Conversion of Hip Hemiarthroplasty to Total Hip Arthroplasty Utilizing a Dual-Mobility Construct Compared With Large Femoral Heads

Dual mobility cups reduce dislocation in isolated cup revision

BACKGROUND

Dual-mobility cup (DMC) is gaining increasing attention in total hip arthroplasty (THA) revision due to its numerous advantages. However, the prognosis after isolated cup revision with DMC remains unclear. This study aimed to compare complications, focusing on dislocation, and analyze clinical outcomes in patients who underwent isolated cup revision after THA.

METHODS

This retrospective cohort study included 119 patients who underwent isolated cup revision after THA and were followed up for ≥ 2 years from January 2009 to February 2020. Patient demographics, including age, sex, surgical approach, reasons for previous joint replacement surgery, and postoperative complications, were investigated. The patients were divided into DMC and conventional cup (CC) groups, and operative data and postoperative complications were compared between the two groups. Clinical outcomes were compared using the Harris hip score.

RESULTS

Forty-nine patients received DMC, and 70 received CC; the two groups had no difference in preoperative evaluation. Although the implants used significantly differed, there was no difference in the cup position. Six patients in the CC group had dislocations, but none had them in the DMC group (p = 0.042). Aseptic loosening was the most frequent postoperative complication but showed no significant difference between the two groups.

CONCLUSIONS

DMC in revision THA can prevent dislocation compared to CC. In particular, DMC is considered a good treatment option in isolated cup revision wherein the surgeon can control the limited options.

Modular dual-mobility constructs outperformed large femoral heads in 299 revision total hip arthroplasties at mid-term follow-up

Aims

The purpose of this study was to directly compare the Modular Dual Mobility (MDM) Mobile Bearing Hip System (Stryker, USA) and large femoral heads (LFHs) in revision total hip arthroplasties (THAs) at mid-term follow-up, with specific emphasis on survival free of re-revision for dislocation, any re-revision, dislocation, and the risk of metal-related complications.

Methods

We identified 299 revision THAs performed at a single tertiary care academic institution from March 2011 to July 2014. Aseptic loosening of the acetabular component (n = 65), dislocation (n = 58), and reimplantation as part of a two-stage exchange protocol (n = 57) were the most common reasons for index revision. MDM constructs were used in 123 cases, and LFHs were used in 176 cases. Mean age was 66 years (28 to 93), mean BMI was 31 kg/m2 (18 to 55), and 45% (n = 136) were female. Mean follow-up was seven years (2 to 12).

Results

The ten-year survival free of re-revision for dislocation was 99% (95% CI 95 to 100) in the MDM cohort and 91% (95% CI 84 to 96) in the LFH cohort, with a significantly increased risk of re-revision for dislocation in the LFH cohort (HR 7.1 (95% CI 1.3 to 40.8); p = 0.023). The ten-year survival free of any re-revision was 92% (95% CI 82 to 99%) in the MDM cohort and 84% (95% CI 74 to 90) in the LFH cohort with a significantly increased risk of any re-revision in the LFH cohort (HR 2.6 (95% CI 1.1 to 5.9); p = 0.024). The ten-year survival free of any dislocation was 95% (95% CI 85 to 99) in the MDM cohort and 87% (95% CI 78 to 92) in the LFH cohort with a significantly increased risk of any dislocation in the LFH cohort (HR 2.7 (95% CI 1.1 to 6.3); p = 0.028). There were no re-revisions or reoperations for metallosis or corrosion in the MDM cohort.

Conclusion

In this head-to-head comparison, revision THAs with a MDM construct safely and effectively lowered the risk of re-revision for dislocation, any re-revision, and any dislocation compared to LFH at mid-term follow-up. There were no re-revisions or reoperations for metallosis or corrosion in the MDM cohort.

Effectiveness of Virtual Surgical Planning and Three-Dimensional Anatomical Models in Radiological Reconstruction of Center of Rotation and Pelvic Brim in Patients with Anterior Column Defects Requiring Revision Hip Arthroplasty

Background: The aim of this study was to show that virtual surgical planning (VSP) and printed anatomical models support the reconstruction of the center of rotation (COR) and pelvic BRIM during revision hip surgery using a dual-mobility revision cup system in patients with anterior pelvic column damage and soft tissue envelope deficiency. Methods: Patients with anterior pelvic column damage and soft tissue envelope deficiency underwent revision hip arthroplasty. Virtual planning included assessment of bone segmentation, positioning of the cementless revision cup while maintaining the COR, and the assumed inclination and anteversion angles. Results: The diameter of the planned revision cups was 65.5 ± 2.1 mm, and the diameter of the revision cups used was 65.3 ± 2.1 mm. The difference in COR position in the horizontal axis was 7.8 ± 9.3 mm, in the vertical axis was 4.3 ± 5.9 mm, and in the axial plane was 1.6 ± 3.3 mm. The differences in inclination angle and in the anteversion angle were 12.4° and 8.7°, respectively. Conclusions: The use of VSP and 3D models supports the process of performing RHA surgery in patients with damage to the anterior pelvic column and soft tissue envelope deficiency.

National Institute of Health and Care Excellence Guidelines for Displaced Intracapsular Hip Fractures: Examining Satisfaction With the Guidelines and Effects on Outcomes

BACKGROUND

The objectives of the study were to: (1) evaluate satisfaction with the new 2023 National Institute of Health and Care Excellence (NICE) criteria for selecting total hip arthroplasty (THA) over hemiarthroplasty and surgical recommendations for treatment of displaced intracapsular hip fractures; (2) describe why THA is performed when NICE criteria are not met; and (3) determine whether satisfaction with these guidelines is associated with improved outcomes.

METHODS

A retrospective chart review of patients who had a displaced intracapsular hip fracture treated with THA at a single tertiary academic center between 2010 and 2022 was performed. Preoperative patient characteristics were reviewed to determine if the indication for THA met NICE criteria. Operative details, perioperative complications, reoperation, and revision arthroplasty within 12 months of surgery were recorded.

RESULTS

Data from 196 patients (63% women; age 67 ± 10 years) were used. There were 161 THAs (82.1%) that satisfied NICE criteria. The 2 most common reasons for performing a THA when NICE criteria were not met (n = 35) included preoperative radiographic osteoarthritis (Tönnis grade ≥ 2; 48.6%) and decreased patient age (< 65 years; 31.5%). Satisfaction with the NICE criteria was associated with fewer perioperative complications (0.6 versus 37.1%; P < .001), reoperations (0.6 versus 31.4%; P < .001), and revisions (0.6 versus 28.6%; P < .001). The most common reason for revision was periprosthetic fracture, possibly secondary to the use of uncemented femoral stems (171 of 196, 87.2%).

CONCLUSIONS

Satisfaction with the new NICE criteria is associated with improved perioperative outcomes. Further studies are necessary to determine if preexisting hip osteoarthritis and younger age merit consideration in patient selection.

Dual-mobility with modular components for primary total hip arthroplasty in bilateral bony ankylosis of the hips: A case report

INTRODUCTION AND IMPORTANCE

Primary total hip arthroplasty (THA) is a procedure performed in the United States for a variety of indications, with operation rates slated to increase over 275 % by 2040 when compared to 2014 (Thilak et al., 2015). Dual-mobility (DM) implants have gained popularity in the United States since gaining approval in the early 2010s (Heckmann et al., 2020). It has been well reported that DM implants decrease the risk of dislocation after primary and revision THA (Vielpeau et al., 2011; Donovan et al., 2022; Heifner et al., 2023; Foissey et al., 2023; Schmidt et al., 2020; Neri et al., 2019).

