The use of a cemented dual mobility socket to treat recurrent dislocation

What is the rate of successful closed reduction of dislocated dual mobility cups following complex revision hip arthroplasty?

PURPOSE

The aim of this study was to assess the difference in success rates of closed reduction in septic and aseptic revision total hip arthroplasty (THA) performed with a dual mobility (DM) implant. Our objective was to answer the following questions: (1) Is there a difference in success rates of closed reduction between septic and aseptic revision THA with a DM implant? (2) Is closed or open reduction more successful in preventing re-dislocation?

METHODS

Between January 2009 and October 2021, 924 revisions were performed with a DM implant. All patients presenting to our institution with a dislocation following septic or aseptic revision THA using a cemented DM cup were included in this study. We analyzed 106 cases of dislocation in 74 patients. For all patients, we collected reason for revision, and classified index surgery as septic or aseptic.

RESULTS

Overall, 106 dislocations occurred (106/924, 11.5%). Thirty-nine cases (52.7%) had a dislocation after a septic exchange THA, while in 35 patients (47.3%), a dislocation occurred after an aseptic rTHA. In 29 patients (39.2%), successful closed reduction under general anesthesia was feasible, while the majority of cases required open reduction. In 31 of these patients (67.4%), open reduction was combined with a revision arthroplasty.

CONCLUSIONS

In case of DM cup dislocation, there is a low success rate of closed reduction. To prevent re-dislocation, total revision leads to a significantly reduced risk compared to open or closed reduction alone. Careful X-ray analysis for a halo sign showing intra-prosthetic DM cup dislocation is mandatory to avoid futile reduction attempts.

LEVEL OF EVIDENCE

III.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique

Background

The use of a cemented monoblock dual-mobility implant into a fully porous cup is indicated for patients with acetabular bone loss who have a high risk of postoperative hip instability. Patients undergoing lumbar fusion for sagittal spinal deformities have an increased risk of hip dislocation (7.1%) and should be assessed on sitting and standing radiographs1. Gabor et al. conducted a multicenter, retrospective study assessing the use of a cemented monoblock dual-mobility bearing in a porous acetabular shell in patients with acetabular bone loss and a high risk of hip instability2. Of the 38 patients, 1 (2.6%) experienced a postoperative dislocation that was subsequently treated with closed reduction without further dislocation. This surgical technique represents a favorable surgical option for patients with acetabular bone loss who are at risk for hip instability. In the example case described in the present video article, the patients had a history of dislocations, lumbar fusion, and evidence of Paprosky 3B acetabular defect; as such, the decision was made to revise to a porous shell and cement a monoblock dual-mobility implant.

Description

With use of the surgeon's preferred approach, the soft tissue is dissected and the hip is aspirated. The hip is dislocated and a subgluteal pocket is made with use of electrocautery to mobilize the trunnion of the femoral stem to aid in acetabular exposure. The femoral component is assessed to ensure appropriate positioning with adequate anteversion. The acetabular component and any acetabular screws are removed. A "ream to fit" technique is performed in the acetabulum until bleeding bone is encountered, with minimal reaming performed in healthy bone from the posterior column. A trial prosthesis is placed within the acetabulum to evaluate if there is satisfactory fixation and if any augment is necessary. Care must be taken during reaming to ensure that enough bone is reamed to accommodate a porous shell that can fit the monoblock dual-mobility implant with a 2-mm cement mantle. Smaller porous shells measuring 56 mm are available for smaller defects but are often not utilized in cases of substantial acetabular bone loss. Fresh-frozen cancellous allograft is utilized to fill any contained defects. The revision porous shell with circumferential screw holes is utilized to allow for screw fixation posterosuperior and anterior toward the pubis. The implants are dried prior to placement of the cement. The cement is applied to the shell and the monoblock dual-mobility implant to ensure adequate coverage. Antibiotic-loaded cement can be utilized according to surgeon preference. Excess cement is removed under direct visualization while the cement is drying, and the position of the dual-mobility implant is adjusted in approximately 20° anteversion and 40° inclination. Stability is assessed after the cement cures, and intraoperative radiography can be performed to confirm cup positioning prior to closure. Any remaining capsule is closed, followed by closure of the remaining soft tissue in a layered fashion.

Alternatives

A fully porous multi-hole jumbo cup with conventional polyethylene liner and femoral head can be utilized to increase the jump distance of the femoral head. Constrained, lipped, or offset polyethylene liners can be utilized if the shell is well fixed and a dual-mobility implant cannot be inserted. A cemented dual-mobility implant can be utilized in a well-fixed acetabular shell without evidence of loosening or osteolysis.

Rationale

Dual-mobility implants have become increasingly utilized because of their advantages: (1) ability to decrease dislocation rate without increasing constraint and (2) increasing range of motion with reduced impingement risk2-8. These implants are particularly useful in the setting of revision cases with large acetabular bone defects. In a study of 76 patients with dual-mobility implants cemented into porous acetabular shells, Muthusamy et al. found that only 3.3% of patients experienced postoperative dislocations9. Moreover, acetabular cup survival was excellent, with 100% survival at 1 year and 96.2% at 2 years.

