Total hip arthroplasty with dual mobility cup in osteonecrosis of the femoral head in young patients: over ten years of follow-up

Ten to 15-Year Outcomes of Monoblock Uncemented Dual Mobility Cups: Excellent Survival Rate and Outcome in Primary Total Hip Arthroplasty

Background

Dual mobility cups (DMCs) have effectively prevented dislocations after total hip arthroplasty (THA). However, use of these cups in primary THAs remains controversial, especially in young patients. This study aimed to determine the long-term survival rate and functional outcomes of a contemporary DMC used in primary THA.

Methods

This retrospective multicenter study identified a cohort of 614 primary THAs performed with the same uncemented monoblock DMC between 2007 and 2010. Survival analysis included 572 THAs, while clinical analysis involved 394 THAs at a minimal follow-up of 10 years. The mean follow-up was 11.1 ± 1.2 years. The mean age was 71.4 ± 11.7 years, with 4.2% of patients under 50 years old. The mean body mass index was 27.0 ± 5.3 kg/m2. The 10-year Kaplan-Meier survival rate was calculated based on cup removal for any reason or cup revision for an aseptic reason as the end point. Harris hip scores were collected at the last follow-up.

Results

The cup-revision-free survival rate was 98.6% at 10 years and 96.2% at 13 years. No cup revisions were reported due to aseptic loosening or dislocation. The cup revisions were due to infection (7 of 572; 1.2%), acetabular fracture (1 of 572; 0.17%), and psoas impingement due to cup malpositioning (n = 1 of 572; 0.17%). Only 3 dislocations (0.52%) were observed, and they did not require revision. The mean Harris hip score significantly improved from 54.1 ± 14.4 preoperatively to 88.0 ± 14.3 at the last follow-up (p < 0.0001). For patients under 50 years old at the time of surgery, the mean Harris hip score showed significant improvement from 53.0 ± 10.2 preoperatively to 89.7 ± 12.8 at the last follow-up (p < 0.0001), with no significant difference compared with the older patients (p = 0.50). No revision or complication was reported in the younger patient population at 13 years of follow-up.

Conclusions

The monoblock uncemented DMC demonstrated excellent survival rates with no DMC-specific complications during a minimum 10-year follow-up. The dislocation rate was very low, and a younger age was not identified as a risk factor for failure. Therefore, monoblock cementless DMCs can be safely used, even in primary THA.

Level of Evidence

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

Results of third generation dual mobility total hip arthroplasties with non-cross-linked polyethylene in patients under 60 years of age: comparative study of full pressfit vs. tripod cups after 8.6 years

BACKGROUND

The concept of dual mobility of total hip arthroplasties (THA) is a revolution in the prevention of dislocations and in the treatment of instability. Its use remains controversial in patients under 60 years old, providing poorer results with first generation cups coated with alumina. This study, carried out on modern dual mobility (DM) cups with a porous bilayer coating, in active patients under 60 years of age aimed to evaluate: (1) the mechanical survival of two latest generation DM THA, with failure defined as revision of acetabular or femoral implants for mechanical loosening, by comparing a tripod cup to a full pressfit cup, (2) to evaluate the complications, (3) to compare the rate of radiographic peri-prosthetic osteolysis between the 2 implants.

HYPOTHESIS

The hypothesis was that the medium-term survival of modern DM cups placed in young patients was the same regardless of the type of acetabular fixation used.

MATERIALS AND METHODS

This was a retrospective study of 119 latest generation DM THA with standard polyethylene, composed of 66 full pressfit cups and 53 tripod fixation cups, used in primary arthroplasty in 111 patients between 2005 and 2016. The survival study was carried out using medical records. The clinical evaluation was carried out using the modified Harris Hip Score (mHHS) as well as the self-administered Hip and Osteoarthritis Outcome Score (HOOS) and Oxford-12 questionnaires. Radiological analysis was carried out on radiographs looking for bone demineralization and acetabular and femoral lines.

RESULTS

At 8.6 years (5-16), no revision for mechanical loosening was observed regardless of the type of cup. The prosthesis dislocation rate (large joint) was 1.7%: 1 case in each group (p = 1), including one revision required in the full pressfit group. Three revisions for mechanical complications were recorded: a recurrent dislocating hip on a full pressfit cup that was not sufficiently anteverted, an acetabular peri-prosthetic fracture on a full pressfit cup and a case of iliopsoas impingement with a retroverted tripod cup. The survival rate for all-cause revision was 93.8% for pressfit (95% CI: 88.2%-99.9%) vs. 96.2% for tripod (95% CI: 91.1%-100%) (p = 0.63) and for revision due to any cause excluding infection, 96.9% for pressfit (95% CI: 92.8%-100%) vs. 98.1% for tripod (95% CI: 94.4%-100%) (p = 0.7). The rate of periacetabular osteolysis was 11%, significantly more present amongst tripod cups (24%, 9 cases) compared to full pressfit cups (2%, 1 case) (p < 0.01).

CONCLUSION

This series demonstrates good performance of 3rd generation DM cups with porous bilayer coating in patients under 60 years of age regardless of the type of acetabular fixation, at 8.6 years of follow-up. The rate of osteolysis around full pressfit cups remains very low, unlike that of tripod cups. The use of Double Mobility prostheses for primary hip osteoarthritis is possible in young patients, preferably with full pressfit cups (i.e., without any pegs or additional screws that may promote diffusion of polyethylene debris and osteolysis).

LEVEL OF EVIDENCE

III; comparative retrospective study.

Outcomes of total hip arthroplasty using dual mobility cups following failed internal fixation of proximal femoral fractures at a mean follow-up of 6 years

INTRODUCTION

Performing total hip arthroplasty (THA) after failed internal fixation of proximal femoral fractures (PFF) is known to be associated with high rates of complications. Dual mobility cups (DMC) are known to lower dislocation events in high-risk patients. Very few reports investigated the outcomes of THA using DMC following failure of internal fixation for PFF.

METHODS

This is a retrospective monocentric continuous study of 31 patients who underwent THA with DMC after failed internal fixation of PFF. The clinical assessment was based on the modified Harris hip score (mHHS) at the last follow-up. The complication rates and radiological analyses were recorded.

