Treatment of recurrent THR dislocation using of a cementless dual-mobility cup: a 59 cases series with a mean 8 years' follow-up

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.

Dislocation and survival rate of dual mobility cups in revision total hip arthroplasty in patients with high risk of instability

PURPOSE

Instability remains as an unsolved complication after revision total hip arthroplasty (rTHA). Dual mobility (DM) cups have decreased dislocation rate in rTHA; however, there are few clinical studies that evaluate the risk of dislocation after rTHA in patients with high risk of instability.

METHODS

Between 2007 and 2019, 95 consecutive rTHA using a DM cup, in 93 patients with instability risk factors were retrospectively reviewed. Instability risk factors were defined as follows: deficient abductor mechanism (22.1%), previous dislocation (68.4%), Paprosky 3 acetabular bone defect (21.1%), neuromuscular disease (4.2%), lumbar spine arthrodesis (6.3%), and more than one previous surgery (33.6%). Mean follow-up was 4.3 ± 2.4 years. Clinical and radiographic parameters were reported. DM cup survival was determined using a Kaplan-Meier analysis with re-revision for any cause as the end-point. Surgical complications and re-dislocation rate was recorded.

RESULTS

Seven DM cups were re-revised; three due to aseptic loosening, three due to peri-prosthetic joint infection (PJI), and one due to instability. At seven years follow-up, the survival rate of the DM cup using re-revision for any reason as the end-point was 82.4% (95% confidence interval, 66.4-98.4%). There were 12 (12.6%) complications: two (2.1%) dislocations, six (6.3%) PJI, four (4.2%) peri-prosthetic fractures.

CONCLUSION

Our findings suggest DM cups are effective reducing dislocation rate in rTHA in patients with a high risk of instability, without increasing early aseptic loosening and with a low rate of dislocation. Nevertheless, longer follow-up is needed to confirm implant stability and dislocation rates in the long term.

Cementless augmented versus cemented Dual Mobility cups: medium-term outcome of case series with a control group

BACKGROUND

Post-operative dislocation and reconstruction of acetabular defects are two challenging topics in revision Total Hip Arthroplasty (rTHA). Cemented Dual Mobility (DM) cups on top of Kerboull Cross and bone graft have been successfully employed to overcome these challenges. The cementless augmented DM cups were recently introduced. In this study medium term results of the augmented cementless DM Coptos cups are reported and compared to the established technique of cemented DM cups and Kerboull plate.

MATERIAL AND METHODS

This is a retrospective analysis of data collected on patients who received rTHA using DM cups in the period between June 2015 and September 2020. Two groups of patients were identified. The first group received cementless augmented DM-cups (NOVAE® Coptos TH-SERF) (Coptos TH cup group). The second comparable group who had Kerboull ring (KE ring group) and cemented DM cups (NOVAE® STICK). Demographic data, surgical technique, functional and radiological outcome as well as complications during the follow-up visits are reported.

RESULTS

Forty-two patients with a mean age at the time of revision 48.8 ± 13.6 years. 29 patients received Coptos TH DM-cup, while 13 patients had Bone Graft (BG), KE ring and cemented DM cups for acetabular reconstruction. Acetabular defects were Paprosky types IIB and IIC in 31 patients and IIIA and B in 11 patients. The follow-up was 52.8 ± 21 months (mean ± STD); and the mean Harris Hip Score (HHS) at last visit was 91 ± 5. Good stability of all cups was reported. Full integration of the impaction graft was observed in 94% of the Coptos and 92% of the KE groups. One of the Coptos cups was readjusted and one case of single dislocation was recorded in the KE group. None of the DM cups in both groups was revised or awaiting revision.

CONCLUSION

Coptos TH cups achieve similar results to the cemented DM on KE ring at the medium term but long term outcome remains to be seen.

A Meta-Analysis of the Incidence and Temporal Trends of Postoperative Dislocation in Revision Total Hip Arthroplasty Utilizing Constrained Acetabular Components or Dual Mobility Implants

BACKGROUND

The incidence of dislocation after revision total hip arthroplasty (rTHA) is reported to be up to 25% and remains a common source of failure. Constrained acetabular components and dual mobility implants are two implant classes being utilized to alleviate this burden in patients who have recurrent instability or major intraoperative instability. This meta-analysis evaluated the incidence and temporal trends of dislocation after implantation with constrained acetabular components and dual mobility implants in rTHA.

METHODS

Longitudinal studies reporting dislocation after the use of constrained acetabular components or dual mobility implants in rTHA were sought from Medline and Embase to October 2022. Secondary outcomes included re-revision surgery for dislocation and all causes. A total of 75 relevant citations were identified comprising 36 datasets of 3,784 constrained acetabular components and 47 datasets of 10,216 dual mobility implants.

RESULTS

For constrained acetabular components, the pooled incidence of dislocation was 9% (95% confidence interval: 7.2, 11.7) (range 0.0%-35.3%) over a weighted mean follow-up of 6 years, in contrast to 3% (95% confidence interval: 2.2, 4.4) (range 0.0%-21.4%) over 5 years for dual mobility implants. Re-revision rates for dislocation after using constrained acetabular components were around 9%, in contrast to 2% for dual mobility implants. Re-revision rates for all causes after using constrained acetabular components were around 19%, in contrast to 8% for dual mobility implants.

CONCLUSION

Dual mobility implants in the context of rTHA demonstrate lower incidences of dislocation (3% versus 9%), re-revision for dislocation (2% versus 9%), and rer-evision for any cause (8% versus 19%) in contrast to constrained acetabular components. This must be considered by surgeons when implanting such devices, often selected to treat instability.

Clinical results at 10 years of minimum follow-up with the ABG 2 hip arthroplasty, matched with ceramic-on-ceramic bearings

Introduction: The current study aimed as a primary goal is to assess the results of a ceramic-on-ceramic (CoC) bearing hip system matched with ABG (Anatomic Benoist Girard) 2 components in terms of survivorship. Secondary objectives addressed specifically ceramic-related complications as well as specific patterns at the bone-implant interface. Material and methods: This is a retrospective bicentric continuous series involving 147 patients (95 males vs. 52 females) who underwent ABG 2 arthroplasties with CoC bearings. One hundred and twenty-five hips were closely followed-up at a mean period of 11.3 years. Results and discussion: With a mean follow-up of 11.3 years, nine cases (5.7%) underwent revision surgery, four caused by acetabular aseptic loosening, three by deep infections, one ceramic head fracture, and one femoro-acetabular impingement. The global survivorship was 92.2% at 12.7 years. The Harris Hip Score (HHS) mean scores increased post-operatively from 50.1 up to 96.1 points (p < 0.001). All stems featured patterns of radiological osseous integration onto the hydroxyapatite (HA)-coated zones. No radiological wear or osteolysis of ceramic bearings was demonstrated however, five patients reported hip squeaking using this bearing. This study demonstrated excellent results at mid-term follow-up in patients younger than 70 years of age using cementless ABG 2 components coupled with CoC bearings with no increase in complication rate.

Instability After Primary Total Hip Arthroplasty: Dual Mobility Versus Jumbo Femoral Heads

BACKGROUND

The use of dual mobility (DM) articulations has grown substantially over the last decade to help minimize dislocation risk. The purpose of this study is to compare the results of DM articulations to jumbo femoral heads of equivalent sizes as they relate to postoperative dislocation.

METHODS

This is a retrospective cohort study of primary total hip arthroplasties (THAs) performed at a single institution between 2005 and 2018. DM articulations and large-diameter metal-on-metal femoral heads were included. Patients were followed with Harris Hip Scores and standard radiographs. Complications were prospectively recorded. Statistical analyses included chi-squared and Brown-Forsythe tests.

RESULTS

In total, 1,288 Magnum femoral head THAs and 365 Active Articulation DM THAs were included for analysis. The same monoblock cup was implanted via a posterior approach in all cases. Age, gender, body mass index, and diagnosis were similar between groups. Average follow-up in the DM group was 49 months, and 126 months in the jumbo head group. The average head sizes in the DM and jumbo head groups were 50 mm. There were no dislocations in the DM hips and only 2 (0.2%) in the jumbo femoral head group. Both groups had significant improvements in Harris Hip Score from their preoperative baseline.

CONCLUSION

Our study found similarly low dislocation rates in DM and jumbo femoral heads in primary THA. No evidence currently exists showing a benefit of the DM articulation beyond that of the large effective head size, and we recommend making every attempt at maximizing head size prior to using DM articulations.

Dual-mobility versus Fixed-bearing in Primary Total Hip Arthroplasty: Outcome Comparison

Purpose

Use of dual mobility (DM) articulations can reduce the risk of instability in both primary and revision total hip arthroplasty (THA). Knowledge regarding the impact of this design on patient-reported outcome measures (PROMs) is limited. This study aims to compare clinical outcomes between DM and fixed bearing (FB) prostheses following primary THA.

