Reduced Revision Risk for Dual-Mobility Cup in Total Hip Replacement Due to Hip Fracture: A Matched-Pair Analysis of 9,040 Cases from the Nordic Arthroplasty Register Association (NARA)

No difference in the level of sports activity between single versus dual mobility total hip arthroplasty in adults: a clinical trial

Current evidence on the quality of sports activity in patients younger than 65 following dual mobility (DM) total hip arthroplasty (THA) is lacking, and whether this coupling allows better performance than single mobility (SM) still needs to be fully clarified. This clinical trial compared sport-related patient-reported outcome measures (PROMs) of the traditional SM versus DM implants in active patients younger than 65. All THAs were performed using a minimally invasive posterolateral approach, polyethylene liner and ceramic head. All implants were cementless. The University of California, Los Angeles (UCLA) activity scores, the High-Activity Arthroplasty Score (HAAS), the visual analogue scale for pain (VAS), and the Harris Hip Score (HHS) were administered to each patient. Patient assessment was conducted on admission, at 12, and at a minimum of 24 months postoperatively. A total of 403 patients were included in the study: 372 SM and 31 DM. The mean age was 56.3 ± 7.2 years. The mean length of the follow-up was 51.3 ± 21.0 months. The present clinical trial found no difference in UCLA, HHS, HAAS, and VAS. Patients returned at a similar level of sports activity in both groups.Level of evidence Level II, prospective group-controlled clinical trial.

Clinical efficacy of THA with dual mobility cup vs. hemiarthroplasty in elderly patients with femoral neck fracture: a retrospective study

Objective

To compare the clinical efficacy of total hip arthroplasty (THA) with or without dual mobility cup (DMC) vs. hemiarthroplasty (HA) in elderly Asian patients with acute femoral neck fracture (FNF).

Methods

Data of 284 elderly FNF patients treated at our institution from January 2017 to December 2021 were retrospectively collected. Patients were divided into the DMC-THA group (THA with DMC, n = 102), C-THA group (conventional THA without DMC, n = 88), and HA group (n = 94). The study assessed perioperative outcomes, hip functional recovery, treatment satisfaction, long-term prognosis, and quality of life.

Results

The Harris Hip Scores in the DMC-THA group were significantly higher than those in the C-THA and HA groups at 3 months, 6 months, and 1 year postoperatively (P < 0.05). The satisfaction rate in the DMC-THA group (92.2%) was significantly higher compared to the C-THA (81.8%) and HA groups (80.9%) (P < 0.05). At 1 year post-surgery, the DMC-THA group demonstrated a significantly lower dislocation rate (2.0% vs. 9.1%) and superior mobility compared to the C-THA group (P < 0.05). Additionally, the DMC-THA group exhibited significantly better mobility and reduced pain/discomfort compared to the HA group (P < 0.05).

Conclusion

THA with DMC offers superior joint function recovery, a lower dislocation rate, and improved quality of life compared to conventional THA and HA, positioning it as a preferred surgical option for elderly patients with acute FNF.

Short-term primary and revision modular dual-mobility cup total hip arthroplasty outcomes in high-risk dislocation patients: a retrospective study

PURPOSE

Modular dual-mobility cups (MDMCs) have a lower risk for dislocation after total hip arthroplasty (THA). The primary aims of our study were to analyze implant survivorship and to determine complications, especially dislocation, and revision rates of primary THAs used for hip fracture patients and for revision THAs. Secondary aims were to evaluate mortality after MDMC surgery and to find out if introduction of MDMC at our institution (Kuopio University Hospital, Finland) have decreased dislocation rate.

METHODS

This retrospective cohort study consisted of 101 MDMC patients who were consecutively operated at our institution between April 1, 2018 and June 30, 2020. The implant survival rate, complications and mortality were evaluated with minimum of 2-year follow-up. Finnish Hospital Discharge Register was used to find out yearly dislocation rates following THA at our institution.

RESULTS

The cumulative estimate implant survival after MDMC in the primary THA group was 97% at 2 years, and in the revision THA group, it was 90% at 2 years. Dislocation was a rare complication in the primary THA group (1.4%), while it was common in revision THA group (12.9%). The cumulative estimate for mortality after MDMC in the primary THA group was 13% at 2 years, and in the revision group, it was also 13% at 2 years. The yearly number of patients who had re-hospitalization period due to THA dislocation decreased 46% after implementation of MDMC.

CONCLUSION

Short-term survival and complication rates after MDMC were excellent after primary THA and moderate after revision THA. Implementation of MDMC THA for hip fracture patients seems to have effectively decrease dislocation rate during a short follow-up.

Latest developments in arthroplasty for hip fractures

Hip fractures pose a major global health challenge, leading to high rates of morbidity and mortality, particularly among the elderly. With an ageing population, the incidence of these injuries is rising, exerting significant pressure on healthcare systems worldwide. Despite substantial research aimed at establishing best practice, several key areas remain the subject of ongoing debate. This article examines the latest evidence on the place of arthroplasty in the surgical treatment of hip fractures, with a particular focus on the choice of implant, the use of cemented versus uncemented fixation, and advances in perioperative care.

A cost-effectiveness analysis of three surgical options for treating displaced femoral neck fractures in active older patients in Japan: A full economic evaluation

For older patients with displaced femoral neck fractures, in which primary osteosynthesis is usually not indicated, there are three primary prosthetic options-bipolar hemiarthroplasty (BHA), single-bearing total hip arthroplasty (SB-THA), and dual-mobility THA (DM-THA). However, the optimal choice for managing displaced femoral neck fractures remains controversial. Accordingly, this study aimed to evaluate the cost-effectiveness of BHA, SB-THA, and DM-THA in active older patients with displaced femoral neck fractures. A decision tree combined with a Markov model was employed to analyze the cost and quality-adjusted life years (QALYs) of BHA, SB-THA, and DM-THA for the management in the Japanese healthcare system. By simulating the five-year trajectory of a 75-year-old woman treated for a displaced femoral neck fracture, the cost-effectiveness of the three surgical options was evaluated. One-way sensitivity analysis and probabilistic sensitivity analysis (PSA) were used to assess parameter uncertainty. Additionally, two scenario analyses were conducted for other settings. The treatment was considered to be cost-effective when the incremental cost-effectiveness ratio (ICER) was below the 5,000,000 yen/QALY threshold. Compared with BHA, SB-THA exhibited higher costs but greater health benefits, resulting in an ICER of 1,499,440 yen/QALY. DM-THA offered additional health benefits compared with SB-THA, with an ICER of 4,145,777 yen/QALY. One-way sensitivity analysis revealed some influential parameters. PSA indicated that the probability of DM-THA, SB-THA, and BHA being cost-effective was 40.1%, 38.5%, and 21.4%, respectively. SB-THA was more cost-effective than BHA in patients aged 65-85 years, while DM-THA was more cost-effective than SB-THA in patients aged 65-75 years. The results suggest that SB-THA is a cost-effective alternative to BHA for displaced femoral neck fractures in active older patients, whereas DM-THA is more cost-effective than SB-THA in relatively younger patients. It is, therefore, recommended that orthopedic surgeons select the most appropriate surgical option based on the individual patient's physiological age.

The Avantage ® dual mobility cup in primary total hip arthroplasty: A registry study

Background

Avantage Cup has been widely used in dual mobility implants. However, in Swedish Registry, the outcome of the Avantage Cup is reported with higher implants revision compared to control. The aim of our study was to verify if the same results are present in the Registry of Prosthetic Orthopedic Implants (RIPO) of Emilia Romagna (ER, Italy), as the Avantage cup was the most implanted dual mobility cup for a long follow-up reported in this Registry (2000-2012). Furthermore, we assessed the survival rate of the implant over the time.

Methods

We included all patients that underwent a primary THA using the Avantage cup during the period 2000-2020 in RIPO Registry. The survivorship of the primary THA implants was calculated and plotted according to Kaplan-Meier method.

Results

886 Avantage cups were included in the analysis. During the observational period 44 hips were revised. The most common reasons for revision were: periprosthetic fractures (PPF) (n = 7, 0.8 %), deep infection (n = 7, 0.8 %), and cup aseptic loosening (n = 13, 1.5 %).The survival rate of the implant was 96.8 % (95.3-97.8) at 5 years, 95.7 at 10 years (94.0-97.0) and 92.1 at 15 years (88.5-94.6).

Conclusion

In conclusion, this study has demonstrated that the Avantage cup in primary hip arthroplasty implanted with a "friendly" femoral stem granted satisfactory long-term survival. Therefore, in the Swedish Registry, the cause of the poor results presented for Avantage Cup could be the thick, rough neck stem of the widely used Lubinus stem.

