Use of dual mobility cups in patients undergoing primary total hip arthroplasty with prior lumbar spine fusion

Radiological assessment of cup anteversion with a novel 3D-printed highly-porous titanium dual mobility cup

BACKGROUND

Cup anteversion after primary total hip arthroplasty (THA) with monobloc dual mobility cups (DMC) is difficult to measure on anterior-posterior (AP) pelvic radiographs because of the implant radiopacity and cup design which do not allow for an accurate visualization of the radiographic projection of the cup equatorial rim and the femoral head. This study aims to radiographically investigate on the reliability and accuracy of different measurement methods for cup anteversion in monobloc DMC THA, by comparing a novel titanium cup with conventional cup designs.

METHODS

97 THAs with a monobloc 3D-printed titanium DMC were radiographically assessed for cup radiographic anteversion (RA) one month postoperatively. RA were measured by three blinded observers through Lewinnek, Woo-Morrey methods and an open access mathematical software (GeoGebra), used as reference method. Intra- and interobserver reliability of RA measurements were evaluated for each method using intraclass correlation coefficient (ICC). Accuracy was assessed comparing Lewinnek and Woo-Morrey methods with GeoGebra. Moreover, further 98 THAs with conventional different brand DMC were radiographically assessed as control group by using the same methods.

RESULTS

ICC for intra- and interobserver reliability for RA measurements with GeoGebra, Lewinnek and Woo-Morrey methods were 0.975-0.980, 0.978 - 0.965, and 0.979 - 0.958, respectively, for the titanium DMC group. Lewinnek resulted more accurate for RA than Woo-Morrey, differing by + 0.4° (p = 0.06) and + 4.4° (p < 0.001) from GeoGebra, respectively. ICC for intra- and interobserver reliability for GeoGebra, Lewinnek and Woo-Morrey methods were 0.848 - 0.756, 0.843 - 0.801, and 0.965 - 0.958, respectively, for the control DMC group. Lewinnek and Woo-Morrey methods differed by -2.3° and + 5.1° from GeoGebra, respectively (p < 0.001).

CONCLUSIONS

RA measurements are more consistent, repeatable and accurate with a titanium DMC than standard DMC, due to the minor radiopacity of the former cup which enable RA measurements on AP radiographs. Conversely, RA measurements of conventional DMC are more consistent but less accurate if performed on cross-table lateral radiographs by Woo-Morrey method than AP radiographs.

Adverse spinopelvic mobility in patients undergoing total hip arthroplasty is associated with high mobility of the hip in a flexed seated position

PURPOSE

Adverse spinopelvic mobility from a standing to a flexed seated position of more than 20° of the spinopelvic tilt (∆SPT) has been shown to have a high risk of dislocation. If hypermobility of the hip analysed with the pelvic femoral angle (∆PFA) has a high risk of impingement, the correlation between the range of motion of the hip from a standing to a flexed seated position and its implication in adverse spinopelvic mobility has not been described.

METHODS

A series of 337 patients treated with primary THA underwent lateral x-ray in standing and flexed seated positions to analyse ∆SPT, ∆PFA and spinopelvic parameters. The objectives were to establish a ∆PFA threshold associated with a ∆SPT ⩾20° and to subsequently investigate its influence in conjunction with spinopelvic risk factors on the occurrence of adverse spinopelvic mobility.

RESULTS

The area under the curve was 0.904 (95%CI, 0.864-0.945) for ∆PFA to predict ∆SPT ⩾ 20°; it was predicted by ∆PFA ⩾ 95° with a sensitivity of 91.7% and a specificity of 74.4% at the Youden optimal threshold. Patients with a ∆SPT < 20° (277 patients) had a mean ∆PFA of 83° compared to 110° if ∆SPT ⩾ 20° (60 patients) (p < 0.001). Patients with a ∆PFA < 95° (203 patients) had a mean ∆SPT of -6° compared to 18° if ∆PFA ⩾ 95° (134 patients) (p < 0.001). ∆PFA ⩾ 95° rates were 95% (57/60) and 27.8% (77/200) in patients with ∆SPT ⩾ 20° and ∆SPT < 20°, respectively (OR 49.35; CI, 15.01-162.28; p < 0.001).

CONCLUSIONS

High mobility of the hip (∆PFA ⩾ 95°) seems to be a necessary condition for adverse spinopelvic mobility. A preoperative analysis of patients with lower hip mobility, associated with spinopelvic risk factors, might identify patients with abnormal spinopelvic mobility after the restoration of femoral flexion.

TRIAL REGISTRATION

IDRCB 2023-A01390, CNIL MR004 2225508 (07/06/2023), retrospectively registered.