RESULTS

The mean follow-up period was 5.96 ± 4.2 years. At the last follow-up, the mean mHHS was 92.9 ± 9.1 with 71% of the patients describing their operated hip as a forgotten hip. No dislocation or aseptic loosening events were noted. One patient developed a septic loosening of the implant. No significant radiological changes were recorded. Sixteen stems (51.6%) were placed in a neutral position, 13 (42%) in valgus (2.74 ± 1.72°), and 2 (6.4%) in varus (6.94 ± 2.02°).

CONCLUSION

This study emphasizes the advantage of using DMC following failed internal fixation of PFF in reducing dislocation and complication events in this high-risk population.

Insight into Steroid-Induced ONFH: The Molecular Mechanism and Function of Epigenetic Modification in Mesenchymal Stem Cells

Osteonecrosis of the femoral head (ONFH) is a common refractory orthopedic disease, which is one of the common causes of hip pain and dysfunction. ONFH has a very high disability rate, which is associated with a heavy burden to patients, families, and society. The pathogenesis of ONFH is not completely clear. At present, it is believed that it mainly includes coagulation dysfunction, abnormal lipid metabolism, an imbalance of osteogenic/adipogenic differentiation, and poor vascularization repair. The prevention and treatment of ONFH has always been a great challenge for clinical orthopedic surgeons. However, recent studies have emphasized that the use of mesenchymal stem cells (MSCs) to treat steroid-induced ONFH (SONFH) is a promising therapy. This review focuses on the role and molecular mechanism of epigenetic regulation in the progress of MSCs in the treatment of SONFH, and discusses the significance of the latest research in the treatment of SONFH from the perspective of epigenetics.

The Performance of Primary Dual-Mobility Total Hip Arthroplasty in Patients Aged 55 Years and Younger: A Systematic Review

Background

Dual-mobility (DM) total hip arthroplasty (THA) combines the stabilization advantage provided by large head articulation with the low friction advantage provided by small head articulation. There is momentum for DM to be used in a wider selection of patients, with some advocating for DM to be the routine primary total hip construct. Further investigation is needed to determine whether the use of DM in younger adults is validated by aggregate data. Our objective was to review the literature for the clinical performance of DM THA in patients aged 55 years and younger.

Methods

A systematic review of the literature was performed according to the guidelines of Preferred Reporting in Systematic Reviews and Meta-Analyses. Inclusion in the review required clinical outcome reporting for DM primary THA in ambulatory patients aged 55 years or younger. The risk of bias was appraised using the Cochrane risk of bias in nonrandomized studies of interventions and the quality of the evidence was appraised using the Grading of Recommendations Assessment, Development and Evaluation framework.

Results

Across a sample of 1048 cases, the frequency weighted term of follow-up was 87.7 months. The pooled rate of revision was 9.5%. The Harris Hip Score significantly improved from 49.1 preoperatively to 93 postoperatively. The Postel-Merle d'Aubigné score significantly improved from 10.5 preoperatively to 17.1 postoperatively.

Conclusions

The literature demonstrates satisfactory short-term outcomes with a mitigated risk of dislocation for DM used as primary THA in patients aged 55 years and younger. The current findings suggest that third-generation designs provide reduced rates of intraprosthetic dislocation and improved survivorship.

Dual-mobility total hip arthroplasty in patients younger than 55 years old: a systematic review

Total hip arthroplasty (THA) is regarded as one of the most successful and cost-effective orthopedic procedures. However, THA is a surgical procedure with potential intraoperative and postoperative risks. Dislocation is one of the common postoperative complications and remains one of the main indications for THA revision. The purpose of this systematic review was to evaluate the role and the outcomes of dual-mobility implant to prevent dislocation in patients younger than < 55 years in primary THA. In this systematic review, we included observational, prospective, and retrospective studies that evaluated the outcome and the complications of the dual-mobility cup in < 55-year-old patients. After applying exclusion criteria (femoral neck fractures or THA revision, case series, reviews, and meta-analyses), ten articles were included in the study. The overall number of participants in all the studies was 1530. The mean age of the participants was 50 years. The mean follow-up was 11.7 years. A total of 46 patients (2.7%) reported intraprosthetic dislocations, in which the polyethylene liner dissociates from the femoral head, while 4.8% of revision was due to aseptic loosening. The mean revision rate at twelve years was 11%. The mean value of Harris Hip Score increased from 50.9 pre-operatively to 91.6 after surgery. Dual mobility is a valid option for young patients with extended survivorship and low rates of instability and dislocation after primary THA.

Survivorship of the dual-mobility construct in elective primary total hip replacement: a systematic review and meta-analysis including registry data

INTRODUCTION

Dislocation is a common complication associated with total hip replacement (THR). Dual-mobility constructs (DMC-THR) may be used in high-risk patients and have design features that may reduce the risk of dislocation. We aimed to report overall pooled estimates of all-cause construct survival for elective primary DMC-THR. Secondary outcomes included unadjusted dislocation rate, revision for instability, infection and fracture.

METHODS

MEDLINE, EMBASE, Web of Science, Cochrane Library and National Joint Registry reports were systematically searched (CRD42020189664). Studies reporting revision (all-cause) survival estimates and confidence intervals by brand and construct including DMC bearings were included. A meta-analysis was performed weighting series by the standard error.

RESULTS

Thirty-seven studies reporting 39 case series were identified; nine (10,494 DMC-THR) were included. Fourteen series (23,020 DMC-THR) from five national registries were included. Pooled case series data for all-cause construct survival was 99.7% (95% CI 99.5-100) at 5 years, 95.7% (95% CI 94.9-96.5) at 10 years, 96.1% (95% CI 91.8-100) at 15 years and 77% (95% CI 74.4-82.0) at 20 years. Pooled joint registry data showed an all-cause construct survivorship of 97.8% (95% CI 97.3-98.4) at 5 years and 96.3% (95% CI 95.6-96.9) at 10 years.

CONCLUSIONS

Survivorship of DMC-THR in primary THR is acceptable according to the national revision benchmark published by National Institute for Clinical Excellence (NICE).

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.

Dual Mobility Total Hip Replacements in Young Patients- A Systematic Review

Background

There is little consensus on outcomes of dual Mobility total hip replacement (DM-THR) in younger patients. We performed a systematic review to examine this.