CASE PRESENTATION

We present the case of a 33-year-old male with a suspected ankylosing spondylitis (AS) diagnosis and bilateral bony ankylosis of the hips who underwent staged THA with modular dual-mobility (MDM) implants. At one year post-operatively, the patient is walking without the use of an assistive device and reports a VAS pain score of 0 at rest and 2 with activity and HHS of 90.

CLINICAL DISCUSSION

Implant selection is important in this patient population due to the increased risk of dislocation. Contemporary reports reveal MDM implants have demonstrated a substantial reduction in dislocation risk compared to fixed-bearing implants in patients with a high risk of dislocation. We opted to place the acetabular component inside the safe zone to improve stability and use the dual-mobility prosthesis to achieve our desired range of motion.

CONCLUSION

The improved stability of DM implants allows for a greater range of acetabular positions in patients who have a highly unpredictable functional outcome at the time of surgery. Our preliminary results contribute to the growing list of indications for MDM total hip arthroplasty.

Conversion of a Failed Hip Hemiarthroplasty to Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background

Hip hemiarthroplasty (HA) and total hip arthroplasty (THA) are common treatments for femoral neck fractures in elderly patients. Despite HA's advantages of shorter operative times, less blood loss, and lower initial costs compared to primary THA, it may lead to conversion THA (cTHA). Our objectives are to evaluate the impact of conversion from HA to THA on Harris hip scores (HHS), compare complication rates between cTHA, revision THA, and primary THA, and assess the rates and types of complications following cTHA.

Methods

A systematic review and meta-analysis were performed, evaluating studies published until 2023, with inclusion criteria entailing studies that explored outcomes and complications following cTHA of failed HA. Data extraction focused on variables such as postoperative HHS and complication rates, including periprosthetic joint infection, periprosthetic fracture, dislocation, stem loosening, acetabular loosening, and overall revision.

Results

This study included 28 retrospective studies (4699 hips), showing a mean increase in HHS by 39.1 points, indicating a significant improvement from preoperative levels. Complication rates were detailed, with a 6.4% rate of periprosthetic joint infection, 2.2% for periprosthetic fracture, 7.6% dislocation, 1.6% stem loosening, 1.9% acetabular loosening, and an overall re-revision rate of 8.7%.

Conclusions

Conversion from HA to THA generally results in improved functional outcomes, as evidenced by HHS improvements. Despite the positive impact on HHS, cTHAs are associated with notable risks of complications and the need for further revision surgeries.

Level of Evidence

IV.

The outcomes of conversion of hemiarthroplasty to total hip arthroplasty, a systematic review and meta-analysis

INTRODUCTION

Acetabular erosion is an important complication in hemiarthroplasty and may lead to total hip arthroplasty as a conversion. The results of total hip arthroplasty as a conversion remain unclear. We performed a systematic review and meta-analysis to compare the outcome of total hip arthroplasty as a conversion with primary total hip arthroplasty.

MATERIALS AND METHODS

PRISMA guidelines were used and Pubmed, Embase and the Cochrane libraries were searched. Both, studies comparing the outcome of total hip arthroplasty as a conversion with the outcome of primary total hip arthroplasty and the outcome of cohort studies limited to total hip arthroplasty as a conversion, were included. Risk of bias was assessed using the Methodological Index for Non Randomized Studies checklist. Meta-analysis was performed concerning pooled annual revision, dislocation and infection rates.

RESULTS

A total of 27 studies were available for analysis; four comparative studies and 23 cohort studies. Comparative studies were defined as high quality and cohort studies as medium quality. Analysis revealed a significantly higher overall revision risk (Hazard Ratio 1.72, 95% confidence interval 1.39 to 2.14) after total hip arthroplasty as a conversion compared to primary total hip arthroplasty. The annual revision rate of total hip arthroplasty as a conversion was 1.63% (95% confidence interval 1.14 to 2.33) in the comparative studies and 1.40% (95% confidence interval 1.17 to 1.66) in the cohort studies. A pooled infection rate of 4.34% (95% confidence interval 2.66 to 7.01) and dislocation rate of 4.79% (95% confidence interval 3.02 to 7.53), was found.

CONCLUSIONS

Literature concerning the results of total hip arthroplasty as a conversion is limited. The risk of revision after conversion of hemiarthroplasty is higher compared to primary total hip arthroplasty.

Metal artifact reduction sequence-MRI abnormalities in asymptomatic patients with dual-mobility hip prostheses

Aims

Modular dual-mobility (DM) articulations are increasingly used during total hip arthroplasty (THA). However, concerns remain regarding the metal liner modularity. This study aims to correlate metal artifact reduction sequence (MARS)-MRI abnormalities with serum metal ion levels in patients with DM articulations.

Methods

A total of 45 patients (50 hips) with a modular DM articulation were included with mean follow-up of 3.7 years (SD 1.2). Enrolled patients with an asymptomatic, primary THA and DM articulation with over two years' follow-up underwent MARS-MRI. Each patient had serum cobalt, chromium, and titanium levels drawn. Patient satisfaction, Oxford Hip Score, and Forgotten Joint Score-12 (FJS-12) were collected. Each MARS-MRI was independently reviewed by fellowship-trained musculoskeletal radiologists blinded to serum ion levels.

Results

Overall, two patients (4.4%) had abnormal periprosthetic fluid collections on MARS-MRI with cobalt levels > 3.0 μg/l. Four patients (8.9%) had MARS-MRI findings consistent with greater trochanteric bursitis, all with cobalt levels < 1.0 μg/l. A seventh patient had a periprosthetic fluid collection with normal ion levels. Of the 38 patients without MARS-MRI abnormalities, 37 (97.4%) had cobalt levels < 1.0 μg/l, while one (2.6%) had a cobalt level of 1.4 μg/l. One patient (2.2%) had a chromium level > 3.0 μg/l and a periprosthetic fluid collection. Of the 41 patients with titanium levels, five (12.2%) had titanium levels > 5.0 μg/l without associated MARS-MRI abnormalities.

Conclusion

Periprosthetic fluid collections associated with elevated serum cobalt levels in patients with asymptomatic DM articulations occur infrequently (4.4%), but further assessment is necessary due to implant heterogeneity.

Dislocation after Revision Total Hip Arthroplasty: A Comparison between Dual Mobility and Conventional Total Hip Arthroplasty

Purpose

The objective of this study was to analyze the results from a cohort of patients who underwent a revision total hip arthroplasty (THA) using a dual mobility cup (DMC) implant.

Materials and Methods

A retrospective review of revised THAs was conducted using the database from a single tertiary referral hospital. A total of 91 revision THAs from 91 patients were included in the study. There were 46 male hips and 45 female hips. The mean age was 56.3±14.6 years, and the mean follow-up period was 6.4±5.9 years. In performance of revision THAs, the DMC implants were used in 18 hips (19.8%), and the conventional implants were used in 73 hips (80.2%).

Results

During the follow-up period, three dislocations were identified, and the overall dislocation rate was 3.3%. Early dislocation (at one month postoperatively) occurred in one patient, while late dislocation (at a mean of 7.5 years) occurred in two patients. There was no occurrence of dislocation in the DMC group (0%), and three dislocations were detected in the conventional group (4.1%). However, no significant difference in the rate of dislocation was observed between the two groups (P=0.891).

Conclusion

Although the rate of dislocation was higher in the conventional group, there were no statistically significant differences between the two groups due to the small number of patients. Nevertheless, we believe that the dual mobility design is advantageous in terms of reducing dislocation rate and can be recommended as an option for a revision THA.

