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

Decreased Instability in High-Risk (Hip-Spine 2B) Patients After Modifications of Surgical Planning and Technique

BACKGROUND

Patients undergoing primary total hip arthroplasty (THA) who have spinal deformity and a stiff spine are the highest-risk group for instability. Despite the increasing use of dual-mobility cups and large femoral heads, dislocation remains a major complication after THA. Preoperative planning becomes a critical aspect of ensuring precise component positioning within a safe zone. The purpose of this study was to investigate dislocation rates over a 9-year period.

METHODS

A retrospective review of 4,731 THAs performed by 3 orthopaedic surgeons between January 2014 and March 2023 was performed. Spinopelvic measurements were conducted to determine the hip-spine classification group for each patient. Only patients classified as 2B (pelvic incidence-lumbar lordosis > 10° and Δsacral slope < 10°) were eligible. Both absolute and relative dislocation frequencies were then analyzed using time-series analysis techniques and Fisher's exact tests.

RESULTS

A total of 281 hip-spine 2B patients undergoing primary THA were eligible for analysis (57% women; mean age, range: 66 years, 23 to 87; mean body mass index, range: 28, 16 to 45). The overall dislocation rate was 4.3%. Use of femoral head sizes ≥ 40 mm increased from 4% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001), while the use of dual-mobility cups decreased from 100% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001). Acetabular component planning was changed from the supine plane to the standing plane in February 2020. Those changes in surgical practice were notably correlated with a significant decrease in dislocation rates from 6.8% in 2014 to 2019 to 1.5% in 2020 to 2023 (P = .03).

CONCLUSIONS

Our study demonstrates that the introduction of advanced preoperative THA planning to the standing plane, coupled with precise intraoperative technology for implant placement, can significantly reduce the risk of instability in high-risk THA patients. Notably, we observed a significant decrease in dislocation rates, which aligned with the shift in surgical practice.

LEVEL OF EVIDENCE

IV.

Hip Osteoarthritis in Patients Undergoing Surgery for Severe Adult Spinal Deformity: Prevalence and Impact on Spine Surgery Outcomes

BACKGROUND

Hip osteoarthritis (OA) is common in patients with adult spinal deformity (ASD). Limited data exist on the prevalence of hip OA in patients with ASD, or on its impact on baseline and postoperative alignment and patient-reported outcome measures (PROMs). Therefore, this paper will assess the prevalence and impact of hip OA on alignment and PROMs.

METHODS

Patients with ASD who underwent L1-pelvis or longer fusions were included. Two independent reviewers graded hip OA with the Kellgren-Lawrence (KL) classification and stratified it by severity into non-severe (KL grade 1 or 2) and severe (KL grade 3 or 4). Radiographic parameters and PROMs were compared among 3 patient groups: Hip-Spine (hip KL grade 3 or 4 bilaterally), Unilateral (UL)-Hip (hip KL grade 3 or 4 unilaterally), or Spine (hip KL grade 1 or 2 bilaterally).

RESULTS

Of 520 patients with ASD who met inclusion criteria for an OA prevalence analysis, 34% (177 of 520) had severe bilateral hip OA and unilateral or bilateral hip arthroplasty had been performed in 8.7% (45 of 520). A subset of 165 patients had all data components and were examined: 68 Hip-Spine, 32 UL-Hip, and 65 Spine. Hip-Spine patients were older (67.9 ± 9.5 years, versus 59.6 ± 10.1 years for Spine and 65.8 ± 7.5 years for UL-Hip; p < 0.001) and had a higher frailty index (4.3 ± 2.6, versus 2.7 ± 2.0 for UL-Hip and 2.9 ± 2.0 for Spine; p < 0.001). At 1 year, the groups had similar lumbar lordosis, yet the Hip-Spine patients had a worse sagittal vertebral axis (SVA) measurement (45.9 ± 45.5 mm, versus 25.1 ± 37.1 mm for UL-Hip and 19.0 ± 39.3 mm for Spine; p = 0.001). Hip-Spine patients also had worse Veterans RAND-12 Physical Component Summary scores at baseline (25.7 ± 9.3, versus 28.7 ± 9.8 for UL-Hip and 31.3 ± 10.5 for Spine; p = 0.005) and 1 year postoperatively (34.5 ± 11.4, versus 40.3 ± 10.4 for UL-Hip and 40.1 ± 10.9 for Spine; p = 0.006).