Methods

A systematic review of all observational studies and randomised controlled trials of patients under 70 with primary DM-THR in MEDLINE, EMBASE, Pubmed, Cochrane was performed according to PRISMA guidelines. Collected data included demographics, revision, dislocation and infection rates and functional scores.

Results

Twelve papers studying 738 DM-THR in 664 patients were included. The mean patient age was 46.9 years (13.5-69.0), with 319 (48.0%) being female and 419 (52.0%) being male. After an average follow-up of 90.0 months (1-371 months), the revision rate was 12.7% (84 hips), 0 dislocations were reported but 2.5% (15 hips) underwent intra-prosthetic dislocation. 32.1% hip revisions were due to aseptic loosening.

Conclusion

Limited literature surrounding the use of DM-THR suggests favourable stability but higher revision rates than conventional THR.

Dual-Mobility Cups in Primary Total Hip Arthroplasty

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

Hip Preservation or Total Hip Arthroplasty? A Retrospective Case-Control Study of Factors Influencing Arthroplasty Decision-Making for Patients with Osteonecrosis of the Femoral Head in China

OBJECTIVE

At present, there is no consensus or guidance on indications for osteonecrosis of the femoral head (ONFH) patients to receive hip arthroplasty (THA) treatment. This study aims to explore the factors that influence the decision-making for THA in patients with ONFH, and to provide references for clinical decision for ONFH patients to be indicated for THA or hip preservation.

METHODS

This retrospective case-control study involved data for ONFH patients from July 2016 to October 2021 from the China Osteonecrosis of the Femoral Head Database (CONFHD). The patients with ONFH, and unilateral hip affected at the first visit were divided into THA group and non-THA group according to if they had undergone THA treatment. The differences between the two groups of patients in terms of gender, age at the time of consultation, body mass index (BMI), etiology, onset side, association research circulation osseous (ARCO) stage, hip joint function, visual analog scale (VAS), etc. were analyzed. Multivariate binomial logistic regression analysis was then applied to evaluate the risk factors of ONFH patients who underwent THA during the first visit.

RESULTS

A total of 640 patients were recruited for analysis, including 209 cases from the THA group and 431 cases from the non-THA group. The results of univariate analysis showed that the two groups of patients were significantly different in the following six indicators: age (59 vs. 46, Z = -9.58, p < 0.001), duration of disease (78 vs. 17, Z = -16.14, p < 0.001), gender composition (χ²  = 8.09, p = 0.004), disease etiology (χ²  = 33.04, p < 0.001), ARCO stage (χ²  = 334.86, p < 0.001), flexion of hip joint (χ²  = 172.33, p < 0.001). However, the comparison between the two groups on VAS (Z = -0.82, p = 0.41), BMI (Z = -1.35, p = 0.18), and onset side (χ²  = 1.53, p = 0.22) did not obviously differ. The results regression analysis showed that the age at the time of consultation, duration of disease, ARCO stage, and the hip joint function affected the decision making if the patients should undergo THA. The results of receiver operating characteristic curve (ROC) analysis showed that aforementioned indicators were satisfactory in predicting whether patients with ONFH would be treated with THA. The regression model using the above four indicators as comprehensive indicators has satisfactory performance in predicting whether to perform THA, and the area under the curve (AUC) is 93.94%.

CONCLUSION

These factors such as age, duration of disease, ARCO stage, and hip flexion function should be considered comprehensively before making decisions to perform THA or not in our clinical practice.

An early experience of the use of dual mobility cup uncemented total hip arhroplasty in young patients with avascular necrosis of the femoral head

INTRODUCTION

THA (Total hip arthroplasty) in advanced grade (grade 4) avascular necrosis (AVN) is a challenge to the treating surgeon as it affects young patients who have high functional demands and increased dislocation risk. The aim of the study was to evaluate the efficacy, survivorship, and dislocation rate of uncemented dual mobility cups (DMC) in advanced grade IV AVN young patients.

METHODS

Retrospective cohort study involving 204 DMC THA for advanced grade IV AVN from January 2013 to December 2015. The sample size of the study was estimated to be 188 hips with an α error of 0.05 and β error of 0.2. Inclusion criterion was patients less than 55 years of age with advanced grade IV AVN. Patients >55 years of age, patients diagnosed with primary osteoarthritis of the hip and hip fracture were excluded from the study. 172 patients (32 with bilateral & 140 with unilateral affection) with 204 DMC THA were evaluated clinically by Harris Hip Score (HHS) and radiologically at a follow up of 60 months. P value < 0.05 was considered significant.

RESULTS

Mean age of the patients was 42.5 ± 5.3. Preoperative HHS was 50.6 ± 10.5. Postoperative HHS at 5 years follow up was 96.4 ± 2.6. None of the operated patient had any dislocation episode or had undergone hip revision surgery (statistically significant against historical control of 2%, p value = 0.042). The radiological evaluation at 5 years showed no signs of radiolucent lines, periprosthetic osteolysis, polyethylene wear and signs of displacement or migration of the DMC. Cumulative survivorship rate at 5 years follow up was 100% without any revision/dislocation.

CONCLUSION

Use of DMC THA in young, advanced grade IV AVN patients was found to be a reliable option showing excellent early functional results with no dislocation. Ongoing follow up of this cohort is required to confirm the maintenance of these excellent functional results at follow up in the long term.

Survivorship of total shoulder arthroplasty vs. hemiarthroplasty for the treatment of avascular necrosis at greater than 10-year follow-up

BACKGROUND

Avascular necrosis (AVN) of the humeral head is a debilitating pathology that can be managed with an array of treatments depending on disease staging. Humeral head arthroplasty for AVN has demonstrated good short-term improvements in pain and range of motion, but the published long-term outcomes data are limited. The objective of this study was to report long-term survivorship and outcomes for patients undergoing hemiarthroplasty (HA) or total shoulder arthroplasty (TSA) for the treatment of AVN of the humeral head.

