Ten- to 16-Year Results of a Modern Cementless Dual-Mobility Acetabular Implant in Primary Total Hip Arthroplasty

The RM Press fit cup™: an investigation in 182 hips at ten-year follow-up

INTRODUCTION

For over 10 years, the RM Pressfit cup™ has been used in our department. This is a one-piece, elastic, cementless implant designed with standard polyethylene (PE), covered with a thin coating of titanium particles. To date, there is no French study evaluating this cup after more than 10 years. Therefore, we conducted a retrospective study in order to: (1) evaluate the survival of the implant with a minimum follow-up of 10 years, (2) evaluate the functional scores at the last follow-up, (3) measure the wear of the PE, (4) identify radiological loosening, (5) search for risk factors for cup removal, (6) identify complications that required management in the operating theatre.

HYPOTHESIS

The working hypothesis was that the survival of this implant was greater than 95% at 10 years' follow-up, in accordance with the criteria of the National Institute for Health and Care Excellence (NICE).

MATERIALS AND METHODS

This was a retrospective monocentric study, including adult patients who underwent total hip arthroplasty (THA) with an RM Pressfit cup™ (28 mm friction size) for coxarthrosis (primary or secondary) or femoral head osteonecrosis. Exclusion criteria were a follow-up period of less than 10 years, the placement of an RM Pressfit cup™ as a secondary intention for a THA (n = 5) or following a trochanteric fracture (n = 1). In total, 163 patients (182 hips) with a median age (Q1-Q3) of 63 (56-68) years, and a sex ratio (M/F) of 1.7 were included. Functional scores were evaluated using the Harris and Oxford scores. Radiographs were analyzed in the immediate postoperative period and at the last follow-up.

RESULTS

The median follow-up was 10.5 (10-11.5) years. Of the 182 included hips, 7 cups were removed, corresponding to a 10-year survival rate of 96.1% (95% CI [93.3; 96.9]). The median Harris and Oxford scores at 10.5 years were 95 (90-98) and 19 (17-23) points, respectively. The median PE wear rate was 0.058 (0.039-0.087) mm/year. Univariate analysis showed that male gender was associated with PE wear (OR = 3.6; 95% CI [1.3; 12.9] [p = 0.012]). Ten cups (6%) showed radiological instability with migration greater than 3 mm and/or variation in inclination greater than 8 °, and only 9 hips (6%) showed bone resorption. No preoperative or perioperative factors analyzed were associated with cup removal. Dislocation accounted for 71% (n = 5) of the causes of cup removal. Additionally, 6 hips experienced at least one dislocation episode requiring reduction by external maneuvers in the operating room, bringing the overall dislocation rate in the series to 6% (n = 11). Increased cup inclination was the only risk factor for prosthetic dislocation (OR = 1.2; 95% CI [1.09; 1.4] [p = 0.0003]). Overall complications requiring surgical intervention included 15 (8.3%) implanted cups (7 removed cups, 6 dislocation episodes requiring reduction by external maneuvers in the operating room, and 2 hips reoperated for washing and changing of mobile components due to early infection).

CONCLUSION

The RM Pressfit cup™ gives good long-term clinical and radiological results with an overall survival of 96.1% and a low complication rate over 10 years. Over the last 2 years the RM Vitamys™ cup has been introduced allowing the use of 32 mm femoral head diameter for size 48 cups, to reduce the risk of dislocation.

LEVEL OF EVIDENCE

IV; retrospective cohort.

[Translated article] Total hip arthroplasty with second generation dual mobility system as a treatment for primary coxarthrosis, medium-term results

INTRODUCTION

Osteoarthritis is a disabling pathology characterised by joint pain and stiffness. A prevalence of coxarthrosis of 7.4% is reported in our country. Total hip joint replacement is indicated in advanced stages, a procedure that is not free of complications, the most frequent being prosthetic dislocation, which can be prevented with dual mobility systems. The following study aims to determine the rate of complications and clinical outcomes in dual mobility systems in primary coxarthrosis.