Increasing trend toward joint-preserving procedures for hip osteonecrosis in the United States from 2010 to 2019

INTRODUCTION

The incidence of osteonecrosis of the femoral head is estimated at about 10 to 20,000 patients annually, and, when left untreated, 80% or more of cases progress to femoral head collapse. A series of joint-preserving procedures have been developed to prevent/delay the need for hip arthroplasty. The aim of this study was to provide a five-year update: (1) evaluating temporal trends of arthroplasty vs. joint-preservation techniques such as core decompression, bone grafting, osteotomies, and arthroscopy; (2) determining proportions of procedures in patients aged less than vs. over 50 years; and (3) quantifying rates of specific operative techniques.

METHODS

A total of 10,334 patients diagnosed with osteonecrosis of the femoral head and having received hip surgery were identified from a nationwide database between 1 January 2010 and 31 December 2019, by using the International Classification of Disease, the Ninth/Tenth revision (ICD-9/10) codes. The percentage of patients managed by each operative procedure was calculated annually. To identify trends, patients were grouped by age under/over 50 years and divided into a joint-preserving and a non-joint-preserving (arthroplasty) group. Chi-squared tests were performed to compare the total number of procedures per year.

RESULTS

Rates of arthroplasty far exceeded those for joint-preserving procedures. However, from 2015 to 2019, significantly more joint-preserving procedures were performed than in 2010 to 2014 (4.3% vs. 3.0%, P < 0.001). Significantly more joint-preserving procedures were performed in patients aged < 50 years relative to those ≥ 50 years (7.56% vs. 1.86%, P < 0.001). Overall, total hip arthroplasty was the most common procedure (9,814; 94.97%) relative to core decompression (331; 3.20%), hemiarthroplasty/resurfacing (102; 0.99%), bone grafting (48; 0.46%), and osteotomy (5; 0.05%).

CONCLUSION

Management of patients who have osteonecrosis of the femoral head continues to be predominantly arthroplasty procedures, specifically, total hip arthroplasty. Our findings suggest a small, but significant trend toward increased joint-preserving procedures, especially in patients under 50 years. In particular, the proportion of patients receiving core decompression has increased significantly from 2015 to 2019 relative to prior years.

Outcomes of Total Hip Replacement for Failed Hemiarthroplasty

Aim

Our study aims to analyze the outcomes of conversion total hip replacement (THR) done for failed hemiarthroplasty.

Patients and Methods

We retrospectively analyzed 104 consecutive patients who underwent conversion THR for failed hemiarthroplasty between January 2012 and December 2018. The patient's records were analyzed for demographic information, index surgery details, preoperative functional status, and perioperative complications. Patients were analyzed according to the various modes of failure of hemiarthroplasty. The radiographs were analyzed for any progressive osteolysis, cup migration and stem subsidence. All the patients were evaluated using the modified Harris hip score (HHS) for clinical outcome. Complications, revision or reoperation in the follow-up period was recorded.

Results

A total of 73 patients were included in the study for final analysis after exclusion criteria. The average follow-up was 48.2 ± 29.6 months. There was a significant improvement in mean HHS from 38.5 ± 9.1 preoperatively to 80.9 ± 4.3 at the last follow-up (p < 0.05). The different modes of failure had no statistically significant difference in the postoperative Harris hip score (p = 0.393). None of the patients had progressive radiolucent lines more than 2 mm or significant subsidence in the final follow-up compared to the initial postoperative radiograph. There was one deep infection, one patient had grade 2 heterotopic ossification, intraoperative calcar fracture was fixed with cerclage wiring in 11 patients, and postoperative periprosthetic fracture in two patients was treated with plate osteosynthesis. There were no neurovascular complications or dislocation during the follow-up.

Conclusion

Conversion THR for failed hemiarthroplasty is a challenging procedure and results in good functional outcome and provides reliable pain relief. Conversion THA for septic loosening by two stage revision have comparable postoperative outcomes like THA for aseptic loosening. Caution is required owing to high incidence of peri-prosthetic fracture during conversion THA. Dislocation rate is negligible even with smaller head provided the prosthesis is implanted in the proper orientation and adequate soft tissue balancing is achieved.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Dual-Mobility Versus Large Femoral Heads in Revision Total Hip Arthroplasty: Interim Analysis of A Randomized Controlled Trial

INTRODUCTION

This multicenter randomized controlled trial evaluated if dual-mobility bearings (DM) lower the risk of dislocation compared to large femoral heads (≥36mm) for patients undergoing revision total hip arthroplasty (THA) via a posterior approach.

METHODS

A total of 146 Patients were randomized to a DM (n=76; 46 mm median effective head size, range 36 to 59 mm) or a large femoral head (n=70; twenty-five 36 mm heads [35.7%], forty-one 40 mm heads [58.6%], and four 44mm heads [5.7%]). There were 71 single-component revisions (48.6%), 39 both-component revisions (26.7%), 24 reimplantations of THA after 2-stage revision (16.4%), seven isolated head and liner exchanges (4.8%), four conversions of hemiarthroplasty (2.7%), and one revision of a hip resurfacing (0.7%). Power analysis determined that 161 patients were required in each group to lower the dislocation rate from 8.4 to 2.2% (power=0.8, alpha=0.05).

RESULTS

At a mean of 18.2 months (range, 1.4 to 48.2), there were three dislocations in the large femoral head group compared to two in the DM cohort (4.3 vs. 2.6%; P=0.67). One patient in the large head group and none in the DM group were successfully treated with closed reduction without subsequent revision.

CONCLUSION

Interim analysis of this randomized controlled trial found no difference in the risk of dislocation between DM and large femoral heads in revision THA, although the rate of dislocation was lower than anticipated and continued follow up is needed.

Changing Surgical Approach From Primary to Revision Total Hip Arthroplasty Is Not Associated With Increased Risk of Dislocation or Re-Revisions

BACKGROUND

No prior studies have examined outcomes based on approach concordance between primary and revision total hip arthroplasty (THA). There is theoretical concern that performing surgery through multiple planes could potentiate dislocation risk. This study aimed to assess the impact of utilizing concordant vs discordant surgical approaches between primary and revision THA on incidence of dislocation, re-revision, reoperation, and nonoperative complications.

METHODS

Between 2000 and 2018, 705 revision THAs were retrospectively identified in patients who underwent primary THA at the same academic center. Surgical approach was determined for primary and revision THA from operative notes with dislocations, re-revisions, reoperations, and complications determined from our total joint registry. Complication rates were compared between those with concordant and discordant surgical approaches. Mean age was 65 years, 50% were female, mean body mass index was 31 kg/m², and mean follow-up was 4 years.

RESULTS

Surgical approach discordance occurred in 97 cases (14%), which was more frequent when the direct anterior approach was used for primary THA (72%, P < .001) compared to lateral (12%) or posterior (10%) approaches. There were no statistically significant differences in the incidence of dislocations, re-revisions, reoperations, and nonoperative complications among those with concordant and discordant approaches for the overall cohort and when analyzed by primary approach (P > .05 for all).

CONCLUSION

Comparable dislocation and complication rates were observed among revision THAs with concordant and discordant approaches between primary and revision THA. These data provide reassurance that changing vs maintaining the surgical approach from primary to revision THA does not significantly increase dislocation or re-revision risk.

LEVEL OF EVIDENCE

IV.

In Revision THA, Is the Re-revision Risk for Dislocation and Aseptic Causes Greater in Dual-mobility Constructs or Large Femoral Head Bearings? A Study from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Dislocation is one of the most common causes of a re-revision after a revision THA. Dual-mobility constructs and large femoral head bearings (≥ 36 mm) are known options for mitigating this risk. However, it is unknown which of these choices is better for reducing the risk of dislocation and all-cause re-revision surgery. It is also unknown whether there is a difference between dual-mobility constructs and large femoral head bearings according to the size of the acetabular component.