Materials and Methods

All patients who underwent primary THA between 2011-2021 were reviewed retrospectively. Patients were separated into three cohorts: FB vs monoblock-D vs modular-DM. An evaluation of PROMs including HOOS, JR, and FJS-12, as well as discharge-disposition, 90-day readmissions, and revisions rates was performed. Propensity-score matching was performed to limit significant demographic differences, while ANOVA and chi-squared test were used for comparison of outcomes.

Results

Of the 15,184 patients identified, 14,652 patients (96.5%) had a FB, 185 patients (1.2%) had a monoblock-DM, and 347 patients (2.3%) had a modular-DM prosthesis. After propensity-score matching, a total of 447 patients were matched comparison. There was no statistical difference in the 90-day readmission (P=0.584), revision rate (P=0.265), and 90-day readmission (P=0.365) and revision rate due to dislocation (P=0.365) between the cohorts. Discharge disposition was also non-significant (P=0.124). There was no statistical difference in FJS-12 scores at 3-months (P=0.820), 1-year (P=0.982), and 2-years (P=0.608) between the groups.

Conclusion

DM bearings yield PROMs similar to those of FB implants in patients undergoing primary THA. Although DM implants are utilized more often in patients at higher-risk for instability, we suggest that similar patient satisfaction may be attained while achieving similar dislocation rates.

Late Breakage of a Dual-Mobility Polyethylene Insert in a Revision Total Hip Arthroplasty: An Unusual Failure Mode

The use of dual-mobility cups has gained popularity in recent years. Thus, surgeons can expect an increase in known and new causes of failure. We report a previously undescribed form of a late intraprosthetic dislocation consisting of a complete breakage of a polyethylene mobile bearing that suffered a dislocation 3 months after its implantation. Two years later, he began feeling anterior groin pain and suffered gait changes. Computed tomography scan revealed an eccentric alignment of the mobile polyethylene bearing suggestive of poly wear. During the revision surgery, the polyethylene was found to be split in 2. Possible causes of this complication are proposed. Our case shows a previously unreported implant-specific complication, so surgeons can identify it.

Dual Mobility Reduces Dislocations-Why I Use It in All Revisions

BACKGROUND

Instability remains the most common complication after revision total hip arthroplasty (THA) and presents a unique treatment dilemma for the orthopedic surgeon. Dual mobility (DM) bearing articulations have been used in France since the 1970s, but have only become more widely adopted in the United States over the last decade. The purpose of this symposium was to discuss the role for DM bearings in revision THA.

METHODS

We reviewed the existing literature on outcomes after DM bearing articulations in revision THA. We also report several case examples of the use of DM in difficult revision THA cases, including acetabular bone loss, failed constrained liner, and adverse local tissue reaction. Finally, we briefly discuss the limitations associated with the use of DM.

RESULTS

Several large retrospective series demonstrate that DM bearings reduce the incidence of dislocation after revision THA when compared with conventional single bearing THA. Specific complications related to DM bearings including polyethylene wear, loosening, intraprosthetic dislocation, and corrosion remain a concern, but appear to have drastically improved over time with modern implant designs.

CONCLUSION

Contemporary DM designs have been established as an effective bearing option to reduce instability in revision THA, although concerns do exist. High-quality prospective studies are necessary to further define the role this bearing option has in the coming years.

Dual mobility for total hip arthroplasty revision surgery: A systematic review and metanalysis

INTRODUCTION

Revision THA (R-THA) is thought to have a higher complication rate if compared to primary THA. Dual Mobility (DM) implants have been designed aiming for achieving greater stability, with good clinical results. However, scarce material can be found about the real improvements provided by this type of implant compared to traditional implant in Revisions of Total Hip Arthroplasties.

METHODS

A systematic review and meta-analysis of comparative studies were performed in December 2019. This was in accordance with the guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Our primary outcome measure was overall survivorship and dislocation rate, either treated with a conservative method or requiring surgery.

RESULTS

Regarding the overall implant survival, we found a slight significant risk ratio, with a statistically meaningful difference between the two groups in questions in favour of the DM implant. A statistically significant difference in favour of the DM group turned out considering only the Dislocation rate Risk ratio and the aseptic loosening risk as well. No statistical difference was found between the two groups about the risk ratio of infection.

DISCUSSION

A steady increase of evidence is demonstrating the efficacy of using a DM cup system in THA revisions with low dislocation rates, but currently there is no study in the literature that demonstrates with statistically significant evidence. The main finding of the present study is that implant's Survivor and prevention of dislocation at medium follow-up showed better results with a DM if compared to a fixed-bearing cup, for Revision THA.

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.

Thirty-Day Readmissions After Aseptic Revision Total Hip Arthroplasty: Rates, Predictors, and Reasons Vary by Surgical Indication

BACKGROUND

Revision total hip arthroplasty (rTHA) is performed for different surgical indications. With increasing attention being focused to minimize readmission risk, the National Surgical Quality Improvement Program (NSQIP) was used to assess 30-day readmissions after rTHA for 3 aseptic indications.

METHODS

Patients undergoing rTHA were identified in the 2013-2017 NSQIP and classified as being performed for osteolysis/aseptic loosening, recurrent dislocation, or periprosthetic fracture. Rates and predictors of 30-day readmission were determined by indication. Reasons for readmission were also assessed as being either related or unrelated to the surgical site.

RESULTS

Of 6104 patients meeting inclusion criteria, osteolysis/aseptic loosening represented 46% of the revisions (readmission rate: 6.2%), recurrent dislocation represented 33.2% (readmission rate: 10.9%), and periprosthetic fractures represented 20.9% (readmission rate: 9.3%). These readmission rates represented statistically significant variation across the 3 indications (P < .0001). On multivariate analysis, demographic, procedural, and postoperative predictors of readmission varied by indication. The osteolysis/aseptic loosening and periprosthetic fracture cohorts had surgical site-related readmissions in 43.9% and 42.4% of readmitted cases, respectively. On the contrary, readmissions after rTHA performed for recurrent dislocation were mostly surgical site-related (63.3%) and driven primarily by a postoperative dislocation. Further multivariate analysis showed that the rTHA indication of recurrent dislocation itself was the strongest predictor (odds ratio, 3.34; P < .0001) of a postoperative dislocation leading to a 30-day readmission.

CONCLUSION

Thirty-day readmissions varied from 6.2% to 10.9% based on surgical indication for aseptic rTHA. Reasons for readmission also differed across the 3 cohorts. These findings may aid postoperative care pathways and protocol optimization.

Dual-mobility cups could yield lesser infections than conventional cups: a meta-analysis of comparative studies

INTRODUCTION

Dual-mobility cups (DMC) are gaining popularity mainly for their reduced rate of dislocation following total hip arthroplasty (THA). Currently, indication for DMC use extends beyond patients with high risk of dislocation or revision THA cases. Many authors reported DMC outcomes in primary THA for all aetiologies. However, some reports claimed that the use of DMC is accompanied with higher rates of infection compared with conventional cups (CC) in both primary and revision THA.

RESEARCH QUESTION

Does the use of DMC generate higher rates of infection when compared with conventional cups?

OBJECTIVES

The aim of this meta-analysis was to look for significant difference in the rate of post-operative infection between DMC cups and conventional cups.

METHODOLOGY

MEDLINE, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar were searched since inception. Only studies with comparative design reporting the outcome infection rate were included.

RESULTS

Seventeen retrospective comparative studies were located comprising 248,541 patients: 16,020 in the DMC group and 232,521 in the CC group. The mean follow-up period was 37.5 ± 42 and 50.2 ± 48.7 months for the DMC and CC groups, respectively. The meta-analytical results indicated the following: (a) significantly lesser infections following DMC compared with CC in revision THA (odds ratio (OR) = 0.75 (95% CI = 0.653 to 0.874, P = 0.0002, I² = 25%); (b) for primary THA and for large-sampled registries, significance was found using only the fixed-effects model estimate; and (c) no significant difference was found for the subgroup of cohort studies.

CONCLUSION

Our results clearly refute the claim that DMC would yield higher rates of infection. On the contrary, the findings demonstrated that the use of DMC reduces the risk of post-operative infection in revision THA and a similar lower infection trend for primary THA when compared with the standard cups.

Dual mobility THR: Resolving instability and providing near normal range of movement

BACKGROUND

Dislocation is a common complication of Total Hip Replacement (THR), particularly when performed in primary (indications with increased risk of instability) and in revision scenarios. Dual mobility THR (DMTHR) minimizes the risk of instability in such scenarios, however most of the evidence is from western literature. Results of DMTHR in Indian scenarios where patient want to go back to their normal routine activities of squatting and sitting cross-legged is lacking. The aim of our study was to evaluate the short to mid-term results of DMTHR for varied indications (both primary and revision) in Indian scenario. To evaluate the outcome of the DMTHR in terms of functional range of motion and the ability to go back to their pre-injury level of activity.

METHODS

This is a retrospective study of 150 patients operated with DMTHR between January 2015 to February 2019 with a minimum follow-up of 12 months. Patients were evaluated clinically using Modified Harris Hip Score (HHS), Range of Motion (ROM), and Patient Reported Outcome Measures (PROM) like ability to squat and sit cross legged. Radiological evaluation was done using radiographs to assess loosening, stress shielding, osteolysis.

