aligning with cup profiles during impingement, and 5) equatorial mi- crogrooves relate to soft-tissue sites of impingement. Relevant risk scenarios were evaluated and included hip impingement in both sitting and standing postures, head subluxation, wear patterns defining in-vivo component posi- tions, and evidence for circulating metal fragments. The study relied on map- How to cite this paper: Donaldson, T.K., Smith, E.J., Koutalos, A., John, A., Lazen- nec, J.Y. and Clarke, I.C. (2018) Adverse Wear in MOM Hip-Arthroplasty Related to the Production of Metal Fragments at Im- pingement Sites. Open Journal of Ortho- pedics, 8, 381-412. https://doi.org/10.4236/ojo.2018.810041 Received: June 2, 2018 Accepted: October 13, 2018 Published: October 16, 2018 Copyright © 2018 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access