MATERIALS AND METHODS

A retrospective study included 120 cases in 114 patients diagnosed with grade III coxarthrosis, mean age was 62.43 years, with a mean follow-up of 4.5 years. Joint replacement was performed by Hardinge approach. All cases were assessed clinically using the Harris Hip Score (HHS) and radiologically to demonstrate mid-term results.

RESULTS

The preoperative value on the HHS scale had a mean of 56.45, postoperative at one month 74.23; 6 months 85.40; 1 year 94.01 and at 5 years 94.84 points, representing a functional improvement of 17.78 postoperative month; 28.95 at 6 months postoperative; 37.56 at one year postoperative and 38.39 points at 5 years postoperative. A complication rate of 3.44%; 0.86% of complications were associated with the prosthetic components.

CONCLUSION

The dual mobility system should be considered as a therapeutic option in primary hip joint replacement due to excellent functional results and low complication rates.

EVIDENCE LEVEL

IV. Retrospective observational case series study.

Total hip arthroplasty with second generation dual mobility system as a treatment for primary coxarthrosis, medium-term results

INTRODUCTION

Osteoarthritis is a disabling pathology characterized by joint pain and stiffness. A prevalence of coxarthrosis of 7.4% is reported in our country. Total hip joint replacement is indicated in advanced stages, a procedure that is not free of complications, the most frequent being prosthetic dislocation, which can be prevented with dual mobility systems. The following study aims to determine the rate of complications and clinical outcomes in dual mobility systems in primary coxarthrosis.

MATERIALS AND METHODS

A retrospective study included 120 cases in 114 patients diagnosed with grade III coxarthrosis, mean age was 62.43 years, with a mean follow-up of 4.5 years. Joint replacement was performed by Hardinge approach. All cases were assessed clinically using the Harris Hip Score (HHS) and radiologically to demonstrate mid-term results.

RESULTS

The preoperative value on the HHS scale had a mean of 56.45, postoperative at one month 74.23; 6 months 85.40; 1 year 94.01 and at 5 years 94.84 points, representing a functional improvement of 17.78 postoperative month; 28.95 at 6 months postoperative; 37.56 at one year postoperative and 38.39 points at 5 years postoperative. A complication rate of 3.44%; 0.86% of complications were associated with the prosthetic components.

CONCLUSION

The dual mobility system should be considered as a therapeutic option in primary hip joint replacement due to excellent functional results and low complication rates.

EVIDENCE LEVEL

IV. Retrospective observational case series study.

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.

No dislocation and low complication rate for a modern dual mobility cup with pre-impacted femoral head in primary hip replacement: A consecutive series of 175 hips at minimum 5-year follow-up

INTRODUCTION

Despite its excellent results in preventing dislocation, the dual mobility cup (DMC) is still struggling to be adopted by some teams due to premature wear and loosening reported on first-generation implants. Therefore, this study aimed to assess the mid-term survivorship of a modern DMC with a pre-impacted head and the radio-clinical results at a minimum follow-up of 5 years.

METHODS

This was a retrospective single-centre study performed on patients who had a primary total hip replacement for osteoarthritis in 2016. The cup was a third-generation DMC with a pre-impacted femoral head. Clinical (harris hip score (HHS)) and radiological (cup abduction, anteversion, overhang, and radiolucent lines) results were recorded, as well as complications, particularly dislocations and survivorship. A minimum of five years of follow-ups was required.

RESULTS

One hundred and seventy-five hips (167 patients) met the inclusion criteria. Five hips (2.9%, 5/175) were lost to follow-up and excluded from the postoperative analysis. The mean follow-up period was 70 ± 2.9 months [63.6-76.5]. Three cups needed revision surgery (1.8%, 3/170): one for septic loosening, and two for chronic infection. At 77 months, the global survival probability was 98.2% ± 1, and the survival probability excluding septic aetiology was 100%. There was a significant improvement in the HHS from pre-operatively (48.3 ± 6.0 [14.0-70.0]) to post-operatively (96 ± 4.5 [50-100]) (p < 0.0001). There were no postoperative dislocations recorded, nor any iliopsoas-impingement or symptomatic cam-effect.