RESULTS

Mean follow up in our study was 25.2 months (Range 12-46 months). Mean Modified HHS was 71.8 ± 8.11 at 6 weeks post-op and 85.8 ± 7.62 at last follow-up. HHS showed excellent outcome in 36 hips (26.7%), good outcome in 76 hips (56.7%), fair outcome in 20 hips (14.6%), poor outcome in 3 hips (2%). All our patients were allowed to squat and sit cross-legged at a mean follow-up period of 13 weeks (8 weeks-20 weeks) except 10 cases of Revision THR where patients were advised not to squat or sit cross-legged. All patients were able to resume their activities of daily living.

CONCLUSION

DMTHR in patients of all ages has shown a good short to midterm clinical outcome which is comparable to conventional THR. It confers the benefit of stability allowing our patients to squat and sit cross legged which is often one of the expectation and requirement of a patient undergoing THR in India. DMTHR in both primary and revision scenarios exhibit a low risk of dislocation, complications and revision surgery.

Retention of Monoblock Femoral Components Using a Dual Mobility Bearing: A Report of 3 Cases

CASE

We present the results of 3 cases followed up for a minimum period of 4.5 years of revision total hip arthroplasty using a metal acetabular shell with retention of a well-fixed monoblock femoral component by inserting a dual mobility polyethylene bearing onto the femoral head in situ.

CONCLUSION

This is the first case series to use this technique to address acetabular osteolysis and avoid removing a well-fixed monoblock femoral component at the time of revision surgery.

Comparison of Constrained Acetabular Components and Dual Mobility Cups in Revision Total Hip Arthroplasty: A Literature Review

Recurrent instability remains a common cause of failure after revision total hip arthroplasty (THA). Dual mobility (DM) cups and designs with constrained acetabular liners (CAL) have both been developed to help overcome this challenge. The aim of this report is to compare safety and efficacy outcomes of both designs based on the literature. A comprehensive literature review including published evidence on the results of DM and CAL in revision THA was performed and summarized. Available literature focusing on overall survival, dislocation, loosening, intra-prosthetic dislocation (IPD), and functional outcomes were analysed. Forty-six reports including an evaluation of 5,617 total hips were evaluated were included in the review. The included studies were divided into two distinct groups based on implantation approach: i) CAL (n=15) and ii) DM (n=31). The DM group had higher overall survival rates (94.7% vs. 81.0%), lower dislocation rates (2.6% vs. 11.0%), and lower acetabular loosening rates (1.0% vs. 2.0%) compared to the CAL group. IPDs were reported in 6 studies (mean rate, 0.6%). No differences in functional outcomes were identified due to incomplete reports. Our observations reveal that designs with CAL have poorer outcomes as compared to DM cups in revision THA. Currently, the use of DM seems more appropriate since they offer lower rates of dislocations, loosening and re-revisions in the short- and mid-term. Concerns regarding the potential of increased wear in a younger, high-demand population require additional data and evaluation by long-term studies for the DM design.

Prospective randomized study using EBRA-FCA to compare bone fixation between cementless SL-PLUS Zweymüller versus SL-PLUS MIA femoral implants in primary total hip arthroplasty with clinical assessment at a minimum 5years' follow-up

INTRODUCTION

Sometimes the slightest changes in implant design can lead to failure, even for a validated prosthesis. A minimally invasive cementless model, the SL-PLUS MIA™, in which the lateral shoulder is eliminated, was developed from the Zweymüller SL-PLUS™ implant. After satisfactory in-vitro tests, it required in-vivo assessment to ensure that bone fixation is good. We therefore conducted a prospective randomized study comparing the two versions of the Zweymüller femoral stem, with the aim of (1) comparing bone fixation up to 2 years' follow-up on EBRA-FCA radiography; and (2) assessing any difference in clinical or radiographic performance.

HYPOTHESIS

Primary stability assessed on EBRA-FCA does not significantly differ between the SL-PLUS MIA™ and SL-PLUS™ implants.

PATIENTS AND METHOD

A single-center multi-surgeon prospective randomized study included 80 patients (79 were operated on) between April 2009 and October 2012, with a mean 6 years' follow-up. Radiographic assessment used the EBRA-FCA application up to 2 years' follow-up; clinical assessment, with a minimum 5 years' follow-up, was performed by a single observer, using the Harris and Oxford-12 scores. The two groups, SL-PLUS™ (n=38) and SL-PLUS MIA™ (n=41), were comparable in gender, age, indications, body-mass index and preoperative functional status.

RESULTS

At a minimum 2 years' follow-up, 24 SL-PLUS™ and 27 SL-PLUS MIA™ implants were analyzed on EBRA-FCA. Mean migration was respectively -0.3mm±0.8 [range, -1.6 to 1.3] and -0.5mm±0.7 [range, -2.2 to 0.5] (p=0.21). There was likewise no significant difference in varus tilt. The number of ectopic ossifications did not differ, despite the absence of shoulder: 7 with SL-PLUS™ (23%), and 10 with SL-PLUS MIA™ (32%), without clinical impact. Oxford score improved from 43±6.8 to 19±7 at 5 years' follow-up with SL-PLUS ™ and from 44±8.8 to 20±7.4 with SL-PLUS MIA™: i.e., no significant inter-group difference. Likewise, Harris score at 2 years' follow-up did not differ: 91.6±8.7 and 89.7±10.2, respectively. Implant survival did not differ: SL-PLUS MIA™, 41/41 (100%); SL-PLUS™, 36/38 (94.7%) (p=0.13).

CONCLUSION

There was no significant difference in fixation quality between the SL-PLUS™ and SL-PLUS MIA™ implants. Elimination of the shoulder did not jeopardize primary or secondary fixation, but neither did it reduce the rate of ossification. The modified Zweymüller implant appeared risk-free at 6 years' follow-up.

LEVEL OF EVIDENCE

II, low-power prospective randomized study.

Dual Mobility Cups in Revision Total Hip Arthroplasty: Efficient Strategy to Decrease Dislocation Risk

BACKGROUND

Revision total hip arthroplasty (rTHA) is a challenging surgery with a higher rate of complications than primary arthroplasty, particularly instability and aseptic loosening. The purpose of this study is to compare dual mobility cup (DMC) and standard mobility cup (SMC) in all rTHAs performed at our institution over a decade with a 1 year minimum follow-up.

METHODS

Two hundred ninety-five rTHAs (acetabular only and bipolar revisions) between 2006 and 2016 were retrospectively reviewed. These were divided into those with a DMC (184 revisions) or SMC (111 revisions). Dislocation and complications requiring re-revision were reported.

RESULTS

The rTHA mean age was 69 years ± 13.9 (19-92) and the mean follow-up was 2.3 years. Dislocation risk was statistically lower (P = .01) with a DMC (3.8%; 7/184) than with an SMC (13.5%; 15/111). DMC required re-rTHA in 24/184 (13%) for any reason compared to SMC in 19/111 (17.1%) (P = .34). There was no significant difference in early aseptic loosening (P = .28) between the 2 groups. For young patients (≤55 years), results were similar with a lower dislocation rate in the DMC group (P = .24) and no increased risk of early aseptic loosening (P = .49).

CONCLUSION

This study demonstrates that for all rTHA indications DMC compared to SMC has a significantly decreased risk of postoperative dislocation without risk of early aseptic loosening at medium term follow-up. The use of DMC in rTHA is an important consideration particularly with the predicted increased incidence of both primary and revision THA globally.

Multivariate analysis of risk factors for re-dislocation after revision for dislocation after total hip arthroplasty

BACKGROUND

The treatment for recurrent dislocation of a total hip arthroplasty is surgical using varied techniques and technologies to reduce the chances of re-dislocation and re-revision. The goal of this study is to compare operative techniques to reduce re-dislocation and re-revision in revision hip arthroplasty due to recurrent dislocations.

METHODS

A retrospective study of revision hip arthroplasties done due to recurrent dislocation prior to 01 January 2014. Electronic physician and provincial health records were used to collect patients' initial and follow-up data. Treatment failure was defined as either aseptic re-revision or re-dislocation without revision. Time to event was considered as the re-revision date or the date of second dislocation when the latter endpoint was used.

RESULTS

Of 379 operations, 88 (23.2%) had aseptic repeat revision or recurrent dislocation. Of these: 66 (75.0%) due to dislocation with re-revision; 10 (11.4%) due to dislocation with no re-revision surgery; 5 (5.7%) due to aseptic loosening of components; 3 (3.4%) due to osteolysis; 3 (3.4%) due to pseudotumour; and 1 (1.1%) due to periprosthetic fracture. The following factors increase risk of failure: the use of augmented-liners (lipped, oblique and high-offset liners; HR = 1.68, 95% CI, 1.05-2.69), periprosthetic femur fracture (HR = 2.80, 95% CI, 1.39-8.21) and pelvic discontinuity (HR = 3.69, 95% CI, 1.66-8.21). Femur head sizes 36-40 mm are protective (HR = 0.54, 95% CI, 0.31-0.86). In abductor dysfunction the use of focal constrained liners decreases the risk of failure (HR = 0.13, 95% CI, 0.018-0.973).