METHODS

The practice of one fellowship-trained shoulder surgeon was queried for the surgical treatment of AVN of the humeral head via appropriate International Classification of Diseases, Ninth and Tenth Revision, codes. Sixteen shoulders that met inclusion criteria were identified. Demographics included the radiographic stage, age, sex, American Society of Anesthesiologists (ASA) score, and body mass index. The primary endpoint was survivorship of the implant. Secondary endpoints were range of motion in forward elevation, internal and external rotation, visual analog scale for pain, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score, and the Simple Shoulder Test score.

RESULTS

Of the 16 shoulders included in the study, 10 underwent HA and 6 underwent TSA. The TSA cohort was significantly older (mean 60.5 vs. 44.2, P = .005), with a higher mean ASA score (mean 3.0 vs. 2.13, P = .02) than the HA group. The 10-year survivorship rates were 88.9% for HA and 80% for TSA with no significant difference between groups. Survivorship data were available for a mean 13.0 ± 5.6 years' follow-up in the HA group and 13.8 ± 4.8 years in the TSA group. When compared to one another, the results between HA and TSA only differed in internal rotation, which was statistically significantly improved in the TSA group compared with HA (2.3 ± 2.6 compared with -3.0 ± 5.0, P = .03).

CONCLUSION

The survivorship of both TSA and HA for the treatment of AVN was at least 80% at 10 years. Secondary endpoints, such as range of motion, pain, and shoulder function, improved significantly postoperatively in each cohort and were similar between the 2 groups, except for internal rotation, which had improved significantly more in the TSA group than in HA. Both TSA and HA are viable options for the treatment of AVN, each with durable long-term survival.

Survival and complications of total hip arthroplasty using third-generation dual-mobility cups with non-cross-linked polyethylene liners in patients younger than 55years

BACKGROUND

In younger patients, total hip prostheses are subjected to wide motion ranges and wear-inducing forces. Dual-mobility cups (DMCs) are effective in decreasing the risk of dislocation. However, wear and osteolysis have been reported with first-generation DMCs. These complications have not been assessed in younger patients managed with third-generation DMCs associated with a lower risk of intra-prosthetic dislocation (IPD). We therefore designed a retrospective study of patients younger than 55years at THA with third-generation DMCs. Our objectives were to evaluate (1) the complication rate, and (2) the survival rate.

HYPOTHESIS

The rate of complications of THA with third-generation DMCs in patients younger than 55years of age is comparable to that in the general population of THA patients.

MATERIAL AND METHODS

This retrospective study included 79 consecutive patients (91 hips) who had total hip arthroplasty (THA) between 2007 and 2012. We included all patients younger than 55years who underwent primary THA with a third-generation DMC and a liner made of non-cross-linked polyethylene. The patients were evaluated clinically and radiologically.

RESULTS

Mean follow-up was 9.8years (range: 2-13years). At last follow-up, no patient had experienced prosthetic dislocation or IPD. Aseptic and septic cup loosening each occurred in 1 patient. In all, 7 (7.7%) patients required revision surgery with exchange of at least one component (cup loosening, n=2; neck fracture with a short stem fixed to the neck, n=1; peri-prosthetic femoral fracture, n=1; infection, n=1; and femoral-stem loosening, n=2). Peri-acetabular osteolysis developed in 2 (2.2%) hips. Cup survival to aseptic loosening was 98.9% (95% confidence interval, 97%-100%) and survival to revision for any reason except infection was 95.6% (95% confidence interval, 82%-100%).

DISCUSSION

In patients younger than 55years, third-generation DMCs were associated with absence of prosthetic dislocation, absence of IPD, and a low revision rate for cup loosening, in the medium term. These implants therefore constitute a viable treatment option in younger patients requiring THA.

LEVEL OF EVIDENCE

IV, retrospective study.

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.

Early Rehabilitation and Periprosthetic Bone Environment after Primary Total Hip Arthroplasty: A Randomized Controlled Trial

Objective

To investigate whether the periprosthetic bone environment could be affected by activity during the early rehabilitation period after primary total hip arthroplasty (THA) and to evaluate the safety and efficacy of activity during the early rehabilitation period.

Methods

This random clinical trial was conducted from January 2017 to July 2017. A total of 22 selected patients with advanced osteonecrosis of the femoral head (ONFH) who underwent primary unilateral THA were randomized (1:1) to a high activity level group (HA group) or a low activity level group (LA group). The HA group included nine men and two women, aged 53.18 ± 13.29 years. The LA group included five men and six women, aged 55.73 ± 11.73 years. The intervention was different postoperative daily walking distances guided by researchers: 1727.27 ± 564.08 m 0–2 months and 4272.73 ± 904.53 m 3–6 months postoperation for the HA group and 909.09 ± 583.87 m 0–2 months and 2409.09 ± 1068.13 m 3–6 months postoperation for LA group. The primary outcomes were radiographic evaluation (prosthetic stability and stress shielding based on the Engh scale) and bone mineral density (BMD) with a femoral prosthesis (individual and intergroup comparison using seven Gruen zones) at 6 months postoperatively. Secondary outcomes were set to confirm the safety and efficacy of activity during early rehabilitation, including day 1 erythrocyte sedimentation rate (ESR), day 1 hypersensitive C‐reactive protein (CRP), length of hospital stay (LOS), and the Harris hip score (HHS) at discharge, 2 months postoperatively, and 6 months postoperatively.

Results

Patients were followed up for 6 months after surgery. Regarding primary outcomes, all prostheses were assessed as stable, with bone in‐growth. There were no adverse events in any cases. The HA group had a higher incidence of stress shielding than the LA group, but there was no statistical significance (63.64% vs 18.18%; P > 0.05). The degree of stress shielding had a different distribution for the two groups (P < 0.05). In the HA group and the LA group, the median percentage difference of the BMD on the operated side was −25% and was −13% in Zone 1, −8% and − 1% in Zone 2, +1% and 3% in Zone 3, +6% and + 6% in Zone 4, −2% and +2% in Zone 5, −3% and −1% in Zone 6, and −24% and −12% in Zone 7 compared with the unoperated side. The BMD was significantly reduced in the medial proximal femur (Zone 1) and the lateral proximal femur (Zone 7) in both groups (P < 0.05). Furthermore, it was increased in the distal femur (Zone 4) in the HA group (P < 0.05). No difference was found in the BMD when comparing between groups. Regarding secondary outcomes, there was no statistical difference in day 1 ESR and day 1 CPR. The average LOS was similar in the HA and LA groups (7.00 days vs 7.18 days, P > 0.05). The HHS on day of discharge was higher in the HA group than in the LA group (60.73 ± 5.37 points vs 51.18 ± 8.05 points, P < 0.05); however, no statistically significant difference was found in postoperative the HHS at 2 months (81.73 ± 6.92 points vs 78.36 ± 9.18 points, P > 0.05) and 6 months (90.45 ± 5.24 points vs 91.55 ± 4.03 points, P > 0.05).