QUESTIONS/PURPOSES

We used data from a large national registry to ask: In patients undergoing revision THA for aseptic causes after a primary THA performed for osteoarthritis, (1) Does the proportion of re-revision surgery for prosthesis dislocation differ between revision THAs performed with dual-mobility constructs and those performed with large femoral head bearings? (2) Does the proportion of re-revision surgery for all aseptic causes differ between revision THAs performed with dual-mobility constructs and those performed with large femoral head bearings? (3) Is there a difference when the results are stratified by acetabular component size?

METHODS

Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) were analyzed for 1295 first-revision THAs for aseptic causes after a primary THA performed for osteoarthritis. The study period was from January 2008-when the first dual-mobility prosthesis was recorded-to December 2019. There were 502 dual-mobility constructs and 793 large femoral head bearings. There was a larger percentage of women in the dual-mobility construct group (67% [334 of 502]) compared with the large femoral head bearing group (51% [402 of 793]), but this was adjusted for in the statistical analysis. Patient ages were similar for the dual-mobility construct group (67 ± 11 years) and the large femoral head group (65 ± 12 years). American Society of Anesthesiologists (ASA) class and BMI distributions were similar. The mean follow-up was shorter for dual-mobility constructs at 2 ± 1.8 years compared with 4 ± 2.9 years for large femoral head bearings. The cumulative percent revision (CPR) was determined for a diagnosis of prosthesis dislocation as well as for all aseptic causes (excluding infection). Procedures using metal-on-metal bearings were excluded. The time to the re-revision was described using Kaplan-Meier estimates of survivorship, with right censoring for death or database closure at the time of analysis. The unadjusted CPR was estimated each year of the first 5 years for dual-mobility constructs and for each of the first 9 years for large femoral head bearings, with 95% confidence intervals using unadjusted pointwise Greenwood estimates. The apparent shorter follow-up of the dual-mobility construct group relates to the more recent increase in dual-mobility numbers recorded in the registry. The results were adjusted for age, gender, and femoral fixation. Results were subanalyzed for acetabular component sizes < 58 mm and ≥ 58 mm, set a priori on the basis of biomechanical and other registry data.

RESULTS

There was no difference in the proportion of re-revision for prosthesis dislocation between dual-mobility constructs and large femoral head bearings (hazard ratio 1.22 [95% CI 0.70 to 2.12]; p = 0.49). At 5 years, the CPR of the re-revision for prosthesis dislocation was 4.0% for dual mobility constructs (95% CI 2.3% to 6.8%) and 4.1% for large femoral head bearings (95% CI 2.7% to 6.1%). There was no difference in the proportion of all aseptic-cause second revisions between dual-mobility constructs and large femoral head bearings (HR 1.02 [95% CI 0.76 to 1.37]; p = 0.89). At 5 years, the CPR of dual-mobility constructs was 17.6% for all aseptic-cause second revision (95% CI 12.6% to 24.3%) and 17.8% for large femoral head bearings (95% CI 14.9% to 21.2%). When stratified by acetabular component sizes less than 58 mm and at least 58 mm, there was no difference in the re-revision CPR for dislocation or for all aseptic causes between dual-mobility constructs and large femoral head bearings.

CONCLUSION

Either dual-mobility constructs or large femoral head bearings can be used in revision THA, regardless of acetabular component size, as they did not differ in terms of re-revision rates for dislocation and all aseptic causes in this registry study. Longer term follow-up is required to assess whether complications develop with either implant or whether a difference in revision rates becomes apparent. Ongoing follow-up and comparison in a registry format would seem the best way to compare long-term complications and revision rates. Future studies should also compare surgeon factors and whether they influence decision-making between prosthesis options and second revision rates. Nested randomized controlled trials in national registries would seem a viable option for future research.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Dual-mobility constructs versus large femoral head bearings in primary and revision total hip arthroplasty: a systematic review and meta-analysis of comparative studies

BACKGROUND

Both dual-mobility (DM) constructs and large femoral head bearings (⩾36 mm) reduce dislocation following total hip arthroplasty (THA). There is limited research comparing DM with large bearings.

METHODS

A systematic review of published literature was performed including studies that compared DM with large femoral head bearings in primary or revision THA according to PRISMA guidelines. The primary outcome was revision surgery for dislocation. The secondary outcome was all-cause revision surgery. Other complications were recorded. 2 authors independently selected studies, performed data extraction, and risk of bias assessment. Treatment effects were assessed using odds ratios and data were pooled using a fixed-effect model, where appropriate.

RESULTS

9 studies, all retrospective, met the final inclusion criteria. 2722 patients received DM and 9,789 large femoral head bearings. The difference in the odds of revision surgery for dislocation (OR 0.67; 95% CI, 0.45-1.01; p = 0.06) and aseptic loosening are unclear (OR 0.61; 95% CI, 0.36-1.05; p = 0.07); including important benefits and no difference. There was a benefit favouring DM for the risk of all-cause revision (OR 0.70; 95% CI, 0.56-0.86; p = 0.001), revision for fracture (OR 0.49; 95% CI, 0.29-0.81; p = 0.005) and dislocation not requiring revision (OR 0.29; 95% CI, 0.14-0.57; p < 0.001). The estimate in the difference in the odds of revision surgery for infection was imprecise (OR 0.78; 95% CI, 05.1-1.20; p = 0.26).

CONCLUSIONS

This study provides evidence that there may be clinically relevant benefits of DM constructs over large femoral head bearings. Prospective randomised studies are warranted given these findings.

Trends of Femoral Neck Fracture Treatment Using Total Hip Arthroplasty: Reported From the American Joint Replacement Registry

INTRODUCTION

Total hip arthroplasty (THA) rather than hemiarthroplasty for displaced femoral neck fracture (FNF) is often chosen for younger patients who are more active and/or have underlying hip osteoarthritis. However, instability remains the primary concern of doing THA. Dual mobility (DM) has been shown to decrease this risk through a larger effective head size and greater head-to-neck ratio compared with conventional THA. The purpose of this study was to identify femoral head size and DM usage patterns for the treatment of FNF with THA in the United States using the American Joint Replacement Registry.

METHODS

A retrospective cohort study was conducted, including all primary THAs done for FNF from 2012 to 2019. THA and FNF were defined using Current Procedural Terminology or International Classification of Diseases-9 or -10 diagnosis and procedure codes. Analysis was based on patient demographics, femoral head size, and DM usage. Descriptive statistics were used using a Pearson chi-square test. All analyses were conducted using SAS version 9.4, and statistical significance was set at P < 0.05.

RESULTS

There were 18,752 THAs done by 3,242 surgeons at 789 institutions during the 8-year study period. The overall population was 66% female, and the mean age was 72.3 ± 11.8 years. The most commonly used femoral head size was 36 mm (48.5%) followed by 32 mm (24.5%), ≤28 mm (10.7%), DM (10.8%), and ≥40 mm (5.7%). A trend was observed toward decreased use of ≤28, 32, and ≥40-mm heads starting in 2016 across the years and increased use of 36-mm heads (P < 0.0001). A significant increase was observed in the usage of DM over time from 6.4% in 2012 to 16.2% in 2019 (P < 0.0001).

DISCUSSION

Most of the femoral heads used were ≥36 mm, and the use of DM increased during the study period. Additional analysis is warranted to understand how these trends will affect overall outcomes and postoperative dislocation rates.