CONCLUSIONS

Larger head sizes and focal constrained liners (abductors dysfunction) should be used and fully constrained liners and augmented-liners should be avoided in a revision hip arthroplasty due to recurrent dislocations.

Dual mobility constructs in revision total hip arthroplasty: survivorship analysis in recurrent dislocation versus other indications at three to twelve-year follow-up

BACKGROUND

The aim of this retrospective study was to evaluate the clinical, radiologic, and survival results of dual mobility (DM) sockets in revision total hip arthroplasty (THA) performed for instability versus revision THAs performed for other reasons.

METHODS

From a computerized database, we identified 84 revision THAs using a modern DM socket performed in 81 patients with a mean age of 71 years. Indication for revision was recurrent dislocation in 47 hips, and other reasons in the remaining 37 hips. A survivorship analysis according to the actuarial method was carried out on the entire series using revision for any cause, revision for dislocation, and radiological cup loosening revised or not, as the end points.

RESULTS

Of the 81 patients, twelve died, six were lost to follow-up, eight had been revised, and 55 patients (58 hips) were unrevised and alive at a mean follow-up of 6.4 years. Dislocation occurred in four of the 47 (8.5%) hips for which indication for revision was dislocation versus one of the remaining 37 (2.7%) hips [odds ratio = 3.4 (0.4-31.3), p = 0.07]. According to our criteria, three acetabular components of which one was revised were considered as loosened. When using revision for dislocation as the end-point, the survival rate at seven years was 90.4 ± 5.3% (IC_95%, 79.9-100) in the 47 hips for which the indication for revision was dislocation versus 100% in the remaining 37 hips (log-rank, p = 0.5).

CONCLUSIONS

The current study indicated that DM sockets represent an interesting solution to prevent dislocation in revision THAs at mid-term follow-up.

Risk factors for dislocation after revision total hip arthroplasty with a dual-mobility cup. Matched case-control study (16 cases vs. 48 controls)

BACKGROUND

Reports of high dislocation rates after revision total hip arthroplasty (THA) have encouraged the widespread use of dual-mobility cups. Dislocation has been less common but not fully abolished with dual-mobility cups, and its causes have remained unidentified. The objectives of this retrospective matched case-control study were: 1) to identify risk factors for dislocation, 2) and to assess dislocation outcomes.

HYPOTHESIS

The causes of dislocation after revision THA with a dual-mobility cup can be identified.

MATERIAL AND METHOD

Among 653 consecutive patients identified retrospectively as having undergone revision THA with a dual-mobility cup (Medial Cup, Aston, Saint-Étienne, France) between January 2007 and December 2017, 16 (2.45%) subsequently experienced dislocation, after a mean of 3.6 months (range, 0.9-19 months). For each of these 16 patients, we collected the main patient characteristics (age, sex, body mass index [BMI], ASA score, and reason for the initial arthroplasty procedure), local history (number of previous surgical procedures, reason for revision, femoral and acetabular bony defects classified according to Paprosky, and status of the abductor apparatus), and characteristics of the revision (approach, diameters of the cup and femoral head, cup inclination, femoral offset, lower limb length, and implant anteversion). Controls were patients without dislocation after revision dual-mobility THA. Each of the 16 patients was matched to 3 controls on age (±10 years), sex, year of revision, and whether revision was only acetabular or bipolar. Univariate and multivariate analyses were done to compare the cases and controls, and dislocation outcomes in the cases were evaluated.

RESULTS

By univariate analyses, factors associated with dislocation were BMI>30 (cases, 37.5%; controls, 10.4%; p=0.02), larger number of previous surgical procedures on the same hip (cases, 2.8; controls, 1.8; p=0.004), larger number of arthroplasties (cases, 2.3; controls, 1.5; p=0.004), history of instability (cases, 31% with chronic dislocation and 13% with recurrent dislocation; controls, 6.25% and 2.1%, respectively; p=0.004), and compromised abductor apparatus (cases, 56.25%; controls, 14.6%; p=0.002). Independent risk factors for dislocation identified by multivariate analysis were instability (odds ratio [OR], 14.5; 95% confidence interval [95%CI], 1.5-149.9) and, most importantly, abductor apparatus compromise (OR, 43.1; 95%CI, 3.18-586.3). Of the 16 cases, 1 was lost to follow-up, 1 had contra-indications to anaesthesia, 1 died after several dislocation episodes, and 1 died 3 months after surgical reduction. In 5 cases, there was a single dislocation episode. Further surgery was performed in 8 cases (surgical reduction, n=1; constrained cup, n=3; trochanteric internal fixation, n=1; exchange of the dual-mobility cup, n=2, including 1 with subsequent dislocation episodes; and femoral component exchange followed by a retentive cup due to further dislocation episodes, n=1).

CONCLUSION

Risk factors for dislocation consisted of a history of instability and, most importantly, abductor apparatus compromise. A constrained cup should be considererd in patients with impaired abductor apparatus. No further dislocations occurred after reduction of the first episode in 31.25% of cases. Recurrent dislocation should prompt measures to correct impaired abductor apparatus whenever possible, as well as correction of any component malposition. Whether a retentive cup should be implanted routinely remains unclear.

LEVEL OF EVIDENCE

III, matched case-control study.

Multicenter Evaluation of a Modular Dual Mobility Construct for Revision Total Hip Arthroplasty

INTRODUCTION

Modular Dual Mobility (MDM) constructs in total hip arthroplasty (THA) offer increased hip stability compared with constrained liners, without compromising hip range of motion. The purpose of this study was to evaluate outcomes of revision THA using MDM.

METHODS

The study was a multiinstitutional retrospective cohort study of 315 hips that underwent revision THA using MDM between 2011 and 2017. Clinical outcomes and reasons for failure were collected.

RESULTS

Three hundred fifteen patients met 1-year minimum follow-up (mean 3.3 years). Nine hips had instability postoperatively (2.9%), and 30 hips required reoperation (9.5%). Seven had recurrent instability (6.5%) which was associated with liner-only exchange (P = .021) and liner outer diameter of ≤ 38 mm (P = .016).

CONCLUSION

Revision THA with MDM provided a low rate of instability and reoperation in a revision cohort. Recurrent instability following use of MDM in revision THA was associated with retention of the acetabular component and polyethylene outer diameter ≤ 38 mm.

LEVEL OF EVIDENCE

Therapeutic Level III.

The Role of Crosslinked Polyethylene in Reducing Aggregated Costs of Total Hip Arthroplasty in the United States

BACKGROUND

Widespread adoption of crosslinked polyethylene for the acetabular articular surface for total hip arthroplasty has substantially reduced revision rates and dislocation rates. We aim to provide estimates of the resulting magnitude of the annual reduction in aggregated costs of total hip arthroplasty surgery in the United States.

METHODS

After we obtained, from the literature, the contrasting mid-term rates of revisions and dislocations of total hip arthroplasty using conventional polyethylene vs those using crosslinked polyethylene, specifically from only registry studies and prospective, randomized controlled studies, we multiplied these incidence figures by the cost estimates of these failures to generate approximations of the cost savings in the United States from the use of crosslinked polyethylene.

RESULTS

The estimates suggest that in the United States these savings might be one billion dollars per annual cohort over a 15-year duration.

CONCLUSION

The use of crosslinked polyethylene has reduced substantially the overall costs of total hip arthroplasty surgery in the United States.

Outcomes for cemented dual mobility cup to treat recurrent instability; A UK case series

Objectives

Recurrent dislocation of Total Hip Replacement (THR) is often multifactorial and remains a significant surgical challenge with a significant risk of further instability. Dual Mobility Cups (DMC) have been used widely with good long term results in France with few studies in the British literature, especially assessing their use for recurrent instability. We set out to assess whether recurrent instability can be successfully treated solely with revision of acetabular component to a dual mobility cup.

Methods

We retrospectively reviewed a prospectively collected electronic database for all consecutive dual mobility cups implanted to address recurrently instability in THR. Radiological and clinical data have been analysed.

Results

From September 2013 to September 2017 54 dual mobility cups have been implanted, mean age 78 (range 49-97). 47 were 1st time revision procedures, 7 were following previous revisions including 5 failed PLADs. Average time post primary was 10 years (range 8 months-23 years). Twenty cases are cement in cement revisions which has become our primary technique for revision of cemented cups. Mean follow up is 1.9 years (range 6 months-5 years), 37 cases have 2 year follow up available. 8 patients have died. There have been no episodes of further instability. One patient has had reoperation for infection (1st stage revision).

Conclusions

This series demonstrates satisfactory early to mid-term results for the use of dual mobility cups to treat recurrent instability. The technique is particularly useful when femoral components are well fixed and can be used with monoblock implants such as the Charnley stem. Cement in cement revision is a convenient technique and potentially reduces complications and cost. Further analysis of longer term data is required but these results suggests this could be a valid solution to a complex problem.