Expected Outcomes

The use of a dual-mobility implant is a viable treatment option in cases of revision total hip arthroplasty, particularly those in which postoperative stability is a concern; monoblock dual-mobility implants cemented into porous shells are particularly useful in this setting2-8. These trends are similarly seen in patients treated with monoblock dual-mobility implants cemented into porous shells. Muthusamy et al. evaluated the use of this construct to treat instability or risk of hip dislocation in 76 hips, reporting a dislocation rate of 3.3% at 2 years. Additionally, the authors reported rates of all-cause acetabular survival from re-revision of 96.7% at 6 months, 93.3% at 1 year, and 89.7% at 2 years9. Physicians should be aware of the possibility for intra-prosthetic dislocations, as although this complication is rare, it has been reported in the literature7,10.

Important Tips

In order to allow for circumferential coverage for fixation and ingrowth potential in cases with acetabular defects, the shell is typically impacted slightly vertical (45° to 50° of inclination) and in neutral version (0° to 5° of anteversion). Positioning can be adjusted to improve osseous contact and ingrowth as determined by the size and shape of the defect.The use of a drill guide for the locking screws allows limited degrees of variable screw angulation. In the revision setting, longer screws may be placed posterosuperior toward the sciatic notch or anteroinferior into the pubis. Surgeons should be aware of the anatomy and should predrill holes to reduce the risk of injury to surrounding neurovascular structures such as the obturator artery anteriorly.Any screw holes that are not filled should be covered with plastic hole covers in order to prevent cement from migrating behind the cup. Implants should be dried prior to the placement of the cement, and the cement should be applied to the shell and the dual-mobility implant to ensure adequate coverage.Utilize a monoblock dual-mobility implant that is designed for cementation in order to avoid implant dissociation from the acetabular shell.Remove all fibrous tissue that may hinder bony integration.Assess for pelvis discontinuity; pelvis discontinuity and acetabular bone loss are risk factors in the setting of any revision and should be properly assessed preoperatively and intraoperatively and managed accordingly.Avoid over-reaming and damage of the posterior column.Utilize a reamer or trial to assess defect size and need for augments.Place a compression screw where the cup is in contact with the bone in order to avoid tilting.Cover unused screw holes.

Acronyms and Abbreviations

THA = total hip arthroplastyS/P = status postTKA = total knee arthroplastyCT = computed tomographyKM = Kaplan MeierDMC = dual-mobility cupPE = polyethylene.

Primary total hip arthroplasty in patients with sequelae of poliomyelitis

INTRODUCTION

Total hip arthroplasty (THA) in patients with residual poliomyelitis (RP) is a surgical challenge. Dysplastic morphology, osteoporosis and gluteal weakness hinder orientation, increase fracture risk and reduce implant stability. The aim of this study is to describe a series of patients with RP treated by THA.

MATERIAL AND METHODS

Retrospective descriptive study of patients with RP treated with THA between 1999 and 2021 in a tertiary hospital, with clinical and radiological follow-up and functional and complication evaluation until present or death, with a minimum of 12months.

RESULTS

Sixteen patients underwent surgery, with 13THA implanted in the paretic limb, 6 for fracture and 7 for osteoarthritis, while the remaining 3 were implanted in the contralateral limb. Four dual mobility cups were implanted as an antiluxation measure. At 1year postoperatively, 11 had complete range of motion with no increase in Trendelenburg cases. The Harris hip score (HHS) improved 32.1points, the visual analog scale (VAS) 5.25 points, and the Merlé-d'Augbiné-Poste scale 6 points. The length discrepancy correction was 13.77mm. Median follow-up was 3.5years (1-24). Two cases were revised for polyethylene wear and two for instability, with no infections, periprosthetic fractures, or cup or stem loosening.

CONCLUSIONS

THA in patients with RP allows improvement of the clinico-functional situation with an acceptable complication rate. The risk of dislocation could be minimized with dual mobility cups.

[Translated article] Primary total hip arthroplasty in patients with sequelae of poliomyelitis

INTRODUCTION

Total hip arthroplasty (THA) in patients with residual poliomyelitis (RP) is a surgical challenge. Dysplastic morphology, osteoporosis and gluteal weakness hinder orientation, increase fracture risk and reduce implant stability. The aim of this study is to describe a series of patients with RP treated by THA.

MATERIAL AND METHODS

Retrospective descriptive study of patients with RP treated with THA between 1999 and 2021 in a tertiary hospital, with clinical and radiological follow-up and functional and complication evaluation until present or death, with a minimum of 12 months.

RESULTS

Sixteen patients underwent surgery, with 13 THA implanted in the paretic limb, 6 for fracture and 7 for osteoarthritis, while the remaining 3 were implanted in the contralateral limb. Four dual mobility cups were implanted as an antiluxation measure. At 1 year postoperatively, 11 had complete range of motion with no increase in Trendelenburg cases. The Harris hip score (HHS) improved 32.1 points, the visual analogue scale (VAS) 5.25 points, and the Merlé-d'Augbiné-Poste scale 6 points. The length discrepancy correction was 13.77mm. Median follow-up was 3.5 years (1-24). Two cases were revised for polyethylene wear and two for instability, with no infections, periprosthetic fractures, or cup or stem loosening.