Cost-effectiveness of dual-mobility components in patients with displaced femoral neck fractures

AIMS

Total hip arthroplasty (THA) with dual-mobility components (DM-THA) has been shown to decrease the risk of dislocation in the setting of a displaced neck of femur fracture compared to conventional single-bearing THA (SB-THA). This study assesses if the clinical benefit of a reduced dislocation rate can justify the incremental cost increase of DM-THA compared to SB-THA.

METHODS

Costs and benefits were established for patients aged 75 to 79 years over a five-year time period in the base case from the Canadian Health Payer's perspective. One-way and probabilistic sensitivity analysis assessed the robustness of the base case model conclusions.

RESULTS

DM-THA was found to be cost-effective, with an estimated incremental cost-effectiveness ratio (ICER) of CAD $46,556 (£27,074) per quality-adjusted life year (QALY). Sensitivity analysis revealed DM-THA was not cost-effective across all age groups in the first two years. DM-THA becomes cost-effective for those aged under 80 years at time periods from five to 15 years, but was not cost-effective for those aged 80 years and over at any timepoint. To be cost-effective at ten years in the base case, DM-THA must reduce the risk of dislocation compared to SB-THA by at least 62%. Probabilistic sensitivity analysis showed DM-THA was 58% likely to be cost-effective in the base case.

CONCLUSION

Treating patients with a displaced femoral neck fracture using DM-THA components may be cost-effective compared to SB-THA in patients aged under 80 years. However, future research will help determine if the modelled rates of adverse events hold true. Surgeons should continue to use clinical judgement and consider individual patients' physiological age and risk factors for dislocation. Cite this article: Bone Joint J 2021;103-B(12):1783-1790.

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.

A Comparison of Revision Rates for Dislocation and Aseptic Causes Between Dual Mobility and Large Femoral Head Bearings in Primary Total Hip Arthroplasty With Subanalysis by Acetabular Component Size: An Analysis of 106,163 Primary Total Hip Arthroplasties

BACKGROUND

Dual mobility (DM) and large femoral head bearings (≥36 mm) both decrease the risk of dislocation in total hip arthroplasty (THA). There is limited comparable data in primary THA. This study compared the revision rates for dislocation and aseptic causes between DM and large femoral heads and subanalyzed by acetabular component size.

METHODS

Data from the Australian Orthopedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis from January 2008 (the year of first recorded DM use) to December 2019. All DM and large femoral head bearings were identified. The primary outcome measure was the cumulative percent revision (CPR) for dislocation and for all aseptic causes. The results were adjusted by age, sex, and femoral fixation. A subanalysis was performed stratifying acetabular component diameter <58 m and ≥58 mm.

RESULTS

There were 4942 DM and 101,221 large femoral head bearings recorded. There was no difference in the CPR for dislocation (HR = 0.69 (95% CI 0.42, 1.13), P = .138) or aseptic causes (HR = 0.91 (95% CI 0.70, 1.18), P = .457). When stratified by acetabular component size, DM reduced the CPR for dislocation in acetabular component diameter <58 mm (HR = 0.55 (95% CI 0.30, 1.00), P = .049). There was no difference for diameter ≥58 mm. There was no difference in aseptic revision when stratified by acetabular component diameter.

CONCLUSION

There is no difference in revision rates for dislocation or aseptic causes between DM and large femoral heads in primary THA. When stratified by acetabular component size, DM reduces dislocation for acetabular component diameter <58 mm.

LEVEL OF EVIDENCE

Level III.

Hip Hemiarthroplasty for Fractured Neck of Femur Revised to Total Hip Arthroplasty: Outcomes Are Influenced by Patient Age Not Articulation Options

BACKGROUND

Hip hemiarthroplasty is the most common arthroplasty option for fractured neck of femur (FNOF). Revision to total hip arthroplasty (THA) is occasionally required. This study aimed to assess the outcome of hemiarthroplasty revised to THA and to assess the impact of femoral head size, dual mobility (DM), and constrained liners.

METHODS

All aseptic 1^st revisions reported to the Australian Joint Replacement Registry after hemiarthroplasty performed for FNOF when a THA was used as the revision procedure were included from September 1999 to December 2019. The primary outcome measure was the cumulative percent revision for all-causes and dislocation. The impact of prosthesis factors on revision THA was assessed: standard head THA (≤32 mm), large head THA (≥36 mm), DM, and constrained liners. Outcomes were compared using Kaplan Meyer and competing risk.

RESULTS

There were 96,861 hemiarthroplasties performed, with 985 revised to THA. The most common reasons for 1^st revision were loosening (49.3%), fracture (17.7%), and dislocation (11.0%). Of the hemiarthroplasty procedures revised to THA, 76 had a 2^nd revision. The most common reasons for 2^nd revision were fracture (27.6%), dislocation (26.3%), loosening (23.7%), and infection (18.4%). Femoral head size, DM, or constrained liner use did not alter the incidence of all-cause 2^nd revision. This did not change when solely looking at patients still alive. A 2^nd revision was more likely in patients aged <75 years.

CONCLUSION

The outcome of hemiarthroplasty performed for FNOF revised to THA is influenced by patient age, not by the articulation used.

Prevalence of Risk Factors for Adverse Spinopelvic Mobility Among Patients Undergoing Total Hip Arthroplasty

BACKGROUND

Patients with adverse spinopelvic mobility have higher complication rates following total hip arthroplasty (THA). Risk factors include a stiff lumbar spine, standing posterior pelvic tilt ≤ -10°, and a severe sagittal spinal deformity (pelvic incidence minus lumbar lordosis mismatch ≥20°). The purpose of this study is to define the spinopelvic risk factors and quantify the prevalence of risk factors for pathologic spinopelvic mobility.

METHODS

A retrospective cohort analysis from January 2014 to February 2020 was performed on a multicenter series of 9414 primary THAs by 168 surgeons, all with preoperative spinopelvic measurements in the supine, standing, and flex-seated positions. All patients were included. The prevalence of adverse spinopelvic mobility and frequency of each spinopelvic risk factor was calculated.

RESULTS

The cohort was 52% female, 48% male, with an average age of 65 years. Thirteen percent of patients exhibited adverse spinopelvic mobility and 17% had one or more of the 3 risk factors. Adverse mobility was found in 35% of patients with at least 1 risk factor, 47% with at least 2 risk factors, and 57% with all 3 risk factors.

CONCLUSION

Forty-six percent of patients had spinopelvic pathology driven by one or more of the risk factors. Number of risk factors present and risk of adverse spinopelvic mobility were positively correlated, with 57% of patients with all 3 risk factors exhibiting adverse spinopelvic mobility. Although this study defines the prevalence of these risk factors in this highly selected cohort, it does not report incidence in a general THA population.

LEVEL OF EVIDENCE

Prognostic Level IV.

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.

Outcomes and survivorship after conversion of failed hip hemiarthroplasty to total hip arthroplasty

BACKGROUND

Arthroplasty is the treatment of choice for elderly patients with displaced femoral neck fractures. When compared to total hip arthroplasty (THA), higher revision rates have been reported for hemiarthroplasty (HA). Conversion of failed HA to THA can be complex, especially in the elderly population at risk for revision surgery complications. We report a single institution's experience with conversion of failed HA to THA at mid-term follow-up.

METHODS

We identified patients converted from failed HA to THA from 2006 to 2016. Clinical data including indication for index and conversion surgery, maintenance or revision of femoral component during conversion, operative time, estimated blood loss, postoperative complications, and need for revision surgery were collected. Descriptive statistics were analysed in SPSS.