Modern Dual-Mobility Cups in Revision Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

The purpose of this systematic review is to analyze the outcomes of dual-mobility (DM) cups in revision total hip arthroplasty (THA). Specifically, we evaluated the following: (1) all-cause and aseptic survivorship rates; (2) dislocation rates; (3) complications; and (4) clinical outcomes reported using validated health status measures.

METHODS

A comprehensive literature search included studies that reported the following: (1) re-revision rates, (2) complications, and (3) clinical outcomes following DM use in revision THA. The following exclusion criteria were used: (1) studies that did not stratify their analysis between primary and revision THA, (2) studies that utilized off-label techniques, (3) review articles, (4) case studies, (5) basic science articles, (6) non-English language reports, and (6) reports on patients who underwent surgery before 2010, in order to reflect modern DM implants use and technology. A total of 9 studies were included in our final analysis.

RESULTS

Aseptic and all-cause survivorship rates were 97.7% and 94.5%. Prevalence of dislocation was 2.2%, and 0.3% for intraprosthetic dislocation. Meta-analysis comparing DM to fixed-bearing prostheses demonstrated a significantly lower odds of dislocation in the DM cohort (odds ratio 0.24, P = .002). Complications occurred in 7.4% of revision THAs with DM cups, while infection rates totaled to 3.3% of cases. Studies comparing outcomes using Harris Hip Scores did not demonstrate a statistically significant difference in improved postoperative scores (P > .05).

CONCLUSION

DM cups have demonstrated excellent survivorship, low dislocation, and overall complication rates. Therefore, it can be considered a safe and effective option, particularly in the high-risk patients who undergo revision THA.

Dual mobility acetabular cups for total hip arthroplasty: advantages and drawbacks

INTRODUCTION

The dual mobility cup (DMC) concept was proposed by Professor Gilles Bousquet in 1974. Its' aims were to prevent postoperative dislocation, restore the physiological range of motion of the hip, and reduce the stresses at the interface. Since it was created, this design has been modified multiple times to reduce the complication rate, improve implant survival, and expand the indications.

AREAS COVERED

The objective of this review is to discuss the advantages and disadvantages of this implant based on its 40-year history and also to propose a range of indications based on published results. This will provide surgeons with a complete overview of DMC.

EXPERT COMMENTARY

Published studies on DMC confirm the low dislocation rate. Improvements made to DMC overtime have greatly reduced the complications related to wear, such as aseptic loosening and intraprosthetic dislocation (IPD). According to the literature, the indications have expanded and are no longer limited to revision surgery only. Long-term studies are needed before we can draw formal conclusions and consolidate these promising results.

How to prevent dislocation after revision total hip arthroplasty: a systematic review of the risk factors and a focus on treatment options

Background

Dislocation represents the most common complication after revision total hip arthroplasty (rTHA). Understanding risk factors for dislocation has a great clinical relevance for every hip surgeon in order to consider all surgical options for effective planning. The aim of this systematic review was to answer two main questions—(1) what are the risk factors for instability after rTHA? and (2) what are the best preoperative assessments and surgical options to avoid dislocation after rTHA?

Materials and methods

Scientific databases were accessed to identify papers dealing with prevention and treatment of dislocation after rTHA. We performed a search using the keywords ‘revision hip arthroplasty’ and ‘dislocation’, ‘instability’, ‘outcome’, ‘failure’, ‘treatment’. After removal of duplicates and exclusion of works published in different languages, 33 articles were reviewed completely.

Results

Risk factors were analysed in order to establish the most relevant and evidence-based treatments available in the current literature.

Conclusions

The risk of dislocation after rTHA can be reduced using some precautions inferred from the literature. The use of a larger femoral and acetabular component, elevated rim liner and dual mobility implants can significantly reduce the risk of dislocation after rTHA. However, care must be taken regarding patient-related risk factors since these cannot be addressed and modified. Hence, a complete evaluation of risk factors should be performed for each patient and procedure before starting rTHA.

An Early Report of the Use of a Modular Dual Mobility Articulation in Revision Acetabular Reconstruction

BACKGROUND

Instability remains one of the main problems after revision hip surgery. The aim of this study was to review the clinical, radiological, and patient-reported outcomes with the use of modular dual-mobility articulation for revision acetabular reconstruction and investigate the risk of fretting corrosion by measuring serum trace metal ion levels.

METHODS

Sixty consecutive patients with a minimum of 24-month follow-up after the insertion of a modular dual-mobility (Stryker, Mahwah, NJ) cup at the time of revision hip surgery were identified. Follow-up included clinical and radiological patient review and functional outcome measures, and a subset of patients had their metal ion (cobalt and chromium) levels checked.

RESULTS

At the most recent follow-up, 5 patients had died, 3 patients have been revised because of ongoing instability, and 3 patients have had revision surgery due to infection. Overall functional outcome (mean Western Ontario and McMaster Universities Osteoarthritis Indexfunction 76, University of California, Los Angeles 5.6, mean Oxford 74.7, Short Form-12 physical 41.6/mental 53.3) and overall pain relief (mean Western Ontario and McMaster Universities Osteoarthritis Index pain score 78.3) scores were good. The mean satisfaction score was 78 of 100. The median serum trace metal chromium and cobalt levels at the most recent follow-up were 0.4 µg/L (range 0.1-6.1 µg/L) and 0.42 µg/L (range 0.21-9.42 µg/L), respectively. The survival with revision as the end point was 90%.

CONCLUSIONS

Dual-mobility cups with modularity represent an excellent option for the patient having revision hip surgery at high risk of instability. This series presents good patient-reported outcome measures and a low complication and revision rate.

Comprehensive Review of Current Constraining Devices in Total Hip Arthroplasty

Hip instability after total joint arthroplasty is a devastating complication. Appropriate management of instability is a challenge. Three components that are commonly used in these challenging scenarios are constrained liners, constrained tripolar components, and nonconstrained tripolar components. The biomaterials and biomechanics of these devices vary. Surgeons must take into account the risks associated with each of these components and some surgical pearls for their use. A thorough review of the recent literature allows comparison of results addressing the short-, medium-, and long-term survival of each component. Constraining devices are a good option when used in salvage procedures in elderly and/or low-demand patients with hip instability. However, constraining devices should not be used to correct deficiencies in surgical technique or implant placement.

Course of dislocated posterior hip arthroplasty: A continuous 232-patient series at a mean 10 years' follow up (range, 1-22 years)

BACKGROUND

Dislocation rates in posterior total hip arthroplasty (THA) range between 2% and 5%, but long-term course (recurrence of dislocation or revision surgery) is not known, most series having short follow-up or small populations. We therefore conducted a retrospective study on a large series, to determine long-term rates of recurrence and surgical revision and recurrence risk factors.

HYPOTHESIS

Long-term follow-up of a large cohort of THA dislocations enables recurrence rate and factors to be determined.

MATERIAL AND METHOD

Five hundred and nine cases of THA dislocation were admitted to our center between 1994 and 2008. A hundred and twenty seven incomplete files and 150 patients who had received their THA elsewhere were excluded, leaving 232 patients: 150 female, 82 male. Mean age at THA (163 primary, 69 revision) was 63 years (range, 15-90 years), and 65 years (range 20-90 years) at first dislocation, with a mean interval to dislocation of 25 months. Minimum follow-up was 8 years up to 2016, or 1 year taking account of deaths (111 deaths). There were 46 anterior, 185 posterior and 1 multidirectional dislocations. The following potential recurrence factors were assessed: gander, age, body-mass index (BMI), etiology, surgical history, bearing diameter and type, component fixation means, dislocation direction, and time to dislocation.

RESULTS

A hundred and thirty three of the 232 patients (57%) showed at least 1 recurrence, at a mean 38 months (range, 0.5-252 months); 78 experienced a second and 32 a third recurrence. Ninety-nine (43%) had only 1 dislocation, without recurrence, but 17 of these (17%) underwent reoperation for other causes. The reoperation rate was 17/232 (7%) excluding recurrent instability, and 84/232 (36%) for instability. Fourty-eight months after the first dislocation, 84/133 cases of recurrence (63%) had been reoperated on: 16 complete replacements, 18 bearing replacements, 42 dual mobility cups, one large diameter cup, seven Lefèvre retentive cups. The rate of revision surgery for instability was high, at 84/232 (36%), and higher again in relation to recurrence (84/133: 63%). Only posterior dislocation emerged as a factor for recurrence (HR=1.774, 95% CI [1.020-3.083]), the other tested factors showing no correlation.14 of the 84 revision surgeries for instability (16.6%) were followed by recurrence, without identifiable risk factors.

CONCLUSION/DISCUSSION

The recurrence rate was 57%, with posterior dislocation as the only risk factor. The rate of revision surgery for recurrence was 84/232 (36%), with 14/84 revision procedures (16.6%) followed by further recurrence.

LEVEL OF EVIDENCE

IV, retrospective, without control group.

