All dual mobility cups are not the same

Malseated Liner in Modular Dual Mobility Total Hip Replacement: A Report of Three Cases

Modular dual mobility total hip arthroplasty (THA) can be associated with complications if the liner is malseated, which can be unappreciated intraoperatively. A meticulous surgical technique is needed to ensure that the liner is perfectly seated. In addition, a malseated liner can be missed if the postoperative films are not carefully reviewed by the surgeon. We present three cases of THA associated with a malseated modular dual mobility liner. In one case, the malpositioned liner was appreciated intraoperatively, but it was wedged in place and could not be removed. The entire shell needed to be revised. In two other cases, malseating was not detected intra-operatively. Both were appreciated postoperatively, and early revision surgery was needed.

Running-in behavior of dual-mobility cup during the gait cycle: A finite element analysis

The running-in process is considered an essential aspect of the comprehensive wear process. The phenomenon of running-in occurs during the initial stages of wear in the prosthetic hip joint. Within the field of tribology, the running-in phenomenon of the hip joint pertains to the mechanism by which the contact surfaces of the artificial hip joint components are adjusted and a suitable lubricating film is formed. During the process of hip joint running-in, there is an interaction between the metal surface of the ball and the joint cup, which results in adjustments being made until a steady state is achieved. The achievement of desirable wear existence and reliable performance of artificial hip joint components are reliant upon the tribological running-in of the hip joint. Despite the establishment of current modeling approaches, there remains a significant lack of understanding concerning running-in wear, particularly the metal-on-polyethylene (MoP) articulations in dual-mobility cups (DMC). An essential aspect to consider is the running-in phase of the dual mobility component. The present study employed finite element analysis to investigate the running-in behavior of dual mobility cups, wherein femoral head components were matched with polyethylene liners of varying thicknesses. The analysis of the running-in phase was conducted during the normal gait cycle. The results of this investigation may be utilized to design a dual-mobility prosthetic hip joint that exhibits minimal running-in wear.

Dual Mobility Cups as the Routine Choice in Total Hip Arthroplasty

Background and Objectives: Total hip arthroplasty (THA) is considered the most successful surgical procedure in orthopedics. However, dislocation remains the main indication for surgical revision. New designs of dual mobility cups (DMC) have lowered the classical complications and have extended the indications of DMC in elective surgeries. Our aim is to assess the trend of DMC indications in THA as well as the incidence of their dislocation. Materials and Methods: We retrospectively reviewed all patients undergoing THA with DMC during the years 2015 and 2021. The original indication for DMC included patients sustaining neck of femur fractures (NOF#) and associated risk factors for dislocations. Five years later, DMC was considered our standard of care in total hip arthroplasty. The approach (anterolateral or posterolateral) was chosen by the surgeon according to his/her preferences, as was the implant. Data collected included patients’ demographics, diagnosis, admission time, surgical approach, cup models, and inclination and complications. Patients sustaining a hip dislocation were prospectively reviewed and assessed for treatment received, new dislocations, and need for surgical revision. Two groups were created for the analysis according to the presence or absence of dislocation during follow-up. Results: In the analysis, 531 arthroplasties were included (mean age 72.2 years) with a mean follow-up of 2.86 years. The trend of indications for DMC increased from 16% of THA in 2015 to 78% of THA in 2021. We found a total of 8 dislocations (1.5%), none of them associated with elective surgery. Closed reduction was unsatisfactory in four cases (50%). There was one case of intraprosthetic dislocation. Dislocations were associated to smaller heads (22 mm) (1.5% vs. 25%, p = 0.008) and cups (51.2 mm vs. 48.7 mm, p = 0.038) and posterior approach (62.5% vs. 37.5%, p = 0.011). Conclusion: Dual mobility cups are a great option to reduce the risk of dislocation after a THA both in the neck of femur fractures and elective cases. The use of an anterolateral approach in THA after a neck or femur fracture might considerably decrease the risk of dislocation.

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

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

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.