RESULTS

The cohort included 21 men and 39 women (mean age of 74.5 years). The mean follow-up after conversion HA to THA was 2.8 years. During conversion surgery, the femoral component was revised in 75.0% and retained in 25.0% of cases. After conversion HA to THA, the rate of major complications and re-revision at 2 years was 11.7% and 10.0%, respectively. Femoral revision versus retention did not affect complication rates (11.1% vs. 6.7%; p = 0.31) or re-revision rates (8.9% vs. 13.3%; p = 1.0).

CONCLUSIONS

In this high-risk population, mid-term follow-up demonstrated tolerable complication and re-revision rates, the majority of which were for instability. We observed high rates of femoral component revision during conversion THA, although this did not increase the likelihood of postoperative complications or need for future surgery.

Hemiarthroplasty versus total arthroplasty for displaced femoral neck fractures in the elderly: meta-analysis of randomized clinical trials

INTRODUCTION

Displaced femoral neck fractures (FNF) are complicated by high mortality rates and continue to represent an important cause of disability, having a negative impact on patient mobility and physical independence. The purpose of this study was to update and analyse current outcomes and evidence concerning hip hemiarthroplasty (HHA) versus total hip arthroplasty (THA) for displaced femoral neck fractures in the elderly. Thus, a meta-analysis of randomized clinical trials was conducted.

MATERIALS AND METHODS

This meta-analysis was conducted according to the PRISMA guidelines. In October 2019, the following databases were accessed: Embase, Google Scholar, Pubmed, Scopus. All randomized clinical trials (RCTs) comparing total hip arthroplasty versus hip hemiarthroplasty for displaced femoral neck fractures were included in the present study. For the statistical analysis and the methodological quality assessment, the Review Manager Software 5.3 (The Nordic Cochrane Collaboration, Copenhagen) and STATA/MP Software 14.1 (StataCorp, College Station, TX) were used.

RESULTS

Data from 2325 (1171 HHA vs 1154 THA) patients were collected. The mean follow-up was 58.12 months. The HHA group reported lower values of the mean Harris hip score (EE 3.22; p = 0.2), surgical duration (EE 21.75; p < 0.0001), length of the hospitalization stay (EE 0.8; p = 0.4). The HHA group evidenced lower dislocations rate (OR 1.78; p = 0.01, Fig. 4), but higher rate of acetabular erosion (OR 0.08; p = 0.0006). At a mean of 58.12 ± 52.8 months follow-up, revisions rate scored reduced in the THA group (OR 0.76; p = 0.2). Subgroup analysis of RCTs < 5 years follow-up revealed reduced revision in favour of the HHA group (OR 2.19; p = 0.03), while subgroup analysis of RCTs > 5 years follow-up revealed reduced revision in favour of the THA group (OR 0.25; p = 0.0003). The Kaplan-Meier curve detected similarity of patients survivorship between the two groups (HR 1.06; p = 0.3).

CONCLUSION

For the elderly population, both HHA and THA are valid solutions to treat displaced femoral neck fractures, with comparable survivorship. HHA detected reduced dislocations, while for THA a lower risk of acetabular erosion and further revision surgeries were reported.

LEVEL OF EVIDENCE

Level I, meta-analysis of randomized clinical trials.

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.

Dual-mobility cups could yield lesser infections than conventional cups: a meta-analysis of comparative studies

INTRODUCTION

Dual-mobility cups (DMC) are gaining popularity mainly for their reduced rate of dislocation following total hip arthroplasty (THA). Currently, indication for DMC use extends beyond patients with high risk of dislocation or revision THA cases. Many authors reported DMC outcomes in primary THA for all aetiologies. However, some reports claimed that the use of DMC is accompanied with higher rates of infection compared with conventional cups (CC) in both primary and revision THA.

RESEARCH QUESTION

Does the use of DMC generate higher rates of infection when compared with conventional cups?

OBJECTIVES

The aim of this meta-analysis was to look for significant difference in the rate of post-operative infection between DMC cups and conventional cups.

METHODOLOGY

MEDLINE, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar were searched since inception. Only studies with comparative design reporting the outcome infection rate were included.

RESULTS

Seventeen retrospective comparative studies were located comprising 248,541 patients: 16,020 in the DMC group and 232,521 in the CC group. The mean follow-up period was 37.5 ± 42 and 50.2 ± 48.7 months for the DMC and CC groups, respectively. The meta-analytical results indicated the following: (a) significantly lesser infections following DMC compared with CC in revision THA (odds ratio (OR) = 0.75 (95% CI = 0.653 to 0.874, P = 0.0002, I² = 25%); (b) for primary THA and for large-sampled registries, significance was found using only the fixed-effects model estimate; and (c) no significant difference was found for the subgroup of cohort studies.

CONCLUSION

Our results clearly refute the claim that DMC would yield higher rates of infection. On the contrary, the findings demonstrated that the use of DMC reduces the risk of post-operative infection in revision THA and a similar lower infection trend for primary THA when compared with the standard cups.

Dual-Mobility Constructs in Primary Total Hip Arthroplasty in High-Risk Patients With Spinal Fusions: Our Institutional Experience

Background

Prior spinal fusion significantly increases the risk of dislocation in patients after total hip arthroplasty (THA). Owing to these high risks, surgeons may use dual-mobility (DM) constructs in these patients to optimize hip stability. However, there is a paucity of data on the outcomes of DM constructs in patients who underwent prior spinal fusions.

Methods

We retrospectively identified 80 patients (86 THAs) who underwent a spinal arthrodesis and a subsequent posterior approach THA with a DM construct. The median number of levels fused was 4, with 59 (74%) patients having 2 or more levels fused; in addition, 50 (63%) patients were fused to the sacrum. Ninety percent and 55% of THAs were within the Lewinnek safe zone for inclination and anteversion, respectively. Patients were evaluated for any episode of hip instability, complications, and patient reported outcome measures.

Results

At 3-year mean follow-up, no patients sustained a postoperative dislocation or intraprosthetic dislocation (0%). Overall, there were 6 (7.5%) complications during the study period leading to reoperation in 3 (4%) patients, none related to the acetabular component or instability. Hip Injury and Osteoarthritis Outcome Score, Joint Replacement scores significantly improved from a mean of 50 preoperatively to 87 postoperatively (P < .001), and the Veterans Rand 12 Item Health Survey physical score improved from a mean of 31 preoperatively to 44 postoperatively (P < .001).

Conclusion

In a high-risk series of patients who underwent prior spinal fusion, posterolateral primary THA with a DM construct demonstrated no dislocations at mean 3-year follow-up. Although these early data are clearly encouraging, more patients with longer term follow-up are needed.

Modular Dual-Mobility Liner Malseating: A Radiographic Analysis

Background

With dislocation as a leading cause for revision after total hip arthroplasty (THA), modular dual-mobility (MDM) constructs are more commonly used at present in an attempt to decrease postoperative instability. With modularity, there is potential for additional complications, including malseating of the liner. The goal of this study was to perform a radiographic analysis on the incidence of MDM liner malseating.

Methods

We retrospectively identified 305 patients (305 THAs) who underwent primary THA with an MDM liner from a single manufacturer inserted by a single surgeon. One hundred fifty-six (51%) patients were male. The mean age was 68 years, and the mean body mass index was 31 kg/m². Only patients with both anteroposterior and cross-table lateral radiographs at a minimum of 6 weeks postoperatively were included. Dislocations and reoperations were determined at 1 year after the procedure. All MDM liners were routinely tested intraoperatively with a "4-quadrant test" to assess for proper seating.

