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Modes of Failure of Osteonics Constrained Tripolar Implants: A Retrospective Analysis of Forty-three Failed Implants

¹ Pavillon T-Département de Chirurgie Orthopédique, Hôpital Edouard Herriot, Lyon, France
² Department of Orthopedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905
Investigation performed at the Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota

Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Stryker Orthopaedics). Also, a commercial entity (Mayo Foundation) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.

Methods: Forty-three failed Osteonics constrained tripolar implants were revised at our institution between September 1997 and April 2005. All revisions related to the constrained acetabular component only were considered as failures. All of the devices had been inserted for recurrent or intraoperative instability during revision procedures. Seven different methods of implantation were used. Operative reports and radiographs were reviewed to identify the modes of failure.

Results: The average time to failure of the forty-three implants was 28.4 months. A total of five modes of failure were observed: failure at the bone-implant interface (type I), which occurred in eleven hips; failure at the mechanisms holding the constrained liner to the metal shell (type II), in six hips; failure of the retaining mechanism of the bipolar component (type III), in ten hips; dislocation of the prosthetic head at the inner bearing of the bipolar component (type IV), in three hips; and infection (type V), in twelve hips. The mode of failure remained unknown in one hip that had been revised at another institution.

Conclusions: The Osteonics constrained tripolar total hip arthroplasty implant is a complex device involving many parts. We showed that failure of this device can occur at most of its interfaces. It would therefore appear logical to limit its application to salvage situations.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

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