CONCLUSIONS

THA in patients with RP allows improvement of the clinico-functional situation with an acceptable complication rate. The risk of dislocation could be minimised with dual mobility cups.

Bimodular femoral stems in primary total hip arthroplasty

INTRODUCTION

This review critically examines the efficacy of dual-modular stems in primary total hip arthroplasty. Given the variability and non-comparability of certain femoral stem designs and stem-neck couplings, with some even being withdrawn from the market, this review offers an in-depth analysis of predominant implant performances.

AREAS COVERED

The paper explores a brief historical summary related to dual-modular stems, including the complications associated with their use, diagnostic tools for evaluation, analysis of both recalled and currently available models, as well as alternative therapeutic options. This information is pertinent for both clinical and research domains.

EXPERT OPINION

While dual-modular systems were initially touted to offer several advantages, the evidence substantiating these benefits has been ambiguous. Further, these systems introduce the risk of alternative complications. In specific cases involving patients with developmental hip dysplasia and certain proximal femoral deformities requiring complex reconstructions, dual-modular systems might be relevant. Nonetheless, the use of long interchangeable necks in patients with a body mass index above 30 kg/m2 is discouraged, and pairing a long varus-oriented neck with an extra-long femoral head should be avoided in all patients.

No Difference in Dislocation Rates Comparing DMC-THA for Displaced Femoral Neck Fracture and for Osteoarthritis-A Matched-Pair Analysis

Background

We hypothesized the risk of prosthetic instability would be similar in patients treated for femoral neck fracture (FNF) comparatively to patients treated for osteoarthritis (OA) using a dual-mobility cup-total hip arthroplasty (DMC-THA).

Methods

One hundred and nine patients (109 hips), with a mean age of 69.6 ± 3 years (65-75 years), underwent DMC-THA using a posterolateral approach for a FNF (study group). Patients were matched for age and sex with 109 OA patients treated by the same procedure (control).

Results

Postoperatively, there were four dislocations of the large articulation in the study group, and none in the control (p = 0.12). Periprosthetic joint infection (PJI) was the most common surgical complication and was more frequent in the study group. Postoperatively, functional results were at least good in > 90% patients in both groups. At the last follow-up, patients in the study group had recovered autonomy and physical activity comparable to those of the preoperative period.

Conclusion

We found no increased risk of dislocation after DMC-THA using a posterolateral approach for FNF as compared to the same procedure for OA. In this study, function and independence were restored postoperatively in the vast majority of patients. DMC-THA appears as a viable therapeutic option in autonomous patients with a displaced FNF.

Is Cemented Dual-Mobility Cup a Reliable Option in Primary and Revision Total Hip Arthroplasty: A Systematic Review

Background: Instability is a common complication following total hip arthroplasty (THA). The dual mobility cup (DMC) allows a reduction in the dislocation rate. The goal of this systematic review was to clarify the different uses and outcomes according to the indications of the cemented DMC (C-DMC). Methods: A systematic review was performed using the keywords "Cemented Dual Mobility Cup" or "Cemented Tripolar Cup" without a publication year limit. Of the 465 studies identified, only 56 were eligible for the study. Results: The overall number of C-DMC was 3452 in 3426 patients. The mean follow-up was 45.9 months (range 12-98.4). In most of the cases (74.5%) C-DMC was used in a revision setting. In 57.5% DMC was cemented directly into the bone, in 39.6% into an acetabular reinforcement and in 3.2% into a pre-existing cup. The overall dislocation rate was 2.9%. The most frequent postoperative complications were periprosthetic infections (2%); aseptic loosening (1.1%) and mechanical failure (0.5%). The overall revision rate was 4.4%. The average survival rate of C-DMC at the last follow-up was 93.5%. Conclusions: C-DMC represents an effective treatment option to limit the risk of dislocations and complications for both primary and revision surgery. C-DMC has good clinical outcomes and a low complication rate.

Major acetabular defects: outcomes of first revision total hip arthroplasty using Kerboull cross-plate with allograft and cemented dual mobility cup at a maximum follow-up of fourteen years

BACKGROUND

The use of dual mobility cups (DMC) has been shown to reduce hip instability after revision surgery. For severe acetabular bone loss, reconstruction with a Kerboull cross-plate and bone allograft would contribute to restoring native hip position and bone stock. Only two papers reported on the combination of Kerboull cross-plate with bone allograft and cemented DMC in revision total hip arthroplasty (THA).

METHODS

This is a monocentric retrospective study (28 cases) of first-time revision THA using such a construct in American Association of Orthopaedic Surgeons (AAOS) grade III and IV acetabular bone defect. Detailed demographic, clinical and radiographic results were recorded and evaluated.

RESULTS

With a mean follow-up of six ± 3.63 years, no case of instability was reported. The modified Harris Hip Score (mHHS) was 88.4 ± 10.1. No hook fracture or mechanical failure was observed. Non-progressive radiolucent lines were recorded. Osteointegration of the allografts was observed in all cases with a mean Grodet score of 7.9 ± 0.97.