CONCLUSIONS

This study of operatively treated ASD revealed that 1 in 3 patients had severe hip OA bilaterally. Such patients with severe bilateral hip OA had worse baseline SVA and PROMs that persisted 1 year following ASD surgery, despite correction of lordosis.

LEVEL OF EVIDENCE

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

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.

Comparison of Outcomes in Dual-Mobility Versus Fixed-Bearing Implants in Primary Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Total hip arthroplasty (THA) is often regarded as one of the most successful surgical techniques developed in the twenty-first century. However, it is associated with complications such as prosthetic instability, dislocations, or infections. Dual-mobility (DM) implants have been developed with the goal of reducing the incidence of dislocations by increasing the femoral head-neck ratio, maximising hip stability, and improving the range of motion (ROM) before impingement and dislocation. This systematic review aims to comprehensively compare the safety and efficacy of DM versus fixed-bearing (FB) implants in primary THA patients. A comprehensive search strategy of PubMed, Embase, Scopus, and Web of Science Core Collection databases was executed to identify pertinent literature comparing DM and FB implants in THAs. Eligible studies underwent independent screening, and data were systematically extracted. The analysis employed pooled risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous variables, each accompanied by their respective 95% confidence intervals (CI). Our systematic review and meta-analysis included nine studies encompassing 22,277 patients. The DM group had a significantly reduced incidence of dislocations compared to the FB group (RR 0.25, 95%CI [0.13, 0.47]; p-value <0.0001) and a significantly shorter length of stay (MD -9.92, 95%CI [-15.53, -4.32]; p-value = 0.0005). The FB group, however, had a significantly shorter operative time compared to the DM group (MD 10.41, 95%CI [7.64, 13.17]; p-value < 0.00001). We did not identify any significant statistical differences between the DM and FB groups regarding patient-reported outcome measures, the incidence of all-cause readmissions, the incidence of peri-prosthetic fractures, the incidence of infections, or the incidence of groyne pain.

Dislocation Following Anterior and Posterior Total Hip Arthroplasty in the Setting of Spinal Deformity and Stiffness: Evolving Trends Using a High-Risk Protocol at a Single Tertiary Center

BACKGROUND

Patients who have spinal stiffness and deformity are at the highest risk for dislocation after total hip arthroplasty (THA). Previous reports of this cohort are limited to antero-lateral and postero-lateral (PL) approaches. We investigated the dislocation rate after direct anterior (DA) and PL approach THA with a contemporary high-risk protocol to optimize stability.

METHODS

We investigated patients undergoing THA who had preoperative biplanar imaging from January-December 2019. Patients were identified using radiographic criteria of spinal-stiffness (<10-degree change in sacral slope from standing to seated) and deformity (flatback deformity with >10-degree difference in pelvic incidence and lumbar lordosis). There were 367 patients identified (181 DA, 186 PL). The primary outcome was dislocation rate at 2-years postoperatively. Risk-factors for dislocation were evaluated using logistic regressions (significance level of 0.05).

RESULTS

There were 6 (1.6%) dislocations in the entire cohort, with low dislocation rates for both DA (0.6%) and PL-THA (2.7%). We observed increased utilization of dual mobility with larger outer head bearings (>38 mm) with PL-THA (34.4 versus 5.0%, P < .01) and conversely increased utilization of 32-mm femoral-heads with DA-THA (39.4 versus 7.0%, P < .001). Surgical approach (PL) was not a significant risk-factor for dislocation (odds ratio: 5.03, P = .15). Patients who had a history of lumbar-fusion had 8-times higher odds for dislocation (OR: 8.20, P = .020).

