Can Dislocation of a Constrained Liner Be Salvaged With Dual-mobility Constructs in Revision THA?

The Use of Dual-Mobility Implants Through a Direct Anterior Approach as a Safe and Effective Technique for Revision Hip Arthroplasty: The Two-Year Follow-Up of a Case Series

Background Dislocation is one of the most prominent and challenging complications following the revision of total hip arthroplasty (THA). Dual-mobility cups are an option to address this problem. There is, however, little data on the outcomes of modern modular dual-mobility (MDM) cups in the revision of THA. In this study, the clinical and radiological outcomes following the revision of THA with an MDM cup using the direct anterior approach (DAA) were evaluated. Methodology We retrospectively reviewed patients who underwent a revision of THA between March 2017 and July 2019. The inclusion criteria were a revision of THA using an MDM cup through the DAA. A uniform acetabular implant was used in each revision. Outcome measures were assessed radiographically and clinically. The clinical outcome measures consisted of dislocation, infection, and re-revision. Functional assessment was performed using the Harris Hip Score preoperatively and at the last clinical examination in our department. Results This study retrospectively identified a cohort of 26 patients who underwent a revision of THA. Two patients were excluded due to incomplete follow-up because they died. Finally, 24 patients were included. A total of 17 isolated acetabular revisions and seven complete revisions were performed with a mean follow-up of 39 months (range = 29-59). No dislocations or deep infections were observed in our population to date. Except for one case of early aseptic loosening of the acetabular component, we observed no other signs of loosening, osteolysis, migration, or intraprosthetic dislocation. Conclusions THA revision through the DAA using an MDM cup is a safe and effective procedure. We observed no dislocation in a high-risk population undergoing THA revision surgery during a minimal follow-up of two years.

Contemporary Aseptic Revision Total Hip Arthroplasty in Patients ≤50 Years of Age: Results of >500 Cases

BACKGROUND

There has been a paucity of long-term outcomes data on aseptic revision total hip arthroplasties (THAs) in the young adult population. The purpose of this study was to evaluate implant survivorship, complications, and clinical outcomes in a large cohort of contemporary aseptic revision THAs in patients ≤50 years of age at the time of the surgical procedure.

METHODS

We identified 545 aseptic revision THAs performed at a single academic institution from 2000 to 2020 in patients who were 18 to 50 years of age. Patients who underwent conversion THAs and patients with a history of any ipsilateral hip infection were excluded. The mean age was 43 years, the mean body mass index (BMI) was 29 kg/m 2 , and 63% were female. The index indication for revision THA was aseptic loosening in 46% of cases, polyethylene wear or osteolysis in 28% of cases (all revisions of conventional polyethylene), and dislocation in 11% of cases. There were 126 hips (23%) that had undergone at least 1 previous revision (median, 1 revision [range, 1 to 5 revisions]). The mean follow-up was 10 years.

RESULTS

In the entire cohort, the 20-year survivorship free of any re-revision was 76% (95% confidence interval [95% CI], 69% to 82%). There were 87 re-revisions, with 31 dislocations, 18 cases of aseptic loosening of the femoral component, and 16 periprosthetic joint infections (PJIs) being the most common reasons for re-revision. Dislocation as the indication for the index revision was associated with an increased risk of re-revision (hazard ratio, 2.9; p < 0.001). The 20-year survivorship free of any reoperation was 73% (95% CI, 66% to 78%). There were 75 nonoperative complications (14%), including 32 dislocations. The mean Harris hip score significantly improved (p < 0.001) from 65 preoperatively to 81 at 10 years postoperatively.

CONCLUSIONS

Contemporary aseptic revision THAs in patients ≤50 years of age demonstrated a re-revision risk of approximately 1 in 4 at 20 years. Dislocation, aseptic loosening of the femoral component, and PJI were the most common reasons for re-revision. Index revision THAs for dislocation had a 3 times higher risk of re-revision.

LEVEL OF EVIDENCE

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

The outcome of revision total hip arthroplasty for instability

Aims

Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocation. The aim of this study was to assess the risk for recurrent dislocation after revision THA for instability.

Methods

Between 2009 and 2019, 163 patients underwent revision THA for instability at Stanford University Medical Center. Of these, 33 (20.2%) required re-revision due to recurrent dislocation. Cox proportional hazard models, with death and re-revision surgery for periprosthetic infection as competing events, were used to analyze the risk factors, including the size and alignment of the components. Paired t-tests or Wilcoxon signed-rank tests were used to assess the outcome using the Veterans RAND 12 (VR-12) physical and VR-12 mental scores, the Harris Hip Score (HHS) pain and function, and the Hip disability and Osteoarthritis Outcome score for Joint Replacement (HOOS, JR).