CONCLUSIONS

In first revision THA, the use of a Kerboull cross-plate with allograft and a cemented DMC in AAOS grade III and IV acetabular bone defects demonstrated excellent clinical and radiological outcomes with no recorded cases of dislocation or mechanical failure.

Does Revision of an Acetabular Shell With Insertion of an Uncemented Constrained Liner Confer Benefit Over Cementing Into a Well-Ingrown Shell?

BACKGROUND

During revision total hip arthroplasty (THA), a constrained acetabular liner (CAL) may be inserted to enhance hip stability. It is unclear, however, whether cementation of a CAL into a retained cup offers an advantage compared to revision of the acetabular cup and insertion of an uncemented CAL. The purpose of our study was to compare outcomes and survivorship between the 2 methods.

METHODS

We identified a total of 177 patients who underwent revision THA with a specific CAL at our center between July 2004 and May 2019 (114 cup revisions and insertion of an uncemented CAL, 63 cementations of a CAL into a retained cup). Kaplan-Meier (KM) survival analysis was performed for implant survival free from aseptic failure of the CAL for both cohorts.

RESULTS

The average follow-up time was 7.2 and 7.02 years for the cemented and uncemented cohort, respectively (P = .55). Five patients (7.93%) in the cemented CAL group experienced failure of the CAL, whereas 10 patients (8.77%) in the uncemented CAL cohort experienced failure (P = .21). Kaplan-Meier (KM) survival analysis demonstrated comparable survivorship at 10 years (P = .055).

CONCLUSION

The results of our study suggest comparable survivorship between cementing a CAL into a retained cup and inserting an uncemented CAL in a revised acetabular cup. As a result of these findings along with the benefits associated with cementing a CAL, we encourage surgeons to readily consider this option in the management of recurrent instability.

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.

Laser Sintering Approaches for Bone Tissue Engineering

The adoption of additive manufacturing (AM) techniques into the medical space has revolutionised tissue engineering. Depending upon the tissue type, specific AM approaches are capable of closely matching the physical and biological tissue attributes, to guide tissue regeneration. For hard tissue such as bone, powder bed fusion (PBF) techniques have significant potential, as they are capable of fabricating materials that can match the mechanical requirements necessary to maintain bone functionality and support regeneration. This review focuses on the PBF techniques that utilize laser sintering for creating scaffolds for bone tissue engineering (BTE) applications. Optimal scaffold requirements are explained, ranging from material biocompatibility and bioactivity, to generating specific architectures to recapitulate the porosity, interconnectivity, and mechanical properties of native human bone. The main objective of the review is to outline the most common materials processed using PBF in the context of BTE; initially outlining the most common polymers, including polyamide, polycaprolactone, polyethylene, and polyetheretherketone. Subsequent sections investigate the use of metals and ceramics in similar systems for BTE applications. The last section explores how composite materials can be used. Within each material section, the benefits and shortcomings are outlined, including their mechanical and biological performance, as well as associated printing parameters. The framework provided can be applied to the development of new, novel materials or laser-based approaches to ultimately generate bone tissue analogues or for guiding bone regeneration.

Influence of dual-mobility acetabular implants on revision and survivorship of cup and Kerboull-type reinforcement ring constructs in aseptic acetabular loosening

INTRODUCTION

Dual-mobility (DM) acetabular implants have been used in revision total hip arthroplasty (THA) to prevent postoperative instability, with excellent mid-term survivorship. However, few comparative studies assessed the long-term outcomes of DM implants used in Kerboull-type reinforcement ring constructs for acetabular revision. The present study aimed to compare long-term survivorship, dislocation rates and clinical outcome between DM acetabular implants and conventional single-bearing (SB) implants when cemented in a reinforcement ring.

HYPOTHESIS

Dual-mobility implants are associated with equivalent survivorship and lower dislocation rates than SB implants.

MATERIAL AND METHODS

A retrospective study included 60 revision THAs for aseptic loosening using a Kerboull-type reinforcement ring, and finally included 2 groups of 23 patients with either DM or SB cemented acetabular implants after matching for age, gender, BMI and preoperative Harris hip score. Mean follow-up was 10 years (range, 6-14 years). Acetabular implant survivorship, dislocation rate and radiographic failure incidence (>5mm migration, progressive radiolucency, graft non-integration, reinforcement ring breakage) were compared between the two groups. Clinical outcomes used the Harris hip score, the Postel-Merle d'Aubigné score and the Parker score.

RESULTS

Survivorship free of aseptic acetabular re-revision was 89% at 10 years, with no significant difference between DM and SB (91% and 86%, respectively; p=0.54). Single-bearing implants showed a hazard ratio for dislocation of 6.7 (95% CI, 1.5-29.6; p=0.01) compared to DM implants. There were no significant differences in radiologic failure (10-year survivorship 72% and 64%, respectively; p=0.88) or functional scores.

DISCUSSION

The present study confirmed the impact of dual-mobility implants in reducing long-term dislocation risk when used in Kerboull-type reinforcement ring constructs for acetabular aseptic revision, with no increased risk of re-revision compared to conventional single-bearing implants.

