Summary

Since its creation in 1974, the dual mobility cup (DMC) has grown in popularity, particularly over the last decade. This extensive use could lead to inappropriate use and consequently to a higher rate of complications. Compliance with the design requirements and surgical techniques will prevent the occurrence of complications that may be wrongly attributed to implants. In this context, we think it is essential to share our tips and tricks as well as an overview and explanation of common errors, based on over 45 years of clinical experience and research. From basic principles, including the indications, the choice of implants, and the computability of the implants, to surgical advice. In this article, orthopaedic surgeons will find a useful overview of the dual mobility acetabular cup in order to use it safely and confidently.

Conclusion :

This article provides advice and recommendations to orthopaedic surgeons using the dual mobility acetabular cup (DMC). The 40 years of history since the introduction of the DMC have shown its contribution to prosthetic hip surgery, as well as refining the appropriate indications for its use and the procedure to follow in the event of complication. With the recommendations and evidence from the literature, combined with our experience, these guidelines will enable a surgeon who is not confident in using the DMC to begin to use it safely.

Introduction:

Instability is one of the most dreaded complications after a total hip arthroplasty. In France, dual mobility cups are widely used in revision acetabular surgery for instability. However, few studies have focused on this type of implant. The hypothesis is as follows: the increased stability provided by the dual mobility implant helps to reduce the risk of dislocation by only replacing the acetabular component in the case of recurrent instability. This hypothesis was tested on the medium-term follow-up of a series of cementless dual mobility cups implanted for an isolated acetabular revision surgery for recurrent dislocation.

Materials and method:

A series of revision surgeries for treating recurrent dislocation was analysed retrospectively. The inclusion criteria were treatment of recurrent dislocation with a cementless dual mobility cup, between 1995 and 2001. The radiological analysis was performed with the Imagika™ software. 59 patients were included in the study (44 NOVAE-1™ and 15 NOVAE-E) with an average age of 68 years at the time of the intervention.

Results:

Among these 59 patients included, 9 died before a clinical radiological follow-up could be performed. The remaining 50 were not lost to follow-up. The average follow-up was 8 years (6-11 years). There was one premature dislocation without recurrence, the dislocation rate was 1.7%. On the last follow-up, the average PMA score was 16.5 (12-18) and the average HHS score was 86.7 (49-99). Radiologically, there was no loosening or migration, but 19% of the x-rays showed a periacetabular radio-translucency less than 1 mm wide. With dislocation as a failure criterion, the survival rate was 98% (CI of 95%: 95-100%).

Discussion :

The dislocation rate (1.7%) and the clinical results were much better than in the majority of the other series for revision surgeries for recurrent dislocation. The increased rate of periacetabular radio-transparency seems to be linked to the cup’s external coating: aluminium oxide in the NOVAE-1 implant and aluminium oxide / hydroxyapatite in the NOVAE-E.

Conclusion:

The use of dual mobility cups to treat the instability of recurrent dislocations produced satisfying results. We recommend dual mobility cups with a hydroxyapatite surface finish over a porous metal substrate, rather than a coating with a bilayer of aluminium oxide or aluminium oxide / hydroxyapatite.

Introduction:

The dual mobility concept involves two mobilities: a “small articulation” first mobility, which is the femoral head in the insert, and a “large articulation” second mobility, which is the insert in the cup. The goal of this study was to evaluate the results of using a SERF NOVAE® dual mobility acetabular cup to resolve the problem of instability in primary or revision total hip arthroplasty.

Materials and method:

A retrospective review was carried out on all the hip arthroplasties performed in a general hospital with implantation of dual mobility acetabular cups from January 2007 to December 2012. Clinical and radiological results were analysed for 44 hips (41 patients), including 20 primary THAs and 24 revision surgeries. The average age of the patients was 70.8 years (56-84) for the primary THA and 76.4 years (56-89) for the revision arthroplasty. Among the primary THAs, still performed for hip osteoarthritis or in the presence of osteoarthritic changes, the reasons for using the dual mobility cup were central nervous system issues such as Parkinson’s disease, cerebrovascular accidents or dementia (10), hip fracture (5), fixation failure of the fractured hip (2), severe stationary deformation of the hip (2), and diffuse peripheral neuropathy (1). The indications for the revision surgeries were recurrent dislocations for 17 cases, aseptic loosening with abductor deficiency (4), hemiarthroplasty failure with abductor deficiency (2), and overlooked dislocation (1).