Results

The median follow-up was 3.1 years (interquartile range 2.0 to 5.1). The one-year cumulative incidence of recurrent dislocation after revision was 8.7%, which increased to 18.8% at five years and 31.9% at ten years postoperatively. In multivariable analysis, a high American Society of Anesthesiologists (ASA) grade (hazard ratio (HR) 2.72 (95% confidence interval (CI) 1.13 to 6.60)), BMI between 25 and 30 kg/m2 (HR 4.31 (95% CI 1.52 to 12.27)), the use of specialized liners (HR 5.39 (95% CI 1.97 to 14.79) to 10.55 (95% CI 2.27 to 49.15)), lumbopelvic stiffness (HR 6.03 (95% CI 1.80 to 20.23)), and postoperative abductor weakness (HR 7.48 (95% CI 2.34 to 23.91)) were significant risk factors for recurrent dislocation. Increasing the size of the acetabular component by > 1 mm significantly decreased the risk of dislocation (HR 0.89 (95% CI 0.82 to 0.96)). The VR-12 physical and HHS (pain and function) scores improved significantly at mid term.

Conclusion

Patients requiring revision THA for instability are at risk of recurrent dislocation. Higher ASA grades, being overweight, a previous lumbopelvic fusion, the use of specialized liners, and postoperative abductor weakness are significant risk factors.

Malseating of Modular Dual Mobility Liners: High Prevalence in Revision Total Hip Arthroplasty

BACKGROUND

Modular dual mobility (MDM) acetabular components have become increasingly more popular in total hip arthroplasty (THA). Uncertainty remains regarding liner malseating and its consequences after 5 to 10 years, especially in patients who undergo revision THA. The objective of this study was to analyze the prevalence of malseating and implant survivorship of patients who underwent revision THA using an MDM liner.

METHODS

We retrospectively identified patients who had a minimum 2-year follow-up and underwent revision THA using an MDM liner. Patient demographics, implant details, mortality, and all-cause revisions were recorded. Patients who had radiographic follow-up were assessed for malseating. Kaplan Meier survival was used to determine implant survivorship. We included 143 hips in 141 patients. Mean age was 70 years (35 - 93 years) and 86 patients (60.1%) were female.

RESULTS

Overall implant survival was 89.3% (95% Confidence Interval (CI) 0.843 - 0.946) at a mean follow-up of 6 years (range 2 to 10) years. There were eight patients excluded from malseating assessment. Upon radiological review, 15 liners (11.1%) were malseated. Survival for all-cause revision for patients with malseated liners was 80.0% (12/15, 95% CI 0.62 - 0.99, P= 0.15) versus 91.5% in patients who had non-malseated liners (110/120, 95% CI 0.86 - 0.96). There were no intraprosthetic dislocations and 3.5% of the patients were revised due to instability. No liners were revised due to malseating, and no patients who had malseated liners were revised due to instability.

CONCLUSIONS

Using MDM components in our cohort comprised of revision THA was associated with a high prevalence of malseating and an overall survival of 89.3% at a mean follow up of 6 years. Malseating does not appear to impact implant survival at a mean follow-up of 6 years.

THE CEMENTED DOUBLE MOBILITY CUP IN HIP REVISION: DIFFERENT POSSIBILITIES OF USE

Introduction

The aim of our work is to review those patients who underwent prosthetic hip revision surgery in our hospital considered to be patients at high risk of dislocation or recurrent dislocation, and who underwent a double mobility cemented cup (CMD). Analyzing the different ways to place these cups and the clinical results and reluxations.

Material and methods

The 69 cases comprised 34 men and 35 women with a mean age of 77,39 years. The mean follow-up was 4.7536 years. The type of intervention performed varied according to the cause of the intervention, the acetabular bone stock and the state of the primary cup. In the cases in which there was a good fixation of the primary metalback, we opted to carry out a cementation of the cemented DMC into the existing well-fixed metal acetabular shell, this occurred in 23 cases. In the cases where there was loosening of the primary cup but there was a good bone stock, a CMD was cemented into the bone (21 cases). In the cases where there was a Paprosky type III we cemented a DMC to a Bursch-Schneider reinforcement ring together with the placement of a cancellous bone graft (25 cases).