LEVEL OF EVIDENCE

III, comparative retrospective study.

The usefulness of dual mobility cups in primary total hip arthroplasty patients at a risk of dislocation

This study aimed to evaluate the early results of primary total hip arthroplasty (THA) using dual mobility (DM) cups in patients at a risk of dislocation and compare them with that of fixed bearing (FB) THA. This retrospective study included patients who had undergone primary THA between January 2016 and December 2018 and were at a risk of dislocation. A propensity score-matched analysis was conducted for 63 THA procedures with vitamin-E infused highly cross-linked polyethylene (VEPE) DM bearing and 63 THA procedures performed with FB from the same manufacturer for a mean follow-up period of 3.1 and 3.5 years, respectively. The radiologic outcomes at the last follow-up and incidence of postoperative complications were evaluated and compared statistically between the two groups. The modified Harris hip score (mHHS) was used to assess patient-reported outcomes. Postoperative dislocation occurred in 4 cases (6.3%) in the FB group, but did not occur in the DM group (p = 0.042). There was no difference in the radiologic outcomes and postoperative complications between the two groups. The mHHS at the last follow-up showed satisfactory outcomes in both the groups (DM group, 90.5; FB group, 88.1), without a statistical difference between the groups. The early results of THA using VEPE DM bearing showed better outcomes than that of THA with FB for patients at a risk of dislocation. A longer follow-up period is recommended to assess the stability and overall outcomes.

A review of the clinical and engineering performance of dual-mobility cups for total hip arthroplasty

Charnley's low-friction principle of total hip arthroplasty (THA) is recognized as the gold standard. However, complications may arise, and one of the major reasons for revising THA is dislocation. Under such a background, Pr. Gilles Bousquet invented dual-mobility cups (DMC) in the 1970s to fight against hip instability. Despite the excellent clinical results of DMC compared with conventional implants, the clinical application of DMC is limited by concerns about the dual articulations, leading to rapid wear and the subsequent osteolysis and the wear on the retaining rim of the liner due to its contact with the femoral neck causing intraprosthetic dislocation (IPD). As a result, the original design of DMC has been upgraded by using highly cross-linked polyethylene, refining the geometry of the femoral neck, etc. After the improvement, the wear rate of the contemporary DMC liners has been largely reduced compared with the first generation DMC, and the IPD incidence rate has been controlled. However, with the increasing fretting corrosion damage found at the taper-trunnion interfaces in conventional implants, the contemporary DMC may face a similar problem. This is because the additional articulation and the larger head design of DMC gain the risk of articulation wear and taper-trunnion interface corrosion. Since there are still many potential DMC engineering issues that have not been extensively researched, future studies focusing on the wear and corrosion aspects are required. The purpose of this review article is to summarize both the clinical and engineering issues for DMC with possible directions for future research.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

The use of a triflange salvage system for catastrophic pelvic osteolysis after failed total hip arthroplasty

Introduction

The custom triflange acetabular implant (CTAI) has been described to address catastrophic pelvic osteolysis, but long-term outcome data is scarce.

Methods

Revision-free survivorship after revision THA with a CTAI was retrospectively reviewed in seven patients.

Results

Mean and median follow-up time were 7.39 (1.61-16.8) years and 7.50 years, respectively. Revision-free survivorship was 85.7% (6/7). One patient underwent revision for recurrent dislocations. All patients were able to ambulate at recent follow-up- 2/7 without assistance.

Conclusions

The CTAI is a viable option for patients with catastrophic pelvic osteolysis. There is a high complication rate, but the incidence of revision is low.

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.

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

BACKGROUND

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

QUESTIONS/PURPOSES

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level III, therapeutic study.

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.

Tripolar Articulations as a "High Stability Bearing" for Revision Total Hip Arthroplasty: Success Rates and Risk Factors for Failure

BACKGROUND

Unconstrained tripolar articulations have been theorized to increase hip stability. The purpose of this study is to report the performance of tripolar articulations in revision THA and identify factors associated with success and failure.

METHODS

Between 1994 and 2016, 67 revision THAs were performed with an unconstrained tripolar articulation. Mean follow-up was 5.4 years. Patient charts were retrospectively reviewed emphasizing factors associated with risk of instability. There were 21 patients with neither a history of instability (HI) nor abductor insufficiency (AI), 20 patients with HI alone, 13 with AI alone, and 13 had both HI and AI.

RESULTS

Twelve THAs sustained at least one postrevision dislocation at an average of 2.1 years. One bipolar dissociation occurred early (1.2 y). Nine hips had a re-revision to address these complications. Survival free from dislocation at 2, 5, and 10 years was 88%, 85%, and 74%, respectively. Survival free from re-revision at 2, 5, and 10 years was 91%, 84%, and 65%, respectively. Patients with combined AI and HI had the worst survivorship free from dislocation at 2, 5, and 10 years (77%, 68%, and 55%), respectively. In contrast, patients with neither HI nor AI experienced zero dislocations. There were no failures associated with bearing wear.