Dual mobility cup in hip arthroplasty: an in-depth analysis of joint registries

Although total hip arthroplasty (THA) has shown successful results, instability remains a major complication. In recent years, dual mobility cups (DMC) have gained interest among clinicians thanks to its low rate of dislocation and good clinical results. The main aim of this work was to describe the accuracy of data on DMC from national and regional joint registries (JRs) and the available worldwide literature. We identified topics on DMC among JRs to propose a new harmonized and standardized section for DMC with the aim to understand its surveillance over the time. We extracted survival and implant data for a separate analysis. After performing a critical exclusion process, nine joint registries were considered eligible and included for final synthesis; these were the results from the available worldwide data from Joints Registries (JRs). In our study, eight analysed JRs reported a slight increase in DMC use in the last decade. In all the JRs evaluated and the available articles, dislocation remains one of the main reasons for revision and re-revision in hip arthroplasties. DMC is considered a valid construct increasingly used worldwide in primary and revision THA with the primary aim of reducing dislocation rates. Annual reports from JRs collect heterogeneous and low-quality information about outcomes and surveillance of DMC, creating a burden for clinicians to extract comparable data from different JR. Longer follow-up and a systematic registering of DMCs with international registry harmonization are needed to monitor DMC outcomes.

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.

Use of a modular hip dual-mobility articulation in patients with high risk of dislocation: a relatively small-sized acetabulum in Asian patients may limit its use

BACKGROUND

Dual-mobility hip component is widely used in Europe and North America, because it effectively reduces hip dislocation in primary and revision total hip arthroplasties. However, reports were limited on the use of dual-mobility articulation in Asian populations.

PURPOSE

The aim of this retrospective study was to review the use of modular dual-mobility hip articulation in Asian patients with the high risk factor for hip dislocation. We also discussed the potential concern on the use of dual-mobility articulation in Asian patients.

METHODS

From Jan 2018 to June 2019, 17 patients were included in this study. The mean age of the patients was (73.8 ± 9.5) years (range: 57-88 years). The mean size of acetabular cup and modular DM liner were (49.5 ± 3.4) mm (range, 46-58 mm) and (40.7 ± 3.4) mm (range, 38-48 mm), respectively. The mean follow-up period was (15.8 ± 3.9) months (range, 11-24 months). The primary outcome was the rate of hip dislocation. The secondary outcomes included the Harris Hip Score. Differences were considered statistically significant at p < 0.05.

RESULTS

Hip dislocation, loosening, peri-prosthetic fractures, or intra-prosthetic dislocation was not found in the series. The mean preoperative and postoperative Harris Hip Scores were 42.2 ± 17.2 (range, 15-80) and 74.7 ± 13.5 (range, 52-97), respectively, giving a mean improvement of 32.5 ± 17.2 (range, 4-72). The improvement was statistically significant (p < 0.05).

CONCLUSIONS

In Asian patients with high risk of hip dislocation, the use of modular dual-mobility hip component produces promising outcomes without hip dislocation, but the relatively small-sized acetabulum may limit it widespread application in other populations worldwide.

TRIAL REGISTRATION

HKUCTR-2913 .

Clinical outcomes and dislocation rates after hip reconstruction using the Bioball system

INTRODUCTION

Instability accounts for 1/3 of revision total hip arthroplasty (rTHA) performed in the UK. Removal of well-fixed femoral stems in rTHA is challenging with a risk of blood loss and iatrogenic damage to the femur. The Bioball universal adaptor (BUA), a modular head neck extension adaptor, provides a mechanism for optimisation of femoral offset, leg length and femoral anteversion. This can avoid the need for femoral stem revision in selected cases.The aim of this study is to present the clinical results and rate of instability following revision with this BUA at a minimum of 2 years follow-up.

PATIENTS AND METHODS

A review of our prospectively collected database was performed. All patients treated with the Bioball device were included. Clinical and radiologic review were performed pre- and post-surgery. Specific enquiry for instability was made. The Oxford Hip Score (OHS), EuroQol (EQ-5D) score and WOMAC scores were calculated pre-and post-operatively. Complications were recorded.

RESULTS

32 rTHA procedures were performed using the Bioball device between 2013 and 2016. 4 patients did not wish to complete post-operative questionnaires. 2 patients (2/28, 7%) complained of recurrent dislocations following their rTHA procedure. 1 patient complained of instability but no dislocation. The median pre-operative EQ-5D was 0.195 (range -0.07-0.85), OHS was 20 (range 5-43) and WOMAC was 29.8 (range 15.5-52.3). The median EQ-5D was 0.85 (range 0.59-1), OHS was 39 (range 21-48) and WOMAC was 91.1 (range 44.5-99.2) at final follow-up. There were significant improvements in the EQ-5D (p = 0.0009), OHS (p = 0.0004) and WOMAC (p = 0.0001).