A Meta-Analysis to Evaluate Implant Survival and Benefits of the Use of Dual Mobility Constructs in Total Hip Replacement Following Hip Fracture

Total hip replacement (THR) is commonly performed to treat hip fractures. Dual-mobility constructs (DMCs) are increasingly used for this indication. The aim of this study was to use evidence synthesis techniques to estimate net all-cause construct survival for THR with DMC performed for hip fracture. Additionally, we aimed to investigate and describe differences in all-cause construct survival (if present) between THRs performed with DMC (DMC-THR) or with a conventional bearing construct following hip fracture. We performed a systematic review and meta-analysis of published studies (including joint registries), including DMC-THR for hip fracture which provided Kaplan-Meier (KM) survival estimates. The primary outcome was all-cause construct survival over time. The study was prospectively registered on PROSPERO (CRD42020173117). A total of 557 papers and 17 registry reports were identified. Six studies (four registry reports, one matched-pair cohort study utilising joint registry data, and one single-institution case series) met the inclusion criteria, including 17,370 DMC THRs and 167,377 conventional THRs. Five-year KM survival estimates (95% confidence intervals) were similar at 95.4% (94.9 to 95.8%) for DMC-THR and 96.2% (96.0 to 96.4%) for conventional THR. The relative risk of revision for DMC-THR at five years was 1.21 (1.05 to 1.41). These results suggest that DMC-THR has a lower all-cause survival than conventional THR following hip fracture. This analysis does not support the routine use of DMC-THR over conventional bearing THR.

Metal artifact reduction sequence-MRI abnormalities in asymptomatic patients with dual-mobility hip prostheses

Aims

Modular dual-mobility (DM) articulations are increasingly used during total hip arthroplasty (THA). However, concerns remain regarding the metal liner modularity. This study aims to correlate metal artifact reduction sequence (MARS)-MRI abnormalities with serum metal ion levels in patients with DM articulations.

Methods

A total of 45 patients (50 hips) with a modular DM articulation were included with mean follow-up of 3.7 years (SD 1.2). Enrolled patients with an asymptomatic, primary THA and DM articulation with over two years' follow-up underwent MARS-MRI. Each patient had serum cobalt, chromium, and titanium levels drawn. Patient satisfaction, Oxford Hip Score, and Forgotten Joint Score-12 (FJS-12) were collected. Each MARS-MRI was independently reviewed by fellowship-trained musculoskeletal radiologists blinded to serum ion levels.

Results

Overall, two patients (4.4%) had abnormal periprosthetic fluid collections on MARS-MRI with cobalt levels > 3.0 μg/l. Four patients (8.9%) had MARS-MRI findings consistent with greater trochanteric bursitis, all with cobalt levels < 1.0 μg/l. A seventh patient had a periprosthetic fluid collection with normal ion levels. Of the 38 patients without MARS-MRI abnormalities, 37 (97.4%) had cobalt levels < 1.0 μg/l, while one (2.6%) had a cobalt level of 1.4 μg/l. One patient (2.2%) had a chromium level > 3.0 μg/l and a periprosthetic fluid collection. Of the 41 patients with titanium levels, five (12.2%) had titanium levels > 5.0 μg/l without associated MARS-MRI abnormalities.

Conclusion

Periprosthetic fluid collections associated with elevated serum cobalt levels in patients with asymptomatic DM articulations occur infrequently (4.4%), but further assessment is necessary due to implant heterogeneity.

Two-Year Outcomes of Novel Dual-Mobility Implant in Primary Total Hip Arthroplasty

Introduction

Dual-mobility (DM) implants for total hip arthroplasty (THA) have gained popularity due to their potential to reduce hip instability and dislocation events that may lead to revision surgery. These implants consist of a femoral head articulated within a polyethylene liner, which articulates within an outer acetabular shell, creating a dual-bearing surface. Our study aimed to report our observations on the survivorship of a novel DM implant for primary total hip arthroplasty at two years.

Methods

We conducted a retrospective, multicenter study to assess the clinical outcomes of patients undergoing a THA with a novel DM implant (OR3O acetabular system™, Smith & Nephew, Inc., Memphis, TN) from January 2020 to September 2021. Patient demographics, surgical information, and survivorship data were collected from medical records for patients with a minimum of two years of follow-up. Primary outcomes included overall implant survivorship at two years as well as aseptic survivorship, revision rates of the DM acetabular shell, and average time to revision. Patient-reported outcomes were collected in the form of HOOS JR.

Results

A total of 250 hips in 245 patients had a minimum two-year follow-up. Primary osteoarthritis (80%) was the most common indication for index THA. The average aseptic survivorship of the DM acetabular components at two years for the cohort was 98.4% and survivorship of the acetabular implants overall was 97.6%. There were a total of four (1.6%) aseptic revisions of the DM acetabular component. Reasons for aseptic acetabular revision included one case of instability, one intraprosthetic dislocation, one periprosthetic acetabular fracture, and one malpositioned acetabular cup resulting in impingement. The mean time of follow-up was 893.9 days. Eighty-seven patients had preoperative and two-year HOOS JR available. HOOS JR improved by an average of 38.5 points.

Conclusion

This novel DM acetabular implant demonstrates excellent survivorship at two years follow-up with low rates of instability and intraprosthetic dislocation and no episodes of metal-on-metal corrosion. Use of the DM implant demonstrated clinically relevant improvements in patient-reported outcomes at two years.

Evolution and New Generation of Dual Mobility Cups

Although total hip arthroplasty (THA) is considered a successful procedure, hip dislocation remains the main cause of early failure. Dual mobility cups (DMCs) have been shown to significantly reduce the dislocation rate in both primary and revision THAs. During the past several decades, DMCs have evolved in design and fixation interface. There have been three generations of DMCs. This article addresses the rationale for a new cementless highly porous titanium DMC to improve component fixation and implant biocompatibility. [Orthopedics. 2023;46(5):e273-e280.].

Modular dual mobility articulation in primary and revision hip arthroplasty: lights and shadows

PURPOSE

The use of dual mobility cups in total hip arthroplasty has gained popularity in light of the fact it enables to reduce dislocation through increased jumping distance (JD) and impingement-free arc of movement. Modular Dual Mobility Cup (modular DMC) systems have been recently introduced to enable the use of dual mobility cups with standard metal-backed shells. The objective of this study was twofold: calculate the JD for each modular DMC system and conduct a systematic literature review to report clinical outcomes and reasons for failure of this construct.

METHODS

The JD was calculated using the Sariali formula: JD = 2Rsin [(π/2 - Ψ - arcsin (offset/R))/2]. A qualitative systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search for English and French articles between January 2000 and July 2020 was run on PubMed, EMBASE, Google Scholar, and Scopus with the primary objective of finding articles about modular DMC systems.

RESULTS

We identified eight 8 different manufacturers of modular DMC systems and 327 publications on the subject. After screening for duplicates and eligibility, we identified 229 publications: 206 articles were excluded because they contained no reports on modular DMC systems, whereas other three were not included because they focused on biomechanical aspects. Among the 11 included articles, 2 were prospective case series, 9 were retrospective case series. True dislocation occurred in 25 cases (0.9%), and six of them were solved by closed reduction without necessity of revision, while all 5 intraprosthetic dislocations were operated.

CONCLUSIONS

Modular DMCs are a valid method to deal with complex THA instability, with good clinical and patient-reported outcomes, low complication rates, and low revision rates at early follow-up. We would advise cautious optimism on the role of modular DMC implants, as it seems safer to use ceramic instead of metallic heads whenever possible to avoid the increase cobalt and chromium trace ion serum levels.

Exuberant Rice Body Formation Associated with Adverse Local Tissue Reaction After Hip Resurfacing Arthroplasty: A Case Report and Review of the Literature

CASE

A 65-year-old man with osteoarthritis of the hip developed a soft-tissue mass of the inferior gluteal region 3 years after metal-on-metal resurfacing hip arthroplasty. Clinical and imaging findings suggested an adverse local tissue reaction. Intraoperatively, nearly 1 liter of intra-articular fibrinous loose bodies (rice bodies) was removed, and histology showed features of an adaptive immune response. The patient had no evidence of an autoimmune disease or mycobacterial infection.

CONCLUSION

To our knowledge, this is the first reported case of florid rice bodies associated with a metal-on-metal hip arthroplasty and adverse local tissue reaction.

Is outcome of total hip arthroplasty for hip fracture inferior to that of arthritis in a contemporary arthroplasty practice?

INTRODUCTION

Outcome of total hip arthroplasty (THA) for femoral neck fractures (FNF) has been associated with higher complication rates. However, THA for FNF is not always performed by arthroplasty-surgeons. This study aimed to compare THA outcomes for FNF to osteoarthritis (OA). In doing so, we described contemporary THA failure modes for FNF performed by arthroplasty surgeons.

METHODS

This was a retrospective, multi-surgeon study from an academic center. Of FNF treated between 2010 and 2020, 177 received THA by an arthroplasty-surgeon [mean age 67 years (range, 42 to 97), sex: 64.4% women]. These were matched (1:2) for age and sex with 354 THAs performed for hip OA, by the same surgeons. No dual-mobilities were used. Outcomes included radiologic measurements (inclination/anteversion and leg-length), mortality, complications, reoperation rates and patient-reported outcomes including Oxford Hip Score (OHS).

RESULTS

Post-operative mean leg-length difference was 0 millimeters (mm) (range, -10 to -10 mm), with a mean cup inclination and anteversion of 41 and 26° respectively. There was no difference in radiological measurements between FNF and OA patients (p=0.3). At 5 years follow-up, mortality rate was significantly higher in the FNF-THA compared to the OA-THA group (15.3 vs. 1.1%; p<0.001). There was no difference in complications (7.3 vs. 4.2%; p=0.098) or reoperation rates (5.1 vs. 2.9%; p=0.142) between groups. Dislocation rate was 1.7%. OHS at final follow-up was similar [43.7 points (range, 10 to 48) vs. 43.6 points (range, 10 to 48); p=0.030].