DISCUSSION

This study showed excellent survival and good radiological and clinical results of this dual mobility cup at a mid-term follow-up. None of the patients had dislocation or any specific complication feared with dual mobility cups.

The Saturne cementless dual-mobility cup grants satisfactory long-term survival

Purpose

To report long-term survival and clinical outcomes of primary total hip arthroplasty (THA) using a Saturne cementless dual-mobility (DM) cup, and investigate whether patient demographics or surgical parameters affect clinical scores.

Methods

A consecutive series of primary THAs implanted with Saturne cementless DM cups between 01/09/2009–31/12/ 2011 was retrospectively assessed. Patients were postoperatively evaluated using modified Harris hip score (mHHS) and forgotten joint score (FJS). Complications, reoperations, and revisions were noted. Regression analyses were performed to determine associations of postoperative mHHS with preoperative and intraoperative variables. Ten-year Kaplan–Meier survival was calculated.

Results

Of 308 patients (308 hips), 111 (36%) had died with their original cups in place, 29 (9%) were lost-to-follow-up, and 5 (2%) required cup revision, leaving a final cohort of 163 (53%) with their original cup in place at a follow-up of ≥ 10 years. Ten-year survival was 98% considering cup revision for any reason as endpoint; 99% considering cup revision for aseptic loosening as endpoint; 96% considering stem revision for any reason as endpoint; and 96% considering any revision as endpoint. The final cohort of 163 patients was assessed at 11 ± 1 years (range, 10–13), mHHS was 85 ± 16 (range, 31–100) and FJS was 84 ± 24 (range, 0–100). Multivariable regression analysis revealed that postoperative mHHS significantly worsened with age (β = -0.48, p = 0.007) and BMI (β = -0.70, p = 0.008), as well as for 22 mm head sizes (β = -6.98, p = 0.046).

Conclusions

The Saturne DM cup granted satisfactory survival and clinical outcomes at a minimum follow-up of 10 years, and resulted in no cases of intra- or extra-prosthetic dislocations.

Outcome and risk factors of failures associated with revision total hip arthroplasty for recurrent dislocation

INTRODUCTION

Recurrent dislocation represents the third most common cause of revision surgery after total hip arthroplasty (THA). However, there is a paucity of information on the outcome of revision total hip arthroplasty for recurrent dislocation. In this study, we investigated (1) clinical outcomes of patients that underwent revision THA for recurrent dislocation, and (2) potential risk factors associated with treatment failure in patients who underwent revision total hip arthroplasty for recurrent dislocation.

METHODS

We retrospectively reviewed 211 consecutive cases of revision total hip arthroplasty for recurrent dislocation, 81 implanted with a constrained liner and 130 with a non-constrained liner with a large-diameter femoral head (> 32 mm). Patient- and implant-related risk factors were analyzed in multivariate regression analysis.

RESULTS

At 4.6-year follow-up, 32 of 211 patients (15.1%) underwent re-revision surgery. The most common causes for re-revision included infection (14 patients) and dislocation (10 patients). Kaplan-Meier analysis demonstrates a 5-year survival probability of 77% for patients that underwent revision THA for recurrent dislocation. Osteoporosis, obesity (BMI ≥ 40), spine disease and abductor deficiency are independent risk factors for failure of revision surgery for recurrent dislocation. Liner type (constrained vs. non-constrained) was found not to be associated with failure of revision THA for recurrent dislocation (p = 0.44).

CONCLUSION

This study suggests that THA revision for recurrent dislocation is associated with a high re-revision rate of 15% at mid-term follow-up. Osteoporosis, obesity (BMI ≥ 40) spine disease and abductor deficiency were demonstrated to be independent risk factors for failure of revision THA for recurrent dislocation.

LEVEL OF EVIDENCE

Level III, case-control retrospective analysis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Incidence and Temporal Trends of Dislocation After the Use of Constrained Acetabular Components and Dual Mobility Implants in Primary Total Hip Replacements: A Systematic Review and Meta-Analysis of Longitudinal Observational Studies

BACKGROUND

Dislocation after a primary total hip replacement (pTHR) remains a common cause of treatment failure. Constrained acetabular components (CACs) and dual mobility implants (DMIs) may mitigate this in patients at high risk of dislocation or with significant intraoperative instability. This meta-analysis evaluated the incidence and temporal trends of dislocation after implantation with CACs and DMIs in pTHR.