Conclusion

High activity levels during early rehabilitation after primary THA accelerate the process of bone remodeling and aggravate stress shielding, with no significant benefits for functional recovery.

Treatment of aseptic osteonecrosis of the femoral head: Historical aspects

The treatment of aseptic osteonecrosis (ON) of the femoral head has been the subject of numerous therapeutic and surgical proposals due to the absence of medical treatment with proven efficacy. For many years, the goal of surgical treatment was to avoid total hip replacement (THR) with uncertain survival in patients considered too young (30-50 years) for this procedure. Numerous conservative treatments were thus proposed: core decompression with numerous variants, non-vascularized and vascularized bone grafts, intertrochanteric and rotational transtrochanteric osteotomies, cementing. The lack of a common classification and a lack of knowledge of natural history complicated the interpretation of the results for a long time. Nevertheless, it appeared that these treatments were effective only in the very early stages and among these in the limited ONs, medial rather than central and especially lateral, with discrepancies according to etiologies apart from sickle cell disease recognized by all as being pejorative. For the same reason, partial arthroplasties have been attempted and abandoned in turn: femoral head total and partial resurfacing and femoral prosthesis. The most recent advances are stem-cell-enhanced core decompression and progress in total arthroplasty, whose reliability has made it possible to extend the indications to increasingly younger patients seeking treatment with guaranteed or near-guaranteed efficacy. Most of the other interventions have disappeared or almost disappeared because of their lack of effectiveness especially in extensive and post-fracture ONs, sometimes because of their complexity and the length of their post-operative management, and also because they complicate and penalize a future total arthroplasty. This argues for early detection of ON at an early stage where the "head can be saved" by stem cell augmented core decompression, a minimally invasive treatment that leaves the chances of success of a THR intact.

Primary total hip arthroplasty: mid-term outcomes of dual-mobility cups in patients at high risk of dislocation

INTRODUCTION

Dual-mobility cups (DMC) are currently used in patients having risk factors of instability. Most of the studies report the use of DMC in patients having a single high-risk variable. The aim of the study was to analyse a continuous series of patients treated with primary total hip arthroplasty (THA) and DMC with different high risk for dislocation.

METHODS

This is a retrospective study analysing the outcomes of primary THA with DMC in patients at high-risk of dislocation. The sample consisted of 215 patients having 1 of 3 aetiologies or risk factors: (1) young subjects (<55 years); (2) osteonecrosis of the femoral head (ONFH); and (3) femoral neck fracture (FNF).

RESULTS

With a mean follow-up duration of 70 ± 24.7 months, the findings showed the following: 2 patients had dislocated their hip following motor vehicle accidents; 1 patient had a traumatic femoral peri-prosthetic fracture; and 1 patient had an acute infection. No intra-prosthetic dislocation or aseptic loosening were encountered. No radiolucent lines were observed on the acetabular side. The mean modified Hip Harris Score was 96.6 ± 7.4%. Out of 186 patients, 170 (90.1%) would label their operated hip as a "forgotten hip". 78 out of the 84 patients (92.8%) who used to practice oriental sitting and/or ablution for prayers were able to return to their usual daily activities of extreme hip position and 74 out of the 84 patients (88%) described their operated hip as "a forgotten hip". No correlation was found between any of the studied variables.

DISCUSSION

The findings of this series of patients at high risk of dislocation showed excellent clinical and radiological results with very few complications. The use of DMC seems to counteract the impact of some aetiologies/risk factors that could lead to higher instability. Most patients practising extreme hip positions resumed their usual practices.

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.

Study protocol: Effectiveness of dual-mobility cups compared with uni-polar cups for preventing dislocation after primary total hip arthroplasty in elderly patients - design of a randomized controlled trial nested in the Dutch Arthroplasty Registry

Background and purpose - Dislocation is the leading reason for early revision surgery after total hip arthroplasty (THA). The dual-mobility (DM) cup was developed to provide more stability and mechanically reduce the risk of dislocation. Despite the increased use of DM cups, high-quality evidence of their (cost-)effectiveness is lacking. The primary objective of this randomized controlled trial (RCT) is to investigate whether there is a difference in the number of hip dislocations following primary THA, using the posterolateral approach, with a DM cup compared with a unipolar (UP) cup in elderly patients 1 year after surgery. Secondary outcomes include the number of revision surgeries, patient-reported outcome measures (PROMs), and cost-effectiveness.Methods and analysis - This is a prospective multicenter nationwide, single-blinded RCT nested in the Dutch Arthroplasty Registry. Patients ≥ 70 years old, undergoing elective primary THA using the posterolateral approach, will be eligible. After written informed consent, 1,100 participants will be randomly allocated to the intervention or control group. The intervention group receives a THA with a DM cup and the control group a THA with a UP cup. PROMs are collected preoperatively, and 3 months, 1 and 2 years postoperatively. Primary outcome is the difference in number of dislocations between the UP and DM cup within 1 year, reported in the registry (revisions), or by the patients (closed or open reduction). Data will be analyzed using multilevel models as appropriate for each outcome (linear/logistic/survival). An economic evaluation will be performed from the healthcare and societal perspective, for dislocation and quality adjusted life years (QALYs).Trial registration - This RCT is registered at www.clinicaltrials.gov with identification number NCT04031820.

