Polyethylene wear of dual mobility cups: a comparative analysis based on patient-specific finite element modeling

Purpose Concerns remain about potential increased wear with dual mobility cups related to the multiple articulations involved in this specific design of implant. This finite element analysis study aimed to compare polyethylene (PE) wear between dual mobility cup and conventional acetabular component, and between the use of conventional ultra-high molecular weight PE (UHMWPE) and highly cross-linked PE (XPLE). Methods Patient-specific finite element modeling was developed for 15 patients undergoing primary total hip arthroplasty (THA). Five acetabular components were 3D modeled and compared in THA constructs replicating existing implants: a dual mobility cup with a 22.2-mm-diameter femoral head against UHMWPE or XLPE (DM22PE or DM22XL), a conventional cup with a 22.2-mm-diameter femoral head against UHMWPE (SD22PE) and a conventional cup with a 32-mm-diameter femoral head against UHMWPE or XLPE (SD32PE or SD32XL). Results DM22PE produced 4.6 times and 5.1 times more volumetric wear than SD32XL and DM22XL (p < 0.0001, Cohen’s d = 6.97 and 7.11; respectively). However, even if significant, the differences in volumetric wear between DM22XL and SD32XL as well as between DM22PE and SD22PE or SD32PE were small according to their effect size (p < 0.0001, Cohen’s |d|= 0.48 to 0.65) and could be therefore considered as clinically negligible. Conclusion When using XLPE instead of UHMWPE, dual mobility cup with a 22.2-mm-diameter femoral head produced a similar amount of volumetric wear than conventional acetabular component with a 32-mm-diameter femoral head against XLPE. Therefore, XLPE is advocated in dual mobility cup to improve its wear performance.

Early Complications of using Dual Mobility Cup in Total Hip Arthroplasty. A Systematic Review

Background Total hip arthroplasty (THA) is considered one of the most successful surgical procedures providing pain relief and improvement of function in patients with end-stage hip arthritis that does not respond to non-operative treatments. As health care continues to improve and life expectancy increases, the demand for total joint replacement will grow to reflect this more active, aging population. Objectives This study aims to review early complications of dual mobility cup arthroplasty. The objective is to perform a systematic review of early complications of dual mobility cup arthroplasty for primary and revision cases. Methodology Types of studies we will include randomized control trails (RCTs), controlled clinical trials, retrospective cohort studies, and we will exclude case reports, case series studies, cross sectional studies, non English studies. Search results will be conducted to systematic review management software and manually screened for eligibility to be included. PRISMA flowchart will be produced based on the search results and the inclusion/exclusion criteria. We will search the MED-LINE database, PubMed, Cochrane Bone and Muscle Trauma Group Specialized Register, Cochrane Register of Controlled Trails (The Cochrane Library) using the following keywords related to: THA, Dual mobility cup, complications, intraprosethetic dislocation. Results Early complication rate in dual mobility cups is significantly higher in revision cases compared to primary cases, with the exception of IPD which was significantly lower in revision cases. Early complication rate of conventional THA was significantly higher than both primary and revision dual mobility cups. Conclusion Dual mobility THAs are a good alternative to traditional bearing surfaces with long survivorship and low rates of instability after primary and revision THA. The rate of complications which are unique to the procedure, including intraprosthetic dislocation, is relatively low and limited mainly to earlier designs. High-quality, prospective, comparative studies are needed to further evaluate the use of dual mobility in primary and revision THA.

Dual-Mobility Cups in Primary Total Hip Arthroplasty

Dual-mobility cups (DMCs) were introduced in France more than 40 years ago and are increasingly used not only in hip revision but also primary hip arthroplasty. Due to a simulated large-head articulation and increased jumping distance, DMCs can contribute to a high range of motion in the hip joint and reduce the risk of instability. Numerous studies have reported low dislocation rates and high survival rates in the mid-term follow-up. Nevertheless, long-term data, especially on primary hip replacement, remain limited, and the effect of recent designs and material innovations is still unclear. Therefore, primary DMCs are mainly proposed in patients at high risk for dislocation (i.e. pelvitrochanteric insufficiency, compromised spinopelvic mobility, neuromuscular disorders, obesity and femoral neck fractures). Based on a review of recently published studies referring to these indications, the current study discusses the advantages and disadvantages of DMCs.

1220 Dual Mobility Cups in Primary and Revision Thas – A Single UK Centre Outcome Study

Aim Total Hip Arthroplasty has been challenged with instability and dislocation (5%) and restricted movements. Risks are further increased in trauma and revision cases (7-14%). Dual Mobility (DM) prosthesis is one solution to these issues and has shown to reduce the rate of dislocation in multiple USA and France studies. Its uses remain limited in the UK due to unfamiliarity. DM implants contain a small femoral head mobile within a polyethylene liner which articulates with a supra-hemispheric metallic acetabular shell. Increased coverage of the shell reduces intra-prosthetic dislocation. The highly crosslinked polyethylene helps to reduce wear while the extra arc of motion improved range of movement. Our centre started using DM prosthesis since 2018 and this study demonstrates our outcomes. Method Retrospective study of all DM replacement from January 2018 – May 2020. Allowing a minimum follow up of 6 months. Data was collected from an electronic database. Results 54 cases were identified (35 elective cases and 19 trauma cases). 34 cases were revision surgery, and 21 cases were primary arthroplasty. The average age was 75, average length of surgery was 3 hours and average stay in hospital was 9 days. No dislocation was noted in this study. All patients reported good range of movement in follow ups with no complaints of instability. Conclusions DM prosthesis provides excellent outcomes with no dislocation and good patient reported satisfaction at our center. This result is supported by various systematic reviews. The reduction of complications is also economically advantageous. Use of Dual Mobility prosthesis should be encouraged in UK.