METHODS

Longitudinal studies reporting dislocation after the use of CACs or DMIs in pTHR were sought from Medline and Embase to September 2020. Secondary outcomes included revision surgery for dislocation and for all causes.

RESULTS

A total of 46 studies (3 CAC and 43 DMI) comprising 582 CACs and 18,748 DMIs were included. The pooled incidence of dislocation was 1.08% (95% confidence interval [CI]: 0.00-3.72; range 0.27%-2.60%) over a weighted mean follow-up of 4.1 years for CACs, compared with 0.25% (95% CI: 0.08-0.46; range 0.00%-4.72%) over 6.2 years for DMIs. For DMIs, there was a temporal decline in dislocations from the 1980s onward, and dislocation rates remained low (<1%) until 15 years postoperatively. There were insufficient data for similar analysis of CACs. All studies were at high risk of bias. The incidence of revision for dislocation after CACs was 0.3% vs 0.1% for DMIs, and the incidence of revision for all causes after CACs was 4.8% vs 2.7% for DMIs.

CONCLUSION

DMIs demonstrated a lower incidence of dislocation compared with CACs; however, there was a relative absence of CACs used in the context of pTHR in the literature. Temporal trends in dislocation have improved over time for DMIs.

Outcomes and survival of a modern dual mobility cup and uncemented collared stem in displaced femoral neck fractures at a minimum 5-year follow-up

INTRODUCTION

The choice of implant type for total hip replacement in the treatment of femoral neck fractures remains debated. Some authors advocate for the systematic use of cemented stems, while others do not use dual mobility first-line. We therefore conducted a retrospective study using a dual mobility cup (DMC) and an uncemented collared stem (UCS) in order to: (1) confirm the low dislocation rate in this indication, (2) assess other surgical complications, in particular periprosthetic fractures, (3) ensure that these benefits are maintained over time, at a minimum follow-up of 5 years and, (4) assess the rate of revision of the implants.

HYPOTHESIS

Our hypothesis was that the dual mobility dislocation rate for the treatment of femoral neck fractures was lower than for bipolar hemiarthroplasties or single mobility hip prostheses.

PATIENTS AND METHODS

A retrospective study of 244 femoral neck fractures (242 patients) treated with DMC and UCS was conducted, between 2013 and 2014. The mean age was 83±10 years (60-104). The occurrence of dislocation, periprosthetic fracture, infection of the surgical site, loosening, reoperation and revision were investigated. The HOOS Joint Replacement (JR) score was collected. The cumulative incidence with mortality was used as a competing risk.

RESULTS

The mean follow-up was 6 years±0.5 (5-7). At the last follow-up, 108 patients (50%) had died. Twenty-three patients (9.5%) were lost to follow-up. One case of symptomatic aseptic loosening of DMC was observed. The cumulative incidence of dislocations and periprosthetic fractures at 5 years were 2% (95% CI: 0.9-5.4) and 3% (95% CI: 1.2-6), respectively. The 5-year cumulative incidence of surgical site infections was 3.5% (95% CI: 1.8-7). The cumulative incidence of reoperations at 5 years was 7% (95% CI: 4.5-11). The causes of reoperation were periprosthetic fracture (n=6), infection (n=8), postoperative hematoma (n=2) and cup malposition (n=2). The cumulative incidence of a revision at 5 years was 2.7% (95% CI: 1.2-6). The cumulative incidence of a surgical complication from any cause at 5 years was 9% (95% CI: 6.7-14.8). The mean HOOS JR score was 79±5 (52-92).

DISCUSSION

The cumulative incidence of dislocation at 5 years is low and other surgical complications (including periprosthetic fractures) do not increase during this period for DMC associated with UCS, in femoral neck fractures. The use of this type of implant is reliable in the treatment of femoral neck fractures.