Soft tissue reinforcement with a Leeds-Keio artificial ligament in revision surgery for dislocated total hip arthroplasty

INTRODUCTION

Since dislocation after total hip arthroplasty (THA) greatly diminishes patient's quality of life, the THA frequently needs revision. However, it is common for the dislocation not to heal even after reconstruction, but rather to become intractable.

METHODS

The 17 patients with dislocated THA, mean age of 71 years (range 51-87 years), who underwent a revision THA together with soft tissue reinforcement with a Leeds-Keio (LK) ligament were enrolled. The purposes of reinforcement with LK ligament were to restrict the internal rotation of the hip joint, and to encourage the formation of fibrous tissue in the posterior acetabular wall to stabilise the femoral head. We determined the success rate of surgical treatment for dislocation, the Harris Hip Score (HHS), a factor of recurrent dislocation.

RESULTS

There was no recurrent dislocation in 82% of the cases (14 joints) during the mean postoperative follow-up period of 63.5 months (15-96 months). The HHS was 82 ± 18 points preoperatively and 82 ± 14 points postoperatively. Recurrent dislocation after this surgical procedure occurred in 2 hips with breakage of the LK ligaments, and intracapsular dislocation in 1 hip with loosening of the LK ligament.

CONCLUSIONS

Although the risk of recurrent dislocation still exists with this procedure, when performed to provide reinforcement with an LK ligament for dislocated THA it may be useful in intractable cases with soft tissue defects around the hip joint.

Mid-Term Outcomes of Dual Mobility Acetabular Cups for Revision Total Hip Arthroplasty

BACKGROUND

This study evaluated (1) survivorship, (2) clinical outcomes, (3) complications, and (4) radiographic outcomes of dual mobility (DM) systems when compared to fixed-bearing prostheses in revision total hip arthroplasty (THA).

METHODS

A cohort of 85 patients who underwent revision THA using DM implants were compared to a prior matching cohort of 170 patients who received fixed-bearing implants. Mean follow-up time was 4 years in the DM cohort and 10 years in the fixed-bearing cohort. Kaplan-Meier analysis was performed to assess survivorships. Clinical outcomes were evaluated using the Harris Hip Score (HHS). Complications and radiographs were evaluated and reported at the final follow-up.

RESULTS

Overall aseptic and all-cause survivorships of the DM cohort were 96.5% and 95.3% compared to 94.7% and 93.5% in fixed-bearing cohort (P = .01 for aseptic and all-cause survivorships). The DM cohort had statistically significant higher survivorship when compared at equivalent follow-up interval in the fixed-bearing cohort. There were 3 aseptic (one due to dislocation) and 1 septic revision in the DM cohort compared to 9 aseptic (6 due to dislocation) and 2 septic revisions in the fixed-bearing cohort. Postoperative HHS scores were 88 and 86 points in the DM and fixed-bearing cohorts. However, the difference in mean improvement in HHS scores from preoperative to postoperative (ΔHHS) was not statistically significant (35 vs 34, P = .533). Except for the aforementioned revisions, there were no progressive radiolucencies or osteolysis on radiographic evaluation in both cohorts.

CONCLUSION

DM articulations demonstrated superior survivorship at equal follow-up intervals when compared to fixed-bearing implants and showed a trend toward lower dislocation rates.

Utilizing Dual Mobility Components for First-Time Revision Total Hip Arthroplasty for Instability

BACKGROUND

Dislocation following total hip arthroplasty (THA) remains a significant clinical problem. Few studies have focused on the use of dual mobility (DM) components in the setting of first-time revision for instability following THA. Here, we investigate patient outcomes following first-time revision THA with DM components for a diagnosis of instability.

METHODS

Institution-wide revision THAs using DM components performed between 2010 and 2013 were identified. Chart review identified 40 patients with average 3-year follow-up who had undergone first-time revision for instability, defined as instability after primary THA. Etiology of instability was classified by Wera type. Patient demographics, medical co-morbidities, re-dislocations, and re-revisions were recorded. Component position and leg-length discrepancy were measured on pre-operative and post-operative radiographs when available. Utilizing Student's t-test or Fisher's exact test, we analyzed differences between those who endured recurrent dislocation and those who did not.

RESULTS

Recurrent dislocation occurred in 2 patients (5%). Both patients underwent re-revision for recurrent instability and carried diagnoses of instability of unresolved etiology. Two patients underwent re-revision for reasons unrelated to the DM construct. All-cause re-revision rate at final follow-up was therefore 10% (4 patients). No medical, demographic, or radiographic factors were significantly associated with risk of recurrent instability (P > .05).

CONCLUSION

The use of DM components for first-time revision THA for a diagnosis of instability carried a re-dislocation rate of 5% and an all-cause re-revision rate of 10% at average 3-year follow-up. Instability of unresolved etiology was associated with re-dislocation following revision surgery.

Otto Aufranc Award: Dual-mobility Constructs in Revision THA Reduced Dislocation, Rerevision, and Reoperation Compared With Large Femoral Heads

BACKGROUND

Dislocation is one of the most common complications after revision THA. Dual-mobility constructs and large femoral heads (ie, 40 mm) are two contemporary, nonconstrained bearing options used in revision THA to minimize the risk of dislocation; however, it is not currently established if there is a clear benefit to using dual-mobility constructs over large femoral heads in the revision setting.

QUESTIONS/PURPOSES

We sought to determine if dual-mobility constructs would provide a reduction in dislocation, rerevision for dislocation, and reoperation or other complications as compared with large femoral heads in revision THA.

METHODS

From 2011 to 2014, a series of 355 THAs underwent revision for any reason and received either a dual-mobility construct (146 THAs) or a 40-mm large femoral head (209 THAs). Indications for either construct were based on surgeon judgment; however, there is a preference to use dual-mobility constructs in patients believed to be at higher risk of dislocation. In the dual-mobility group, 20 of 146 (14%) were excluded because of loss of followup before 2 years or because they had a dual-mobility shell cemented into a preexisting acetabular component. In the large head group, 33 of 209 (16%) were lost to followup before 2 years. Followup in the dual-mobility group was 3.3 ± 0.8 years and followup in the large head group was 3.9 ± 0.9 years. Primary endpoints included dislocation, rerevisions for dislocation, and reoperations, which were determined through our institution's total joint registry and verified by individual patient chart review. Age and body mass index were not different with the numbers available between the groups, but there was a slight predominance of females in the dual-mobility group (52% [66 of 126] female) versus the 40-mm large head group (41% [72 of 176] female) (p = 0.05). Notably, 33% (41 of 126) of patients receiving the dual-mobility constructs had the index revision THA done for a diagnosis of recurrent dislocation versus 9% (17 of 176) in the 40-mm large head group. Mean effective head size in the dual-mobility group was 47 mm (range, 38-58 mm).

RESULTS

The subsequent frequency of dislocation in the dual-mobility construct group was less (3% [four of 126] dual-mobility versus 10% [17 of 176] in the 40-mm large head group; hazard ratio, 3.2 [1.1-9.4]; p = 0.03). Rerevision for dislocation in the dual-mobility construct group was less frequent (1% [one of 126] dual-mobility versus 6% [10 of 176] in the 40-mm large head group; hazard ratio, 7.1 [0.9-55.6]; p = 0.03). Reoperation for any cause in the dual-mobility construct group was less frequent (6% [eight of 126] dual-mobility versus 15% [27 of 176] in the 40-mm large head group; hazard ratio, 2.5 [1.1-5.5]; p = 0.02); there were no differences between the groups in terms of the overall percentage of complications in each group.

CONCLUSIONS

When compared with patients treated with a 40-mm large femoral head, patients undergoing revision THA who received a dual-mobility construct had a lower risk of subsequent dislocation, rerevision for dislocation, and reoperation for any reason in the first several years postoperatively. Those findings were present despite selection bias in this study to use the dual-mobility construct in patients at the highest risk for subsequent dislocation. Given the lower risk of subsequent dislocation, rerevision, and reoperation with the dual-mobility construct, some surgeons may wish to consider whether the role of dual-mobility should be judiciously expanded in contemporary revision THA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Outcomes of dual mobility components in total hip arthroplasty

Aims

Instability remains a challenging problem in both primary and revision total hip arthroplasty (THA). Dual mobility components confer increased stability, but there are concerns about the unique complications associated with these designs, as well as the long-term survivorship.

Materials and Methods

We performed a systematic review of all English language articles dealing with dual mobility THAs published between 2007 and 2016 in the MEDLINE and Embase electronic databases. A total of 54 articles met inclusion criteria for the final analysis of primary and revision dual mobility THAs and dual mobility THAs used in the treatment of fractures of the femoral neck. We analysed the survivorship and rates of aseptic loosening and of intraprosthetic and extra-articular dislocation.