CONCLUSION

The BUA is associated with significant functional improvement and relatively low dislocation rates in revision THA. It is a viable option for use in the revision setting.

Trends in the use of dual mobility bearings in hip arthroplasty

Aims

Dual mobility (DM) bearings are an attractive treatment option to obtain hip stability during challenging primary and revision total hip arthroplasty (THA) cases. The purpose of this study was to analyze data submitted to the American Joint Replacement Registry (AJRR) to characterize utilization trends of DM bearings in the USA.

Methods

All primary and revision THA procedures reported to AJRR from 2012 to 2018 were analyzed. Patients of all ages were included and subdivided into DM and traditional bearing surface cohorts. Patient demographics, geographical region, hospital size, and teaching affiliation were assessed. Associations were determined by chi-squared analysis and logistic regression was performed to assess outcome variables.

Results

A total of 406,900 primary and 34,745 revision THAs were identified, of which 35,455 (8.7%) and 8,031 (23.1%) received DM implants respectively. For primary THA, DM usage increased from 6.7% in 2012 to 12.0% in 2018. Among revision THA, DM use increased from 19.5% in 2012 to 30.6% in 2018. Patients < 50 years of age had the highest rates of DM implantation in every year examined. For each year of increase in age, there was a 0.4% decrease in the rate of DM utilization (odds ratio (OR) 0.996 (95% confidence interval (CI) 0.995 to 0.997); p < 0.001). Females were more likely to receive a DM implant compared to males (OR 1.077 (95% CI 1.054 to 1.100); p < 0.001). Major teaching institutions and smaller hospitals were associated with higher rates of utilization. DM articulations were used more commonly for dysplasia compared with osteoarthritis (OR 2.448 (95% CI 2.032 to 2.949); p < 0.001) during primary THA and for instability (OR 3.130 (95% CI 2.751 to 3.562) vs poly-wear; p < 0.001) in the revision setting.

Conclusion

DM articulations showed a marked increase in utilization during the period examined. Younger patient age, female sex, and hospital characteristics such as teaching status, smaller size, and geographical location were associated with increased utilization. DM articulations were used more frequently for primary THA in patients with dysplasia and for revision THA in patients being treated for instability. Cite this article: Bone Joint J 2020;102-B(7 Supple B):27–32.

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

Highly porous titanium cup in cementless total hip arthroplasty: registry results at eight years

PURPOSE

Highly porous cups were developed to improve osseointegration and reduce the rate of aseptic loosening. Highly porous titanium cups could mix the reliability of titanium metal with an enhanced porosity, improving the bony ingrowth. The aim of this report was to assess the survival rates and reasons for revision of a highly porous titanium cup, Fixa Ti-Por (Adler Ortho, Milan, Italy), fabricated using an additive manufacturing.

METHODS

The Registry of Prosthetic Orthopedic Implants (RIPO), the Emilia-Romagna region arthroplasty registry, was enquired about cementless cups, implanted since July 2007. Ti-Por cups were compared to all the other cementless sockets, acting as a control group. The survival rates and reasons for revision were evaluated and compared. Comparisons with the same articular couplings were also provided.

RESULTS

When all the articular couplings were included, Ti-Por performed better, achieving a statistically higher survival rate than the control group (98.7% vs 97.9%) and a statistically lower incidence of cup aseptic loosening. In case of ceramic on polyethylene couplings, Ti-Por achieved similar survival rate: cup aseptic loosening in Ti-Por group was 0.2%, whereas the control group rated 0.4%. In ceramic-on-ceramic implants, the survival rate was similar in the two groups, Ti-Por achieving a cup aseptic loosening rate of 0.1% (vs 0.14% in the control group).

CONCLUSION

Highly porous titanium cups showed trustworthy results at eight years, reducing the rate of aseptic loosening. Longer follow-ups, ion analyses, and pre-clinical in vivo studies would be helpful to better define the reliability of these devices and their advantages.

Asymptomatic intraprosthetic dual mobility cup dislocation with increased metal ion levels

With the increased use of dual-mobility cups (DMCs) in total-and revision hip arthroplasties, surgeons can expect an increase of known and new complications. During routine follow-up, we observed an asymptomatic patient with an intraprosthetic-dislocation (IPD) and elevated levels of serum metal ions (1.8 ppb of cobalt and 28.0 ppb of chromium). Revision surgery was inevitable. Perioperative metallosis and severe wear of the metal shell and metal femoral head supported the IPD. Literature showed that the modularity of the DMC can result in increased serum metal ions, create excessive wear, and possibly affect implant survival. Our case and review of the literature may form an argument not to consider DMC for primary cases. Furthermore, we advise yearly clinical and radiological follow-up and, on indication, metal ion testing for DMCs.