Korean epidemiology and trends in hip joint replacements

This study aimed to analyze the epidemiologic characteristics of patients who underwent hip arthroplasty using the Korean nationwide database and investigate the recent trends in implant fixation methods and bearing surface selection. We aimed to compare clinical characteristics and differences with the results from the registry of other western countries. We analyzed the data collected by the Health Insurance Review and Assessment Service database of Korea from 2007 to 2011 and the Main Surgery Statistical Yearbook from 2014 to 2018, published by the National Health Insurance Service. The number and rate of patients who underwent hip joint arthroplasty per 10,000 persons have been steadily increasing since 2007. There was a big difference in mean age and preoperative diagnosis of patients between the bipolar hemiarthroplasty and total hip arthroplasty groups. Most patients underwent surgery using a cementless biological fixation method, and the cemented fixation method was selectively used for a small portion of old aged osteoporotic patients. In relation to the use of bearing surfaces, the registry data showed that ceramic-ceramic bearings were used at an overwhelmingly high rate (81%) in Korea compared to other countries. The reason was attributable to various factors, such as patient’s age or economic status, differences in the health insurance system between countries, and recently reported complications, such as ceramic fracture or noise.

Pelvic mobility before and after total hip arthroplasty

BACKGROUND

Pre-operative evaluation of pelvic motion using the sacral slope (SS) has been proposed for risk assessment of dislocation after total hip arthroplasty (THA). The purposes of this study were to elucidate the statistical characteristics of pre-operative and post-operative pelvic mobility and investigate the relationship between pre-operative spinopelvic factors and post-operative pelvic mobility.

METHODS

Eighty-six patients with osteoarthritis were assessed. The parameters evaluated were lumbar lordosis angle and the SS in the standing and sitting preo-peratively and post-operatively. The pelvic mobility was defined as the difference in the SS between standing and sitting. The presence of osteoarthritis in the contralateral hip, spondylolisthesis, vertebral compression fracture and lumbar scoliosis was investigated.

RESULTS

The median (interquartile range) pre-operative and post-operative pelvic mobility was 19.0 (13.75-27.0) and 16.0 (10.0-25.25), respectively, with significant difference. The pre-operative SS while standing and pre-operative pelvic mobility were associated with post-operative pelvic mobility (r = 0.409, P < 0.05 and r = 0.533, P < 0.05). The multivariate linear regression analysis showed that the following factors contributed to post-operative pelvic mobility: incidence of osteoarthritis in the contralateral hip, lumbar scoliosis, pre-operative SS while standing and pre-operative SS while sitting.

CONCLUSION

The pre-operative and post-operative pelvic mobility is not equal and ranges widely among patients. In addition to assessment of pre-operative pelvic mobility, other pre-operative spinopelvic factors may also influence post-operative pelvic mobility, such as the SS while standing and sitting, the condition of the contralateral hip and the presence of scoliosis. Risk assessment for dislocation using these pre-operative factors may be useful before THA.

Nontraumatic Osteonecrosis of the Femoral Head: Where Do We Stand Today?: A 5-Year Update

➢. Clinicians should exercise a high level of suspicion in at-risk patients (those who use corticosteroids, consume excessive alcohol, have sickle cell disease, etc.) in order to diagnose osteonecrosis of the femoral head in its earliest stage. ➢. Nonoperative treatment modalities have generally been ineffective at halting progression. Thus, nonoperative treatment is not appropriate in early stages when one is attempting to preserve the native joint, except potentially on rare occasions for small-sized, medially located lesions, which may heal without surgery. ➢. Joint-preserving procedures should be attempted in early-stage lesions to save the femoral head. ➢. Cell-based augmentation of joint-preserving procedures continues to show promising results, and thus should be considered as an ancillary treatment method that may improve clinical outcomes. ➢. The outcomes of total hip arthroplasty in the setting of osteonecrosis are excellent, with results similar to those in patients who have an underlying diagnosis of osteoarthritis.

Mortality Rate and Mid-Term Outcomes of Total Hip Arthroplasty Using Dual Mobility Cups for the Treatment of Femoral Neck Fractures in a Middle Eastern Population

BACKGROUND

The dual mobility cups (DMCs) were shown to reduce dislocation rate following total hip arthroplasty for any etiology, including femoral neck fractures. No reported studies evaluating DMC results for femoral neck fracture in a Middle Eastern population were found in the literature.

METHODS

This study aims to look for mortality rate, clinical, and functional outcomes in a population having specific rituals involving extreme hip positions as part of their daily activities.

RESULTS

Of an initial sample of 174 patients (177 operated hips), 18 (10.3%) patients (20 hips) died after a mean of 39.6 ± 13.8 months (ranging from 2 to 49 months) with only 3 (1.7%) during the first post-operative year. Twelve patients (13 hips) were lost to follow-up and 19 patients (19 hips) had their radiological data incomplete. In the final sample of 125 patients (125 hips), no dislocation, aseptic loosening, or infection was encountered. The mean modified Hip Harris Score was of 94.8 ± 8.4. The mean modified Hip Harris Score of 40 patients who used to practice regularly oriental sitting position or prayers was 94.1 ± 3.1. After surgery, 36 of these 40 patients (90%) described their hip as "a forgotten hip." Multivariate analyses found correlation only between mortality and cardiovascular co-morbidities.

CONCLUSION

DMC implants showed excellent clinical and functional results. The majority of patients having rituals and customs involving extreme hip positions were able to resume their daily activities. The observed low mortality rate should incite future research to investigate its correlation with the use of DMCs.

Implant Survival and Patient-Reported Outcomes After Total Hip Arthroplasty in Young Patients

BACKGROUND

Younger patients are undergoing total hip arthroplasty (THA) for various conditions that affect the hip joint. This study evaluates the implant survival and long-term patient-reported outcomes of THA in patients aged 35 years or younger.

METHODS

Data were collected through a retrospective chart review, and follow-up surveys were conducted to determine implant survival and patient-reported outcomes. Kaplan-Meier survival analysis was performed to evaluate implant survival, and the hip disability and osteoarthritis outcome score (HOOS) was used to describe patient-reported outcomes. Descriptive statistics were used to summarize baseline and follow-up data, and univariate and multivariate analyses were used to compare implant survival and patient-reported outcomes.