Results

Four (4/305, 1.3%) MDM liners were noted to be radiographically malseated at early follow-up with three (3/147, 2.0%) occurring in a thinner two dimentional (2D) ongrowth shell and only one (1/158, 0.6%) observed in a thicker three dimentional (3D) additively manufactured shell. They were inferiorly prominent by a median of 1.2 mm, best seen on the cross-table lateral radiograph. In patients with at least 1-year follow-up, no MDM liners dissociated and no patients sustained a dislocation. Five (1.6%) patients required reoperation unrelated to the acetabular or MDM construct.

Conclusions

Surgeons should be aware that malseating of dual-mobility liners may occur. However, with utilization of a consistent surgical technique to test for seating of the liner, the radiographic incidence of MDM liner malseating was low at 1%. Although there were no short-term clinical implications of liner malseating, long-term follow-up is needed.

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

Background

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

Methods

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

Results

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

Conclusion

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

Outcomes of total hip arthroplasty using dual mobility components in patients with a femoral neck fracture

AIMS

Dislocation is the most common indication for further surgery following total hip arthroplasty (THA) when undertaken in patients with a femoral neck fracture. This study aimed to assess the complication rates of THA with dual mobility components (THA-DMC) following a femoral neck fracture and to compare outcomes between THA-DMC, conventional THA, and hemiarthroplasty (HA).

METHODS

We performed a systematic review of all English language articles on THA-DMC published between 2010 and 2019 in the MEDLINE, EMBASE, and Cochrane databases. After the application of rigorous inclusion and exclusion criteria, 23 studies dealing with patients who underwent treatment for a femoral neck fracture using THA-DMC were analyzed for the rate of dislocation. Secondary outcomes included reoperation, periprosthetic fracture, infection, mortality, and functional outcome. The review included 7,189 patients with a mean age of 77.8 years (66.4 to 87.6) and a mean follow-up of 30.9 months (9.0 to 68.0).

RESULTS

THA-DMC was associated with a significantly lower dislocation rate compared with both THA (OR 0.26; 95% CI 0.08 to 0.79) and HA (odds ratio (OR) 0.27; 95% confidence interval (CI) 0.15 to 0.50). The rate of large articulations and of intraprosthetic dislocation was 1.5% (n = 105) and 0.04% (n = 3) respectively.

CONCLUSION

THA-DMC when used in patients with a femoral neck fracture is associated with a lower dislocation rate compared with conventional arthroplasty options. There was no increase in the rates of other complication when THA-DMC was used. Future cost analysis and prospective, comparative studies are required to assess the potential benefit of using THA-DMC in these patients. Cite this article: Bone Joint J 2020;102-B(7):811-821.

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.

Conversion of Failed Hemiarthroplasty to Total Hip Arthroplasty Remains High Risk for Subsequent Complications

BACKGROUND

Few studies have described the outcomes following conversion of failed hemiarthroplasties to total hip arthroplasty (THA) and the impact of mortality when estimating implant survivorship. The aims of this study were to evaluate the following: (1) the risks and predictors of complications, dislocations, reoperations, and revisions and (2) the extent of competing risk of death when evaluating outcomes in patients converted from hemiarthroplasty to THA.

METHODS

The study comprised 389 patients treated with conversion THA following hemiarthroplasty for femoral neck fractures between 1985 and 2014. Revision rates were calculated using both the Kaplan-Meier method and cumulative incidence accounting for death as a competing risk. Risk factors were evaluated using Cox regression models.

RESULTS

During an average 9.3 years of follow-up, there were 122 complications, 34 dislocations, 69 reoperations, and 51 revisions. Conversion for periprosthetic fractures was associated with a higher risk of reoperations (hazard ratio 4.30, 95% confidence interval 1.94-9.52). Increasing age was a risk factor for reoperations (hazard ratio 1.32, 95% confidence interval 1.10-1.59). No decrease in the rate of complications, dislocations, reoperations, or revisions was observed over the entire 30 years of the study either when evaluating year of surgery as a continuous variable or when comparing specific calendar year intervals (1985-1989, 1990-1999, 2000-2009, 2010-2014) (P > .05). Compared to the cumulative incidence accounting for the competing risk of death, the Kaplan-Meier method overestimated the risk of revision by 7% at 15 years and 10% at 20 years.

CONCLUSION

Conversion from hemiarthroplasty to THA remains at high risk for subsequent complications. The cumulative incidence estimate provides a more accurate estimate of revision risk.

Multicenter Evaluation of a Modular Dual Mobility Construct for Revision Total Hip Arthroplasty

INTRODUCTION

Modular Dual Mobility (MDM) constructs in total hip arthroplasty (THA) offer increased hip stability compared with constrained liners, without compromising hip range of motion. The purpose of this study was to evaluate outcomes of revision THA using MDM.

METHODS

The study was a multiinstitutional retrospective cohort study of 315 hips that underwent revision THA using MDM between 2011 and 2017. Clinical outcomes and reasons for failure were collected.

RESULTS

Three hundred fifteen patients met 1-year minimum follow-up (mean 3.3 years). Nine hips had instability postoperatively (2.9%), and 30 hips required reoperation (9.5%). Seven had recurrent instability (6.5%) which was associated with liner-only exchange (P = .021) and liner outer diameter of ≤ 38 mm (P = .016).

CONCLUSION

Revision THA with MDM provided a low rate of instability and reoperation in a revision cohort. Recurrent instability following use of MDM in revision THA was associated with retention of the acetabular component and polyethylene outer diameter ≤ 38 mm.

LEVEL OF EVIDENCE

Therapeutic Level III.

Simplifying the Hip-Spine Relationship for Total Hip Arthroplasty: When Do I Use Dual-Mobility and Why Does It Work?

Recent data indicate that the contemporary prevalence of dislocation after primary total hip arthroplasty is up to 5- to 10-fold greater in those patients with spinal deformities that lead to stiffness and/or significant pelvic tilt. Moreover, the interplay between the hip and spine is complex, dynamic, and changes over the lifetime of a patient. Finally, the interplay is not fully understood. As such, consideration should be given to the use of dual-mobility constructs in this cohort of patients given the increased effective head size, combined with the dual articulation before hard impingement.

Uniformly low serum cobalt levels after modular dual-mobility total hip arthroplasties with ceramic heads: a prospective study in high-risk patients

AIMS

Modular dual-mobility constructs reduce the risk of dislocation after revision total hip arthroplasty (THA). However, questions about metal ions from the cobalt-chromium (CoCr) liner persist, and are particularly germane to patients being revised for adverse local tissue reactions (ALTR) to metal. We determined the early- to mid-term serum Co and Cr levels after modular dual-mobility components were used in revision and complex primary THAs, and specifically included patients revised for ALTR.

PATIENTS AND METHODS

Serum Co and Cr levels were measured prospectively in 24 patients with a modular dual-mobility construct and a ceramic femoral head. Patients with CoCr heads or contralateral THAs with CoCr heads were excluded. The mean age was 63 years (35 to 83), with 13 patients (54%) being female. The mean follow-up was four years (2 to 7). Indications for modular dual-mobility were prosthetic joint infection treated with two-stage exchange and subsequent reimplantation (n = 8), ALTR revision (n = 7), complex primary THA (n = 7), recurrent instability (n = 1), and periprosthetic femoral fracture (n = 1). The mean preoperative Co and Cr in patients revised for an ALTR were 29.7 μg/l (2 to 146) and 21.5 μg/l (1 to 113), respectively.