CONCLUSION

Off-the-shelf tripolar articulations were associated with reasonable survival at midterm follow-up. In patients with both AI and HI, the risks and benefits of alternative options such as dual mobility or constrained liners should be explored as the risk of dislocation at 10 years approached 50%.

Surgical Treatment of Femoral Neck Fractures: A Brief Review

Hip fracture is a cause for concern in the geriatric population. It is one of the leading causes of traumatic injury in this demographic and correlates to a higher risk of all-cause morbidity and mortality. The Garden classification of femoral neck fractures (FNF) dictates treatment via internal fixation or hip replacement, including hemiarthroplasty or total hip arthroplasty. This review summarizes existing literature that has explored the difference in outcomes between internal fixation, hemiarthroplasty, and total hip arthroplasty for nondisplaced and displaced FNF in the geriatric population, and more specifically highlights the risks and benefits of a cemented vs. uncemented approach to hemiarthroplasty.

Dual mobility in primary total hip arthroplasty: current concepts

Total hip arthroplasty (THA) is one of the most successful surgical procedures – reducing pain and providing functional improvement. However, THA instability is a disabling condition and remains the most common indication for revision THA. To combat the risk of instability, the concept of dual mobility (DM) was developed. This article provides a comprehensive review of DM in the literature.

Widespread use of first-generation DM was limited due to concern regarding wear of the polyethylene head and the unique complication of intraprosthetic dislocation (IPD). Implant modifications using highly cross-linked, durable polyethylene and a smooth, cylindrical femoral neck have all but eliminated IPD in contemporary DM.

In multiple studies, DM demonstrates statistically significant reductions in dislocation rates comparative to standard bearing primary THA. These results have been particular promising in high-risk patient populations and femoral neck fractures – where low dislocation rates and improved functional outcomes are a recurrent theme. From an economic perspective, DM is equally exciting – with lower accrued costs and higher accrued utility comparative to standard bearing THA.

Longer-term clinical evidence and higher-quality prospective comparative studies are required to strengthen current research. Dual mobility may well represent the future gold standard for THA in high-risk patient populations and femoral neck fractures, but due diligence of long-term performance is needed before recommendations for widespread use can be justified.

Cite this article: EFORT Open Rev 2019;4:640-646. DOI: 10.1302/2058-5241.4.180089

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.

Cementation of a monoblock dual mobility bearing in a newly implanted porous revision acetabular component in patients undergoing revision total hip arthroplasty

Background

The most common indications for revision total hip arthroplasty are instability/dislocation and mechanical loosening. Efforts to address this have included the use of dual mobility (DM) articulations. The aim of this study is to report on the use of cemented DM cups in complex acetabular revision total hip arthroplasty cases with a high risk of recurrent instability.

Methods

A multicenter, retrospective study was conducted. Patients who received a novel acetabular construct consisting of a monoblock DM cup cemented into a fully porous metal shell were included. Outcome data included 90-day complications and readmissions, revision for any reason, and Harris Hip Scores.

Results

Thirty-eight hips in 38 patients were included for this study. At a median follow-up of 215.5 days (range 6-783), the Harris Hip Score improved from a mean of 50 ± 12.2 to 78 ± 11.2 (P < .001). One (2.6%) patient experienced a dislocation on postoperative day 1, and was closed reduced with no further complications. There was 1 (2.6%) reoperation for periprosthetic joint infection treated with a 2-stage exchange.

Conclusions

In this complex series of patients, cementation of a monoblock DM cup into a newly implanted fully porous revision shell reliably provided solid fixation with a low risk of dislocation at short-term follow-up. Although longer term follow-up is needed, utilization of this novel construct should be considered in patients at high risk for instability.

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.

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.

Late Dislocation Following Total Hip Arthroplasty: Spinopelvic Imbalance as a Causative Factor

BACKGROUND

Late dislocations after total hip arthroplasty (THA) are challenging for the hip surgeon because the cause is often not evident and recurrence is common. Recently, decreased spinopelvic motion has been implicated as a cause of dislocation. The purpose of this study was to assess the mechanical causes of late dislocation, including the influence of spinopelvic motion.

METHODS

Twenty consecutive patients were studied to identify the cause of their late dislocation. Cup inclination and anteversion were measured on standard pelvic radiographs. Lateral standing and sitting spine-pelvis-hip radiographs were used to measure pelvic motion, femoral mobility, and sagittal cup position by assessing sacral slope, pelvic-femoral angle, and cup ante-inclination. Spinopelvic motion was defined as the difference between the standing and sitting sacral slopes (Δsacral slope). A new measurement, the combined sagittal index, which measures the sagittal acetabular and femoral positions, was used to assess the functional motion of the hip joint and risk of impingement.

RESULTS

There were 9 anterior dislocations (45%) and 11 posterior dislocations (55%) at a mean of 8.3 years after a primary THA. Eight of the 9 patients with an anterior dislocation had spinopelvic abnormalities such as fixed posterior pelvic tilt when standing, increased standing femoral extension, and an increased standing combined sagittal index. Ten of the 11 patients with a posterior dislocation had abnormal spinopelvic measurements such as decreased spinopelvic motion (average Δsacral slope [and standard error] = 9.0° ± 2.4°), increased femoral flexion, and a decreased sitting combined sagittal index. For every 1° decrease in spinopelvic motion, there was an associated 0.9° increase in femoral motion and, in some patients, this resulted in osseous impingement and dislocation.

