Bernard N. Stulberg, MD¹, Kathy K. Trier,
PhD², Marybeth Naughton, BS³ and
Jayson D. Zadzilka, MS¹

¹ Cleveland Clinic Orthopaedic and Rheumatologic
Institute, 1730 West 25th Street, 4E, Cleveland, OH 44113.
² Corin USA, 10500 University Center Drive, Suite 190, Tampa, FL
33612
³ Stryker Orthopaedics, 325 Corporate Drive, Mahwah, NJ 07430

Disclosure: In support of
their research for or preparation of this work, one or more of the
authors received, in any one year, outside funding or grants in
excess of $10,000 from Stryker Orthopaedics. In addition, 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 (Corin, Tampa, Florida). Commercial entities (Corin, Tampa,
Florida, and Stryker, Mahwah, New Jersey) 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.

Background: Improvements in metal-on-metal bearings have made
hybrid hip surface replacement a potential alternative for the
young active patient with end-stage hip disease. Possible advantages
include greater hip joint stability, bone preservation, and decreased
osteolysis. In this study, we compared the clinical and radiographic
results of a new resurfacing device with those in a historical group
of standard total hip arthroplasties.

Methods: In 2001, the Cormet 2000 Hip Resurfacing Investigational
Device Exemption study was initiated at twelve centers. A total
of 337 patients treated with unilateral hip surface replacement with
the Cormet device were enrolled in that study. These patients were
compared with 266 patients in a previous study who had undergone
unilateral total hip arthroplasty with ceramic bearing surfaces.
Clinical and radiographic results were compared at similar time
intervals. A newly recommended performance standard, the composite
clinical success score, was used to assess non-inferiority of the hip
resurfacing compared with the total hip arthroplasty used in the
historical comparison population.

Results: At the time of follow-up, at a minimum of two years,
the Harris hip scores were comparable between the resurfacing
and total hip arthroplasty groups. Statistical evaluation of the
composite clinical success scores confirmed the non-inferiority
hypothesis. Revision was required in twenty-four patients in the
resurfacing group and five patients in the total hip arthroplasty
group. The most common cause of revision following resurfacing was
failure of the femoral component (fracture of the femoral neck or
loosening of the femoral component).

Conclusions: Careful review of this study population revealed
several important criteria for successful introduction of this
resurfacing device into the United States. These include careful
patient selection based on clinical and radiographic parameters and
attention to various surgical details of implantation. These findings
can be used to focus the training process for surgeons who wish to
add implantation of this device to their surgical armamentarium. Such
efforts should help to ensure safe and effective introduction of this
new technology.

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