Results

The clinical evaluation at the end of the follow-up, according to the MD Scale, showed the mean value was 16.454 (SD 0.79472), with a survival at the end of the follow-up of 100% of the placed DMC.

Conclusion

The use of cemented DMC is a good solution in the replacement of THA, especially in cases of reluxation or risk of dislocation due to personal or technical predisposing factors. The use of these DMC cemented can be directly to the bone, into the existing well-fixed metal Shell, or cemented to a reinforcing ring, depending on the acetabular defect. Evidence Level III; Comparative Case Series .

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.

Monobloc press-fit cups with large-diameter bearings are safe in revision total hip arthroplasty

BACKGROUND

Instability is a major cause of failure of revision total hip arthroplasty (THA) which can be avoided with the use of monobloc press-fit cups with large diameter heads (LDH).

OBJECTIVE

This consecutive case series analyses whether LDH monobloc components are a safe and clinically beneficial option for revision THA.

METHODS

This consecutive case series includes 47 revision THA with LDH monobloc acetabular cup. Acetabular bone defects were Paprosky type I (42), type IIA (2) and type IIC (3). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and the Patient's Joint Perception (PJP) scores were analysed and a radiographic evaluation for signs of implant dysfunction was performed.

RESULTS

After a mean follow-up of 4.5 years, there were 5 (10.6%) acetabular cup re-revisions: 2 loss of primary fixation and 3 instabilities. Implant survivorship at 4-years was 89.4% (95% CI: 89.3 to 89.5). Recurrent hip dislocation was reported in 1 patient (2.1%) and remains under conservative treatment. The mean WOMAC and FJS were 19.5 (16.8; 0.0 to 58.3) and 57.3 (28.9; 6.3 to 100.0), respectively. Regarding the PJP, 3 (8.8%) patients perceived their hip as natural, 8 (23.5%) as an artificial joint with no restriction, 14 (41.2%) with minor restriction and 9 (26.5%) with major restriction.

CONCLUSION

In cases of revision THA with limited bone loss, press-fit primary fixation with LDH monobloc acetabular components are valuable options that offer excellent mid-term out-comes with low re-revision and joint instability rates.

Outcome and risk factors of failures associated with revision total hip arthroplasty for recurrent dislocation

INTRODUCTION

Recurrent dislocation represents the third most common cause of revision surgery after total hip arthroplasty (THA). However, there is a paucity of information on the outcome of revision total hip arthroplasty for recurrent dislocation. In this study, we investigated (1) clinical outcomes of patients that underwent revision THA for recurrent dislocation, and (2) potential risk factors associated with treatment failure in patients who underwent revision total hip arthroplasty for recurrent dislocation.

METHODS

We retrospectively reviewed 211 consecutive cases of revision total hip arthroplasty for recurrent dislocation, 81 implanted with a constrained liner and 130 with a non-constrained liner with a large-diameter femoral head (> 32 mm). Patient- and implant-related risk factors were analyzed in multivariate regression analysis.

RESULTS

At 4.6-year follow-up, 32 of 211 patients (15.1%) underwent re-revision surgery. The most common causes for re-revision included infection (14 patients) and dislocation (10 patients). Kaplan-Meier analysis demonstrates a 5-year survival probability of 77% for patients that underwent revision THA for recurrent dislocation. Osteoporosis, obesity (BMI ≥ 40), spine disease and abductor deficiency are independent risk factors for failure of revision surgery for recurrent dislocation. Liner type (constrained vs. non-constrained) was found not to be associated with failure of revision THA for recurrent dislocation (p = 0.44).

CONCLUSION

This study suggests that THA revision for recurrent dislocation is associated with a high re-revision rate of 15% at mid-term follow-up. Osteoporosis, obesity (BMI ≥ 40) spine disease and abductor deficiency were demonstrated to be independent risk factors for failure of revision THA for recurrent dislocation.

LEVEL OF EVIDENCE

Level III, case-control retrospective analysis.

Dual-mobility bearings in complex revision hip arthroplasty

BACKGROUND

Revision total hip arthroplasty (rTHA) is associated with an increased dislocation risk. Dual-mobility (DM) bearings have been used to address this issue. Such constructs offer increased range of motion and enhanced stability whilst avoiding some issues associated with fully-constrained devices. DM bearings have been used in our unit since 2013.

METHODS

All rTHA cases since 2013 were reviewed using the following criteria: (1) use of a DM bearing; (2) extensive soft tissue or bone loss resulting from ARMD, infection or multiple revisions, or requiring custom or megaprosthetic reconstruction; (3) minimum 2-month follow-up.