CONCLUSION

Total hip arthroplasty for the treatment of FNF is a reliable option and is associated with satisfactory outcomes. Instability was not a common reason of failure, despite not using dual-mobility articulations in this at-risk population. This is likely due to THAs being performed by the arthroplasty staff. When patients live beyond 2-years, similar clinical and radiographic outcomes with low rates of revision can be expected, comparable to elective THA for OA.

Total Hip Arthroplasty in fracture neck of femur: A review of the literature

Fracture Neck of Femur (FnF) is a major cause of loss of independence, morbidity and mortality in a vulnerable group of elderly patients; as well as a substantial economic burden on healthcare systems across the world. An increasingly ageing population has resulted in a rise in incidence and prevalence of FnF. Over 76,000 patients were admitted with FnF in the United Kingdom in 2018, with the resulting health and social costs estimated to be in excess of £2 billion. It is therefore important that the outcomes of all management options be evaluated to ensure constant improvement as well as allocation of resources as appropriate. It is widely agreed that patients presenting with displaced intracapsular FnF injuries are managed operatively; with options including internal fixation, hemiarthroplasty or Total Hip Arthroplasty (THA). The volume of THA performed for FnF has significantly increased in recent years. However, compliance with national guidelines on FnF patient selection for THA has been shown to be inconsistent. The aim of this study was to review current literature with regards to the use of THA in management of FnF patients. The literature describes managing FnF in ambulant and independent patients by THA with dual-mobility acetabular cup and cemented femoral component via the anterolateral approach. There is scope for further research in assessing the outcomes of different prosthetic femoral head sizes and choice of bearing surfaces (tribiology) used for THA as well as cementation of the acetabular cup component specifically in FnF patients.

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.

Comparing Outcomes of Total Hip Arthroplasty for Displaced Neck of Femur Fractures in Elderly Patients Utilizing Dual Mobility Cups and Conventional Implants: A Single Center Retrospective Study of 129 Patients

Introduction

Studies comparing the use of total hip arthroplasty (THA) with conventional implants and hemiarthroplasty for displaced femoral neck fractures (DFNF) have reported better patient satisfaction scores and outcomes in the former, but also significant dislocation rates (6.9-13%).The total hip arthroplasty with dual mobility cup (THA-DMC) design is mechanically proven to increase the hip range of motion and jump distance to dislocation relative to conventional implants. Despite its potential benefit, clinical studies analyzing the use of THA-DMC in the treatment of DFNF in comparison to conventional THA within the Asian population are still limited. Our study aims to compare the rate of complications and functional outcomes between the 2 implants in the treatment of DFNF.

Materials and Methods

This was a retrospective cohort study conducted in a single tertiary care institution. From January 2015 to May 2020, data from 129 consecutive patients who satisfied the inclusion criteria and underwent either a THA or THA-DMC for DFNF were collected and divided into 2 groups. All patients received a standardized post-operative treatment and follow-up regime. Both groups of patients were assessed for post-operative complications such as dislocation, peri-prosthetic fractures, surgical site infections, medical complications. Their functional outcomes as well as patient-reported outcome scores were also assessed via the SF-36 score and Oxford hip score questionnaires at 6 months and 1 year.

Results

A total of 42 patients with dual mobility implants and 87 patients with conventional implants were recruited. There was no dislocation in the THA-DMC group while there were 4 cases (4/87, 4.6%) of dislocation in the THA group. Regarding post-operative function, both groups had comparable functional outcomes. There were no statistically significant differences between the patient-reported outcome scores (Oxford hip score and SF-36) at 6 months and 1 year.

Conclusion

We report promising short-term outcomes utilizing dual mobility implants in total hip arthroplasty for the treatment of DFNFs.

Do Dual-mobility Cups Reduce Revision Risk in Femoral Neck Fractures Compared With Conventional THA Designs? An International Meta-analysis of Arthroplasty Registries

BACKGROUND

Dual-mobility cups in THA were designed to reduce prosthesis instability and the subsequent risk of revision surgery in high-risk patients, such as those with hip fractures. However, there are limited data from clinical studies reporting a revision benefit of dual-mobility over conventional THA. Collaboration between anthroplasty registries provides an opportunity to describe international practice variation and compare between-country, all-cause revision rates for dual-mobility and conventional THA.

QUESTIONS/PURPOSES

We summarized observational data from multiple arthroplasty registries for patients receiving either a dual-mobility or conventional THA to ask: (1) Is dual-mobility use associated with a difference in risk of all-cause revision surgery compared with conventional THA? (2) Are there specific patient characteristics associated with dual-mobility use in the hip fracture population? (3) Has the use of dual-mobility constructs changed over time in patients receiving a THA for hip fracture?

METHODS

Six member registries of the International Society of Arthroplasty Registries (from Australia, Denmark, Sweden, the Netherlands, the United Kingdom, and the United States) provided custom aggregate data reports stratified by acetabular cup type (dual-mobility or conventional THA) in primary THA for hip fracture between January 1, 2002, and December 31, 2019; surgical approach; and patient demographic data (sex, mean age, American Society of Anesthesiologists class, and BMI). The cumulative percent revision and mortality were calculated for each registry. To determine a global hazard ratio of all-cause revision for dual-mobility compared with conventional THA designs, we used a pseudoindividual patient data approach to pool Kaplan-Meier prosthesis revision data from each registry and perform a meta-analysis. The pseudoindividual patient data approach is a validated technique for meta-analysis of aggregate time-to-event survival data, such as revision surgery, from multiple sources. Data were available for 15,024 dual-mobility THAs and 97,200 conventional THAs performed for hip fractures during the study period.

RESULTS

After pooling of complete Kaplan-Meier survival data from all six registries, the cumulative percent revision for conventional THA was 4.3% (95% confidence interval [CI] 4.2% to 4.5%) and 4.7% (95% CI 4.3% to 5.3%) for dual-mobility THA at 5 years. We did not demonstrate a lower risk of all-cause revision for patients receiving dual-mobility over conventional THA designs for hip fracture in the meta-analysis once between-registry differences were adjusted for (HR 0.96 [95% CI 0.86 to 1.06]). A lower proportion of dual-mobility procedures were revised for dislocation than conventional THAs (0.9% versus 1.4%) but a higher proportion were revised for infection (1.2% versus 0.8%). In most registries, a greater proportion of dual-mobility THA patients were older, had more comorbidities, and underwent a posterior approach compared with conventional THA (p < 0.001). The proportion of dual-mobility THA used to treat hip fractures increased in each registry over time and constituted 21% (2438 of 11,874) of all THA procedures in 2019.

CONCLUSION

The proportion of dual-mobility THAs in patients with hip fractures increased over time, but there was large variation in use across countries represented here. Dual-mobility cups were not associated with a reduction in the overall risk of revision surgery in patients with hip fractures. A randomized controlled trial powered to detect the incidence of dislocation and subsequent revision surgery is required to clarify the efficacy of dual-mobility cups to treat hip fractures.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Dual mobility versus conventional total hip arthroplasty in femoral neck fractures (DISTINCT): protocol for a registry-nested, open-label, cluster-randomised crossover trial

INTRODUCTION

Hip fractures treated with total hip arthroplasty (THA) are at high risk of prosthesis instability, and dislocation is the most common indication for revision surgery. This study aims to determine whether dual mobility THA implants reduce the risk of dislocation compared with conventional THA in patients with hip fracture suitable to be treated with THA.

METHODS AND ANALYSIS

This is a cluster-randomised, crossover, open-label trial nested within the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The clusters will comprise hospitals that perform at least 12 THAs for hip fracture per annum. All adults age ≥50 years who meet the Australian and New Zealand Hip Fracture Registry guidelines for THA will be included. The intervention will be dual mobility THA and the comparator will be conventional THA. Each hospital will be allocated to two consecutive periods, one of dual mobility THA and the other of conventional THA in random order, aiming for an average of 16 patients eligible for the primary analysis per group (32 total per site), allowing different recruitment totals between sites. Data will be collected through the AOANJRR and linked with patient-level discharge data acquired through government agencies. The primary outcome is dislocation within 1 year. Secondary outcomes include revision surgery for dislocation and all-cause, complications and mortality at 1, 2 and 5 years. If dual mobility THA is found to be superior, a cost-effectiveness analysis will be conducted. The study will aim to recruit 1536 patients from at least 48 hospitals over 3 years.

ETHICS AND DISSEMINATION

Ethics approval has been granted (Sydney Local Health District - Royal Prince Alfred Hospital Zone (approval X20-0162 and 2020/ETH00680) and site-specific approvals). Participant recruitment is via an opt-out consent process as both treatments are considered accepted, standard practice. The trial is endorsed by the Australia and New Zealand Musculoskeletal Clinical Trials Network.

TRIAL REGISTRATION NUMBER

ACTRN12621000069853.

Is the Revision Rate for Femoral Neck Fracture Lower for Total Hip Arthroplasty Than for Hemiarthroplasty?: A Comparison of Registry Data for Contemporary Surgical Options

BACKGROUND

When arthroplasty is indicated for a femoral neck fracture (FNF), it is unclear whether total hip arthroplasty (THA) or hemiarthroplasty (HA) is best. This study compares data from the Australian Orthopaedic Association National Joint Replacement Registry using contemporary surgical options.

