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    Does the Use of Dual-Mobility Bearings Reduce Dislocation Risk after Revision THA?

    Editor’s Note: Research papers intended for presentation at the canceled annual meeting of the American Academy of Orthopaedic Surgeons are now available online at the AAOS Virtual Education Experience. We’ll be highlighting a few of the more interesting papers throughout the summer.

    Dislocation remains one of the most common reasons that patients undergo revision total hip arthroplasty (THA), occurring in up to 2% of primary THAs. [1] The risk of dislocation doesn’t always end with a revision procedure, however: The reported dislocation rate following revisions or implant exchange surgeries is as high as 28%. [2,3]

    The use of dual-mobility implants during revision THA has been proposed as a solution to improve stability. Are these implants really a good option for this patient population?

    A study from The Rothman Institute suggests that the answer is yes: Compared with conventional bearings, dual-mobility bearing articulations were associated with a lower risk of dislocation after revision THA.

    Because so few studies investigating the role of dual-mobility bearings in reducing postoperative dislocations have a control group, the researchers from The Rothman Institute wanted to directly compare outcomes with 2 types of implants:

    • Modular dual-mobility bearing articulation (n=95)
    • Conventional bearing surface with a large head and a highly cross-linked polyethylene liner (n=127)

    Their retrospective review included 267 patients who underwent revision THA at their institution between 2012 and 2016 and who had a minimum of 2 years of follow-up (mean follow-up, 37.8 months; range, 24-73 months). The researchers collected data on rates of re-revision, dislocation, and complications, as well as scores on the SF-12 health survey.

    Before revision THA, patients in the dual-mobility group had experienced significantly more dislocations than patients in the control group, 22.8% and 3.6%, respectively (P<0.001). After surgery, the reverse was true: There were 2 dislocations (2.1%) in the dual-mobility group compared with 14 dislocations (8.1%) in the control group (P=0.058). Controlling for confounding variables, the researchers found that patients in the control group had a higher rate of postoperative dislocation than patients in the dual-mobility group (OR 7.69, 95% CI 1.64-66.66; P=0.024).

    There were no differences between groups with regard to the re-revision rate, fracture rate, or postoperative SF-12 scores.

    Although the study showed a lower dislocation rate for dual-mobility bearing articulations with intermediate-term follow-up, the researchers said that, “[f]urther study is needed to identify any potential longer-term complications which may result from a modular [dual-mobility] bearing.”

    Source

    Li WT, Kozick Z, Sherman M, Restrepo C, Smith EB, Courtney PM. Dual Mobility Bearing Articulations Result in Lower Rates of Dislocation following Revision Total Hip Arthroplasty. Poster P0056. AAOS Virtual Education Experience.

    References

    1. Meek RM, Allan DB, McPhillips G, Kerr L, Howie CR. Epidemiology of dislocation after total hip arthroplasty. Clin Orthop Relat Res. 2006;447:9–18.
    2. Wetters NG, Murray TG, Moric M, Sporer SM, Paprosky WG, Della Valle CJ. Risk factors for dislocation after revision total hip arthroplasty. Clin Orthop Relat Res. 2013;471:410–416.
    3. Berend KR, Sporer SM, Sierra RJ, Glassman AH, Morris MJ. Achieving stability and lower-limb length in total hip arthroplasty. J Bone Joint Surg. 2010;92:2737–2752.