RESULTS

Mean Co and Cr levels were 0.30 μg/l and 0.76 μg/l, respectively, at the most recent follow-up. No patient had a Co level ≥ 1 μg/l. Only one patient had a Cr level ≥ 1 μg/l. That patient's Cr level was 12 μg/l at 57 months after revision THA for ALTR (and decreased ten-fold from a preoperative Cr of 113 μg/l).

CONCLUSION

At a mean of four years, no patient with a modular dual-mobility construct and ceramic femoral head had elevated Co levels, including seven patients revised specifically for ALTR. While further studies are required, we support the selective use of a modular dual-mobility construct in revision and complex primary THAs for patients at high risk for instability. Cite this article: Bone Joint J 2019;101-B(6 Supple B):57-61.

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.

Lumbar fusion involving the sacrum increases dislocation risk in primary total hip arthroplasty

AIMS

Concurrent hip and spine pathologies can alter the biomechanics of spinopelvic mobility in primary total hip arthroplasty (THA). This study examines how differences in pelvic orientation of patients with spine fusions can increase the risk of dislocation risk after THA.

PATIENTS AND METHODS

We identified 84 patients (97 THAs) between 1998 and 2015 who had undergone spinal fusion prior to primary THA. Patients were stratified into three groups depending on the length of lumbar fusion and whether or not the sacrum was involved. Mean age was 71 years (40 to 87) and 54 patients (56%) were female. The mean body mass index (BMI) was 30 kg/m² (19 to 45). Mean follow-up was six years (2 to 17). Patients were 1:2 matched to patients with primary THAs without spine fusion. Hazard ratios (HR) were calculated.

RESULTS

Dislocation in the fusion group was 5.2% at one year versus 1.7% in controls but this did not reach statistical significance (HR 1.9; p = 0.33). Compared with controls, there was no significant difference in rate of dislocation in patients without a sacral fusion. When the sacrum was involved, the rate of dislocation was significantly higher than in controls (HR 4.5; p = 0.03), with a trend to more dislocations in longer lumbosacral fusions. Patient demographics and surgical characteristics of THA (i.e. surgical approach and femoral head diameter) did not significantly impact risk of dislocation (p > 0.05). Significant radiological differences were measured in mean anterior pelvic tilt between the one-level lumbar fusion group (22°), the multiple-level fusion group (27°), and the sacral fusion group (32°; p < 0.01). Ten-year survival was 93% in the fusion group and 95% in controls (HR 1.2; p = 0.8).

CONCLUSION

Lumbosacral spinal fusions prior to THA increase the risk of dislocation within the first six months. Fusions involving the sacrum with multiple levels of lumbar involvement notably increased the risk of postoperative dislocation compared with a control group and other lumbar fusions. Surgeons should take care with component positioning and may consider higher stability implants in this high-risk cohort.

Management and outcome of the dislocated hip hemiarthroplasty

AIMS

This study describes and compares the operative management and outcomes in a consecutive case series of patients with dislocated hemiarthroplasties of the hip, and compares outcomes with those of patients not sustaining a dislocation.

PATIENTS AND METHODS

Of 3326 consecutive patients treated with hemiarthroplasty for fractured neck of femur, 46 (1.4%) sustained dislocations. Of the 46 dislocations, there were 37 female patients (80.4%) and nine male patients (19.6%) with a mean age of 83.8 years (66 to 100). Operative intervention for each, and subsequent dislocations, were recorded. The following outcome measures were recorded: dislocation; mortality up to one-year post-injury; additional surgery; residential status; mobility; and pain score at one year.

RESULTS

Of 43 dislocations, 30 (70%) occurred within one month and 42 (98%) occurred within three months of hip fracture surgery. Seven (16%) of these patients were treated with a single closed reduction and sustained no further dislocations. Four (9%) were treated with open reduction and experienced no further dislocations. Three (7%) hips were left dislocated and the remaining 32 (74%) patients required additional surgery of further closed reduction, revision, or excision arthroplasty. The one-year mortality rates for patients treated with two or fewer reductions (open or closed), successful revision arthroplasty, and excision arthroplasty were 3/14 (21%), 1/7 (14%), and 8/14 (57%) respectively. The only statistically significant difference in mortality was the difference between patients who did not sustain a dislocation and those who did and were treated by excision arthroplasty (p = 0.03). Patients treated by excision arthroplasty had the greatest reduction in mobility scores and highest pain scores. The excision arthroplasty group also included the greatest proportion of patients not able to mobilize and the smallest proportion of patients remaining in their own home.

CONCLUSION

Most dislocations of hemiarthroplasties of the hip occur within one month of surgery. Closed reduction is generally unsuccessful. For those patients with unsuccessful closed reduction, revision arthroplasty should be considered when possible, as this results in a better functional outcome with a lower mortality than excision arthroplasty.

The efficacy of dual-mobility cup in preventing dislocation after total hip arthroplasty: a systematic review and meta-analysis of comparative studies

PURPOSE

Although long-term reports of total hip arthroplasty (THA) showed successful results, instability remains a major complication. Recently, dual-mobility cups (DMC) have gained more and more interest among clinicians, with encouraging results in terms of lower rate of dislocation associated with good clinical results, but a lack of evidence exists regarding the real efficacy of this implant design compared to traditional fixed-bearing total hip arthroplasties.

METHODS

A systematic search was performed in PubMed, Google scholar, Cochrane Library, and EMBASE by two independent reviewers for comparative studies available till December 2017, with the primary objective to demonstrate a real lower dislocation rate of DMC implants compared to unipolar fixed-bearing cup designs. A meta-analysis was conducted with the collected pooled data about dislocation rate, calculating the risk difference (RD) and relative risk (RR) with 95% CI for dichotomous variables. Heterogeneity was tested using the χ² and Higgins' I² tests. A fixed-effect model was used because the statistical heterogeneity was below 50%.

RESULTS

After performing a critical exclusion process, the number of eligible studies included for final synthesis considered was 15, describing the results of a total of 2408 total hip arthroplasties (50.6% with a dual-mobility acetabular cup design, 49.4% with a standard fixed-bearing design). The fixed-effect meta-analysis showed a slight significant risk ratio of 0.16 (95% CI, 0.09, 0.28; I² = 0%, p < 0.00001); a statistically significant difference in favor of the DMC group was maintained also considering only primary or revision arthroplasties, traumatic fractures or elective patients with diagnosis of osteoarthritis, avascular osteonecrosis or rheumatic arthritis.

CONCLUSIONS

With the intrinsic limitations of our study design and based on the current available data, this study demonstrates that dual-mobility acetabular components decrease the risk of post-operative instability also in high-risk patients, both in primary and revision hip arthroplasties. However, new high-quality studies, possibly with a randomized control design, should be undertaken in order to strengthen the present data.

STUDY DESIGN

Level of Evidence III, therapeutic study.

Dual-Mobility Constructs in Revision Total Hip Arthroplasties

Dislocation after revision total hip arthroplasty (THA) continues to be one of the most common and concerning complications after the procedure. As with every hip arthroplasty, it is essential to optimize component positioning, minimize impingement, and maintain the integrity of the abductor complex during the revision THAs. However, in several revision circumstances, additional strategies are required to mitigate the risk of dislocation, particularly those being revised for instability or those with cognitive or neuromuscular disorders. In such revision THAs, dual-mobility constructs offer lower rates of dislocations and re-revisions for dislocations in the midterm. However, it is important to note that dual-mobility constructs should not be considered as compensation for poor surgical technique or technical errors such as poor cup orientation or inappropriate restoration of soft-tissue tension. While intraprosthetic dislocations are a unique complication to dual-mobility constructs, they are exceedingly rare. Furthermore, additional follow-up is required with modular dual-mobility constructs utilized with increasing frequency during revision THAs in North America.