Direct anterior vs other surgical approaches in patients with lumbar stiffness undergoing total hip arthroplasty: a systematic review and meta-analysis

INTRODUCTION

The effectiveness of the direct anterior approach (DAA) compared to other surgical approaches for total hip arthroplasty (THA) in patients with lumbar spine stiffness remains unclear. This systematic review and meta-analysis aimed to compare clinical outcomes, including dislocation rates and other complications, between DAA and other surgical approaches for THA in patients with lumbar spine stiffness.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis to compare the DAA with other surgical approaches (anterolateral, direct lateral, posterolateral and direct superior) in patients with lumbar spine stiffness undergoing THA. We searched PubMed, Embase, and Cochrane Central databases for cohort studies and randomized controlled trials and calculated risk ratios (RRs) with 95% confidence intervals (CIs) to assess dislocation rates.

RESULTS

This analysis included 11 non-randomized studies comprising 2505 patients, of whom 738 patients (29.4%) underwent THA via DAA. The results demonstrated that the DAA group had significantly reduced dislocation rates (RR 0.31, 95% CI 0.14-0.67, P = 0.003, I2 = 0%) compared to other surgical approaches. Subgroup analysis showed significantly lower dislocation rates in DAA patients versus those undergoing the posterior approach (RR 0.22, 95% CI 0.10-0.52, P = 0.001, I2 = 0%). However, there was no statistically significant difference in dislocation rates between DAA and the lateral approach (RR 0.53, 95% CI 0.19-1.47, P = 0.22, I2 = 0%), although the rate was numerically lower.

CONCLUSION

The DAA was associated with lower dislocation rates compared to other surgical techniques in patients with lumbar spine stiffness undergoing THA.

Archetype analysis of the spine-hip relationship identifies distinct spinopelvic profiles

INTRODUCTION

The position of the pelvis in the sagittal plane can vary considerably between different functional positions. Adapting the position of the acetabular cup in relation to the alignment between the spine and the hip of each individual, prior to prosthesis placement, can prevent the risk of prosthetic impingement. Taken individually, risk factors for unfavorable spinopelvic kinematics can be difficult to interpret when trying to precisely predict which patients are at risk. Furthermore, the use of classifications or algorithms can be complex, most often associated with limited values and often difficult to apply in current practices of risk assessment.

HYPOTHESIS

We hypothesized that the deconstruction of the data matrix including age and spinopelvic parameters (SPT, LL, PI, LF and PI-LL) correlated with the analysis of spinopelvic kinematics could be used to define an individualized hip-spine relationship.

MATERIAL AND METHOD

We applied archetypal analysis, which is a probabilistic, data-driven and unsupervised approach, to a complete phenotype cohort of 330 patients before total hip arthroplasty to define the spinopelvic profile of each individual using the spinopelvic parameters without threshold value. For each archetype, we analyzed the spinopelvic kinematics, not implemented in the creation of the archetypes.

RESULTS

An unsupervised learning method revealed seven archetypes with distinct spinopelvic kinematic profiles ranging from -8.9 ° to 13.15 ° (p = 0.0001) from standing to sitting and -5. 35 ° to -10.81 ° (p = 0.0001) from supine to standing. Archetype 1 represents the "ideal" patient (A1); young patients without spinopelvic anomaly and the least at risk of mobility anomaly. Followed by 3 archetypes without sagittal imbalance according to their lumbar lordosis and pelvic incidence, from the highest to the lowest (archetypes 2-4), archetype 4 exposing a greater risk of spinopelvic kinematic anomaly compared to others. Then 2 archetypes with sagittal imbalance: archetype 5, with an immobile pelvis in the horizontal plane from standing to sitting position in anterior tilt and archetype A6, with significant posterior pelvic tilt standing, likely compensating for the imbalance and associated with the greatest anomaly of spinopelvic kinematics. Finally, archetype 7 with the stiffest lumbar spine without sagittal imbalance and significant unfavorable kinematics from standing to sitting.

CONCLUSION

An archetypal approach to patients before hip replacement can refine diagnostic and prognostic features associated with the hip-spine relationship and reduced heterogeneity, thereby improving spinopelvic characterization. This risk stratification of spinopelvic kinematic abnormalities could make it possible to target patients who require adapted positioning or types of implants before prosthetic surgery.

LEVEL OF EVIDENCE

IV retrospective study.

In silico analysis of the patient-specific acetabular cup anteversion safe zone

INTRODUCTION

Various computer-assisted surgical systems claim to improve the accuracy of cup placement in total hip arthroplasties after assessing spinopelvic mobility to prevent prosthetic impingement. However, no study has yet analyzed the extent of the patient-specific cup anteversion safe zones.

HYPOTHESIS

We hypothesized that most patients have a safe zone >10 °, except those with abnormal spinopelvic mobility, who have a much narrower safe zone.

MATERIALS AND METHODS

We simulated the risks of prosthetic impingement using the planned cup anteversion. The consecutive cohort included 341 patients who underwent total hip arthroplasty. Our primary endpoint was the patient-specific impingement-free zone for cup anteversion, which was then divided into four subgroups: 0 °, 1 ° to 5 °, 6 ° to 10 °, and >10 °. This data was then secondarily analyzed for abnormal spinopelvic mobility (the difference in the spinopelvic tilt [ΔSPT] from a standing to a flexed seated position >20 °).