RESULTS

This study included 400 patients (548 THAs). The average age at the time of surgery was 27 (range: 8-35) years, and the mean time to follow-up was 14 (range: 2-29.7) years. The 10- and 20-year implant survival was 87% and 61%, respectively. Implant survival differed based on primary diagnosis (P = .05), and it was significantly better in patients aged 25 years or older at the time of surgery, male patients, and patients with ceramic-on-ceramic or ceramic-on-plastic implants (P < .05). Mean HOOS scores at follow-up were 86 for pain, 84 for symptoms, 86 for ADLs, and 77 for sports. All HOOS scores were significantly worse after revision THA (P < .01).

CONCLUSION

Young patients have good implant survival and favorable long-term outcomes after THA. There are several predictors of implant survival and patient-reported outcomes after THA in young patients.

Femoral revision with primary cementless stems: a systematic review of the literature

The use of primary cementless stems in femoral revision has gained popularity, but no clear consensus about the correct indication is still present. The aim of our systematic review is to: (1) summarize the available literature focused on the use of cementless primary stem in revision total hip arthroplasty (THA); (2) evaluate whether the use of cementless primary stems could represent a feasible option in hip revision; (3) define the proper indication of this surgical approach. A systematic literature review was performed about the use of cementless primary stems in revision THA. The PRISMA 2009 checklist was considered to edit our review. A total of nine articles were included. The current evidence is primarily Level IV. A total of 439 patients (454 hips) underwent THA revision with primary cementless stem. Partial cementless porous coated stems were used in 246 hips (54.2%). The majority of patients were affected by type I or II Paprosky femoral defects. The mean stem-related survival rate is 95.6% ± 3.8 with a mean follow-up of 4.7 years ± 1.3. Poor standardization of methodological analysis was observed. Current literature shows lacking evidence about primary cementless stems in revision THA. Despite these limitations, we can affirm that primary cementless stems in femoral revision surgery represent a viable option in selected patients. The proper indication is a patient with femoral Paprosky defect types I or II, with low number of previous surgeries and a previous cementless stem.

Cardiovascular and Cerebrovascular Events Are Associated With Nontraumatic Osteonecrosis of the Femoral Head

BACKGROUND

Endothelial dysfunction has been identified as an etiologic factor for osteonecrosis of the femoral head (ONFH) and major adverse cardiovascular and cerebrovascular events (defined as major cardiovascular disease [CVD] and cerebrovascular accident [CVA]). However, the incidence of major adverse cardiovascular and cerebrovascular events in patients with nontraumatic ONFH and any association between the two diagnoses remain unclear.

QUESTIONS/PURPOSES

We compared a large cohort of patients with nontraumatic ONFH and a matched control group without this diagnosis and (1) examined the frequency and hazard ratio (HR) of major adverse cardiovascular and cerebrovascular events in both groups adjusted for age, sex, socioeconomic status, and associated comorbidities (which we defined as the adjusted HR), (2) determined whether any association of ONFH and major adverse cardiovascular and cerebrovascular events was stable after adjusting for confounding variables, and (3) compared the occurrence of major adverse cardiovascular and cerebrovascular events with time in both groups.

METHODS

A population-based cohort with a 14-year dataset period (1997-2010) from the Taiwan National Health Insurance Research Database was used for this retrospective study. The database includes a greater than 99.5% Asian population randomly selected from more than 23 million citizens and foreigners residing in Taiwan for longer than 6 months. A total of 1562 patients with nontraumatic ONFH were identified from a population of one million patients in the database after excluding initially concomitant diagnoses of major CVD and CVA. The comparison group (n = 15,620) without ONFH was analyzed in a one-to-10 ratio by matching the study cohort based on age, sex, income, and urbanization.

RESULTS

The patients with ONFH had a higher frequency of major adverse cardiovascular and cerebrovascular events than their counterparts without ONFH (19% versus 14%; p < 0.001). The patients with ONFH had 1.34- and 1.27-fold adjusted HRs for occurrence of major CVD and CVA as compared with the normal population (95% CI, 1.11-1.61, p = 0.002, and 95% CI, 1.09-1.47, p = 0.002, respectively). Sensitivity analysis showed a consistent association between ONFH and major adverse cardiovascular and cerebrovascular events after controlling for potentially relevant confounding variables such as hypertension and diabetes. After adjusting for potential confounders including surgery and medications, ONFH remained independently associated with major CVD (adjusted HR, 1.51, 95% CI 1.09-2.03, p = 0.026) and CVA (adjusted HR, 2.44, 95% CI 1.69-3.51, p < 0.001), apart from age older than 65 years and traditional atherosclerotic risk factors. The cumulative incidence of major adverse cardiovascular and cerebrovascular events also was higher in the ONFH group than the non-ONFH group (30.3% vs 23.1% at the end of followup, p < 0.001).

CONCLUSIONS

Patients with ONFH have a strong association with major adverse cardiovascular and cerebrovascular events as compared with the normal population, suggesting a potential common pathway involving endothelial dysfunction. In view of this association in the relatively young population with ONFH, it is important to closely monitor these patients, treat relevant comorbidities early, and investigate preventative measures for these major adverse events.

LEVEL OF EVIDENCE

Level III, prognostic study.

Early results of total hip arthroplasty using dual-mobility cup in patients with osteonecrosis of the femoral head

INTRODUCTION

Osteonecrosis of the femoral head (ONFH) remains a therapeutic challenge for patients undergoing total hip arthroplasty (THA). The majority of these patients are young with high functional demand, and show an increased risk of dislocation following surgery than patients with osteoarthritis. The use of double mobility cup (DMC) has been linked with lower rates of complications when compared to conservative cups; however, the literature is scarce over DMC results in patients with ONFH. The aim of the study is to report the early outcomes of patients with ONFH treated with THA-DMC.

MATERIALS

A retrospective analysis of patients suffering from ONFH who underwent THA using DMC (THA-DMC) from 2006 to 2015 were evaluated for functional status and risk of post-operative complications. Thirty THA-DMC in 26 patients with a mean follow-up of 51 months were evaluated clinically (modified Hip Harris Score) and radiologically.

RESULTS

The mean age of the included patients was 54.9 years. At final follow-up, the mean modified Hip Harris score was 98.7 ± 2.7 and no dislocation episodes or revision surgeries were recorded. The radiological assessment revealed no signs of migration/tilting, radiolucent lines, periprosthetic osteolysis or heterotopic ossification over the DMC component and the femoral stem. The survival rate over 51 months of follow-up was 100%.