Results

For the 10 783 primary dual mobility THAs, the incidence of aseptic loosening was 1.3% (142 hips); the rate of intraprosthetic dislocation was 1.1% (122 hips) and the incidence of extra-articular dislocation was 0.46% (41 hips). The overall survivorship of the acetabular component and the dual mobility components was 98.0%, with all-cause revision as the endpoint at a mean follow-up of 8.5 years (2 to 16.5). For the 3008 revision dual mobility THAs, the rate of aseptic acetabular loosening was 1.4% (29 hips); the rate of intraprosthetic dislocation was 0.3% (eight hips) and the rate of extra-articular dislocation was 2.2% (67 hips). The survivorship of the acatabular and dual mobility components was 96.6% at a mean of 5.4 years (2 to 8). For the 554 dual mobility THAs which were undertaken in patients with a fracture of the femoral neck, the rate of intraprosthetic dislocation was 0.18% (one hip), the rate of extra-articular dislocation was 2.3% (13 hips) and there was one aseptic loosening. The survivorship was 97.8% at a mean of 1.3 years (0.75 to 2).

Conclusion

Dual mobility articulations are a viable alternative to traditional bearing surfaces, with low rates of instability and good overall survivorship in primary and revision THAs, and in those undertaken in patients with a fracture of the femoral neck. The incidence of intraprosthetic dislocation is low and limited mainly to earlier designs. High-quality, prospective, comparative studies are needed to evaluate further the use of dual mobility components in THA. Cite this article: Bone Joint J 2018;100-B:11–19.

Comparison of dual mobility cup and other surgical construts used for three hundred and sixty two first time hip revisions due to recurrent dislocations: five year results from Lithuanian arthroplasty register

PURPOSE

Recently, there has been increasing interest in the use of dual mobility systems in the treatment of hip instability. The aim of this study was to investigate the re-revision rate of dual mobility cup compared to different surgical concepts when used for first-time hip revisions due to recurrent dislocations.

METHODS

The data were derived from the Lithuanian Arthroplasty Register. For survival analysis, we used both re-revision for all reasons and for dislocations as an end-point. Cox proportional hazards models were used to analyze the influence of various covariates (age, gender, and implant concept).

RESULTS

A total of 1388 revisions were recorded from 2011 to 2015, of which 362 were performed due to recurrent dislocation. Of the revisions, 247 were performed using dual mobility cups, while 115 were performed using a variety of other surgical constructs including constrained acetabular cups, conventional cups, femoral head exchanges, stem exchanges or anti-luxation rings. There were 27 re-revisions of which 15 were for additional dislocations. There were only 2% re-revisions due to dislocation with dual mobility vs 9% when using other surgical constructs. Cox regression adjusting for age and gender showed that in the short-term, dual mobility cup had a lower risk of revision due to dislocation as well as for all reasons compared to the other surgical constructs.

CONCLUSION

In revision of total hip arthroplasties for dislocation, significantly lower short-term re-revision rate was observed for patients revised with dual mobility cup.

Risk of revision and dislocation in single, dual mobility and large femoral head total hip arthroplasty: systematic review and network meta-analysis

Postoperative dislocation is a challenging complication after total hip arthroplasty (THA) that affects patient outcome worldwide. Instability is one of the main complications with rates exceeding 20% in some series. Currently, alternative acetabular components are available with dual mobility (DMTHA) bearing surfaces and larger femoral head size that may reduce the risk of dislocation, yet provide the functional benefit of standard single mobility (STHA) bearing surface THA. However, whether STHA, big femoral head (BTHA) and DMTHA should be used is still controversial. This systematic review and meta-analysis aim to compare postoperative dislocation and revision (aseptic loosening and infection) of BTHA, STHA and DMTHA in primary or revision THA. These clinical outcomes consist of postoperative dislocation and revision (aseptic loosening and infection). This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Relevant studies were identified from Medline and Scopus from inception to June 8, 2017, that reported postoperative dislocation and revision (aseptic loosening and infection) of either implant THA. Eleven of 677 studies (nine comparative studies and two RCTs) (N = 4084 patients) were eligible; all 11 studies were included in pooling. Intervention included dual mobility THA (N = 1068 patients), standard THA (N = 2568 patients), big head THA (N = 378 patients) and constrain THA (N = 70 patients). A network meta-analysis showed that risk of revision and dislocation of DMTHA was significantly lower with RR of 2.19 (1.36, 3.53) and 4.19 (2.04, 8.62) when compared to STHA. While there was no statistically significant risk of having revision and dislocation of DMTHA when compared to BTHA and CTHA. The SUCRA probability of DM and BTHA was in the first and second rank with 46.5 and 44.8% in the risk of revision and 46.7 and 45.1% in the risk of dislocations. In short-term outcomes (5 years or less, with follow-up of 0-5 years), the best implant of choice that has lowest risk of revision and dislocation after THA is DMTHA follow by BTHA. We recommend using dual mobility and big head as an implant for safety in THA. However, there were only two studies that reported long-term survivorship (more than 5 years, with follow-up of 5-15 years). Further research that assesses long-term survivorship is necessary to further evaluate which implants are the best for THA.

Total hip arthroplasty revision by dual-mobility acetabular cup cemented in a metal reinforcement: A 62 case series at a minimum 5 years' follow-up

INTRODUCTION

Total hip arthroplasty (THA) requires bone reconstruction in case of severe acetabular injury, with risk of dislocation, especially postoperatively. Dual-mobility cups have proved effective in preventing dislocation in THA revision for instability, but their behavior when cemented in a metal reinforcement has been little studied.

OBJECTIVES

The present study assessed results for a dual-mobility cup cemented in a metal reinforcement, in terms of aseptic loosening and postoperative instability.

MATERIAL AND METHODS

A single-center continuous series of 62 patients receiving such an assembly in THA revision was assessed retrospectively at a minimum 5 years' follow-up. Failure due to aseptic loosening or instability and implant survival at last follow-up were analyzed.

RESULTS

Radiological and clinical analysis was performed at a mean 77 months' follow-up. Mean Merle-d'Aubigné-Postel score was 14, Harris score 73 and Oxford-12 score 23.9 at last follow-up. Complications comprised 5 cases of loosening and 2 of dislocation. Loosening risk was significantly greater in case of<2mm cement thickness between cup and reinforcement. Eight-year infection-free survival was 91.9%.

DISCUSSION

The present clinical results were comparable to those in series using the same kind of assembly; the dislocation rate was low, but the rate of aseptic loosening was higher than reported elsewhere. Cement thickness between cup and reinforcement was a determining factor for stability. Cup design may also be relevant to loosening. This technique seemed to be a good option in THA revision with severe bone loss.

LEVEL OF EVIDENCE

IV, retrospective study.

Early intraprosthetic dislocation in dual-mobility implants: a systematic review

BACKGROUND

Dual mobility implants are subject to a specific implant-related complication, intraprosthetic dislocation (IPD), in which the polyethylene liner dissociates from the femoral head. For older generation designs, IPD was attributable to late polyethylene wear and subsequent failure of the head capture mechanism. However, early IPDs have been reportedly affecting contemporary designs.

METHODS

A systematic review of the literature according to the preferred reporting items for systematic reviews and meta-analyses guidelines was performed. A comprehensive search of PubMed, MEDLINE, Embase, and Google Scholar was conducted for English articles between January 1974 and August 2016 using various combinations of the keywords "intraprosthetic dislocation," "dual mobility," "dual-mobility," "tripolar," "double mobility," "double-mobility," "hip," "cup," "socket," and "dislocation."

RESULTS

In all, 16 articles met our inclusion criteria. Fourteen were case reports and 2 were retrospective case series. These included a total of 19 total hip arthroplasties, which were divided into 2 groups: studies dealing with early IPD after attempted closed reduction and those dealing with early IPD with no history of previous attempted closed reduction. Early IPD was reported in 15 patients after a mean follow-up of 3.2 months (2.9 SD) in the first group and in 4 patients after a mean follow-up of 15.1 months (9.9 SD) in the second group.

CONCLUSIONS

Based on the current data, most cases have been preceded by an attempted closed reduction in the setting of outer, large articulation dislocation, perhaps indicating an iatrogenic etiology for early IPD. Recognition of this possible failure mode is essential to its prevention and treatment.

Increase in safe zone area of the acetabular cup using dual mobility cups in THA

BACKGROUND

Dual mobility cup (DMC) inserts reduce the risk of dislocation after total hip arthroplasty (THA). No available research has clearly delineated stability advantages of DMC inserts in primary and revision THA. We investigated: (i) the degree of change in the safe zone of the cup when a DMC insert is used compared to a fixed insert; (ii) the method of selecting candidates for a DMC insert without changing the position of the acetabular (cup) component during revision THA in frequent dislocation cases caused by implant impingement.

METHODS

A model of the pelvis and femur was developed from computed tomography images. The safe zone was defined as the area in the acetabular component, over which conditions for stable range of motion were satisfied. The safe zone was calculated for both a fixed and a DMC insert over a predetermined range of 3-D motion, and the effect of increasing the anteversion position of the femoral component from 5° to 35° was quantified.

RESULTS

The lowest ratio of the area of the safe zone was about 4.9 at 20° anteverison of the femoral component. Safe zone of DMC inserts zone had increased stability of 10°-15° in both vertical and horizontal directions, compared to fixed inserts.A 5- to10-fold expansion of the safe zone can be expected with the use of DMC insert.

