Early Failure of Articular Surface Replacement XL Total Hip Arthroplasty

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Abstract

The ASR (articular surface replacement) XL (DePuy, Warsaw, Ind) metal-on-metal hip arthroplasty offers the advantage of stability and increased motion. However, an alarming number of early failures prompted the evaluation of patients treated with this system. A prospective study of patients who underwent arthroplasty with the ASR XL system was performed. Patients with 2-year follow-up or any revision were included. Failure rates, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and radiographs were evaluated. Ninety-five patients (105 hips) were included. There were 16 revisions. Thirteen (12%) were aseptic acetabular failures. Eight were revised for aseptic loosening; 4, for metallosis; 1, for malposition; 2, for infection; and 1, for periprosthetic fracture. Mean time to revision was 1.6 years (0.18-3.4 years). The ASR XL with a revision rate of 12% is the second reported 1 piece metal-on-metal system with a significant failure rate at early follow-up. This particular class of implants has inherent design flaws that lead to early failure.

Section snippets

Methods

A retrospective review of a consecutive series of ASR implants was performed at 2 centers. Institutional review board approval was obtained by each institution. Cases were selected from institutional prospective total joint registries. All primary total hips performed with an ASR implant between 2006 and 2008 were included in the study. Patient age at the date of surgery and sex was recorded. Postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were

Results

At an average of only 1.6 years (0.18-3.4 years), the overall revision rate in this consecutive series was 15% (16/105). Of these 16 revisions, 13 were aseptic acetabular component failures. Eight were revised for aseptic loosening, 4 were revised for metallosis, 2 were revised for infection, 1 was revised for a periprosthetic fracture, and 1 was revised due to acetabular implant malposition. Therefore, the aseptic acetabular component failure rate was 12% (13/105).

Of the 89 remaining unrevised

Discussion

Metal-on-metal articulations have been heralded as a solution for wear and osteolysis inherent in metal-on-plastic articulations in young active patients [21]. An added benefit of this articulation is the ability to use large femoral heads, thus improving intrinsic hip stability 1, 2, 3, 4. The original ASR implant was designed as a surface replacement coupling a nonmodular cementless acetabular component, a resurfaced femoral head, and a metal-on-metal articulation.

Because both stability and

Conclusion

The purpose of our study was to determine the clinical and radiographic outcome of the ASR XL total hip system. Although the theoretical advantages of extra large heads are attractive, the 12% early aseptic revision rate and the 28% combined clinical and radiographic failure rates are clearly unacceptable. This implant is the second recently reported 1-piece metal-on-metal hip system with a significant failure rate at early follow-up. This particular class of implants, that is, 1-piece

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    The Conflict of Interest statement associated with this article can be found at doi:10.1016/j.arth.2011.03.027.

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