Commentary and Perspective
Jobory et al. reviewed a large data set to evaluate a population of patients who underwent primary total hip replacement with use of a standard acetabular component or a dual-mobility acetabular cup (DMC) to treat a hip fracture. This review included patients from 3 different national registries in the Nordic Arthroplasty Register Association (NARA) database: Denmark, Norway, and Sweden. Assessment for medical comorbidities is not uniform across these national registries. However, the registries contain similar outcome data on revision rates.
The authors report a statistically significant but quite small difference in revision rates in favor of DMCs (4.0% versus 5.4%). However, the overall mortality rate was higher for patients with a DMC than for those with a conventional cup (40.1% versus 26.6%). These differences probably are not clinically relevant, particularly when considering factors such as fracture type, surgeon experience, and the fact that a standard assessment of medical comorbidities could not be performed across the individual registries. A recent review of data from the NARA registry that compared primary total hip arthroplasties using a standard acetabular component with those using a DMC showed no differences in revision rates1.
Dislocation was an important source of the difference in the revision rates between the 2 types of acetabular components. However, nearly 70% of the standard cups and >80% of the DMCs were placed through a posterior approach. Of relevance to this topic, the American Academy of Orthopaedic Surgeons (AAOS) clinical practice guidelines note evidence that anterior approaches for arthroplasty after hip fracture are associated with a significantly lower rate of dislocation2. It is not clear how the data may have differed if anterior approaches had been utilized more commonly in this series. The authors state that the difference in revision rates was consistent between the groups when the data analysis was controlled for approach. However, the prevalence of anterior versus direct lateral approaches is not provided to the reader, who is thus left with questions about the influence of approach and other factors on the difference in the revision rates.
The study provides moderate-to-strong evidence suggesting non-inferiority of DMCs as compared with standard acetabular components for geriatric patients with hip fractures treated with primary total hip arthroplasty.
1. Kreipke R, Rogmark C, Pedersen AB, Kärrholm J, Hallan G, Havelin LI, Mäkelä K, Overgaard S. Dual mobility cups: effect on risk of revision of primary total hip arthroplasty due to osteoarthritis: a matched population-based study using the Nordic Arthroplasty Register Association database. J Bone Joint Surg Am. 2019 Jan 16;101(2):169-76.
2. Brox WT, Roberts KC, Taksali S, Wright DG, Wixted JJ, Tubb CC, Patt JC, Templeton KJ, Dickman E, Adler RA, Macaulay WB, Jackman JM, Annaswamy T, Adelman AM, Hawthorne CG, Olson SA, Mendelson DA, LeBoff MS, Camacho PA, Jevsevar D, Shea KG, Bozic KJ, Shaffer W, Cummins D, Murray JN, Donnelly P, Shores P, Woznica A, Martinez Y, Boone C, Gross L, Sevarino K. The American Academy of Orthopaedic Surgeons evidence-based guideline on management of hip fractures in the elderly. J Bone Joint Surg Am. 2015 Jul 15;97(14):1196-9.