Dual-Mobility Articulations in Revision Hip Arthroplasty

Commentary Hip arthroplasty volume continues to increase substantially, and accordingly there continues to be a predictable concomitant increase in revision total hip arthroplasty (rTHA) volume1. Patient outcomes after rTHA are reported to be inferior to those after primary THA2. Hip instability is the indication for as many as 22.5% of rTHAs, and instability is also a leading cause of re-revision after rTHA2,3. Instability is a common and difficult problem for both patients and surgeons. Dual-mobility articulations (DMs) have emerged as a technique to presumably decrease the risk of instability in primary THA and rTHA by allowing for a larger head size, increased jump distance, and greater range of motion before impingement. Khatod et al. present a timely study on a series of 3,725 rTHAs performed by 345 surgeons at 64 hospitals in an integrated health system. In an adjusted analysis, they show that a DM reduced the risk of dislocation in rTHA compared with a cross-linked polyethylene liner (XLPE), regardless of the head diameter of the latter, but was not significantly better than a constrained liner. In an adjusted analysis of their primary outcome of interest, DMs importantly also reduced the risk of re-revision for aseptic loosening compared with XLPE and constrained liners. DMs were used more commonly later in the series, for obvious reasons, and coinciding temporal advances in prosthetic materials, surgical techniques, and rehabilitation protocols are likely also responsible for improving the rTHA outcomes. However, the authors controlled for this with a subgroup analysis of 5-year time frames showing that in the 1,425 hip revisions performed between 2018 and 2022, the DM hips likewise had a lower rate of re-revision for aseptic loosening compared with constrained liners or XLPE, and a lower risk of instability compared with XLPE regardless of head diameter, but not compared with constrained liners. This manuscript provides longitudinal data supporting the emerging role of DMs in rTHA to achieve not only lower dislocation risk but also the lowest risk of subsequent aseptic re-revision. Each revision has unique circumstances for the surgeon to consider, including the indication for revision, patient-specific factors, and the status of and modular options available for the existing implants. The surgeon must rely on the literature and the unique attributes of each case to attempt to obtain the best possible outcome for the patient in these often-complex scenarios, and this study provides valuable information for this process. Although this study is potentially limited in that it evaluated a variety of primary and revision implants, including multiple designs of DM constructs, this is reflective of the clinical realities that surgeons face when performing rTHA. The use of constrained liners may have been more common in cases with very severe soft-tissue loss, abductor insufficiency, or high-risk patient comorbidities, which could not be evaluated in this study, and perhaps DM constructs would not perform as well in some of these difficult circumstances. Given the potential high forces generated and reduced range of motion associated with constrained liners, and the known risks, including the possibility of liner dissociation, their use to reduce dislocations comes with an understood compromise4. Although DM articulations can have unique complications, such as intraprosthetic dislocation, and DMs have a variety of similar but distinct prosthetic designs and materials that may ultimately have different long-term outcomes, this well-done study provides evidence of the value of considering the use of DMs where possible when performing rTHA—to reduce the risk of both instability and, importantly, the risk of re-revision for aseptic reasons.