METHODS

Patients from 60 to 85 years old who were treated with arthroplasty for FNF, between September 1999 and December 2019, were included if the femoral stems were cemented. Only THAs with femoral heads of ≥36 mm or dual-mobility articulations were included. Patients who had monoblock HA were excluded. Rates of revision for all aseptic failures and dislocation were compared. Competing risks of revision and death were considered using the cumulative incidence function. Subdistribution hazard ratios (HRs) for revision or death from a Fine-Gray regression model were used to compare THA and HA. Interactions of procedure with age group and sex were considered. Secondary analysis adjusting for body mass index (BMI) and American Society of Anesthesiologists (ASA) classification was also considered.

RESULTS

There were 4,551 THA and 29,714 HA procedures included. The rate of revision for THA was lower for women from 60 to 69 years old (HR = 0.58 [95% confidence interval (CI), 0.39 to 0.85]) and from 70 to 74 years old (HR = 0.65 [95% CI, 0.43 to 0.98]) compared with HA. However, women from 80 to 85 years old (HR = 1.56 [95% CI, 1.03 to 2.35]) and men from 75 to 79 years old (HR = 1.61 [95% CI, 1.05 to 2.46]) and 80 to 85 years old (HR = 2.73 [95% CI, 1.89 to 3.95]) had an increased rate of revision when THA was undertaken compared with HA. There was no difference in the rate of revision for dislocation between THA and HA for either sex or age categories.

CONCLUSIONS

When contemporary surgical options for FNF are used, there is a benefit with respect to revision outcomes for THA in women who are <75 years old and a benefit for HA in women who are ≥80 years old and men who are ≥75 years old. There is no difference in dislocation rates.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Lower Rates of Ceramic Femoral Head Use in Non-White Patients in the United States, a National Registry Study

BACKGROUND

The purpose of our study was to investigate the association of race and ethnicity with the use of the newest technology and postoperative outcomes in total hip arthroplasty (THA) using the American Academy of Orthopaedic Surgeons (AAOS) American Joint Replacement Registry (AJRR).

METHODS

Adult THA procedures were queried from the AJRR from 2012 to 2020. A mixed-effects multivariate regression model was used to evaluate the association of race and ethnicity with the use of the newest technology (ceramic femoral head, dual-mobility implant, and robotic assist) at 30-day, and 90-day readmission. A proportional subdistribution hazard model was used to model a risk of revision THA.

RESULTS

There were 85,188 THAs with complete data for an analysis of outcomes and 103,218 for an analysis of ceramic head usage. The median length of follow-up was 37.9 months (interquartile range [IQR] 21.6 to 56.3 months). In multivariate models, compared to White non-Hispanic patients, Black (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.69-0.92, P < .001), Hispanic (OR 0.76, CI 0.59-0.99, P = .037), Asian (OR 0.74, CI 0.55-1.00, P = .045), and Native American (OR 0.52, CI 0.30-0.87, P = .004) patients all had significantly lower rates of ceramic head use in THA. Compared to White non-Hispanic patients, Asian (hazard ratio [HR] 0.39, CI 0.18-0.86, P = .008) and Hispanic (HR 0.43, CI 0.19-0.98, P = .043) patients had significantly lower rates of revision. No differences in 30-day or 90-day readmission rates were seen.

CONCLUSION

Black, Hispanic, Native American, and Asian patients had lower rates of ceramic head use in THA when compared to White patients. These differences did not translate into worse clinical outcomes on a short-term follow-up. In fact, Asian patients had lower revision rates compared to non-Hispanic White patients. Additional study is necessary to evaluate the long-term consequence of lower ceramic head use in non-White patients in the United States.

The association of surgical approach and bearing size and type with dislocation in total hip arthroplasty for acute hip fracture

AIMS

Patients with femoral neck fractures (FNFs) treated with total hip arthroplasty (THA) have an almost ten-fold increased risk of dislocation compared to patients undergoing elective THA. The surgical approach influences the risk of dislocation. To date, the influence of differing head sizes and dual-mobility components (DMCs) on the risk of dislocation has not been well studied.

METHODS

In an observational cohort study on 8,031 FNF patients with THA between January 2005 and December 2014, Swedish Arthroplasty Register data were linked with the National Patient Register, recording the total dislocation rates at one year and revision rates at three years after surgery. The cumulative incidence of events was estimated using the Kaplan-Meier method. Cox multivariable regression models were fitted to calculate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for the risk of dislocation, revision, or mortality, stratified by surgical approach.

RESULTS

The cumulative dislocation rate at one year was 8.3% (95% CI 7.3 to 9.3) for patients operated on using the posterior approach and 2.7% (95% CI 2.2 to 3.2) when using the direct lateral approach. In the posterior approach group, use of DMC was associated with reduced adjusted risk of dislocation compared to 32 mm heads (HR 0.21 (95% CI 0.07 to 0.68); p = 0.009). This risk was increased with head sizes < 32 mm (HR 1.47 (95% CI 1.10 to 1.98); p = 0.010). Neither DMC nor different head sizes influenced the risk of revision following the posterior approach. Neither articulation was associated with a statistically significantly reduced adjusted risk of dislocation in patients where the direct lateral approach was performed, although this risk was estimated to be HR 0.14 (95% CI 0.02 to 1.02; p = 0.053) after the use of DMC. DMC inserted through a direct lateral approach was associated with a reduced risk of revision for any reason versus THA with 32 mm heads (HR 0.36 (95% CI 0.13 to 0.99); p = 0.047).

CONCLUSION

When using a posterior approach for THA in FNF patients, DMC reduces the risk of dislocation, while a non-significant risk reduction is seen for DMC after use of the direct lateral approach. The direct lateral approach is protective against dislocation and is also associated with a lower rate of revision at three years, compared to the posterior approach. Cite this article: Bone Joint J 2022;104-B(7):844-851.

In Revision THA, Is the Re-revision Risk for Dislocation and Aseptic Causes Greater in Dual-mobility Constructs or Large Femoral Head Bearings? A Study from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Dislocation is one of the most common causes of a re-revision after a revision THA. Dual-mobility constructs and large femoral head bearings (≥ 36 mm) are known options for mitigating this risk. However, it is unknown which of these choices is better for reducing the risk of dislocation and all-cause re-revision surgery. It is also unknown whether there is a difference between dual-mobility constructs and large femoral head bearings according to the size of the acetabular component.

QUESTIONS/PURPOSES

We used data from a large national registry to ask: In patients undergoing revision THA for aseptic causes after a primary THA performed for osteoarthritis, (1) Does the proportion of re-revision surgery for prosthesis dislocation differ between revision THAs performed with dual-mobility constructs and those performed with large femoral head bearings? (2) Does the proportion of re-revision surgery for all aseptic causes differ between revision THAs performed with dual-mobility constructs and those performed with large femoral head bearings? (3) Is there a difference when the results are stratified by acetabular component size?

METHODS

Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) were analyzed for 1295 first-revision THAs for aseptic causes after a primary THA performed for osteoarthritis. The study period was from January 2008-when the first dual-mobility prosthesis was recorded-to December 2019. There were 502 dual-mobility constructs and 793 large femoral head bearings. There was a larger percentage of women in the dual-mobility construct group (67% [334 of 502]) compared with the large femoral head bearing group (51% [402 of 793]), but this was adjusted for in the statistical analysis. Patient ages were similar for the dual-mobility construct group (67 ± 11 years) and the large femoral head group (65 ± 12 years). American Society of Anesthesiologists (ASA) class and BMI distributions were similar. The mean follow-up was shorter for dual-mobility constructs at 2 ± 1.8 years compared with 4 ± 2.9 years for large femoral head bearings. The cumulative percent revision (CPR) was determined for a diagnosis of prosthesis dislocation as well as for all aseptic causes (excluding infection). Procedures using metal-on-metal bearings were excluded. The time to the re-revision was described using Kaplan-Meier estimates of survivorship, with right censoring for death or database closure at the time of analysis. The unadjusted CPR was estimated each year of the first 5 years for dual-mobility constructs and for each of the first 9 years for large femoral head bearings, with 95% confidence intervals using unadjusted pointwise Greenwood estimates. The apparent shorter follow-up of the dual-mobility construct group relates to the more recent increase in dual-mobility numbers recorded in the registry. The results were adjusted for age, gender, and femoral fixation. Results were subanalyzed for acetabular component sizes < 58 mm and ≥ 58 mm, set a priori on the basis of biomechanical and other registry data.

RESULTS

There was no difference in the proportion of re-revision for prosthesis dislocation between dual-mobility constructs and large femoral head bearings (hazard ratio 1.22 [95% CI 0.70 to 2.12]; p = 0.49). At 5 years, the CPR of the re-revision for prosthesis dislocation was 4.0% for dual mobility constructs (95% CI 2.3% to 6.8%) and 4.1% for large femoral head bearings (95% CI 2.7% to 6.1%). There was no difference in the proportion of all aseptic-cause second revisions between dual-mobility constructs and large femoral head bearings (HR 1.02 [95% CI 0.76 to 1.37]; p = 0.89). At 5 years, the CPR of dual-mobility constructs was 17.6% for all aseptic-cause second revision (95% CI 12.6% to 24.3%) and 17.8% for large femoral head bearings (95% CI 14.9% to 21.2%). When stratified by acetabular component sizes less than 58 mm and at least 58 mm, there was no difference in the re-revision CPR for dislocation or for all aseptic causes between dual-mobility constructs and large femoral head bearings.

