Acetabular revision arthroplasty
================================

* Robert B. Bourne

Total hip arthroplasty has revolutionized the care of arthritic patients suffering from the severe pain and functional disability that accompanies end-stage degenerative processes of the hip.1,2 In 1997–1998, 19 000 total hip replacements were performed in Canada (Canadian Institute for Health Information: personal communication, 2000). Inevitably, some total hip replacements fail owing to such factors as infection, wear, loosening, dislocation and trauma.3 The actual burden of revision total hip arthroplasties is poorly understood because diagnostic codes do not separate primary and revision total hip replacements or the side of the operation. Revision rates vary but are estimated to represent 6% to 12% of all total hip replacements performed in a given year.4 With the aging Canadian population, the number of revision total hip arthroplasties required is expected to increase. It is against this backdrop that 2 timely papers by Jain and associates appear in this issue. They deal with the important issue of acetabular revision arthroplasty.

In the article on cementless acetabular revision arthroplasty (see page 269), the authors investigated potential predictors of function after this procedure.5,6 Despite shortcomings in terms of a relatively small number of acetabular revisions (41), a retrospective methodology, only a 67% participation rate and relatively short-term follow-up (mean 3.4 years), the authors found that aseptic acetabular loosening was the commonest mode of failure (73%), supplementary screw fixation of the metal acetabular shell was often needed (42%) and morcellized allograft bone was frequently required (24%). The procedure was less successful in female and elderly patients, possibly because of poor bone stock. Complications were common (20%). Hip-specific and general health outcomes were inferior to those achieved by primary total hip arthroplasty. Radiographic radiolucencies were present in almost a quarter of revisions, suggesting poorer cementless fixation than in primary total hip arthroplasties. Further studies of this important topic were suggested.

For their study on functional outcomes after acetabular revision with reinforcement roof rings (see page 276), the authors used a similar methodology in more difficult acetabular revisions with severe bone stock deficiency, requiring reinforcement rings.5,7,8 Twenty-four (71%) of 34 eligible patients agreed to participate in this retrospective study. Most patients (75%) were women, and an initial diagnosis of osteoarthritis and aseptic loosening was the principal reason for revision arthroplasty. Disease-specific and most global health parameters were poorer than in the simpler acetabular revisions reported in the first article. Complications were more frequent (46%). One reinforcement ring loosened, requiring revision.

In summary, these 2 papers highlight the need for more research in the field of revision total hip arthroplasty. Efforts must be made to minimize the patient, surgical and implant factors that contribute to implant failure and the need for revision total hip arthroplasty. National registries and the stepwise introduction of new implant devices have been demonstrated to be an effective strategy in this regard.1,4,9 Finally, much remains to be done in defining techniques to maximize outcomes after revision total hip arthroplasty.

## References

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2.  Laupacis A, Bourne R, Rorabeck C, Feeny D, Wong C, Tugwell P, et al. The effect of elective total hip replacement on health-related quality of life. J Bone Joint Surg [Am] 1993;75: 1619–26.
    
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3.  Garby D, Morsi E, Mahomed N, Gross AE. Classification and reconstruction in revision acetabular arthroplasty with bone stock deficiency. Clin Orthop 1996;323:98–107.
    
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5.  Lawrence JM, Engh CA, Macalino GE, Lauro GR. Outcome of revision hip arthroplasty done without cement. J Bone Joint Surg [Am] 1994;76:965–73.
    
    [Abstract/FREE Full Text](http://canjsurg.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamJqc2FtIjtzOjU6InJlc2lkIjtzOjg6Ijc2LzcvOTY1IjtzOjQ6ImF0b20iO3M6MTg6Ii9janMvNDMvNC8yNDcuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

6.  Paprosky WG, Magnes RE. Principles of bone grafting in revision total hip arthroplasty. Clin Orthop 1994;298: 147–55.
    
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7.  Berry DJ, Muller ME. Revision arthroplasty using an anti-protrusio cage for massive acetabular bone deficiency. J Bone Joint Surg [Br] 1992;74:711–715.
    
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8.  Rosson J, Schatzker J. The use of reinforcement rings to reconstruct deficient acetabula. J Bone Joint Surg [Br] 1992;74:716–20.
    
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9.  Malchau H. On the importance of stepwise introduction of new hip implant technology. PhD thesis, Goteborg University, Sweden, 1995.