LEVEL OF EVIDENCE

IV; retrospective study without control group.

Long-term results of metal-on-metal hip resurfacing in patients 65 years of age or older

BACKGROUND

Metal-on-metal hip resurfacing arthroplasty (MMHRA) is typically used in young and active patients because they have the most to gain from this bone-preserving procedure. However, there is very little long-term data on the performance of MMHRA in patients 65 years of age or older because of the efficacy of conventional total hip arthroplasty in this patient population.

METHODS

109 patients (124 hips) age ⩾65 years were treated with Conserve Plus MMHRA. There were 83 male and 26 female patients. Their mean age at surgery was 69.5 (range 65-83) years. UCLA hip scores, SF-12 quality of life score were collected at follow-up visits. Radiographic and survivorship analyses were performed.

RESULTS

SF-12 scores and UCLA scores were maintained over time except for a small decrease in activity. 4 patients underwent revision surgery. The 15-year Kaplan-Meier survivorship of the cohort was 93.7%. All revisions surgeries were successful at a mean follow-up time of 113 (range 30-218) months. Unusual radiographic findings from our previous publication did not progress over time except for 1 hip that showed a complete radiolucency around the acetabular component.

CONCLUSIONS

Our results clearly show that HRA is a viable prosthetic solution with many advantages for all active patients, regardless of their age at the time of surgery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Risk factors and modes of failure in the modern dual mobility implant. A systematic review and meta-analysis

Background

The aims of this meta-analysis were to: (1) validate the outcome of modern dual mobility (DM) designs in patients who had undergone primary and revision total hip arthroplasty (THA) procedures and (2) to identify factors that affect the outcome.

Methods

We searched for studies that assessed the outcome of modern DM-THA in primary and revision procedures that were conducted between January, 2000 to August, 2020 on PubMed, MEDLINE, Cochrane Reviews and Embase. The pooled incidence of the most common failure modes and patient reported outcomes were evaluated in patients who have received: (1) primary THA, (2) revision THA for all causes or (3) for recurrent dislocation. A meta-regression analysis was performed for each parameter to determine the association with the outcome. The study design of each study was assessed for potential bias and flaws by using the quality assessment tool for case series studies.

Results

A total of 119 studies (N= 30016 DM-THAs) were included for analysis. The mean follow-up duration was 47.3 months. The overall implant failure rate was 4.2% (primary: 2.3%, revision for all causes: 5.5%, recurrent dislocation: 6.0%). The most common failure modes were aseptic loosening (primary: 0.9%, revision for all causes: 2.2%, recurrent dislocation: 2.4%), septic loosening (primary:0.8%, revision for all causes: 2.3%, recurrent dislocation: 2.5%), extra-articular dislocation (primary:0.6%, revision for all causes:1.3%, recurrent dislocation:2.5%), intra-prosthetic dislocation (primary:0.8%, revision for all causes:1.0%, recurrent dislocation:1.6%) and periprosthetic fracture (primary:0.9%, revision for all causes:0.9%, recurrent dislocation:1.3%). The multi-regression analysis identified younger age (β=-0.04, 95% CI -0.07 – -0.02) and female patients (β=3.34, 95% CI 0.91–5.78) were correlated with higher implant failure rate. Age, gender, posterolateral approach and body mass index (BMI) were not risk factors for extra-articular or intra-prosthetic dislocation in this cohort. The overall Harris hip score and Merle d’Aubigné score were 84.87 and 16.36, respectively. Level of evidence of this meta-analysis was IV.

Conclusion

Modern dual-mobility designs provide satisfactory mid-term implant survival and clinical performance. Younger age and female patients might impact the outcome after DM-THA. Future research directions should focus on, (1) long-term outcome of modern dual-mobility design, including specific concerns such as intra-prosthetic dislocation and elevated metal ion, and (2) cost-effectiveness analysis of dual-mobility implant as an alternative to conventional THA for patients who are at high risk of dislocation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04404-4.

