Outcomes and survival of a modern dual mobility cup and uncemented collared stem in displaced femoral neck fractures at a minimum 5-year follow-up

Maxence Bordes (1) , Anthony Viste (1, 2) , Mathieu Fauvernier (3, 4) , Marcelle Mercier (1) , Philippe Chaudier (1) , Mathieu Severyns (5) , Michel-Henri Fessy (1, 2)

1 CHLS - Centre Hospitalier Lyon Sud [CHU - HCL]
2 LBMC UMR T9406 - Laboratoire de Biomécanique et Mécanique des Chocs
3 LBBE - Laboratoire de Biométrie et Biologie Evolutive - UMR 5558
4 Service de Biostatistiques [Lyon]
5 Hôpital Pierre Zobda-Quitman [CHU de la Martinique]

IntroductionThe choice of implant type for total hip replacement in the treatment of femoral neck fractures remains debated. Some authors advocate for the systematic use of cemented stems, while others do not use dual mobility first-line. We therefore conducted a retrospective study using a dual mobility cup (DMC) and an uncemented collared stem (UCS) in order to: (1) confirm the low dislocation rate in this indication, (2) assess other surgical complications, in particular periprosthetic fractures, (3) ensure that these benefits are maintained over time, at a minimum follow-up of 5 years and, (4) assess the rate of revision of the implants.HypothesisOur hypothesis was that the dual mobility dislocation rate for the treatment of femoral neck fractures was lower than for bipolar hemiarthroplasties or single mobility hip prostheses.Patients and methodsA retrospective study of 244 femoral neck fractures (242 patients) treated with DMC and UCS was conducted, between 2013 and 2014. The mean age was 83±10 years (60-104). The occurrence of dislocation, periprosthetic fracture, infection of the surgical site, loosening, reoperation and revision were investigated. The HOOS Joint Replacement (JR) score was collected. The cumulative incidence with mortality was used as a competing risk.ResultsThe mean follow-up was 6 years±0.5 (5-7). At the last follow-up, 108 patients (50%) had died. Twenty-three patients (9.5%) were lost to follow-up. One case of symptomatic aseptic loosening of DMC was observed. The cumulative incidence of dislocations and periprosthetic fractures at 5 years were 2% (95% CI: 0.9-5.4) and 3% (95% CI: 1.2-6), respectively. The 5-year cumulative incidence of surgical site infections was 3.5% (95% CI: 1.8-7). The cumulative incidence of reoperations at 5 years was 7% (95% CI: 4.5-11). The causes of reoperation were periprosthetic fracture (n=6), infection (n=8), postoperative hematoma (n=2) and cup malposition (n=2). The cumulative incidence of a revision at 5 years was 2.7% (95% CI: 1.2-6). The cumulative incidence of a surgical complication from any cause at 5 years was 9% (95% CI: 6.7-14.8). The mean HOOS JR score was 79±5 (52-92).DiscussionThe cumulative incidence of dislocation at 5 years is low and other surgical complications (including periprosthetic fractures) do not increase during this period for DMC associated with UCS, in femoral neck fractures. The use of this type of implant is reliable in the treatment of femoral neck fractures.Level of evidenceIV; retrospective study without control group.

Mots clés: Dual mobility; Uncemented stem; Displaced femoral neck fracture; Total hip arthroplasty; Hip Dislocation; Periprosthetic fracture

Domaines: Biomécanique [physics.med-ph]

Maxence Bordes, Anthony Viste, Mathieu Fauvernier, Marcelle Mercier, Philippe Chaudier, et al.. Outcomes and survival of a modern dual mobility cup and uncemented collared stem in displaced femoral neck fractures at a minimum 5-year follow-up. Orthopaedics & Traumatology: Surgery & Research, 2022, 108 (1), pp.103164. ⟨10.1016/j.otsr.2021.103164⟩. ⟨hal-04009327⟩