CONCLUSIONS

Patients with a late dislocation have abnormal spinopelvic motion that precipitates the dislocation, especially when combined with cup malposition or soft-tissue abnormalities. Spinopelvic stiffness is associated with increased age and increased femoral motion, which may lead to impingement and dislocation. Lateral spine-pelvis-hip radiographs may predict the risk and direction of dislocation.

LEVEL OF EVIDENCE

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

Cadaver-Specific Models for Finite-Element Analysis of Iliopsoas Impingement in Dual-Mobility Hip Implants

BACKGROUND

Joint dislocation is a major cause of failure in total hip arthroplasty. Dual-mobility implants provide a femoral head diameter that can match the native hip size for greater stability against dislocation. However, such large heads are prone to impingement against surrounding soft tissues. To address this concern, the concept of an anatomically contoured dual-mobility implant was evaluated using cadaver-specific finite-element analysis (FEA).

METHODS

The stiffness of 10 iliopsoas tendons was measured and also 3D bone models, contact pressure, and iliopsoas tendon stress were evaluated for 2 implant designs according to a previous cadaveric experiment. The iliopsoas interaction with an anatomically contoured and conventional dual-mobility implant was analyzed throughout hip flexion.

RESULTS

The tensile test of cadaveric iliopsoas tendons revealed an average linear stiffness of 339.4 N/mm, which was used as an input for the FEA. Tendon-liner contact pressure and tendon von Mises stress decreased with increasing hip flexion for both implants. Average contact pressure and von Mises stresses were lower in the anatomically contoured design compared with the conventional implant across all specimens and hip flexion angles.

CONCLUSIONS

This study was built upon a previous cadaver study showing reduced tenting of the iliopsoas tendon for an anatomically contoured design compared with a conventional dual-mobility implant. The present cadaver-specific FEA study found reduced tendon-liner contact pressure and tendon stresses with contoured dual-mobility liners. Anatomical contoured design may be a solution to avoid anterior soft-tissue impingement when using hip prostheses with large femoral heads.

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.

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.

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.

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.

Constrained Acetabular Components Used in Revision Total Hip Arthroplasty: A Registry Analysis

BACKGROUND

Constrained acetabular components have a mechanism to lock in the femoral head. They have been developed to control postoperative dislocation, particularly in revision total hip arthroplasty (THA). Although these components may reduce dislocation, there are durability concerns: with reports of locking mechanism failures and loosening. We wanted to determine the outcome of constrained components in controlling dislocation, and if these components had a higher rate of second revision when compared with standard nonconstrained components.

METHODS

Revision THA procedures from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) with a recorded primary procedure and initial diagnosis of osteoarthritis were used to compare constrained and standard nonconstrained components. Kaplan-Meier estimates of survivorship were calculated, and hazard ratios using Cox proportional hazard models were used to compare groups.

RESULTS

There were 9509 THA first-revision procedures and 700 constrained components. Constrained components had a significantly higher revision rate after 3 months when large-head metal-on-metal components were included (hazard ratio = 1.37; P = .005). When large-head metal-on-metal components were excluded, there was no difference in the rate of second revision between the 2 groups. When the analysis was limited to first revision for dislocation, constrained components had a higher second revision rate for further dislocation after 9 months.

CONCLUSION

Constrained acetabular components had similar second-revision rates when compared with standard nonconstrained components, both for all first-revision reasons and when used to treat dislocation. Although possibly used for the more difficult unstable hips, constrained components had a higher rate of second revision for further dislocation.

Evidence based management of intracapsular neck of femur fractures

Neck of femur fractures are occurring at an increased incidence. Functionally independent patients without cognitive impairment can expect reasonable life expectancy. This indicates the need for a durable surgical option that optimises the chance to return to pre-injury functional status, with minimal risk of complications and reoperation. Most fractures are displaced. Surgical options include internal fixation, hemiarthroplasty or total hip arthroplasty (THA). Evidence is conclusive that arthroplasty options outperform internal fixation in terms of function, quality of life and reoperation rates. In anyone other than young patients where head preserving surgery is required, arthroplasty is the standard of care. Hemiarthroplasty is the heavily favoured arthroplasty option for surgeons. However, in patients other than the extreme elderly, medically infirm, neurologically impaired, or with little or no ambulatory capacity, the evidence to support hemiarthroplasty is lacking. In functionally independent patients without cognitive impairment, THA should be considered the gold standard, producing better functional and quality of life outcomes, lower reoperation rates and better cost effectiveness, with no difference in complications or mortality. An increased risk of dislocation does exist. This may be reduced with modern surgical technique and implant options. Low amounts of research have been afforded to undisplaced fractures. For this fracture type, surgery is the standard of care. Despite a higher risk of reoperation, internal fixation is the preferred option for all age groups. Further study is required to identify the difference between internal fixation and THA, in particular, for unstable fracture patterns in elderly patients.

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.

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.