CONCLUSIONS

To the best of our knowledge, this is the largest series to date evaluating DA and PL-THA in the hip-spine 2B-group. Our results demonstrate lower dislocation rate than expected with either surgical approach using a high-risk protocol.

The use of dual mobility acetabular cups in total hip replacement reduces dislocation rates in hip dysplasia patients

Total hip replacement arthroplasty (THA) in hip dysplasia patients has a higher dislocation rate than in patients with simple hip osteoarthritis due to anatomical deformation. Therefore, to reduce postoperative THA dislocation is the challenge for arthroplasty surgeons. From 2015 to 2020, 1525 patients underwent THA performed by two surgeons at a single institution. A total of 152 patients involving 172 THAs were included. The patients were classified into dual-mobility (DM) and fixed-bearing (FB) acetabular cup groups. The occurrence of postoperative dislocation and functional evaluation of the hip joint, was analyzed before and after surgery using the modified Harris hip score(mHHS). There was no difference in the preoperative demographics and radiographic parameters between the groups. The incidence of postoperative hip dislocation was significantly lower in the DM group (DM 0% vs. FB 9.0%) (P value = 0.003). The mHHS showed no difference before surgery and after surgery (DM 91.80 vs FB 92.03). Treating hip dysplasia patients with THA using a dual-mobility acetabular cup can reduce postoperative dislocations, and could be used for the better management of these patients.

Total Hip Arthroplasty in Ochronotic Arthropathy: A Case Report

Introduction

Total hip arthroplasty (THA) is a common procedure used to treat various hip conditions. However, patients with ochronotic arthropathy, a rare genetic disorder characterized by the abnormal accumulation of homogentisic acid, are at a higher risk of post-surgical dislocation and instability due to poor bone quality and joint degeneration.

Case Report

This case study features a 52-year-old male patient diagnosed with ochronotic arthropathy who underwent bilateral THA with the use of a dual mobility cup (DMC). Ochronotic arthropathy had caused significant joint degeneration and stiffness, leading to considerable functional impairment.

Conclusion

The application of a DMC in THA for patients with ochronotic arthropathy has shown promising outcomes. The DMC offers increased range of motion and improved stability, effectively reducing the risk of post-surgical dislocation and implant failure. This case study highlights the potential of DMC as a viable solution for addressing the challenges posed by poor bone quality in patients with ochronotic arthropathy undergoing THA.

Selective Use of Dual-Mobility Did Not Significantly Reduce 90-Day Readmissions or Reoperations after Total Hip Arthroplasty

INTRODUCTION

Selective use of dual mobility (DM) implants in total hip arthroplasty (THA) patients at high dislocation risk has been proposed. However, evidence-based utilization thresholds have not been defined. We explored whether surgeon-specific rates of DM utilization correlate with rates of readmission and reoperation for dislocation.

METHODS

We retrospectively reviewed 14,818 primary THA procedures performed at a single institution between 2011 and 2021, including 14,310 FB and 508 DM implant constructs. Outcomes including 90-day readmissions and reoperations were compared between patients who had fixed-bearing (FB) and DM implants. Cases were then stratified into three groups based on the attending surgeon's rate of DM utilization (≤1, 1 to 10, or >10%) and outcomes were compared.

RESULTS

There were no differences in 90-day outcomes between FB and DM implant groups. Surgeon frequency of DM utilization ranged from 0 to 43%. There were 48 surgeons (73%) who used DM in ≤ 1% of cases, 11 (17%) in 1 to 10% of cases, and 7 (10%) in >10% of cases. The 90-day rates of readmission (7.3 vs 7.6 vs 7.2%, P=0.7) and reoperation (3.4 vs 3.9 vs 3.8%, P=0.3), as well as readmission for instability (0.5 vs 0.6 vs 0.8%, P=0.2) and reoperation for instability (0.5 vs 0.5 vs 0.8%, P=0.6), did not statistically differ between cohorts.