Dual-Mobility Cup Total Hip Arthroplasty for Displaced Femoral Neck Fractures: A Retrospective Study With a Median Follow-Up of 5 Years

Introduction:

Patient outcomes following modern dual-mobility cup total hip arthroplasty (DM-THA) remains a concern. Few reports have focused on the use of modern DM-THA in the setting of Asian populations for displaced osteoporotic femoral neck fractures (FNFs). This study aimed to investigate the outcomes of Chinese population with displaced osteoporotic FNFs initially treated with modern DM-THA.

Materials and Methods:

Data from 112 consecutive patients (112 hips) with displaced osteoporotic FNFs initially treated with modern DM-THA during 2011-2018 were retrospectively analyzed. Follow-ups were performed at 3 months, 6 months, 12 months, and then every 1 year after surgery. The primary endpoint was the Harris Hip Score (HHS); the secondary endpoint was the main orthopedic complication rate.

Results:

The mean HHS improved from 58.62 (±15.79) prior to surgery to 86.13 (±9.92) at the final follow-up. The main complication rate was 14.2% (16/112). Sixteen complications in 10 patients were recorded. Of the 16 complications, there were 2 (1.7%) cases requiring revision DM-THA, 3 (2.6%) cases of loosening, 2 (1.7%) cases of migration, 3 (2.6%) intra-prosthetic dislocation (IPD), 4 (3.5%) cases of tilting, and 2 (1.7%) cases of severe wear. The need for revision was attributed to prosthesis loosening associated with poor bony quality.

Conclusion:

In patients with displaced osteoporotic FNFs, DM-THA may yield favorable functional outcomes and a low rate of main orthopedic complications, in particular, a low dislocation rate.

Dual mobility acetabular construct with freedom constrained liner for treatment of recurrent dislocations after total hip arthroplasty: A case report and literature review

•

Dual-mobility bearings improve stability in total hip arthroplasty (THA) but may fail to prevent postoperative dislocation.

•

Dry revision with a compatible constrained liner system can provide an effective salvage option for instability after THA.

•

The unique G7 constrained liner system offers good short-term stability and range of motion.

Introduction

Recurrent dislocation after total hip arthroplasty (THA) using the dual mobility cup system can present challenges, while dual-mobility THA bearings can improve stability in both primary and revision total hip arthroplasties.

Presentation of case

A 72-year-old woman with a history of schizophrenia underwent a left primary THA using the G7 dual mobility system. Two postoperative posterior dislocations occurred within 2 months post-surgery. The patient underwent revision surgery in which the metal liner and dual mobility head were exchanged using the Freedom constrained liner system without revision of the cup and stem. As of this writing, 28 months after the revision surgery, no further dislocations have occurred. The implants are stable, and the patient has good range of motion.

Discussion

Dual-mobility bearings are utilized to improve stability in both primary and revision total hip arthroplasties, but even if the dual mobility system is chosen, it sometimes fails to prevent postoperative dislocation. Although a relatively high failure rate has been reported in THA using the constrained liner system, this patient’s clinical course suggests that the G7 Freedom constrained liner system can be an efficacious option for some patients with unstable hip joints who undergo THA using the dual mobility system.

Conclusion

A modern constrained liner system such as the G7 Freedom liner may provide an improved salvage solution for joint instability in dual mobility THA.

Transitioning the total hip arthroplasty technique from posterior approach in lateral position to direct anterior approach in supine position-risk factors for acetabular malpositioning and the learning curve

PURPOSE

Cup positioning is important for optimum hip stability, avoiding component impingement and decreasing both bearing surface wear and revision rate. Transitioning from posterior approach in a lateral position to direct anterior approach (DAA) in a supine presents unique challenges for surgeons. The aim of this study was to examine the learning curve when using standard instrumentation that was not specific to DAA.

METHODS

A consecutive retrospective series of 537 total hip arthroplasty by DAA from May 2013 to December 2017. Cup positioning was analysed on radiographs and classified whether inside or outside two safe zones (inclination 30-50° and anteversion 10-30°). The demographic data (age, BMI, gender, neck shaft angle (NSA)), surgeon's dominant side and experience were assessed as risk factors.