CONCLUSION

Either dual-mobility constructs or large femoral head bearings can be used in revision THA, regardless of acetabular component size, as they did not differ in terms of re-revision rates for dislocation and all aseptic causes in this registry study. Longer term follow-up is required to assess whether complications develop with either implant or whether a difference in revision rates becomes apparent. Ongoing follow-up and comparison in a registry format would seem the best way to compare long-term complications and revision rates. Future studies should also compare surgeon factors and whether they influence decision-making between prosthesis options and second revision rates. Nested randomized controlled trials in national registries would seem a viable option for future research.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Bipolar Hemiarthroplasty Does Not Result in a Higher Risk of Revision Compared with Total Hip Arthroplasty for Displaced Femoral Neck Fractures: An Instrumental Variable Analysis of 36,118 Procedures from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Previous randomized studies have suggested that there is no short-term difference between the risk of revision following total hip arthroplasty (THA) and hemiarthroplasty (HA) for hip fracture in elderly patients. The aim of the present study was to compare the long-term revision rates of primary THA and HA for femoral neck fracture in order to determine whether unipolar or bipolar HA increases the all-cause risk of revision in patients 50 to 79 years old.

METHODS

Data for 36,188 patients who underwent primary arthroplasty, including 13,035 unipolar and 8,220 bipolar HAs and 14,863 THAs, from September 1, 1999, to December 31, 2019, were obtained from the Australian Orthopaedic Association National Joint Replacement Registry. Unadjusted analyses were performed, as well as analyses adjusted for age, sex, femoral cement, and procedure year. The primary outcome was time to first revision for any cause. Secondary analyses were performed for the reason for revision (i.e., infection, dislocation, and periprosthetic fracture). Instrumental variable analysis of hospital preference (for either HA or THA) was performed in order to mitigate the effect of any unmeasured confounding. All analyses were restricted to hospitals performing at least 10 procedures in the prior year.

RESULTS

A total of 18,955 procedures were available for the comparison of modular unipolar HA to THA. Both the adjusted analysis performed with use of Cox proportional hazards (hazard ratio [HR], 1.94; 95% confidence interval [CI], 1.64 to 2.31; p < 0.001) and the instrumental variable analysis (HR, 2.82; 95% CI, 1.89 to 4.22; p < 0.001) demonstrated a higher risk of revision following modular unipolar HA compared with THA from 3 months postoperatively. A total of 13,168 procedures were available for the comparison of bipolar HA to THA. The adjusted analysis performed with use of Cox proportional hazards showed a significantly higher risk of revision for bipolar HA (HR, 1.29; 95% CI, 1.08 to 1.54; p = 0.01). The instrumental variable analysis showed a similar effect size that was not significant (HR, 1.27; 95% CI, 0.91 to 1.78; p = 0.16).

CONCLUSIONS

Bipolar HA and THA demonstrated no significant difference in revision risk at long-term follow-up. Unipolar HA demonstrated higher risk of revision from 3 months postoperatively compared to THA. The higher risk of revision for dislocation observed following THA may be offset by the higher risk of revision for acetabular erosion or pain following bipolar HA, resulting in more equivalent revision risk.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Dual-mobility constructs versus large femoral head bearings in primary and revision total hip arthroplasty: a systematic review and meta-analysis of comparative studies

BACKGROUND

Both dual-mobility (DM) constructs and large femoral head bearings (⩾36 mm) reduce dislocation following total hip arthroplasty (THA). There is limited research comparing DM with large bearings.

METHODS

A systematic review of published literature was performed including studies that compared DM with large femoral head bearings in primary or revision THA according to PRISMA guidelines. The primary outcome was revision surgery for dislocation. The secondary outcome was all-cause revision surgery. Other complications were recorded. 2 authors independently selected studies, performed data extraction, and risk of bias assessment. Treatment effects were assessed using odds ratios and data were pooled using a fixed-effect model, where appropriate.

RESULTS

9 studies, all retrospective, met the final inclusion criteria. 2722 patients received DM and 9,789 large femoral head bearings. The difference in the odds of revision surgery for dislocation (OR 0.67; 95% CI, 0.45-1.01; p = 0.06) and aseptic loosening are unclear (OR 0.61; 95% CI, 0.36-1.05; p = 0.07); including important benefits and no difference. There was a benefit favouring DM for the risk of all-cause revision (OR 0.70; 95% CI, 0.56-0.86; p = 0.001), revision for fracture (OR 0.49; 95% CI, 0.29-0.81; p = 0.005) and dislocation not requiring revision (OR 0.29; 95% CI, 0.14-0.57; p < 0.001). The estimate in the difference in the odds of revision surgery for infection was imprecise (OR 0.78; 95% CI, 05.1-1.20; p = 0.26).

CONCLUSIONS

This study provides evidence that there may be clinically relevant benefits of DM constructs over large femoral head bearings. Prospective randomised studies are warranted given these findings.

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

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, patient-reported 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.

Dual-Mobility Implants and Constrained Liners in Revision Total Hip Arthroplasty

BACKGROUND

Instability remains the most common complication after revision total hip arthroplasty (THA). The purpose of this study was to determine whether there was a difference in aseptic revision rates and survivorship between dual-mobility (DM) and constrained liners (CL) in revision THA.

METHODS

We reviewed a consecutive series of 2432 revision THA patients from 2008 to 2019 at our institution and identified all patients who received either a CL or DM bearing. We compared demographics, comorbidities, indications, dislocations, and aseptic failure rates between the two groups. Bivariate and multivariate regression analyses were used to determine risk factors for failure, and a Kaplan-Meier survivorship analysis was performed with an aseptic re-revision as the endpoint.

RESULTS

Of the 191 patients, 139 (72%) received a DM bearing, and 52 (28%) had a CL. At a mean follow-up of 14.3 months, there was no statistically significant difference in rates of dislocation (10.4% vs 14.0%, P = .667), aseptic revision (30.9% vs 46.2%, P = .073), or time to revision (3.78 vs 6 months, P = .565) between the two groups. The multivariate analysis revealed CL had no difference in aseptic re-revision rates when compared with DM (odds ratio 1.47, 95% confidence interval 0.84-2.52, P = .177). The survivorship analysis found no difference in aseptic failure between the groups at 12 months (P = .059).

CONCLUSION

Both CL and DM bearings have high aseptic failure rates at intermediate term follow-up after revision THA. CL did show a higher risk of failure than DM bearings, but it was not statistically significant with the numbers available for this study. Further prospective studies are needed to determine the optimal treatment for recurrent instability.

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

INTRODUCTION

The 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.

HYPOTHESIS

Our 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 METHODS

A 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.

RESULTS

The 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).

DISCUSSION

The 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 EVIDENCE

IV; retrospective study without control group.

Total, hemi, or dual-mobility arthroplasty for the treatment of femoral neck fractures in patients with neurological disease : analysis of 9,638 patients from the Swedish Hip Arthroplasty Register

AIMS

The aim of this study was to investigate the potentially increased risk of dislocation in patients with neurological disease who sustain a femoral neck fracture, as it is unclear whether they should undergo total hip arthroplasty (THA) or hemiarthroplasty (HA). A secondary aim was to investgate whether dual-mobility components confer a reduced risk of dislocation in these patients.

METHODS

We undertook a longitudinal cohort study linking the Swedish Hip Arthroplasty Register with the National Patient Register, including patients with a neurological disease presenting with a femoral neck fracture and treated with HA, a conventional THA (cTHA) with femoral head size of ≤ 32 mm, or a dual-mobility component THA (DMC-THA) between 2005 and 2014. The dislocation rate at one- and three-year revision, reoperation, and mortality rates were recorded. Cox multivariate regression models were fitted to calculate adjusted hazard ratios (HRs).

RESULTS

A total of 9,638 patients with a neurological disease who also underwent unilateral arthroplasty for a femoral neck fracture were included in the study. The one-year dislocation rate was 3.7% after HA, 8.8% after cTHA < 32 mm), 5.9% after cTHA (= 32 mm), and 2.7% after DMC-THA. A higher risk of dislocation was associated with cTHA (< 32 mm) compared with HA (HR 1.90 (95% confidence interval (CI) 1.26 to 2.86); p = 0.002). There was no difference in the risk of dislocation with DMC-THA (HR 0.68 (95% CI 0.26 to 1.84); p = 0.451) or cTHA (= 32 mm) (HR 1.54 (95% CI 0.94 to 2.51); p = 0.083). There were no differences in the rate of reoperation and revision-free survival between the different types of prosthesis and sizes of femoral head.

CONCLUSION

Patients with a neurological disease who sustain a femoral neck fracture have similar rates of dislocation after undergoing HA or DMC-THA. Most patients with a neurological disease are not eligible for THA and should thus undergo HA, whereas those eligible for THA could benefit from a DMC-THA. Cite this article: Bone Joint J 2022;104-B(1):134-141.

Cost-effectiveness of dual-mobility components in patients with displaced femoral neck fractures

AIMS

Total hip arthroplasty (THA) with dual-mobility components (DM-THA) has been shown to decrease the risk of dislocation in the setting of a displaced neck of femur fracture compared to conventional single-bearing THA (SB-THA). This study assesses if the clinical benefit of a reduced dislocation rate can justify the incremental cost increase of DM-THA compared to SB-THA.

METHODS

Costs and benefits were established for patients aged 75 to 79 years over a five-year time period in the base case from the Canadian Health Payer's perspective. One-way and probabilistic sensitivity analysis assessed the robustness of the base case model conclusions.