DISCUSSION

The use of the new generation of dual mobility cup in patients with ONFH showed excellent functional early results with no major complications such as dislocation.

The effect of the anterior boundary of necrotic lesion on the occurrence of collapse in osteonecrosis of the femoral head

PURPOSE

The location of the necrotic lesion is one of the important factors for collapse in osteonecrosis of the femoral head (ONFH). The significance of anterior localization has been little studied. This study evaluated the effects of anterior boundary of a necrotic lesion on collapse.

METHODS

We reviewed the outcomes of 113 consecutive non-collapsed asymptomatic hips in 98 ONFH patients with mean follow-up of 4.7 years (2.0-11.8) after the initial magnetic resonance (MR) imaging. The presence or absence of collapse was investigated using follow-up radiographs. The location of the anterior boundary of a necrotic lesion was assessed using the anterior necrotic angle between the midline of the femoral neck shaft and the line passing from the femoral head centre to the anterior boundary on mid-oblique MR imaging. Multivariate analysis was performed to identify risk factors for collapse, and further analyses were executed according to the lateral boundary of the necrotic lesion.

RESULTS

During the follow-up period, collapse was confirmed in 61 hips (54.0%). Multivariate analysis revealed that the anterior necrotic angle was independently associated with collapse as well as the lateral boundary of the necrotic lesion. When the lateral boundary was located at the middle third of weight-bearing portion (32 hips), that was generally categorized as a low risk of collapse, all five cases with anterior necrotic angle ≥ 79° developed collapse, whereas only one of 27 cases (3.7%) with an anterior necrotic angle < 79° developed collapse (p < 0.0001).

CONCLUSIONS

This study indicates that ONFH patients with anterior localization of a necrotic lesion can develop collapse even if the necrotic lesion is medially located.

Does the Additional Articulation in Retrieved Bipolar Hemiarthroplasty Implants Decrease Trunnionosis Compared to Total Hip Arthroplasty?

BACKGROUND

Trunnionosis at the modular head-neck taper interface in metal-on-polyethylene total hip arthroplasty (MoP THA) has been shown to occur, and represents a potential mode of MoP THA failure. The purpose of the present investigation is to elucidate differences in fretting and corrosion at the head-neck taper interface of prostheses retrieved from bipolar hemiarthroplasty (BH) and MoP THA.

METHODS

A retrieval analysis of BH and MoP THA prostheses featuring a single taper design from a single manufacturer and in vivo for a minimum 2 years was performed. Fifteen femoral heads of 28-mm diameter and corresponding femoral stems retrieved from BH were compared with MoP THA implants matched based on time in vivo and head length (28 mm, -3 mm to 28 mm, +8 mm). Fretting and corrosion damage scoring was completed under stereomicroscopic visualization.

RESULTS

Femoral head bore tapers retrieved from BH exhibited decreased overall fretting (P = .02), when compared to those retrieved from MoP THA. Total corrosion scores for all retrieved implants were positively correlated with implantation time (ρ = 0.54, P < .02).

CONCLUSION

Femoral heads retrieved from BH exhibit decreased fretting damage compared to those retrieved from MoP THA. The added articulation in BH implants may decrease torque produced at the head-neck taper junction, thereby decreasing fretting. Increased fretting damage in implants from MoP THA is not associated with increased corrosion in 28-mm heads of this taper design. The longer a BH or MoP THA prosthesis is implanted, the greater the risk of damage due to corrosion.

Outcomes of dual mobility components in total hip arthroplasty

Aims

Instability remains a challenging problem in both primary and revision total hip arthroplasty (THA). Dual mobility components confer increased stability, but there are concerns about the unique complications associated with these designs, as well as the long-term survivorship.

Materials and Methods

We performed a systematic review of all English language articles dealing with dual mobility THAs published between 2007 and 2016 in the MEDLINE and Embase electronic databases. A total of 54 articles met inclusion criteria for the final analysis of primary and revision dual mobility THAs and dual mobility THAs used in the treatment of fractures of the femoral neck. We analysed the survivorship and rates of aseptic loosening and of intraprosthetic and extra-articular dislocation.

Results

For the 10 783 primary dual mobility THAs, the incidence of aseptic loosening was 1.3% (142 hips); the rate of intraprosthetic dislocation was 1.1% (122 hips) and the incidence of extra-articular dislocation was 0.46% (41 hips). The overall survivorship of the acetabular component and the dual mobility components was 98.0%, with all-cause revision as the endpoint at a mean follow-up of 8.5 years (2 to 16.5). For the 3008 revision dual mobility THAs, the rate of aseptic acetabular loosening was 1.4% (29 hips); the rate of intraprosthetic dislocation was 0.3% (eight hips) and the rate of extra-articular dislocation was 2.2% (67 hips). The survivorship of the acatabular and dual mobility components was 96.6% at a mean of 5.4 years (2 to 8). For the 554 dual mobility THAs which were undertaken in patients with a fracture of the femoral neck, the rate of intraprosthetic dislocation was 0.18% (one hip), the rate of extra-articular dislocation was 2.3% (13 hips) and there was one aseptic loosening. The survivorship was 97.8% at a mean of 1.3 years (0.75 to 2).

Conclusion

Dual mobility articulations are a viable alternative to traditional bearing surfaces, with low rates of instability and good overall survivorship in primary and revision THAs, and in those undertaken in patients with a fracture of the femoral neck. The incidence of intraprosthetic dislocation is low and limited mainly to earlier designs. High-quality, prospective, comparative studies are needed to evaluate further the use of dual mobility components in THA. Cite this article: Bone Joint J 2018;100-B:11–19.

[Use of dual mobility cups for revision hip arthroplasty]

The dual mobility cup (DMC) is an increasingly important tool not only in primary but also in revision total hip arthroplasty to prevent dislocation and eventually reduce postoperative complication rates. Various studies have shown survival rates with DMCs of up to 100% with an average dislocation rate of less than 1.5% after primary hip arthroplasty and a follow-up of 10 years. In revision surgery, survival rates of up to 99% were reported with dislocation rates between 0 and 10% after an average of 5 years after implantation. This article is intended to provide an overview of the principle and function of DMCs. Furthermore, indications as well as complications are presented.