RESULTS

52 cases were identified with a median of 2 previous operations (range 1-6) and mean follow-up of 14 (2-41) months. The Novae-Stick component was used in 50 cases, the Avantage in 2 and the Trident MDM in 1 case. 19 required acetabular reconstruction using trabecular metal and four required custom acetabular components. 19 required femoral reconstruction with a proximal or total femoral replacement.Postoperatively, 8 patients (15.4%) sustained a dislocation at a mean of 1.6 (range 1-3) months. 3 (5.8%) requiring re-revision. 1 required excision arthroplasty and 2 a constrained liner, 1 of which went on to have further instability. There were no intraprosthetic dislocations.

CONCLUSIONS

Dual-mobility components are a viable option in the complex rTHA setting. Early dislocations can occur but the rate of instability is acceptable in this high-risk group.

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.

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.

Fretting Corrosion, Third-Body Polyethylene Damage, and Cup Positioning in Primary vs Revision Dual Mobility Total Hip Arthroplasty

BACKGROUND

Dual mobility (DM) articulations were introduced for total hip arthroplasty to reduce the risk of instability for patients who have a high risk of dislocation. The use of DM constructs in both primary and revision total hip arthroplasty has been steadily increasing, leading to concerns regarding potential risks of fretting corrosion, polyethylene wear, metal release, and failure due to component positioning.

METHODS

A total of 56 retrieved DM constructs were collected. The inner and outer polyethylene liner surfaces were assessed for 7 damage mechanisms, and fretting corrosion was evaluated for the femoral stem, head, and modular liner. Three polyethylene liners with the greatest amounts of embedded debris were examined using scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to determine the elemental content of the debris. Acetabular cup orientation was analyzed radiographically using the EBRA (Einzel-Bild-Roentgen-Analyse) method.

RESULTS

The devices were revised most frequently for infection (36%), loosening (21%), and instability/dislocation (18%). The most common polyethylene damage mechanisms were scratching, pitting, burnishing, and embedded debris, and no difference in total damage was found between primary and revision cases. Scanning electron microscopy/energy-dispersive X-ray spectroscopy revealed that debris morphology and composition were consistent with porous titanium coating, resulting from cup loosening or broken screws and augments. A total of 71% and 50% of the constructs were determined to be within the Lewinnek safe zone for inclination and anteversion, respectively.

CONCLUSION

The most notable mechanisms of surface damage were due to third-body debris, especially for the polyethylene surfaces which articulate against cobalt-chromium femoral heads and acetabular liners. Scratching of the femoral head and the metal liner from this debris may support the clinical use of ceramic for DM bearing surfaces in the future.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04404-4.

Dual Mobility and Conventional Bearings Have Comparably Low Dislocation Rates for Anterior-Based Approaches in Total Hip Arthroplasty

BACKGROUND

Dual mobility (DM) bearings for total hip arthroplasty (THA) have been proposed to reduce the risk of instability in select patients, especially those undergoing revision surgery. The use of DM bearings has not been studied as extensively for use in primary THA. The purpose of this study is to compare outcomes following primary THA with anterior-based approaches between patients receiving DM bearings vs standard bearing hip implants.

METHODS

We retrospectively reviewed a consecutive series of patients undergoing primary THA through an anterior-based approach. A 3:1 propensity score match was performed between the standard and DM bearing patients to control for possible risk factors for instability. Functional outcomes, dislocations, and aseptic revisions were identified for each patient. The effect of DM on postoperative outcomes was determined using univariate statistical analyses.

RESULTS

In total, 250 DM bearings were compared to 753 standard bearings. We found no difference in dislocation rate between single bearings and DM bearings (0.53% vs 0.4%). There was 1 DM dislocation occurring in a liner with outer diameter of 38 mm. There were no DM dislocations with outer diameter >38 mm. Aseptic revision surgery was more common in DM. This difference was driven by higher incidence of femoral periprosthetic fracture. There were no differences in functional outcomes.

CONCLUSION

Dislocation rates are comparably low between DM bearings and standard bearings for THA done using an anterior approach to the hip. Further investigation is needed to determine if specific patient populations may benefit from DM implants for primary THA when an anterior approach to the hip is being used.

Dual Mobility Bearing Articulations Result in Lower Rates of Dislocation After Revision Total Hip Arthroplasty

INTRODUCTION

The purpose of our study is to directly compare the rates of instability after revision total hip arthroplasty (THA) between a modular dual mobility (DM) and a conventional polyethylene single-bearing surface.

