To The Editor:

While I read with interest the authors’ encouraging results in revising femoral-side failures of current-generation hip surface replacement arthroplasties, I was surprised that their well-researched bibliography, with references dating back into the 1970s, failed to note a pertinent article on this subject that I and my co-authors published over twenty years ago.(1) That paper presented two-to-three year follow-up observations of three femoral-side revisions of first-generation resurfacing failures using an outer-diameter matched, press-fit bipolar prosthesis to articulate with the retained acetabular cup. These novel revisions had “created” the theretofore unreported surgical entity of a true bipolar total hip arthoplasty, with two distinct, but biomechanically linked, metal-on-polyethylene articulating interfaces. Fluoroscopic evaluations of these three hips (and one set of x-rays included in the article) strongly suggested the preservation and predominance of inner- bearing motion which, we inferred, might be beneficial in enhancing the longevity of the retained acetabular components. Unfortunately, these procedures were performed in a highly mobile military population, and no follow-up beyond that noted in the article was possible. Moreover, concerns about the subsequent longevity of the relatively thin, non-metal backed acetabular shells undoubtedly led many surgeons to opt for revising such failures to a conventional total hip replacement.

The current generation of hip resurfacing implants, with its use of metal-on-metal articulations and cementless technology, has significantly minimized concerns about frictional torque and the wear debris from larger articulating interfaces as potential causes of premature failure. However, despite these advances, isolated femoral-side failures of these procedures do still occur; and as the authors have shown, revision using a head diameter matched unipolar stem appears to be a technically feasible and highly satisfactory surgical solution. However, should the currently unresolved issue of accumulated metal ion release from these implants rise to a level of concern that leads to the reconsideration of a technology- enhanced metal-on-plastic resurfacing option, the concept of a bipolar conversion for those femoral-side failures may be worth a more formalized revisiting and assessment.

The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated .

Reference:

1. McClelland SJ, Godfery JD, Benton PC, and Slemmons, BK. Revision of Failed Hip Surface Replacement Arthroplasties With A Bipolar Prosthesis. Three Case Reports with Two-to-Three Year Follow-Up Observations. Clin Orthop Relat Res. 1986; 208: 243-248.