CONCLUSIONS

DMC insert could help to set the acetabular component more accurately in primary and revision THA.

Retrieval evidence of impingement at the third articulation in contemporary dual mobility cups for total hip arthroplasty

PURPOSE

We aimed to assess polyethylene liners of retrieved hips of one design of a dual mobility (DM) cup liner and two designs of femoral stems to better understand the role of femoral stem design on polyethylene impingement.

METHODS

This was a case-control study involving 70 retrieved highly cross-linked polyethylene (X3) liners used with ABGII (n = 35) and Rejuvenate (n = 35) stems (Stryker). All polyethylene liners were assessed for evidence of rim deformation and the damage quantified using metrology methods.

RESULTS

A total of 80% of polyethylene liners paired with ABGII necks had macroscopic evidence of neck impingement resulting in a raised lip whilst 23% of liners paired with Rejuvenate necks had evidence of a raised lip (p < 0.0001). The height of the raised rims of the DM cups paired with ABGII necks had a median (range) of 139 μm (72-255). The height of the raised rims of the DM cups paired with Rejuvenate necks had a median (range) of 52 μm (45-90) (p < 0.0001).

CONCLUSION

Our new findings from retrieved dual mobility bearings showed that polyethylene liner rim deformation resulting from impingement with the femoral neck occurs in early in-human function, is circumferential in distribution, and is affected by the stem neck design. We recommend the use of highly polished and non-edged neck designs when used in conjunction with DM cups.

The Cost-Effectiveness of Dual Mobility Implants for Primary Total Hip Arthroplasty: A Computer-Based Cost-Utility Model

BACKGROUND

Dislocation remains a clinically important problem following primary total hip arthroplasty, and it is a common reason for revision total hip arthroplasty. Dual mobility (DM) implants decrease the risk of dislocation but can be more expensive than conventional implants and have idiosyncratic failure mechanisms. The purpose of this study was to investigate the cost-effectiveness of DM implants compared with conventional bearings for primary total hip arthroplasty.

METHODS

Markov model analysis was conducted from the societal perspective with use of direct and indirect costs. Costs, expressed in 2013 U.S. dollars, were derived from the literature, the National Inpatient Sample, and the Centers for Medicare & Medicaid Services. Effectiveness was expressed in quality-adjusted life years (QALYs). The model was populated with health state utilities and state transition probabilities derived from previously published literature. The analysis was performed for a patient's lifetime, and costs and effectiveness were discounted at 3% annually. The principal outcome was the incremental cost-effectiveness ratio (ICER), with a willingness-to-pay threshold of $100,000/QALY. Sensitivity analyses were performed to explore relevant uncertainty.

RESULTS

In the base case, DM total hip arthroplasty showed absolute dominance over conventional total hip arthroplasty, with lower accrued costs ($39,008 versus $40,031 U.S. dollars) and higher accrued utility (13.18 versus 13.13 QALYs) indicating cost-savings. DM total hip arthroplasty ceased being cost-saving when its implant costs exceeded those of conventional total hip arthroplasty by $1,023, and the cost-effectiveness threshold for DM implants was $5,287 greater than that for conventional implants. DM was not cost-effective when the annualized incremental probability of revision from any unforeseen failure mechanism or mechanisms exceeded 0.29%. The probability of intraprosthetic dislocation exerted the most influence on model results.

CONCLUSIONS

This model determined that, compared with conventional bearings, DM implants can be cost-saving for routine primary total hip arthroplasty, from the societal perspective, if newer-generation DM implants meet specific economic and clinical benchmarks. The differences between these thresholds and the performance of other contemporary bearings were frequently quite narrow. The results have potential application to the postmarket surveillance of newer-generation DM components.

LEVEL OF EVIDENCE

Economic and decision analysis Level III. See Instructions for Authors for a complete description of levels of evidence.

Constrained liners, dual mobility or large diameter heads to avoid dislocation in THA

Dislocation remains a common cause of failure after total hip arthroplasty. The limitations of existing approaches to address instability have led to the development of powerfull options: constrained liners, dual mobility and large heads. These implant-related options have proven to be very efficient, but have raised concerns.With constrained liners, restricted range of motion (ROM) is responsible for impingement leading to high likelihood of failure, depending on the design, with various failure modes.Improvements of the bearing materials have addressed some of the concerns about increased volumetric wear of conventional polyethylene and offer an option to reduce instability: large diameter heads have the advantage of increased ROM before impingement, increased head-neck ratio, and jump distance. Highly cross-linked polyethylene helps address the risk for increased wear, and also large heads provide improved stability without the risk of mechanical failures observed with constrained liners. However, the increase of the head size remains limited as reducing the thickness of the liner may lead to fractures. In addition, the jump distance decreases as the cup abduction increases.The dual mobility concept simultaneously attempts to address head-neck ratio, constraint, and jump distance. Despite the need for longer follow-up, concerns raised about potential increased wear and intra-prosthetic dislocation with first generation implants have been addressed with modern designs.With a dramatic increase of the head-neck ratio whilst reducing the risk of mechanical failure or excessive wear, dual mobility THA outperforms large diameter heads and constrained liners at 10 years follow-up. For these reasons, dual mobility continues to gain interest worldwide and is becoming the most popular option to manage instability. Cite this article: Guyen O. Constrained liners, dual mobility or large diameter heads to avoid dislocation in THA. EFORT Open Rev 2016;1:197-204. DOI: 10.1302/2058-5241.1.000054.

Dislocation following total hip arthroplasty using dual mobility acetabular components: a systematic review

AIMS

The aim of this systematic review was to report the rate of dislocation following the use of dual mobility (DM) acetabular components in primary and revision total hip arthroplasty (THA).

MATERIALS AND METHODS

A systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines was performed. A comprehensive search of Pubmed/Medline, Cochrane Library and Embase (Scopus) was conducted for English articles between January 1974 and March 2016 using various combinations of the keywords "dual mobility", "dual-mobility", "tripolar", "double-mobility", "double mobility", "hip", "cup", "socket". The following data were extracted by two investigators independently: demographics, whether the operation was a primary or revision THA, length of follow-up, the design of the components, diameter of the femoral head, and type of fixation of the acetabular component.

RESULTS

In all, 59 articles met our inclusion criteria. These included a total of 17 908 THAs which were divided into two groups: studies dealing with DM components in primary THA and those dealing with these components in revision THA. The mean rate of dislocation was 0.9% in the primary THA group, and 3.0% in the revision THA group. The mean rate of intraprosthetic dislocation was 0.7% in primary and 1.3% in revision THAs.

CONCLUSION

Based on the current data, the use of DM acetabular components are effective in minimising the risk of instability after both primary and revision THA. This benefit must be balanced against continuing concerns about the additional modularity, and the new mode of failure of intraprosthetic dislocation. Longer term studies are needed to assess the function of these newer materials compared with previous generations. Cite this article: Bone Joint J 2017;99-B(1 Supple A):18-24.

[Use of dual mobility cups for revision hip arthroplasty]

The dual mobility cup (DMC) is an increasingly important tool not only in primary but also in revision total hip arthroplasty to prevent dislocation and eventually reduce postoperative complication rates. Various studies have shown survival rates with DMCs of up to 100% with an average dislocation rate of less than 1.5% after primary hip arthroplasty and a follow-up of 10 years. In revision surgery, survival rates of up to 99% were reported with dislocation rates between 0 and 10% after an average of 5 years after implantation. This article is intended to provide an overview of the principle and function of DMCs. Furthermore, indications as well as complications are presented.

Dual mobility cups: an effective prosthesis in revision total hip arthroplasties for preventing dislocations

PURPOSE

Postoperative dislocation is one of the most common complications following total hip arthroplasty (THA), and dual mobility articulations have been designed to provide greater hip stability. However, there are few studies that have assessed outcomes of these designs in revision THAs. Our purpose was to evaluate differences in dislocation rates, aseptic survivorship, and patient outcomes between dual mobility articulations and conventional arthroplasties in the revision setting.

METHODS

Patients who underwent revision THA with dual mobility articulations (n = 60) were matched (1:2) to patients who had conventional single articulation prostheses (n = 120). They were matched for body mass index, age, gender, and Paprosky acetabular defect classification, and were followed up for a mean of 30 months (range, 18 to 52 months). The outcomes were evaluated preoperatively and at final follow-up using Harris Hip Scores, the University of California Los Angeles activity scale, and the Short Form-36 questionnaires.

RESULTS

The dual mobility group had lower dislocation (1.7% (1 out of 60) versus 5.8% (7 out of 120)) and aseptic loosening rates (1.7% (1 out of 60) versus 4.2% (5 out of 120)) compared to the control group. There were no significant differences in functional outcomes, activity level, or overall physical and mental health status between the 2 cohorts.

CONCLUSIONS

When used in the revision setting, dual mobility bearings had fewer dislocations. We believe that these designs may lead to clinically significant improvements in complications while also improving patient reported and functional outcomes, but larger cohort studies are necessary for evaluation.