Dual-Mobility Constructs in Primary and Revision Total Hip Arthroplasty: A Systematic Review of Comparative Studies

BACKGROUND

Utilization of dual-mobility constructs in total hip arthroplasties (THA) has increased in the recent years. Benefits and risks of these implants in terms of reducing dislocations, long-term survivorship, and associated complications are uncertain when compared to non-dual-mobility articulations.

METHODS

A systematic review of prospective and retrospective studies that compared dual-mobility constructs with controls for primary or revision THAs between 1986 and 2018 was performed. All articles in both English and French were reviewed.

RESULTS

Five studies with primary THAs and 6 with revision THAs were analyzed. For primary THAs, the overall rate of dislocation was 0.9% in the dual-mobility group compared to 6.8% in the control group (P < .001) at a mean follow-up of 7.6 years. The odds ratios for the control group to the dual-mobility group were 4.06 (P < .001) for dislocation, 1.18 (P = .87) for revision, 2.97 (P = .04) for revision due to dislocation, 1.67 (P = .57) for infection, 0.6 (P = .53) for fracture, and 1.21 (P = .81) for aseptic loosening. Similarly, for revision THAs, the overall dislocation rates were 2.2% compared to 7.1% (P < .001) at a mean follow-up of 4.1 years. The odds ratios for the control group to the dual-mobility group were 3.59 (P < .001) for dislocation, 2.46 (P < .001) for re-revision, 4.88 (P = .007) for re-revision due to dislocation, 1.51 (P = .32) for infection, 1.18 (P = .81) for fracture, and 2.71 (P = .003) for aseptic loosening.

CONCLUSION

This systematic review of comparative studies supports the efficacy of dual-mobility constructs to minimize dislocation after both primary and revision THAs in addition to excellent mid-term survivorship compared to control constructs. However, further evidence is needed to evaluate the long-term risks and benefits of dual-mobility constructs in the primary and revision THA setting when compared to contemporary conventional implants.

LEVEL OF EVIDENCE

III, therapeutic.

Revision total hip arthroplasty with a Kerboull plate: comparative outcomes using standard versus dual mobility cups

INTRODUCTION

Instability is a major complication in revision total hip arthroplasty (THA). Dual mobility (DM) cups were shown to reduce the risk of post-operative implant dislocation. Few case-series studies assessed the outcomes of cemented DM cups when associated to acetabular reconstruction antiprotrusio cages. No published comparative studies were found to look for outcome differences between standard cups (SC) and DM cups in first revision THA associated with a Kerboull plate (KP) and acetabular bone grafting.

MATERIALS AND METHODS

This is a retrospective comparative study of two groups of patients in two institutions. All cases were first revision THA with KP reconstruction; a cemented standard cup (SC) was used in one institution (THA-SC group) while a cemented DM cup was used in the second institution (THA-DM group). The posterolateral approach and the same technique for KP placement, the cross technique, were performed in both groups. Primary outcomes were dislocation and revision rates. Survivorship and clinical and radiological results were set to be secondary outcomes. There were ten patients (13 hips) in the first group and 16 patients (16 hips) in the second with a mean follow-up clinical and radiological evaluation of 74.2 ± 47.9 months.

RESULTS

Besides age, no significant demographic differences were present between both groups. There were three dislocations (23%) in the first group treated with close reduction compared to none in the second (p = 0.04). No further episode of dislocation or revision surgery occurred until the last follow-up in both groups. The mean Harris Hip Scores for the THA-SC and THA-DM groups were 87.5 ± 10.9 and 87.4 ± 12.1, respectively. When present, radiolucent lines were less than 1 mm thick and were non-progressive in both groups. In all patients, complete trabeculation remodeling or cortical repair of the graft was observed.

CONCLUSION

The cup type was the single variable which could account for the observed dislocation rate difference. The mid-term results of using DM cups with KP in first revision THA seem very encouraging. Our findings add to the previously published results on the excellent outcomes in terms of stability in revision THA when using DM cups.