RESULTS

DM-THA was found to be cost-effective, with an estimated incremental cost-effectiveness ratio (ICER) of CAD $46,556 (£27,074) per quality-adjusted life year (QALY). Sensitivity analysis revealed DM-THA was not cost-effective across all age groups in the first two years. DM-THA becomes cost-effective for those aged under 80 years at time periods from five to 15 years, but was not cost-effective for those aged 80 years and over at any timepoint. To be cost-effective at ten years in the base case, DM-THA must reduce the risk of dislocation compared to SB-THA by at least 62%. Probabilistic sensitivity analysis showed DM-THA was 58% likely to be cost-effective in the base case.

CONCLUSION

Treating patients with a displaced femoral neck fracture using DM-THA components may be cost-effective compared to SB-THA in patients aged under 80 years. However, future research will help determine if the modelled rates of adverse events hold true. Surgeons should continue to use clinical judgement and consider individual patients' physiological age and risk factors for dislocation. Cite this article: Bone Joint J 2021;103-B(12):1783-1790.

Modular Dual Mobility Constructs Used for Recurrent Hip Instability

Background

Recurrent hip dislocation despite prior attempts at surgical stabilization is a dreadful and technically challenging complication. A modular dual mobility (MDM) articulation has shown promise in addressing this problem, which might seem intractable. Our purpose was to examine the outcomes of revision total hip arthroplasty (THA) with an MDM placed through a direct anterior (DA) approach when all other conservative and surgical treatments have failed.

Methods

Fifteen patients revised with an MDM for recurrent instability (RI) between 2012 and 2018 by a single surgeon at a single institution were reviewed retrospectively, with a minimum of two years' follow-up. All patients underwent full acetabular revision with an MDM articulation through a DA approach with intraoperative fluoroscopy. No stems were revised. Dislocations, complications, and clinical outcomes are reported.

Results 

All patients had recurrent posterior instability with a mean number of 4 ± 2 (range: 2 to 8) dislocations prior to MDM revision THA (MDM rTHA). Eight patients had already failed surgical intervention for instability, and seven had failed repeated closed reductions and conservative care. After MDM rTHA, there were no dislocations at a mean follow-up of 4 ± 1 years (range: 2 to 8). Similarly, there were no further revisions or reoperations. Postoperatively, the mean cup inclination improved to 45 ± 2 degrees (range: 41 to 48), and the mean anteversion improved to 20 ± 2 degrees (range: 17 to 23). All cups were well-positioned utilizing fluoroscopic guidance. The mean effective head size increased from 32 mm to 44 mm. The mean hip disability and osteoarthritis disability score (HOOS, Jr) was 73 ± 25% (range: 40 to 100).

Conclusion

Refractory hip instability in THA may be effectively managed with an MDM articulation, even when prior attempts at surgical stabilization have failed. Intraoperative imaging and a direct anterior approach may aid the challenges of implant positioning and achieving hip stability in a revision setting.

Dual Mobility in Total Hip Arthroplasty: Biomechanics, Indications and Complications-Current Concepts

Dual-mobility (DM) articulations are increasingly utilized to prevent or manage hip instability after total hip arthroplasty (THA). DM cups offer enhanced stability due to the dual articulation resulting in larger jump distance and greater range of motion before impingement. Improvement in design features and biomaterials has contributed to increased interest in dual-mobility articulations due to lower risk of complications compared to their historic rates. The incidence of implant-specific complications like intra-prosthetic dislocation (IPD) and wear has reduced with newer-generation implants. DM THAs are used in primary THA in patients with high risk for dislocation, e.g. neuromuscular disorder, femoral neck fracture, spinopelvic deformity, etc. They offer an attractive alternative option to constrained liner for treatment of hip instability in revision THA. The medium- to short-term results with DM THA have been encouraging in primary and revision THA. However, there are concerns of fretting, corrosion and long-term survivorship with DM THA. Hence, longer-term studies and surveillance are required for the safe use of DM THA in clinical practice.

Dual Mobility hip replacement in hip fractures offer functional equivalence and a stability advantage - A case-controlled study

BACKGROUND

Hip fracture is a common and serious injury in the elderly. Hip arthroplasty is the most frequently performed procedure for patients with an  intracapsular hip fracture. The majority of national guidelines recommend total hip arthroplasty (THA) for more active patients. Literature indicates significant stability advantages for dual mobility (DM) acetabular components in non-emergent scenarios. Evidence supporting the use of DM in hip fracture patients is limited.

AIM

We set out to ascertain if DM implants offer stability and/or functional advantages over standard THA in patients with hip fracture.

METHODS

We utilised our local National Hip Fracture Database to identify all patients undergoing either a standard or DM THA for hip fracture (n=477) We matched cohorts based on age, AMTS, mobility status pre-operatively, gender, ASA and source of admission. Our primary outcome of interest was functional status using the oxford hip score (OHS). Secondary outcome measures included  dislocation, fracture and deep infection requiring further surgery.

RESULTS

62 patient pairs were available for this study. Mean OHS for DM THA was 41.5 and for standard THA this was 42.7 (p=0.58). There were 4 dislocations in the standard THA group and 0 with DM THA. No difference was seen with infection or peri-prosthetic fracture.

CONCLUSION

This study demonstrates functional equivalence between DM and standard THA. In addition it shows a trend towards less dislocation with DM THA. Cost savings from less instability may outweigh initial prosthesis costs. This study suggests a suitably powered RCT using instability as the primary outcome measure is indicated.

A Comparison of Revision Rates for Dislocation and Aseptic Causes Between Dual Mobility and Large Femoral Head Bearings in Primary Total Hip Arthroplasty With Subanalysis by Acetabular Component Size: An Analysis of 106,163 Primary Total Hip Arthroplasties

BACKGROUND

Dual mobility (DM) and large femoral head bearings (≥36 mm) both decrease the risk of dislocation in total hip arthroplasty (THA). There is limited comparable data in primary THA. This study compared the revision rates for dislocation and aseptic causes between DM and large femoral heads and subanalyzed by acetabular component size.

METHODS

Data from the Australian Orthopedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis from January 2008 (the year of first recorded DM use) to December 2019. All DM and large femoral head bearings were identified. The primary outcome measure was the cumulative percent revision (CPR) for dislocation and for all aseptic causes. The results were adjusted by age, sex, and femoral fixation. A subanalysis was performed stratifying acetabular component diameter <58 m and ≥58 mm.

RESULTS

There were 4942 DM and 101,221 large femoral head bearings recorded. There was no difference in the CPR for dislocation (HR = 0.69 (95% CI 0.42, 1.13), P = .138) or aseptic causes (HR = 0.91 (95% CI 0.70, 1.18), P = .457). When stratified by acetabular component size, DM reduced the CPR for dislocation in acetabular component diameter <58 mm (HR = 0.55 (95% CI 0.30, 1.00), P = .049). There was no difference for diameter ≥58 mm. There was no difference in aseptic revision when stratified by acetabular component diameter.

CONCLUSION

There is no difference in revision rates for dislocation or aseptic causes between DM and large femoral heads in primary THA. When stratified by acetabular component size, DM reduces dislocation for acetabular component diameter <58 mm.

LEVEL OF EVIDENCE

Level III.

Superior functional outcome with dual mobility THR as compared to conventional THR in fracture neck femur: a prospective cohort study

Introduction: Total Hip Replacement (THR) in displaced Fracture Neck of Femur (FNOF) is associated with higher dislocation rates. Conventional THR with a large femoral head and anterior approach has reduced the instability, but it remains higher than THR done for other aetiology. Recent studies have shown reduced dislocation rates with dual mobility THR (DMTHR) for FNOF; however, there is a lack of comparative research to show its superiority over conventional THR. Further, its role in the Asian subcontinent, where the patient requires sitting cross-legged or squatting, has not been studied. Methods: A prospective cohort study of 103 elderly patients with displaced FNOF with a minimum follow-up of 1-year. Fifty-two patients were operated on with DMTHR and fifty-one patients with conventional THR. Both the groups were matched in terms of demographic data, surgical approach, and postoperative protocol. Radiological and functional outcomes in terms of Harris Hip Score (HHS), Range of motion, Patient Reported Outcome Measures (PROM), and Dislocation rate were compared between the two groups. Results: Mean HHS of the DMTHR group was 76.37 at three months and 87.02 at the end of the 1-year postoperatively, which was significantly better than the conventional THR group 65.65 at three months and 72.96 at 1-year. The range of motion was significantly better in the DMTHR group than the conventional THR group. There was no significant difference in radiological outcomes and postoperative dislocation rate between the two groups. Conclusion: Dual mobility implants give better results than conventional implants for primary THA in elderly patients of displaced FNOF regarding better function and greater range of motion.