RESULTS

Eighty per cent of cups (n = 426) were in the combined safe zones. Eighty-eight per cent (n = 470) were in appropriate anteversion and 87% (n = 463) abduction. Two factors that were significant were identified: Cups of left hips operated by right-handed surgeons were more anteverted (OR = 4.06) and more vertical (OR = 2.23); females had a higher anteversion of the cup (OR = 2.42). Obesity, age and NSA were not risk factors for cup malposition. There was a spike of cups too horizontal at the beginning of the experience (OR = 3.86), and no learning curve was observed in the other orientations.

CONCLUSION

With our DAA technique using standard instrumentation, there were no risk factors linked to the patient identified for cup malposition. DAA-specific instrumentation is not required to achieve optimum positioning of the cup. Surgeon has to be aware of an excess of abduction at the beginning of his experience and an excess of anteversion and adduction when performing THA on the opposite side of his dominant hand.

Postero-posterolateral approach in total hip arthroplasty

Introduction

Evolving surgical techniques in total hip arthroplasty (THA) have sought to make the surgical procedures safer. This requires having highly reproducible incision landmarks and simplifying the procedures. The postero-posterolateral approach, a very posterior incision in the hip, meets those requirements. However, this has not helped to reduce the post-operative dislocation rate. The aim of this study was to assess the relevance of combining the postero-posterolateral approach and next-generation dual mobility cups (DMC) in terms of dislocation risk.

Materials and methods

One hundred and fifty-eight THA were performed consecutively using the postero-posterolateral approach on 150 patients, by a single surgeon, over a 49-month period (November 2010 to December 2014). All acetabular implants were impacted.

Results

Average length of the incision was 7 cm (6 to 9 cm). Mean duration of the surgical procedure was 75 minutes (40 to 100). Mean blood loss was estimated at 210 cc (25 to 410 cc). All patients could walk with assistance the day before transferring to a rehabilitation centre. There was one posterior dislocation (0.63%), without recurrence.

Conclusion

The straightforwardness and reproducibility of the anatomical landmarks used for the postero-posterolateral approach, added to the stability of the dual mobility cup, result in a safe combination in the therapeutic THA arsenal.

Absence of instabilities and intra-prosthetic dislocations at 7 to 11 years following THA using a fourth-generation cementless dual mobility acetabular cup

PURPOSE

Dual-mobility (DM) cups are increasingly used in total hip arthroplasty (THA) but there lacks literature on their long-term results. We aimed to investigate outcomes of a fourth-generation cementless DM acetabular cup at 7-11 years.

METHODS

We retrospectively evaluated 240 consecutive hips that received cementless THA using the same dual mobility cup (Novae Sunfit TH) and femoral stem (Corail). Patients were recalled at ≥7 years to collect Oxford hip scores (OHS), Harris hip scores (HHS), and inspect for radiolucent lines and granulomas. Multi-variable analyses were performed to determine whether HHS or OHS were associated with pre- or intra-operative variables.

RESULTS

At 8.4 ± 0.8 years (range, 7-11), 6 hips were revised (2.5%), 54 deceased (22.5%), and 14 could not be reached (5.8%). Four revisions (2 cup+stem, 2 liners only) were due to sepsis (1.7%), one (cup and stem) for trauma (0.4%), and one (stem) due to aseptic loosening (0.4%). For the remaining 166 hips, HHS was 83.6 ± 13.2 and OHS was 20.3 ± 6.7. Multi-variable analysis confirmed that HHS (β = - 0.38; p = 0.039) and OHS (β = 0.36; p < 0.001) worsened with age, and that OHS was worse for Charnley C patients (β = 3.17; p = 0.009). Neither granulomas nor radiolucenies were observed around any cups, but radiolucenies were seen around 25 stems (20.3%).

CONCLUSIONS

This fourth-generation DM cup demonstrated satisfactory outcomes at 7-11 years, with no instabilities or cup revisions due to aseptic loosening. Better OHS was observed for younger patients and those presenting higher Charnley grade.

LEVEL OF EVIDENCE

Level IV, retrospective case study.