RESULTS

The mean anteversion safe zone was 22.8 ° with 82.4% (281/341) of patients with a zone strictly >10 °. The mean safe zone was 8.9 ° (+/- 9 °) in patients with an ΔSPT ≥20 ° (18.2%), with 37.1% of these patients having a zone of 0 °, 16.13% a zone between 1 ° and 5 °, 8.06% a zone between 6 ° and 10 ° and 38.71% a zone >10 °. The mean safe zone was 25.9 ° (+/- 9 °) in patients with an ΔSPT <20 ° (81.8%), and the proportion of cases in each zone was 2.51%, 1.08%, 4.3%, and 92.11%, respectively (p < 0.001).

CONCLUSION

The safe zone for anteversion appears to be fairly wide in most patients. However, identifying patients at risk of abnormal spinopelvic mobility seems necessary to identify the two-thirds of patients with a narrow safe zone.

LEVEL OF EVIDENCE

IV; retrospective study.

Dual mobility in primary total hip arthroplasty: A temptation from the devil or a blessing from above

Dual mobility (DM) bearings have gained significant attention in the field of total hip arthroplasty (THA) as a valid treatment option in cases of revision for instability after THA whereas its use in primary THA is still a matter of debate. This manuscript explores the pathology, incidence, diagnosis, treatment options, prognosis, ongoing studies in the literature, and future perspectives related to the use of DM bearings employed in primary THA. DM bearings are primarily designed to address one of the major concerns in THA: Instability of the prosthetic hip. Instability is both for the surgeon and the patient a devastating postoperative complication, leading to significant pain and subsequent apprehension by the patient and may require revision surgeries. The use of DM implants poses the worry of wear-related complications, such as accelerated polyethylene wear and osteolysis, which also pose challenges to long-term implant survival. This technique has seen a steady rise in recent years, with multiple studies reporting favorable outcomes. The incidence of their utilization varies among institutions and surgeons, reflecting differing preferences and patient populations. The diagnosis of instability and wear-related complications in THA often involves clinical assessment, imaging modalities such as X-rays, computed tomography scans, and sometimes advanced imaging techniques like magnetic resonance imaging. DM bearings can be considered as an option when patients present neurologic pathologies such as Parkinson's disease or recurrent dislocations after THA. DM bearings provide an additional articulation point within the implant, facilitating a greater range of motion and inherent stability. This design allows for reduced risk of dislocation and improved functional outcomes. Various implant manufacturers offer different designs and sizes of DM bearings to suit individual patient needs. Current literature suggests that the use of DM bearings in primary THA has demonstrated promising outcomes in terms of enhanced stability, reduced dislocation rates, and improved patient satisfaction. However, long-term studies with larger patient cohorts are necessary to establish the durability and longevity of these implants. Several ongoing studies are investigating the role of DM bearings in primary THA. These studies focus on evaluating long-term implant survivorship, assessing wear patterns, analyzing patient-reported outcomes, and comparing the effectiveness of DM bearings with traditional THA designs. The future of DM bearings in primary THA holds potential for further advancements. Research efforts are aimed at refining implant materials, optimizing designs, and studying the influence of surgical techniques on implant performance. Additionally, continued investigation into the long-term outcomes and cost-effectiveness of DM bearings will play a crucial role in shaping their future use. While further research is warranted, the current evidence supports their potential as a beneficial solution in improving surgical outcomes and patient satisfaction.

Outcomes and complications of Total Hip Arthroplasty in patients with a pre-existing pathologic spine-hip relation. A systematic review of the literature

BACKGROUND

There has been a growing interest in pathologic spine-hip relations (PSHR) in current literature, with the aim of reducing the risk of prosthetic impingement, dislocation, and edge loading in total hip arthroplasty (THA). The primary objective of this review is to determine the effect of different PSHR on primary THA outcomes and complication profile. The secondary objective is to stratify the risk of different subgroups of PSHR patients.

METHODS

A systematic review of the literature was performed in accordance with PRISMA guidelines. Randomised controlled trials, comparative cohort studies and case-control studies comparing outcomes and complication rates of primary THA in patients with and without a PSHR (spinal fusion; degenerative spinal conditions determining stiff spine and/or spinal misalignment) were included. The quality of the included studies and the risk of bias were assessed. The revision rate, complications, and clinical and radiological data were analysed. Complications included: aseptic loosening (AL), periprosthetic joint infections (PJI), hip dislocations and periprosthetic fractures (PF).