Total Hip Arthroplasty (THA) for Femoral Neck Fractures: Comparison between Standard and Dual Mobility Implants

The purpose of this retrospective study is to compare the short-term clinical and radiological results between standard and dual mobility THA for femoral neck fractures (FNF) in older patients. The hypothesis is that the dual mobility cup (DMC) has the same outcomes but a lower dislocation rate than the standard THA. The study population included 56 patients (mean age 77.7 years, range 71-85) that underwent THA for displaced FNF. Patients were divided in two comparable groups for baseline characteristics (age, sex and comorbidities): 28 patients underwent THA with a standard cup (SC) and 28 THA with DMCs. The clinical records and radiograms were reviewed to search relevant data in their postoperative history. Two postoperative dislocations occurred in the SC group and none in the DMC group. At an average follow up of 23 months (12-40), 48 patients were available for the final evaluation. The WOMAC score for all patients averaged 6.26 (0-46) and was slightly better in the DMC group (4.94 vs. 7.58; p-value = 0.41); scores were significantly better in presence of neurological comorbidities (p-value = 0.04), in the absence of diabetes (p-value = 0.04) and in the case of psychiatric disorders (p-value = 0.02). Radiographic evaluation at one year showed signs of osteointegration in 42/48 (87.5%) acetabular components (20 DMCs, 22 SC). According to our experience, DMCs proved to be a valid option for the treatment of displaced FNF in older patients, since it allowed them to achieve short-term outcomes comparable to conventional THA, while decreasing the incidence of postoperative dislocations.

Spine Fusions, Yoga Instructors, and Hip Fractures: The Role of Dual Mobility in Primary Total Hip Arthroplasty

BACKGROUND

Despite the increased use of dual mobility (DM) in primary total hip arthroplasty (THA), debate exists regarding the indications for its use. No specific algorithm exists to guide this decision-making process. Therefore, the purpose of this article is to summarize the currently available literature regarding the use of DM in primary THA and provide evidence-based guidelines based on specific patient populations and risk factors for instability.

METHODS

We reviewed the current literature for studies evaluating risk factors for dislocation in primary THA, as well as the clinical use and results of DM in primary THA. Based on the strength of the literature, we discuss the use of DM in specific patient populations. We provide a decision-making algorithm to determine whether a patient may be indicated for DM in primary THA.

RESULTS

Surgeons should consider preoperative patient demographics, risk factors for instability (eg, significant hip-spine issues), type of procedure to be performed (eg, conversion arthroplasty), and indications for surgery (eg, THA for femoral neck fracture). Based on this algorithmic assessment, DM may be warranted in the primary THA setting if a patient's combined risk reaches an established threshold based on the literature.

CONCLUSION

This evidence-based algorithm may help guide current practice in the use of DM in primary THA. We advocate the continued judicious use of DM in hip arthroplasty. Longer term studies are needed in order to evaluate the durability of DM, as well as any complications related to the DM articulation.

Total Hip Arthroplasty for Femoral Neck Fracture: What Are the Contemporary Reasons for Failure?

BACKGROUND

Total hip arthroplasty (THA) for femoral neck fracture (FNF) appears to provide superior functional outcomes compared to hemiarthroplasty in selected active, elderly patients; however, the historical tradeoff has been higher risk of complications including dislocation. We aimed to describe implant survivorship and reasons for failure after THA for FNFs.

METHODS

We identified 217 FNFs treated with THA from 2000 to 2017 from our institutional total joint registry (during the same time period 2039 FNFs were treated with hemiarthroplasty). Mean age was 70 years, and 65% were female. Cemented femoral components were utilized in 41%. Approach was anterolateral in 71%, posterior in 21%, and direct anterior in 8%. Dual-mobility constructs were utilized in 3%. A competing risk model accounting for death was used to analyze revisions and complications. Mean follow-up was 6 years.

RESULTS

The 5-year cumulative incidence of any revision was 8%. Nineteen hips were revised for the following indications: postoperative periprosthetic femur fracture (6: 3 uncemented stems and 3 cemented), infection (5), aseptic loosening of the femoral component (3: 2 cemented and 1 uncemented), dislocation (3), iliopsoas impingement (1), and liner dissociation (1). The 5-year cumulative incidence of periprosthetic femur fractures was 7%, including 7 intraoperative fractures and 11 postoperative fractures. The 5-year cumulative incidence of dislocation was 1.4%.

CONCLUSION

The 5-year cumulative incidence of any revision after THA for FNFs was 8%, mostly attributed to periprosthetic fracture and infection. Hip instability was not as common after FNF with contemporary patient selection, techniques, and implants compared to previous series.

LEVEL OF EVIDENCE

Prognostic, level III.

Risk factors and modes of failure in the modern dual mobility implant. A systematic review and meta-analysis

BACKGROUND

The aims of this meta-analysis were to: (1) validate the outcome of modern dual mobility (DM) designs in patients who had undergone primary and revision total hip arthroplasty (THA) procedures and (2) to identify factors that affect the outcome.

METHODS

We searched for studies that assessed the outcome of modern DM-THA in primary and revision procedures that were conducted between January, 2000 to August, 2020 on PubMed, MEDLINE, Cochrane Reviews and Embase. The pooled incidence of the most common failure modes and patient reported outcomes were evaluated in patients who have received: (1) primary THA, (2) revision THA for all causes or (3) for recurrent dislocation. A meta-regression analysis was performed for each parameter to determine the association with the outcome. The study design of each study was assessed for potential bias and flaws by using the quality assessment tool for case series studies.

RESULTS

A total of 119 studies (N= 30016 DM-THAs) were included for analysis. The mean follow-up duration was 47.3 months. The overall implant failure rate was 4.2% (primary: 2.3%, revision for all causes: 5.5%, recurrent dislocation: 6.0%). The most common failure modes were aseptic loosening (primary: 0.9%, revision for all causes: 2.2%, recurrent dislocation: 2.4%), septic loosening (primary:0.8%, revision for all causes: 2.3%, recurrent dislocation: 2.5%), extra-articular dislocation (primary:0.6%, revision for all causes:1.3%, recurrent dislocation:2.5%), intra-prosthetic dislocation (primary:0.8%, revision for all causes:1.0%, recurrent dislocation:1.6%) and periprosthetic fracture (primary:0.9%, revision for all causes:0.9%, recurrent dislocation:1.3%). The multi-regression analysis identified younger age (β=-0.04, 95% CI -0.07 - -0.02) and female patients (β=3.34, 95% CI 0.91-5.78) were correlated with higher implant failure rate. Age, gender, posterolateral approach and body mass index (BMI) were not risk factors for extra-articular or intra-prosthetic dislocation in this cohort. The overall Harris hip score and Merle d'Aubigné score were 84.87 and 16.36, respectively. Level of evidence of this meta-analysis was IV.

CONCLUSION

Modern dual-mobility designs provide satisfactory mid-term implant survival and clinical performance. Younger age and female patients might impact the outcome after DM-THA. Future research directions should focus on, (1) long-term outcome of modern dual-mobility design, including specific concerns such as intra-prosthetic dislocation and elevated metal ion, and (2) cost-effectiveness analysis of dual-mobility implant as an alternative to conventional THA for patients who are at high risk of dislocation.

Dual-mobility cups in total hip arthroplasty after femoral neck fractures: A retrospective study comparing outcomes between cemented and cementless fixation

INTRODUCTION

Total hip arthroplasty (THA) after femoral neck fracture (FNF) is associated with an increased risk of dislocation. The goals of our study were (1) to determine dislocation and revision rates when dual-mobility cups (DMCs) are used in these patients, (2) to analyze clinical and radiographic outcomes, survivorship, complications and mortality rate, and (3) to compare results between cemented and cementless cups.

PATIENTS AND METHODS

We retrospectively reviewed patients with FNF treated using DMC-THA between 2011 and 2018. A minimum 2-year follow-up was required for clinical and radiographic assessment. The clinical outcome was assessed using the Harris Hip Score (HHS) and Merlé D´Aubigné-Postel score (MDP). Radiolucent lines, osteolysis and cup loosening were analyzed.

RESULTS

We included 105 patients (105 hips) with a mean age of 75.5 years. There were no dislocations. One patient (1.0%) underwent cup revision at 39 months for aseptic cup loosening. The mean HHS and MDP were 80.5 and 14.2 respectively at a mean follow-up of 4.1 years. A higher MDP was found in patients with cementless rather than cemented cups (15.0 vs. 13.1; p = 0.006). Four patients had radiolucent lines > 1 mm, around cemented cups. At 6.8 years, estimated cup survival was 98.2% for revision for aseptic loosening and 97.3% for revision for any reason. The mortality rates were 6.7% at 1 year and 23.8% at last follow-up.

CONCLUSION

Our findings suggest that using DMC in THA for FNF may prevent dislocation with a low revision rate. Cementless cups had a higher MDP than cemented cups.

Uncemented or cemented stems in first-time revision total hip replacement? An observational study of 867 patients including assessment of femoral bone defect size

Background and purpose - Uncemented stems are gradually replacing cemented stems in hip revision surgery. We compared the risk of re-revision between uncemented and cemented revision stems and assessed whether the different fixation methods are used in similar femoral bone defects.Patients and methods - 867 patients operated on with uncemented or cemented stems in first-time hip revision surgery due to aseptic loosening performed 2006-2016 were identified in the Swedish Hip Arthroplasty Register. Preoperative femoral bone defect size was assessed on radiographs of all patients. Cox regression models were fitted to estimate the adjusted risk of re-revision during different postoperative time periods. Re-revision of any component for any reason, and stem re-revision, as well as risk of cause-specific re-revision was estimated.Results - Most patients in both fixation groups had Paprosky class IIIA femoral bone defects prior to surgery, but there were more severe bone defects in the cemented group. The adjusted risk of re-revision of any component for any reason was higher in patients with uncemented compared with those with cemented revision stems during the first 3 years after index surgery (hazard ratio [HR] 4, 95% confidence interval [CI] 2-9). From the 4th year onward, the risk of re-revision of any component for any reason was similar (HR 0.5, CI 0.2-1.4). Uncemented revision stems conferred a higher risk of dislocation compared with cemented stems (HR 5, CI 1.2-23) during the first 3 years.Interpretation - Although not predominantly used in more complex femoral defects, uncemented revision stem fixation confers a slightly higher risk of re-revision during the first years, but this risk is attenuated after longer follow-up.