Results:

With an average follow-up of 22 months (6-63 months), none of the hips presented with dislocation, instability, or infection. No hip required surgical reintervention. Radiological evaluation showed that a cementless cup used for a recurrent dislocation (revision surgery) had changed position but was stable in the new position. This patient had no complications and did not require surgical intervention.

Conclusion:

In general, post-operative stability of the hip depends on several factors other than those related to design. This study shows promising early results in reducing the risk of instability in this patient group undergoing primary and revision hip arthroplasty.

Introduction:

Total hip arthroplasty is a common surgery with well-known setbacks that can require revision surgery. To reduce the risk of dislocation after a revision THA (total hip arthroplasty), we are putting forward a hypothesis on the value of using a new generation dual mobility cup while evaluating its survival and complication rates.

Materials and method:

The analysis focused on the survival and complication rates of 91 patients who underwent a revision THA with a NOVAE® E TH dual mobility cup (SERF). The indications for the revision surgery were: 59 aseptic loosening or extensive wear (61.5%), 10 recurrent dislocations (10.9%), and 22 deep infections (24.1%). All patients underwent the same surgical technique and clinical and radiological examinations.

The intervention was defined as a failure because of aseptic loosening.

Results:

During follow-up, 17 patients died and 5 were lost to follow-up. The average follow-up for the 86 patients included was 33 months (0-71) with an average age of 71 years (44-99) at the time of the intervention. The Postel Merle d’Aubigné (PMA) score rose by an average of 6.8 points between the preoperative condition and the last consultation. No aseptic loosening was reported.

The rate of postoperative dislocation was 3.5% and the rate of deep infections was 4.6%. The survival rate was 91.4% on the last follow-up (or 8.1% overall revision).

Discussion:

A new choice of design and coating for the cup has shown good results in reducing the rate of aseptic loosening in relation to other studies. The three hip dislocations involved two patients with histories of recurrent dislocation and psychiatric pathologies. The limit of this study is its short follow-up. This is partially explained by the occurrence of 10 deaths during the first year of follow-up.

Conclusion:

The use of a cementless dual mobility tripod cup for revision THA has confirmed its place in the potential therapeutic range through its excellent medium-term results.

Introduction:

Total hip arthroplasty in patients with acetabular bone defects is associated with an increased risk of dislocation and aseptic loosening. No study to date has examined the use of a cementless dual mobility cup in patients presenting with acetabular anomalies. We have put forward the hypothesis that the use of a dual mobility cup in these conditions would reduce the dislocation rate and lead to satisfactory bone integration in the medium-term despite the acetabular bone defects.

Materials and method:

This ongoing multi-centre study included all cases of dual mobility cups implanted between 2010 and 2017 in patients presenting with acetabular bone loss (Paprosky 2A: 46%, 2B: 32%, 2C: 15%, and 3A: 6%). The indications for implantation were revision surgeries for aseptic loosening: cup (n=45); femoral rod (n=3); bipolar (n=11), then for septic loosening (n=10), periprosthetic fracture (n=5), chronic dislocation (n=4), intraprosthetic dislocation (n=2), cup conflict (n=1), primary post-traumatic arthroplasty (n=8), and acetabular dysplasia (n=4).

All of these patients received a COPTOS TH® acetabular cup with a cemented or cementless stem.

The clinical evaluation included the Harris Hip Score (HHS), the Postel Merle d’Aubigné (PMA) score, and radiographs (preoperative and last follow-up). The main evaluation criterion was surgical revision for aseptic acetabular loosening or a dislocation.

Results:

Altogether, 93 patients were reviewed with an average follow-up of 5.3 ± 2.3 years [0, 10]. At the last check, 7 patients had died (unrelated to the THA) and 6 were lost to follow-up. The acetabular cup was changed for 5 cases: 3 for acetabular cup aseptic loosening (3.2%) and 2 for infections (2.1%). As such, the overall survival rate for the acetabular cup was 94.6% and the survival rate for the femoral rod was 96.8%. Three patients (3%) suffered a dislocation.

On the last follow-up, the PMA and HHS scores were 14.75 and 72.15 respectively, reflecting significant improvements in relation to the preoperative scores.

Conclusion:

The use of cementless dual mobility acetabular cups for indications of acetabular bone defects leads to satisfactory medium-term results with low rates of dislocation and loosening. We recommend its use in these cases.