RESULTS

Fifteen articles were included with 3.306.342 THAs. The mean follow-up (FU) was 31.4 ± 21.7 months. The population was divided into three subgroups: spinal fusion patients (48.315 THAs); non-fused patients with spinal stiffness (106.110 THAs); non-fused patients with normal spines (3.151.917 THAs). A statistically significant risk stratification was observed about dislocation rate (5.98 ± 6.9% SF, 3.0 ± 1.9% non-SF Stiff and 2.26 ± 1.4% non-SF; p = 0.028). Similarly, about THA revision rate, a statistically significant risk stratification was also observed (7.3 ± 6.8% SF, 6.4 ± 3.1% non-SF Stiff and 2.7 ± 1.7% non-SF; p = 0.020). No statistically significant difference was observed when analysing AL, PJI and PF.

CONCLUSION

A statistically significant risk stratification of dislocation and revision rate was observed in the different PHSR, as theorised by the Bordeaux classification. Fused patients present a higher risk, degenerated and/or stiff spine an intermediate risk and mobile spines a lower risk profile. A standardised approach to THA candidate patients must consider the possible PSHR to improve clinical outcomes and reduce adverse events of THA.

Hip-spine relationship: clinical evidence and biomechanical issues

The hip-spine relationship is a critical consideration in total hip arthroplasty (THA) procedures. While THA is generally successful in patient, complications such as instability and dislocation can arise. These issues are significantly influenced by the alignment of implant components and the overall balance of the spine and pelvis, known as spinopelvic balance. Patients with alteration of those parameters, in particular rigid spines, often due to fusion surgery, face a higher risk of THA complications, with an emphasis on complications in instability, impingement and dislocation. For these reasons, over the years, computer modelling and simulation techniques have been developed to support clinicians in the different steps of surgery. The aim of the current review is to present current knowledge on hip-spine relationship to serve as a common platform of discussion among clinicians and engineers. The offered overview aims to update the reader on the main critical aspects of the issue, from both a theoretical and practical perspective, and to be a valuable introductory tool for those approaching this problem for the first time.

Superior outcomes of total hip arthroplasty without prior lumbar arthrodesis: a systematic review and meta-analysis

PURPOSE

The number of patients undergoing total hip arthroplasty (THA) surgery after previous lumbar arthrodesis (LA) is rising. Literature suggests that LA may significantly impact pelvic biomechanics and potentially compromise the success of prosthetic hip replacement. This study aims to evaluate complication rates, dislocation rates, and revision rates in patients with prior LA undergoing THA surgery compared to those undergoing THA surgery without prior LA.

METHODS

A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A PICOS template was developed to ensure a structured approach. The search for relevant studies was performed across five databases, including Pubmed, Scopus, Embase, Medline, and Cochrane. The selected articles were evaluated based on the Levels of Evidence (LoE) criteria. The Coleman Methodology Score (mCMS) was employed to analyze the retrospective studies. This systematic review and meta-analysis were registered in the International Prospective Register of Systematic Reviews (PROSPERO). For the outcomes that allowed for a meta-analysis performed using R software, a p < 0.05 was considered statistically significant.

RESULTS

The final analysis included seventeen studies comprising a total of 3,139,164 cases of THA. Among these cases, 3,081,137 underwent THA surgery alone, while 58,027 patients underwent THA with a previous LA. The study investigated various factors, including dislocation rates, revision rates, and complication, as well as the surgical approach and type of implant used, for both the THA-only group and the group of patients who underwent THA with prior LA. The analysis revealed a statistically significant difference (p < 0.05) for all variables studied, favoring the group of patients who underwent THA alone without prior LA.

CONCLUSIONS

This systematic review and meta-analysis demonstrated a statistically significant superiority in all analyzed outcomes for patients who underwent THA-only without prior LA. Specifically, patients with isolated THA implants experienced significantly lower incidences of THA dislocation, wound complications, periprosthetic joint infection, revision, and mechanical complications.

LEVEL OF EVIDENCE

Level IV.

Patients Who Have Had Three or More Levels Fused During Lumbar Spinal Fusion Have Worse Functional Outcomes After Total Hip Arthroplasty

BACKGROUND

Lumbar spinal fusion (LSF) and total hip arthroplasty (THA) are commonly performed in patients who have concomitant spine and hip pathology. While patients who have three or more levels fused during LSF have increased postoperative opioid consumption after undergoing THA, it is unknown whether the number of levels fused during LSF affects THA functional outcomes.

METHODS

A retrospective study was conducted at a tertiary academic center for patients who underwent LSF first and then had a primary THA performed with a minimum of one-year follow-up for the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS-JR). Operative notes were reviewed to determine the number of levels fused during LSF. There were 105 patients who underwent one-level LSF, 55 patients underwent two-level LSF, and 48 patients underwent three-or-more-level LSF. No significant differences existed in age, race, body mass index, and comorbidities between the cohorts.

