Implant survival of 662 dual-mobility cups and 727 constrained liners in primary THA: small femoral head size increases the cumulative incidence of revision

Oskari Pakarinen; Olli Lainiala; Aleksi Reito; Perttu Neuvonen; Keijo Mäkelä; Antti Eskelinen

doi:10.1080/17453674.2021.1939597

Authors

Oskari Pakarinen Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technology, University of Tampere, Tampere
Olli Lainiala Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technology, University of Tampere, Tampere; Department of Radiology, Tampere University Hospital, Tampere
Aleksi Reito Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technology, University of Tampere, Tampere
Perttu Neuvonen Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technology, University of Tampere, Tampere
Keijo Mäkelä Department of Orthopedics and Traumatology, Turku University Hospital, and University of Turku, Turku, Finland
Antti Eskelinen Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technology, University of Tampere, Tampere

DOI:

https://doi.org/10.1080/17453674.2021.1939597

Abstract

Background and purpose — In total hip arthroplasty (THA), the risk for dislocation can be reduced using either dual-mobility cups (DMCs) or constrained liners (CLs). There are few studies comparing these concepts in primary THA. Therefore, we compared the cumulative incidence of revision in primary THA patients treated with DMC or CL with varying head sizes with conventional THA patients as reference group.

Patients and methods — We performed a cohort study based on the Finnish arthroplasty register, comparing DMCs and CLs operated over the period 2000–2017. DMCs were divided into 2 groups based on the implant design: “DMC Trident” group (n = 399) and “DMC Others” group (n = 263). CLs were divided based on the femoral head size: “CL 36 mm” group (n = 425) and “CL < 36 mm” group (n = 302). All conventional primary THAs operated on in 2000–2017 with 28–36 mm femoral head were included as control group (“Conventional THA” group, n = 102,276). Implant survival was calculated by the corresponding cumulative incidence function with revision as the endpoint and death as compet- ing event. Also, the prevalence of different reasons for revi- sion was compared.

Results — The 6-year cumulative incidence function esti- mates for the first revision were 6.9% (95% CI 4.0–9.7) for DMC Trident, 5.0% (CI 1.5–8.5) for DMC Others, 13% (CI 9.3–17) for CL < 36 mm, 6.3% (3.7–8.9) for CL 36 mm, and 4.7% (CI 4.5–4.8) for control group (conventional THA). The prevalence of dislocation revision was high (5.0%, CI 2.9– 8.2) in the CL < 36 mm group compared with other groups.

Interpretation — The DMC and CL 36 mm groups had promising mid-term survival rates, comparable to those of primary conventional THA group. The revision rate of CLs with < 36 mm head was high, mostly due to high prevalence of dislocation revisions. Therefore, CLs with 36 mm femoral head should be preferred over smaller ones.