The Journal of Bone and Joint Surgery (American). 2008;90:1282-1289.
doi:10.2106/JBJS.F.00847
© 2008 The Journal of Bone and Joint Surgery, Inc.
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Histopathologic Retrieval Analysis of Clinically Failed Porous Tantalum Osteonecrosis Implants

M. Tanzer, MD1, J.D. Bobyn, PhD2, J.J. Krygier, CET2 and D. Karabasz, BSc2

1 Division of Orthopaedics, Department of Surgery, McGill University, 1650 Cedar Avenue #B5.159, Montreal, Quebec H3G 1A4, Canada
2 Jo Miller Orthopaedic Research Laboratory, Montreal General Hospital, 1650 Cedar Avenue, Room LS1-409, Montreal, Quebec H3G 1A4, Canada

Investigation performed at the Jo Miller Orthopaedic Research Laboratory, McGill University, Montreal, Quebec, Canada

Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families 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 authors, or a member of their immediate families, are affiliated or associated.

Background: An Osteonecrosis Intervention Implant made of porous tantalum was recently developed to provide structural support and a compatible surface for tissue ingrowth in osteonecrotic femoral heads. From an investigational device exemption study that comprised 113 implants, we carried out a retrieval analysis of clinically failed implants.

Methods: Seventeen porous tantalum implants that had been used for the treatment of Steinberg stage-II osteonecrosis of the hip were retrieved at the time of conversion to a total hip arthroplasty. Fifteen implants that had been transected near the base of the femoral neck with the proximal portion left in situ within the femoral head underwent histopathologic analysis at an average of 13.4 months (range, three to thirty-six months) after implantation.

Results: Residual osteonecrosis was present in fourteen of the fifteen specimens. Fracture of the subchondral bone of the femoral head was present in all instances, and collapse of the femoral head was present in nine instances (60%). Backscattered scanning electron microscopy confirmed the presence of bone ingrowth in thirteen (87%) of the fifteen specimens. The mean extent of bone ingrowth was 1.9% (range, 0% to 4.4%).

Conclusions: The retrieved implants were associated with little bone ingrowth and insufficient mechanical support of subchondral bone. The implant design, the surgical technique, its application, and the clinical characteristics of candidates for this procedure should continue to be monitored closely.

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


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