RESULTS

While preoperative HOOS-JR was similar among the three cohorts, patients who had three-or-more-level LSF had significantly lower HOOS-JR scores than patients who had two-level or one-level LSF (71.4 versus 82.4 versus 78.2; P = .010) and a lower delta HOOS-JR (27.2 versus 39.4 versus 35.9; P = .014). Patients who had three-or-more-level LSF had a significantly lower rate of achieving minimal clinically important difference (61.7% versus 87.2% versus 78.7%; P = .011) and the patient acceptable symptom state (37.5% versus 69.1% versus 59.0%; P = .004) for the HOOS-JR, compared to patients who had two-level or one-level LSF, respectively.

CONCLUSIONS

Surgeons should counsel patients who have had three-or-more-level LSF that they may have a lower rate of hip function improvement and symptom acceptability after THA, compared to patients who have had a less number of levels fused during LSF.

A geometric assessment method for estimating dimensional change of retrieved dual mobility liners for total hip arthroplasty

Despite their emerging use, the current understanding of the in-vivo functional mechanisms of Dual Mobility (DM) Total Hip Replacements (THRs) is poor, and current characterisation methodologies are not suitable for the unique function and design of these types of devices. Therefore, the aim of this study was to develop a geometric characterisation methodology to estimate dimensional change across the articulating surfaces of retrieved DM polyethylene liners so that their invivo function may be better understood. The method involves the acquisition of three-dimensional coordinate data from the internal and external surfaces of DM liners. The data is processed using a bespoke MATLAB script which approximates the unworn reference geometry of each surface, calculates geometric variance at each point and produces surface deviation heatmaps so that areas of wear and/or deformation may be visualised across the implant. One as-manufactured and five retrieved DM liners were assessed, which demonstrated the efficacy, repeatability and sensitivity of the developed method. This study describes an automated and non-destructive approach for assessing retrieved DM liners of any size and from any manufacturer, which may be used in future research to improve our understanding of their in-vivo function and failure mechanisms.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparing dislocation rates by approach following elective primary dual mobility total hip arthroplasty: a systematic review

BACKGROUND

Dual mobility components can be implanted during total hip arthroplasty (THA) for primary osteoarthritis via a direct anterior approach (DAA), anterolateral approach (ALA), direct lateral approach (DLA), or posterior/posterolateral approach (PLA). This review compares dual mobility hip dislocation rates using these approaches for elective primary THA.

METHODS

PubMed, Embase, and Cochrane databases were systematically searched for articles published after January 1, 2006 that reported dislocation rates for adult patients after primary THA with dual mobility implants. Articles were excluded if they reported revision procedures, nonelective THA for femoral neck fractures, acetabular defects requiring supplemental implants, prior surgery, or ≤ 5 patients. The primary outcome was hip dislocation rate. Secondary outcomes included infection, Harris Hip Score (HHS), and Postel-Merle d'Aubigné (PMA) score.

RESULTS

After screening 542 articles, 63 met inclusion criteria. Due to study heterogeneity, we did not perform a meta-analysis. Eight studies reported DAA, 5 reported ALA, 6 reported the DLA, and 56 reported PLA. Study size ranged from 41 to 2,601 patients. Mean follow-up time ranged from 6 months to 25 years. Rates of infection and dislocation were low; 80% of ALA, 87.5% of DAA, 100% of DLA, and 82.1% of PLA studies reported zero postoperative dislocations. Studies reporting postoperative HHS and PMA scores showed considerable improvement for all approaches.

CONCLUSIONS

Patients undergoing primary THA with dual mobility implants rarely experience postoperative dislocation, regardless of surgical approach. Additional studies directly comparing DAA, ALA, DLA, and PLA are needed to confirm these findings.

Dislocation Rates of Primary Total Hip Arthroplasty in Patients With Prior Lumbar Spine Fusion and Lumbar Degenerative Disk Disease With and Without Utilization of Dual Mobility Cups: An American Joint Replacement Registry Study

INTRODUCTION

Patients undergoing primary total hip arthroplasty (THA) with a previous history of lumbar spine fusion (LSF) are at increased risk of dislocation. The purpose of this study was to compare the 90-day and 1-year dislocation rates of patients with LSF or lumbar degenerative disk disease who underwent primary THA with and without dual mobility (DM) constructs.

METHODS

An American Joint Replacement Registry data set of patients aged 65 years and older undergoing primary THA with minimum 1-year follow-up with a history of prior LSF or a diagnosis of lumbar degenerative disk disease was created. DM status was identified, and dislocation and all-cause revision at 90 days and 1 year were assessed.

RESULTS

A total of 15,572 patients met study criteria. The overall dislocation rates for the non-DM and DM groups were 1.17% and 0.68%, respectively, at 90 days, and 1.68% and 0.91%, respectively, at 1 year ( P = 0.005). The odds of 90-day (OR = 0.578, [ P = 0.0328]) and 1-year (OR = 0.534, [ P = 0.0044]) dislocation were significantly less with DM constructs, compared with non-DM constructs. No statistically significant difference was observed in revision rates between groups.