CONCLUSION

Selective DM utilization did not reduce 90-day readmissions or reoperations following primary THA. Other dislocation-mitigation strategies (i.e., surgical approach, computer navigation, robotic assistance, and large diameter fixed-bearings) may have masked any benefits of selective DM use.

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.

Analysis of contact pressure in a 3D model of dual-mobility hip joint prosthesis under a gait cycle

Hip joint prostheses are used to replace hip joint function in the human body. The latest dual-mobility hip joint prosthesis has an additional component of an outer liner that acts as a cover for the liner component. Research on the contact pressure generated on the latest model of a dual-mobility hip joint prosthesis under a gait cycle has never been done before. The model is made of ultrahigh molecular weight polyethylene (UHMWPE) on the inner liner and 316L stainless steel (SS 316L) on the outer liner and acetabular cup. Simulation modeling using the finite element method is considered static loading with an implicit solver for studying the geometric parameter design of dual-mobility hip joint prostheses. In this study, simulation modeling was carried out by applying varying inclination angles of 30°, 40°, 45°, 50°, 60°, and 70° to the acetabular cup component. Three-dimensional loads were placed on femoral head reference points with variations of femoral head diameter used at 22 mm, 28 mm, and 32 mm. The results in the inner surface of the inner liner, the outer surface of the outer liner, and the inner surface of the acetabular cup showed that the variations in inclination angle do not have a major effect on the maximum contact pressure value on the liner component, where the acetabular cup with an inclination angle of 45° can reduce contact pressure more than the other studied inclination angle variations. In addition, it was found that the 22 mm diameter of the femoral head increases the contact pressure. The use of a larger diameter femoral head with an acetabular cup configuration at a 45° inclination can minimize the risk of implant failure due to wear.

Large Femoral Heads and Select Dual-Mobility Bearings Are Associated With Reduced Instability in Contemporary Posterior Approach Total Hip Arthroplasty

BACKGROUND

Postoperative dislocation is considered the main drawback of posterior approach total hip arthroplasty (THA). Thinner highly cross-linked polyethylene and dual-mobility bearings allow maximizing femoral head diameter per a given cup size. This study evaluated dislocation rates as large femoral head bearings were introduced into a practice over an 11-year period.

METHODS

A total of 1,511 consecutive primary THAs were retrospectively reviewed. Demographics, implant sizes, femoral head-acetabular cup ratio, and dislocation status were collected from the electronic medical record. Data were evaluated using time series analysis techniques as larger femoral heads, thinner polyethylene liners, and dual-mobility bearings were introduced. The cohort was 57% women with mean age and body mass index of 62 years (range, 13 to 93) and 31 kg/m² (range, 13 to 54), respectively.

RESULTS

The overall dislocation rate was 0.98%. Use of femoral head sizes ≥ 40 millimeters increased from 4% in the years 2010 to 2016 to 51% in the years 2017 to 2021, correlating with a 50% reduction in dislocation rate from 1.4% to 0.7% (P = .279). Also, no dislocations occurred in patients who had dual-mobility bearings or ≥ 40-millimeter femoral heads (P = .007). Twelve of 14 dislocations occurred in cases with head-cup ratio < 0.7 (P = .013). Thirteen of 14 dislocations were in women (P = .005).

CONCLUSION

Maximizing the femoral head diameter per given cup size correlated with a decrease in dislocation rate in modern posterior approach THA. Furthermore, these results suggest that dual-mobility articulations should be reserved for high-risk patients or patients in whom a 40-millimeter femoral head is not possible.

LEVEL OF EVIDENCE

IV-consecutive case series; no control group.