METHODS

We retrospectively reviewed a consecutive series of patients who underwent revision THA from 2012 to 2016 at a single institution with a minimum of 2 years of follow-up. Rates of re-revision, dislocation, complications, and short-form (SF-12) scores were compared between the DM and single-bearing groups. To control for confounding variables, a multivariate logistic regression analysis was performed.

RESULTS

Of the 267 revision THA patients, 94 patients had a DM bearing articulation (36%), whereas 173 patients (64%) had a conventional single-bearing with a mean follow-up of 37.8 months (range 24 to 73 months). The DM group was more likely to undergo revision THA for instability compared with the single-bearing group (8.5% versus 1.2%, P ≤ 0.005) but had reduced incidence of postoperative dislocations (2.1% versus 8.7%, P = 0.067) and no difference in the rates of re-revisions (9.6% versus 11.6%, P = 0.770). When controlling for confounding variables, patients who received a DM liner had lower rates of dislocation postoperatively than those of single-bearing (odds ratio 0.12, P = 0.019).

DISCUSSION

Even with a selection bias of surgeons using DM for patients at high risk of instability, patients undergoing revision THA with a DM bearing have reduced rates of dislocation at the intermediate-term follow-up. Further study is needed to identify any potential longer-term complications which may result from a modular DM bearing.

Cementation of a Dual Mobility Cup Into an Existing Well-Fixed Metal Shell: A Reliable Option to Manage Wear-Related Recurrent Dislocation in Patients With High Surgical Risk

BACKGROUND

During revision total hip arthroplasty (THA), the "double-socket" technique has been proposed as a straightforward solution in order to reduce the overall perioperative morbidity in patients with high surgical risk. However, the option of cementing a dual mobility cup into an existing well-fixed metal shell was sparsely reported. Therefore, this study aimed to evaluate the outcome of a "double-socket" technique performed with a cemented dual mobility cup in revision THA for late instability.

METHODS

Twenty-eight revision THAs (28 patients) were performed for wear-related recurrent dislocation using a "double-socket" technique with a cemented dual mobility cup and retrospectively reviewed. The age at revision averaged 82 years (range 74-93). According to the American Society of Anesthesiologists (ASA) physical status classification, 12 patients (43%) were ASA II and 16 patients (57%) were ASA III before revision.

RESULTS

At a mean follow-up of 3.5 years (range 2-5), the mean preoperative to postoperative functional outcome improved significantly (P < .01). The mean operative time was 107 minutes (range 75-140). The mean intraoperative bleeding was 200 mL (range 110-420). No postoperative complication, reoperation, or re-revision was reported. Importantly, no dislocation, dissociation of the cemented dual mobility cup construct, or aseptic loosening of the retained metal shell was observed.

CONCLUSION

The "double-socket" technique with a dual mobility cup cemented into an existing well-fixed and well-positioned metal shell ensured a straightforward and blood-sparing revision technique that was efficient to restore stability and provide a secure acetabular construct in frail patients with high surgical risk and/or older than their natural life expectancy.

Serum metal ion levels in modular dual mobility acetabular components: A systematic review

Background

Dual mobility (DM) constructs effectively reduce the risk of dislocation in revision and high risk primary total hip arthroplasty. However, modular DM designs require the use of a cobalt-chrome liner against a titanium cup which may induce corrosion, metal ions release, and associated biologic response. The purpose of this systematic review study was to collect all reported cases of serum metal ions after DM in the literature and ask the following questions: 1) what is the overall rate of significantly elevated Cobalt and Chromium metal ions and how do these levels change over time? 2) Does femoral head material composition influence serum metal ion levels? and 3) were there any atypical lymphocytic associated lesions after modular DM that required revision surgery?

Methods

A systematic review was performed according to PRISMA guidelines. In addition to patient demographics, information specific to the performance of the DM implant were recorded including: cobalt and chromium serum ion levels and all reported timepoints, the material composition of the femoral head, all revision and reoperations and any failure related to corrosion of the DM bearing. A significant elevation in cobalt or chromium was defined as >1.0 or >1.6 mcg/L.

Results

248 modular DM THAs were analyzed. The cumulative mean cobalt and chromium levels for all included studies was 0.47mcg/L and 0.53mcg/L, respectively. At final follow-up 13 patients (5.2%) had elevated cobalt ion levels and 4 patients (1.6%) had elevated chromium ion levels. Femoral head material composition trended towards but did not significantly increase serum ion levels. Ceramic heads had elevated cobalt and chromium ions in 4/135 (3%) of patients compared to metal heads which had elevated cobalt ions in 9/113 (8%) and elevated chromium ions in 0/113 (0%), (p = 0.09). There were no reoperations or revisions for metal related reactions at final follow-up (mean 27.4 months).