DISCUSSION

This large registry-based study identified a reduced risk of dislocation in patients at risk for spinal stiffness when a DM compared with non-DM construct was used in primary THA at 90-day and 1-year follow-up intervals. Our data support the use of DM constructs in high-risk patients with stiff spines and altered spinopelvic mobility as a promising option to mitigate the risk of postoperative hip instability after primary THA.

LEVELS OF EVIDENCE

Level III. Therapeutic retrospective cohort.

Dual-Mobility Cups in Primary Total Hip Arthroplasty

Dual-mobility cups (DMCs) were introduced in France more than 40 years ago and are increasingly used not only in hip revision but also primary hip arthroplasty. Due to a simulated large-head articulation and increased jumping distance, DMCs can contribute to a high range of motion in the hip joint and reduce the risk of instability. Numerous studies have reported low dislocation rates and high survival rates in the mid-term follow-up. Nevertheless, long-term data, especially on primary hip replacement, remain limited, and the effect of recent designs and material innovations is still unclear. Therefore, primary DMCs are mainly proposed in patients at high risk for dislocation (i.e. pelvitrochanteric insufficiency, compromised spinopelvic mobility, neuromuscular disorders, obesity and femoral neck fractures). Based on a review of recently published studies referring to these indications, the current study discusses the advantages and disadvantages of DMCs.

Spinopelvic Relationship and Its Impact on Total Hip Arthroplasty

The dynamic, complex interaction among the spine, pelvis, and hip is often underappreciated, yet understanding it is vital for both arthroplasty and spinal surgeons. There is an increasing incidence of degenerative hip and spinal pathologies as a result of the ageing population. Furthermore, hip pathology can cause spine pathology and vice versa through “hip-spine” and “spine-hip syndrome.” Consequently, total hip arthroplasty (THA) and spinal fusion surgery, which both affect spinopelvic mobility, are also on the rise. Alteration in spinopelvic motion can affect the orientation of the acetabulum and, therefore, implant positioning in THA, leading to complications such as dislocation, impingement, aseptic loosening, and wear of components. This makes it imperative to assess spinopelvic motion and pelvic tilt prior to patients undergoing THA. In this paper, we explore how the surgeon should proceed to reduce risk of component malalignment, as well as the role of navigation systems in acetabular cup positioning.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Minimum Five-Year Outcomes of Modular Dual Mobility in Primary Total Hip Arthroplasty

BACKGROUND

Using a modular dual-mobility (MDM) bearing in primary total hip arthroplasty (THA) has not been widely evaluated. The purpose of this study is to evaluate clinical outcomes and survivorship following MDM bearings in primary THA.

METHODS

We used our registry database for patients with an MDM bearing on primary THA, performed by 6 surgeons through supine direct lateral or direct anterior approach. MDM bearings were used most often when impingement or subluxation was present intraoperatively despite proper component position. Another indication was a patient with planned activities who might be at a higher risk of instability postoperatively.

RESULTS

A total of 127 MDM bearings were used in primary THA in 119 patients. Mean follow-up was 6.77 years (range 5-8.9). Five hips were revised, none of which were due to MDM bearing failure. Preoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement, Veterans RAND/Short Form 12 Physical Health Score and Mental Health Score increased from 25.81 to 52.40 (P < .0001), 30.42 to 44.50 (P < .0001), and 36.21 to 52.70 (P < .0001) at latest completed survey follow-up, respectively.

CONCLUSION

This MDM bearing shows excellent functional outcomes at a minimum 5 years of follow-up with no bearing-related failures. It can be an excellent choice in primary THA specifically in females where the use of increased head size to prevent instability is not possible due to anatomical restrictions and liner thickness.

Liner malseating is rare with two modular dual-mobility designs

AIMS

The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes.

METHODS

We retrospectively identified 256 primary total hip arthroplasties (THAs) that included a DM component (144 Stryker MDM and 112 Zimmer-Biomet G7) in 233 patients, performed between January 2012 and December 2019. Postoperative radiographs were reviewed independently for malseating of the liner by five reviewers. The mean age of the patients at the time of THA was 66 years (18 to 93), 166 (65%) were female, and the mean BMI was 30 kg/m² (17 to 57). The mean follow-up was 3.5 years (2.0 to 9.2).

RESULTS

Three liners (1.2%) were malseated, including two MDMs (1.4%) and one G7 (0.9%). No clinical consequence was identified from malseating. The five-year survival free of dislocation was 97.1%, including two DM and one intraprosthetic dislocation. The five-year survival free of revision was 95.4%, with seven revisions. The mean Harris Hip Scores increased from 46 (24 to 69) preoperatively to 81 (40 to 100) at two years postoperatively (p < 0.001).

CONCLUSION

The incidence of DM liner malseating after primary THA was low, with no known clinical consequences at mid-term follow-up. Malseating is not exclusive of design, and these findings emphasize the importance of careful evaluation of the liner after impaction to avoid this complication. Cite this article: Bone Joint J 2022;104-B(5):598-603.