All dual mobility cups are not the same

PURPOSE

Although the natural history of dual mobility has been exclusively borne for 20 years by a single company (due to industrial ownership), the concept has undeniably been very widely popularised with nearly 40 cups on the French market which should be regarded as a weight bearing surface, both broadly and in their own right. However, within the same original idea, these implants are not all identical (design, material, fixation ect.).The aim of this work is to propose a classification of different dual mobility cups by distinguishing between thegeneral characteristics of a conventional cup and those particular to this type of implant.

METHODS

By comparison with a standard metal-back cup, dual mobility is based on at least one additional interface corresponding to the mobility of the polyethylene insert in the concavity of the acetabular cup called the outersurface. Design, constitutive material, fixation of the cup and characteristics of the retentive insert are analysed through the published results.

RESULTS

The complications associated, in particular, the intraprosthetic dislocation and to a lesser extent fixation failures undoubtedly condemned the dissemination of the dual mobility concept, as witnessed by the fact that despite the precedence of this 40-year old concept, the overriding majority of publications (more than 95%) have only appeared in the last ten years.

CONCLUSION

The latest generation of dual mobility cups combines: 1) a cast chrome-cobalt alloy cup covered with a bilayer coating of porous titanium and hydroxyapatite for long-term press-fit fixation to 2) an insert designed to eliminate all of the risks of intraprosthetic dislocation, whilst keeping all of the elasticity properties of the polyethylene, which has demonstrated its medium and long term effectiveness on preventing instability by overcoming other complications.

The evolution of outcomes and indications for the dual-mobility cup: a systematic review

PURPOSE

Instability following total hip arthroplasty remains a common and disabling complication. The dual mobility cup (DMC) allows a reduction in the dislocation rate. An increasing number of studies have been undertaken to better understand DMC long term outcomes and complications. The goal of this systematic review was to clarify its different uses and outcomes according to the indications.

METHODS

A comprehensive literature review was performed using the keywords 'dual mobility' and 'tripolar cup' with no limit regarding the year of publication. One hundred seventy six publications were identified.

RESULTS

Current literature shows that "contemporary" dual mobility cup are a significant indication to manage instability following primary and revision hip arthroplasty. Survivorship at midterm is comparable to other articulations for primary THA, but is more difficult to evaluate in revision. Intra-prosthetic dislocation, wear, and loosening are now uncommon with new generations of DMC.

CONCLUSIONS

Compared to previous generations of DMC, the current "contemporary" DMC presents a significant improvement. Current literature reveals a tendency to increase the indications but further studies with long term follow up remain important to consolidate these findings.

Dual mobility total hip replacement in a high risk population

Objective: The purpose of the study was to evaluate results of dual mobility total replacement in a high risk population who take hip into hyperflexed position while sitting and praying on the floor.

Method: The study included 65 (35 primary total replacement and 30 complex total hip replacement) cases of total hip replacement using avantage privilege dual mobility cup system from biomet. A cemented acetabular component and on femoral side a bimetric stem, either cemented or uncemented used depending on the canal type. Ten cases were examined fluoroscopically in follow up.

Result: There was dislocation in one patient undergoing complex hip replacement. Fluoroscopy study showed no impingement between the neck of prosthesis and acetabular shell at extremes of all movements.

Conclusion: The prevalence of dislocation is low in our high risk population and we consider it preferred concept for patients undergoing complex total hip replacement.

Dual-mobility arthroplasty failure: a rationale review of causes and technical considerations for revision

PURPOSE

Dual-mobility arthroplasty is an alternative to conventional total hip arthroplasty (THA) in appropriately selected, active adults with degenerative, necrotic or post-traumatic hip disease or with revision hip arthroplasty. Numerous papers have been published with results of dual-mobility arthroplasty, but there have been no comprehensive literature reviews that summarise the most recent findings and help the orthopaedic surgeon facing different scenarios in which revision of one or both components of a dual-mobility arthroplasty is indicated.

METHODS

We performed a PubMed search for papers published on dual-mobility arthroplasty that provided data on revision and add our experience in order to describe different revision scenarios. We collected data on revision for any reason, for aseptic loosening, for infection, or for dislocation. For each complication, we summarise causes and diagnosis of this complication and describe the direction of possible therapeutic options.

RESULTS

The dual-mobility arthroplasty offers the benefit of increased stability without compromising clinical outcomes and implant longevity. However, as with conventional arthroplasties, complications are also reported, with the most frequent being cup loosening, dislocation, accelerated wear and infection. Dual-mobility implants also have some specific complications secondary to their specific design, with the presence of a third joint. For example, intraprosthetic dislocation due to retentive failure of the polyethylene (PE) liner on the femoral head is a complication observed exclusively with this type of implant and involves articulation failure between the femoral head and the PE liner. Mechanical conflict with the iliopsoas tendon has also been reported, probably due to femoral head size, cup design, and/or a dysplastic hip. This systematic review of the literature identified several options for treating each complication, and in particular, options regarding conserving or not of one the two articulating devices.

CONCLUSIONS

These findings can inform discussions relating to risks and benefits of different therapeutic options when performing revision of a dual-mobility arthroplasty.