Cemented Dual Mobility Cup for Primary Total Hip Arthroplasty in Elder Patients with High-Risk Instability

Several studies have shown that double mobility (DM) cups reduce postoperative dislocations. Does the cemented dual mobility cup reduce dislocations in a specific cohort of elder patients with a high dislocation risk? Our hypothesis is that this implant is optimal for elder patients because it reduces early dislocation. We have retrospectively reviewed elder patients who underwent total hip arthroplasty (THA) with cemented double mobility cup between March 2009 and January 2018. The inclusion criteria were patients (>75 years) who were operated on for primary THA (osteoarthritis or necrosis) with a cemented dual mobility cup and a high-risk instability (at least two patient-dependent risk factors for instability). The exclusion criteria were revision surgeries or hip fracture. In all the cases, the same surgical approach was performed with a Watson Jones modified approach in supine position. We have collected demographic data, instability risk factors. Patients were classified using the Devane's score, Merle d'Aubigné score and the patient's likelihood of falling with the Morse Fall Scale. Surgical and follow-up complications were collected from their medical history. Sixty-eight arthroplasties (68 patients) were included in the study. The median age was 81.7 years (SD 6.4), and the American Society of Anesthesiologists (ASA) score showed a distribution: II 27.94%, III 63.24% and IV 8.82%. Devane's score was less than five in all of the cases. At least two patient-dependent risk factors for instability (87% had three or more) were present in each case. The median follow-up time was 49.04 months (SD 22.6). Complications observed were two cases of infection and one case of aseptic loosening at 15 months which required revision surgery. We did not observe any prosthetic dislocation. The cemented dual mobility cup is an excellent surgical option on primary total hip arthroplasties for elder patients with high-risk instability.

Low revision rate of dual mobility cups after arthroplasty for acute hip fractures: report of 11,857 hip fractures in the Dutch Arthroplasty Register (2007-2019)

Background and purpose - Dislocation is one of the most frequent reasons for cup revision after total hip arthroplasty (THA) for an acute fracture. A dual mobility cup (DMC) might reduce this risk. We determined the cup revision rate after THA for an acute fracture according to type of cup.Patients and methods - All THAs for an acute fracture registered in the Dutch Arthroplasty Register (LROI) during 2007-2019 were included (n = 11,857). Type of cup was divided into DMC and unipolar cup (UC). Competing risk analyses were performed with cup revision for any reason as endpoint. Multivariable Cox regression analyses with outcome cup revision were performed adjusted for sex, age, ASA class, and surgical approach, stratified for UC THA with femoral head size of 32 mm and 22-28 mm.Results - A DMC was used in 1,122 (9%) hips. The overall 5-year cup revision rate for any reason after THA for acute fracture was 1.9% (95% CI 1.6-2.2). Cup revision for dislocation within 5 years was performed in 1 of 6 DMC THAs versus 108 of 185 (58%) UC THAs. Univariable Cox regression analyses showed no statistically significant difference in cup revision rate between DMC and UC (HR = 0.8; CI 0.4-1.5). Multivariable Cox regression analyses showed lower risk of cup revision in DMC THA (n = 1,122) compared with UC THA with 22-28 mm femoral head size (n = 2,727) (HR = 0.4; CI 0.2-0.8).Interpretation - The 5-year cup cumulative incidence of revision after THA for acute fracture was comparable for DMC and UC THA. However, DMC THA had a lower risk of cup revision than UC THA with 22-28 mm femoral head.

THA for a Fractured Femoral Neck: Comparing the Revision and Dislocation Rates of Standard-head, Large-head, Dual-mobility, and Constrained Liners

BACKGROUND

THA is a reasonable surgical option for some patients with fragility fractures of the femoral neck, but it has the risk of prosthesis dislocation. The prosthesis combination that reduces the risk of dislocation and the rate of revision surgery is not known.

QUESTIONS/PURPOSES

In patients receiving primary THA for a femoral neck fracture, does (1) the rate of all-cause revision or (2) the reason for revision and rate of revision for dislocation differ among THA with a standard head size, large head size, dual mobility (DM), or constrained liner? (3) Is there a difference in the revision risk when patients are stratified by age at the time of surgery?

METHODS

Data were analyzed for 16,692 THAs performed to treat fractures of the femoral neck reported in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from January 2008 to December 2018, as this included the first use of DM prostheses. The AOANJRR includes information on more than 98% of arthroplasty procedures performed in Australia. Most patients were female (72%) and the mean age was 74 years ± 11. There were 8582 standard-head prostheses, 5820 large-head prostheses, 1778 DM prostheses, and 512 constrained prostheses identified. The cumulative percent revision (CPR) was determined for all causes as well as CPR for dislocation. The time to the first revision was described using Kaplan-Meier estimates of survivorship, with right censoring for death or closure of the database at the time of analysis. The unadjusted CPR was estimated each year of the first 10 years for standard heads, 10 years for large heads, 8 years for constrained liners, and 7 years for DM prostheses, with 95% confidence intervals using unadjusted pointwise Greenwood estimates. The results were adjusted for age, sex, femoral fixation, and head size where appropriate and were considered by age groups < 70 and ≥ 70 years.

RESULTS

When adjusted for age, sex, femoral fixation and head size, there was no difference in the rate of all-cause revision at 7 years for any of the four groups. There was no difference in the rate of all-cause revision when patients were stratified by < 70 or ≥ 70 years of age. Dislocation was the most common reason for revision (32%). When analyzing revision for dislocation alone, large-head THA had a lower rate of revision for dislocation compared with standard head (HR 0.6 [95% CI 0.4 to 0.8]; p < 0.001) and DM prostheses had a lower rate of revision for dislocation than standard head for the first 3 months (HR 0.3 [95% CI 0.1 to 0.7]; p < 0.004) but not after this time point.

CONCLUSION

The Australian registry shows that there is no difference in the rate of all-cause revision for standard-head, large-head, DM prostheses or constrained liner THA after femoral neck fractures for all patients or for patients stratified into younger than 70 years and at least 70 years of age groups. Dislocation is the most common cause of revision. Large-head prostheses are associated with a lower revision risk for dislocation and DM prostheses have a lower rate of revision for dislocation than standard heads for the first 3 months only. Surgeons treating a femoral neck fracture with THA might consider a large head size if the diameter of the acetabulum will allow it and a DM prosthesis if a large head size is not possible. The age, life expectancy and level of function of patients with femoral neck fractures minimizes the potential long-term consequences of these prostheses. The lack of significant differences in survival between most prosthesis combinations means surgeons should continue to look for factors beyond head size and prosthesis to minimize dislocation and revision surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Use of dual mobility components in total hip arthroplasty: Indications and outcomes

Instability after total hip arthroplasty (THA) can be a problematic complication and remains one of the leading causes of revision surgery in the early post-operative period. Dual mobility (DM) implants decrease dislocation risk after THA but they come with their own set of complications. Selective use of DM implants for THA in high risk groups can confer the advantages of this construct while mitigating the risks. In this paper, we review the current literature to examine the evidence for or against use of DM implants in various clinical scenarios and provide an algorithm for when to consider using DM design construct in THA.

Study protocol: The DUALITY trial-a register-based, randomized controlled trial to investigate dual mobility cups in hip fracture patients

Background and purpose - Physically and mentally fit patients with a displaced femoral neck fracture (FNF) are mostly treated with total hip arthroplasty (THA). Dislocation is a severe and frequent complication in this group, and dual mobility cups (DMC) were developed to reduce the risk of dislocation after THA. The DUALITY trial investigates whether the use of DMC in FNF patients treated with a THA reduces the risk of dislocation.Patients and methods - The trial is a national, multicenter, register-based, randomized controlled trial (rRCT). Patients ≥ 65 years with a non-pathological, displaced FNF (Type Garden 3-4/AO 31-B2 or B3) who are suitable for a THA according to local guidelines are assessed for eligibility using the web-based registration platform of the Swedish Fracture Register (SFR). 1,600 patients will be randomized 1:1 to either insertion of a DMC (intervention group) or a standard cup (control group). The study is pragmatic in that the choice of implant brands, surgical approach, and peri- and postoperative protocols follow the local routines of each participating unit. All outcome variables will be retrieved after linkage of the study cohort obtained from the SFR with the Swedish Hip Arthroplasty Register and the National Patient Register.Outcomes - The primary outcome is the occurrence of any dislocation of the index joint treated with closed or open reduction within 1 year after surgery, expressed as a relative risk when comparing groups, and a risk reduction of at least 45% is considered clinically relevant. Secondary outcomes are the relative risk of any reoperation of the index joint, periprosthetic joint infection, and mortality within 90 days and 1 year. Patient-reported outcomes and health economics are evaluated.Start of trial and estimated duration - The DUALITY trial started recruiting patients in January 2020 and will continue for approximately 5 years.Trial registration - The trial is registered at clinicaltrials.gov (NCT03909815; December 12, 2019).