Does Prior Lumbar Fusion Influence Dislocation Risk in Hip Arthroplasty Performed for Femoral Neck Fracture?

BACKGROUND

Immobility of the lumbar spine predicts instability following elective total hip arthroplasty (THA). The purpose of this study is to determine how prior lumbar fusion (LF) influenced dislocation rates and revision rates for patients undergoing THA or hemiarthroplasty (HA) for femoral neck fracture (FNF).

METHODS

A retrospective cohort analysis was conducted utilizing the PearlDiver database from 2010 to 2018. Patients who underwent arthroplasty for FNF were identified based on history of LF and whether they underwent THA or HA. Univariate and multivariate analyses were performed.

RESULTS

A total of 328 patients with prior LF and FNF who underwent THA were at increased risk for 1-year dislocation (odds ratio [OR] 2.19, P < .001) and 2-year revision (OR 2.22, P < .001) compared to 14,217 patients without LF. The 461 patients with prior LF and FNF who underwent HA were at increased risk for dislocation (OR 2.22, P < .001) compared to 42,327 patients without LF. Patients with prior LF and FNF who underwent THA had higher rates of revision than patients with prior LF who underwent HA for FNF (OR 2.11, P < .001). In patients with prior LF and FNF, THA was associated with significantly increased risk for dislocation (OR 3.07, P < .001) and revision (OR 2.53, P < .001) compared to THA performed for osteoarthritis.

CONCLUSION

Patients with prior LF who sustained an FNF and underwent THA or HA were at increased risk for early dislocation and revision compared to those without prior LF. This risk of dislocation and revision is even greater than that observed in patients with prior LF who underwent THA for osteoarthritis.

LEVEL OF EVIDENCE

Level III.

Implant survival of 662 dual-mobility cups and 727 constrained liners in primary THA: small femoral head size increases the cumulative incidence of revision

Background and purpose - In total hip arthroplasty (THA), the risk for dislocation can be reduced using either dual-mobility cups (DMCs) or constrained liners (CLs). There are few studies comparing these concepts in primary THA. Therefore, we compared the cumulative incidence of revision in primary THA patients treated with DMC or CL with varying head sizes with conventional THA patients as reference group.Patients and methods - We performed a cohort study based on the Finnish arthroplasty register, comparing DMCs and CLs operated over the period 2000-2017. DMCs were divided into 2 groups based on the implant design: "DMC Trident" group (n = 399) and "DMC Others" group (n = 263). CLs were divided based on the femoral head size: "CL 36 mm" group (n = 425) and "CL < 36 mm" group (n = 302). All conventional primary THAs operated on in 2000-2017 with 28-36 mm femoral head were included as control group ("Conventional THA" group, n = 102,276). Implant survival was calculated by the corresponding cumulative incidence function with revision as the endpoint and death as competing event. Also, the prevalence of different reasons for revision was compared.Results - The 6-year cumulative incidence function estimates for the first revision were 6.9% (95% CI 4.0-9.7) for DMC Trident, 5.0% (CI 1.5-8.5) for DMC Others, 13% (CI 9.3-17) for CL < 36 mm, 6.3% (3.7-8.9) for CL 36 mm, and 4.7% (CI 4.5-4.8) for control group (conventional THA). The prevalence of dislocation revision was high (5.0%, CI 2.9-8.2) in the CL < 36 mm group compared with other groups.Interpretation - The DMC and CL 36 mm groups had promising mid-term survival rates, comparable to those of primary conventional THA group. The revision rate of CLs with < 36 mm head was high, mostly due to high prevalence of dislocation revisions. Therefore, CLs with 36 mm femoral head should be preferred over smaller ones.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

[What are the benefits of patient-specific reconstruction in total hip replacement?]

BACKGROUND

The success of primary total hip replacement (THR) is predominately determined by the primary stability of the implant and the restoration of the patient-specific joint biomechanics. The three-dimensional (patho-) anatomy, size, geometry, and shape of the acetabulum and proximal femur is highly variable in patients with advanced hip osteoarthritis. Accurate preoperative planning is an essential prerequisite for all replacement procedures.

CURRENT SITUATION

Current data demonstrates clinical advantages for patient-specific reconstruction of functional joint geometry via surrogate parameters (offset and leg length). Frequently cited "target zones" for the positioning and orientation of the cup are increasingly in the focus of scientific discussion, as individually adjusted target zones for implant positioning allow for a potential reduction of impingement risk. Patients with spinal fusions or pathologic spinopelvic alignment require that particular attention be paid to patient-specific preoperative preparation, the surgical technique, and implant selection in order to reduce the risk of postoperative instability.