Conclusion

In this systematic review including 248 modular DM THAs, elevated serum cobalt ions were present in 5.2% of patients at a mean follow-up of 27.4 months. While a trend towards increased Cobalt serum ions with the use of cobalt chrome femoral heads, femoral head composition was not significantly associated with increased serum metal ion levels. At final follow-up, metal ion levels appear to decrease in the majority of patients between 1 and 2 years and no patient was revised for metal ion related complications. Continued serum metal ion surveillance is recommended to ensure the safety of DM constructs in THA with longer term follow-up.

Mid-Term Survivorship of a Novel Constrained Acetabular Device

BACKGROUND

Recurrent instability after total hip arthroplasty is a difficult complication. In certain cases, a constrained acetabular device is needed to address these issues. The purpose of this study is to report the midterm outcomes and survivorship of a single novel constrained liner device.

METHODS

A retrospective review as performed on all procedures (except first stage exchange for infection) in which a Freedom Constrained (Zimmer Biomet, Warsaw, IN) liner was used between December 2003 and November 2016. Patients with 2-year minimum follow-up or failure were included, yielding a cohort of 177 patients. Procedures were 130 aseptic revisions, 40 reimplantations following infection eradication, and 7 complex primaries. The constrained mechanism was implanted in 46 hips (26%) to treat active instability and 131 hips (74%) for increased risk of instability and intraoperative instability. Patients had on average 3.4 previous surgeries.

RESULTS

With an average 7.1-year follow-up, 11 hips dislocated (6.2%), and 13 hips (7.3%) were revised for acetabular aseptic loosening, resulting in an overall constrained aseptic or mechanical failure rate of 13.6%. Nineteen hips (10.7%) failed from infection with 58% of these having had a previous infection. Patients with active instability had significantly higher failure for dislocation than patients who were at risk (15.2% vs 3%, P = .01). All-cause survival rate at 7 years was 74.8%, aseptic survival was 83.6%, and survival for instability was 91.8%.

CONCLUSION

Revision for instability remains challenging as many patients have had numerous previous surgeries and at-risk anatomy. Constrained inserts are one option to manage instability, but a high rate of recurrence can still occur.

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.

Dislocation rates with combinations of anti-protrusio cages and dual mobility cups in revision cases: Are we safe?

Background

Due to the increasing numbers of revision total hip arthroplasty (THA) procedures being carried out, the frequency of major acetabular defects is also rising. A combination of an anti-protrusio cage and a dual mobility cup has been used in our department since 2007 in order to reduce the dislocation rate associated with complex defects. Although both implants have an important place in endoprosthetics, there are as yet limited data on the dislocation and complication rates with this combination.

Methods

This retrospective study included all patients in whom a Burch–Schneider cage and a dual mobility cup were implanted in our department between 2007 and 2014 and who had a minimum follow-up period of 24 months.

Results

The study included 79 patients with a mean follow-up period of 5.3 years. The implant survival rate was 85% at 65 months. Postoperative dislocation occurred in two cases (2.1%), with the first dislocation taking place within the first 3 weeks in both of these patients.

Conclusions

The present study shows a promising dislocation rate with a combination of an anti-protrusio cage and a dual mobility cup. Particularly in the medium-term follow-up, no further dislocations occurred in the study. A maximum cup inclination of 45° in revision cases was associated with a lower dislocation rate in this group of patients.

Outcomes of Surgical Treatment of Periprosthetic Acetabular Fractures

Periprosthetic acetabular fractures sustained following acute trauma after total hip arthroplasty are rare and historically have poor outcomes. This article reviews 5 cases and the treatment algorithm used by a single orthopaedic surgeon specializing in acetabular fracture care with a co-surgeon specializing in arthroplasty. Team-based surgical management with arthroplasty- and fracture-trained surgeon(s) is paramount for optimal outcome. The following approach resulted in satisfactory outcomes without need for revision implants. In fracture patterns with columnar involvement, the columns were restored with plates and screws. In fracture patterns with wall involvement, the acetabular component functioned as a template for wall reconstruction with use of a buttress plate. The acetabular component was revised when deemed loose during stress of the component through the surgical approach used for fracture fixation.