Dual mobility cups do not reduce the revision risk for patients with acute femoral neck fracture: A matched cohort study from the Swedish Arthroplasty Register

Abstract

Introduction: Dual mobility cups (DMC) are gaining in popularity, as a method to reduce the risk of dislocation after fracture-related hip arthroplasty. Our aim was to compare revision rate in general, as well as due to dislocation and infection, after DMC and conventional THA due to femoral neck fracture, for each of the two groups of lateral and posterior approach. Materials and Methods: This observational cohort study based on the Swedish Arthroplasty Register (SAR) compared 2242 patients with dual mobility cups (DMC) and 6726 with conventional total hip arthroplasty (cTHA), all due to acute fracture 2005-2019. This was after propensity score matching of 1:3 (age, gender, ASA). Kaplan-Meier survival analysis was used to investigate the 5-year revision rate after DMC and cTHA in the posterior and lateral approach groups. Results: The rates of revision in general, and due to dislocation or infection, were similar for DMC and cTHA in the different approach groups during the follow-up. The cumulative revision rate after posterior approach was 4.7% (95% CI 3.1-6.2) for DMC and 4.8% (3.8-5.7) for cTHA at 5 years. For lateral approach, the result was 2.3% (CI 1.3-3.3) for DMC and 3.7% (CI 3.0-4.4) for cTHA.The 5-year results for cumulative revision rate due to dislocation after posterior approach were 1.3% (0.4-2.2) for DMC and 2.2% (1.5-2.8) for cTHA. Corresponding results for lateral approach was 0.4% (0-0.8) for DMC and 0.7% (0.4-1) for cTHA. Discussion: With implant revision surgery as outcome, we could not detect any differences between DMC and cTHA. Further studies with high external validity are needed regarding total dislocation rate, patientreported outcome, cost-effectiveness and learning curve, to make a definitive recommendation on the use of DMC for fracture cases. Conclusions: As treatment of acute femoral neck fractures, total hip arthroplasty with a dual mobility cup have similar outcome in terms of revisions in general, and due to dislocation or infections specifically, as one with conventional bearing. The similar outcome is regardless of surgical approach.

What’s New in Hip Replacement

“…Dual-mobility cups do not reduce the revision risk for patients with acute femoral neck fracture, as concluded by Rogmark and Nauclér in an observational cohort of 2,242 patients with dual-mobility cups compared with a matched cohort of 6,726 patients treated with a conventional total hip implant 1 . The authors reported that, with implant revision surgery as the outcome, they “could not detect any differences between a total hip arthroplasty with a dual mobility cup and one with conventional bearing.” Outcomes were similar and independent of whether the implants were inserted via a direct lateral or posterior approach as well as for subgroup analyses of revision for dislocation and infection.…”

Does Garden type I incomplete femoral neck fracture really exist in older adults? To evaluate the stability and consistency of Garden classification

“…Therefore, in the elderly, Garden I incomplete FNF may not exist. The elderly have decreased bone mineral density and osteoporosis, so their femoral necks are prone to fracture once they are subjected to external force [ 31 ]. Besides, the bones of the elderly have the features of decreased elasticity and enhanced brittleness, and the anatomical position of femoral neck is the turning part of force line [ 32 ].…”

Total hip replacement or hip hemiarthroplasty for the treatment of displaced femoral neck fractures in the elderly?

“…An observational cohort study based on the Swedish Arthroplasty Register (SAR) compared 2,242 patients with dual mobility cups (DMCs) and 6,726 with conventional total hip arthroplasty, all due to acute fractures. [ 10 ] The authors concluded that total hip arthroplasty with a DMC had similar outcomes in terms of revisions and, due to dislocation or infections specifically, as one with conventional bearing. Similar outcomes were regardless of the surgical approach.…”