Comparable dislocation and revision rates for patients undergoing total hip arthroplasty with subsequent or prior lumbar spinal fusion: a meta-analysis and systematic review

BACKGROUND

There is a known correlation between the procedures of lumbar spinal fusion (LSF), total hip arthroplasty (THA) and the complication of hip dislocation and revision occurring in patients. However there is no consensus as to whether the risk of this complication is higher if THA is performed before or after LSF. This meta-analysis aims to determine the influence of surgical sequence of lumbar spinal fusion and total hip arthroplasty on the rates of hip dislocation and revisions.

METHODS

A meta-analysis was conducted with a multi-database search (PubMed, OVID, EMBASE, Medline) according to PRISMA guidelines on 27th May 2020. Data from all published literature meeting inclusion criteria were extracted and analyzed with an inverse variance statistical model.

FINDINGS

A total of 25,558 subsequent LSF and 43,880 prior LSF THA patients were included in this study. There was no statistically significant difference in all-cause revisions (OR = 0.86, 95%CI: 0.48-1.54, p = 0.61), dislocation (OR = 0.82, 95%CI: 0.25-2.72, p = 0.75) or aseptic loosening (OR = 1.14, 95%CI: 0.94-1.38, p = 0.17) when comparing patients receiving LSF subsequent versus prior to THA.

CONCLUSION

Lumbar spinal fusion remains a risk factor for dislocation and revision of total hip arthroplasties regardless of whether it is performed prior to or after THA. Further preoperative assessment and altered surgical technique may be required in patients having THA who have previously undergone or are likely to undergo LSF in the future.

EVIDENCE LEVEL

Level II, Meta-analysis of homogeneous studies.

Pathologic spinopelvic balance in patients with hip osteoarthritis : Preoperative screening and therapeutic implications

Recently spinopelvic balance and mobility, i.e. the dynamic interaction of the spine, pelvis and the femur in the sagittal plane between different postures, has been identified as a relevant factor influencing the outcome of primary total hip arthroplasty (THA). Individual spinopelvic balance and mobility seem to affect patient reported outcome and the risk of impingement and dislocation following THA. The aim of this article is to provide a concise overview of normal and pathologic spinopelvic alignment, to characterize relevant spinopelvic parameters and the diagnostic assessment in patients with hip OA and to discuss potential implications for THA with respect to implant selection and component orientation.Spinopelvic characteristics are highly variable. Patients with stiff lumbar spines and mobile hips seem to be at an increased risk of impingement and dislocation and can be screened with single lateral standing radiographs of the spinopelvic complex before THA. In patients with hip and spine pathology, particular attention should be paid to evaluate the individual pathoanatomy of the hip and established clinical measurements should be diligently taken with respect to the reconstruction of the center of rotation, hip offset, leg length and soft tissue tension in order to minimize the risk of impingement and dislocation. No evidence-based recommendations for novel target zones concerning implant position can currently be made. In patients at risk 36 mm heads should be used whenever possible. In high risk patients, such as the combination of a stiff unbalanced lumbar spine ("flatback") and a mobile hip or in the presence of long spinal fusions or fusions involving the sacrum, dual mobility cups offer additional stability.

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

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

[Battle: Total hip arthroplasty or spine surgery first in patients with hip-spine-syndrome? : The arthroplasty surgeon's point of view]

BACKGROUND

Frequently, patients with hip complaints also report lower back pain, and elective surgery may be indicated due to end-stage hip osteoarthritis and degenerative disc disease. Thus, we aim to answer the question of whether total hip arthroplasty (THA) or lumbar spine surgery should be performed first in patients with hip-spine-syndrome, from an arthroplasty surgeon's point of view.

DECISION-MAKING

The present review demonstrates that in patients with an acute neurological deficit, lumbar spine surgery should be performed first. However, in patients without these symptoms, several arguments favour performing THA first, especially the increased risk of dislocation when performing THA after lumbar spine fusion (LSF) in comparison to "THA first" (4.6 vs. 1.7% after 2 years; p < 0,001). However, the risk of dislocation after THA remains increased in both scenarios, independent of surgical order. Consequently, arthroplasty surgeons should pay great attention to optimum component positioning, reconstruction of the hip anatomy, leg length and soft-tissue tension, while considering using large prosthesis heads or dual mobility cups when performing primary THA in patients with an increased risk of dislocation. In complex cases, we would encourage arthroplasty and spine surgeons working in cooperation on highly individual treatment concepts.

[Hip-spine syndrome-current developments and state of the evidence]

The movements between the spine, pelvis and hip joints are coordinated to allow for a physiological balance of the upper body and the pelvis during sitting and standing. Degenerative changes or spondylodesis of the spine result in decreased pelvic mobility and can lead to increased rates of instability in the presence of total hip arthroplasty (THA). To reduce the risk of THA dislocation several authors have recently recommended functional radiographs of the spine and pelvis, as well as individual safe zones for THA components. The aim of this article is to summarize the current body of knowledge regarding the influence of spinopelvic alignment on THA and provide recommendations for everyday clinical practice.