Instability after total hip arthroplasty

Enhancing recovery and reducing readmissions: The impact of remote monitoring on acute postoperative care in outpatient total joint arthroplasty

Introduction

Outpatient total joint arthroplasty (TJA) is gaining popularity in the United States. With a shift towards value-based healthcare and bundled payment models, the importance of safe discharge after TJA is pertinent in reducing readmissions and subsequent cost of care. However, many acute issues or complications may not occur until after discharge which can result in emergency department visits and readmission. Our study aims to characterize the effect of remote monitoring devices on acute postoperative recovery in TJA discharged within 24 h. We hypothesized there would be a decreased readmission rate in the remote home monitoring cohort.

Methods

This prospective cohort compared 50 outpatient TJAs (primary total hip and total knee replacements) defined as discharged within 24 h with a remote home monitoring device to 50 outpatient TJAs who did not receive remote monitoring. Demographics, hospital length of stay, American Society of Anesthesiology scores, and Charlson Comorbidity Index were compared with no significant difference observed between cohorts (p > 0.05). Patients' vital signs were transmitted to a virtual response center for up to 48 h after discharge. An on-call medical team reviewed the transmissions and if prompted, would contact the patient to troubleshoot and triage. Primary outcome was 30-day hospital readmissions rates, while 30-day ED visits and patient satisfaction scores for the remote home monitoring were measured as secondary outcomes.

Results

Within the remote monitoring cohort there was a 20 % incidence (10 patients) of abnormal vitals captured and 2 patients visited the ED, however there were no readmissions attributed to this group. Readmission rates and ED visits in the control non-monitored group were significantly higher at 12 % (p = 0.03), secondary to syncope, uncontrolled postoperative pain, cellulitis, hip dislocations, and postoperative fever. Of the patients who received remote monitoring, 14 % had trouble connecting the device to their smartphone, 44 % felt home monitoring helped in their care while recovering at home, 52 % made them feel safer, and 70 % would recommend this program.

Conclusions

Remote home monitoring with a virtual response team after outpatient TJA is a feasible way to mitigate readmissions in the acute postoperative period and increase patient satisfaction. Efforts to minimize costs should not be implemented at the expense of patients' health outcomes with a goal to find an appropriate balance between both agendas.

Level of evidence

Therapeutic Level III.

Early Prosthetic Hip Dislocation: Does the Timing of the Dislocation Matter?

BACKGROUND

Early dislocation following total hip arthroplasty (THA) is a common reason for revision. The purpose of this study was to determine if the acuity of the dislocation episode affects the risk of revision surgery.

METHODS

A retrospective review of a national, all-payer administrative database comprised of claims from 2010 to 2020 was used to identify patients who had a prosthetic hip dislocation at various postoperative time intervals (0 to 7, 7 to 30, 30 to 60, and 60 to 90 days). Of the 45,352 primary unilateral THA patients who had sufficient follow-up, there were 2,878 dislocations within 90 days. Dislocators were matched 1:1 based on age, sex, and a comorbidity index with a control group (no dislocation). Demographics, surgical indications, comorbidities, ten-year revision rates, and complications were compared among cohorts. Multivariable logistic regression analysis was performed to identify risk factors for revision THA following early dislocation.

RESULTS

Among matched cohorts, dislocation at any time interval was associated with significantly increased odds of subsequent 10-years revision (OR [odds ratio] = 25.60 to 33.4, P < .001). Acute dislocators within 7 days did not have an increased risk of all cause revisions at 10 years relative to other early dislocators. Revision for indication of instability decreased with time to first dislocation (<7 days: 85.7% versus 60 to 90 days: 53.9%). Primary diagnoses of posttraumatic arthritis (OR = 2.53 [1.84 to 3.49], P < .001), hip fracture (OR = 3.8 [2.53 to 5.72], P < .001), and osteonecrosis (OR = 1.75 [1.12 to 2.73], P = .010) were most commonly associated with revision surgery after an early dislocation.

CONCLUSIONS

Dislocation within 90 days of THA is associated with increased odds of subsequent revision. Early dislocation within 7 days of surgery has similar all cause revision-free survivorship, but an increased risk of a subsequent revision for instability when compared to patients who dislocated within 7 to 90 days.

Total hip arthroplasty outcomes in Ehlers-Danlos patients: data from the Statewide Planning and Research Cooperative System

INTRODUCTION

Ehlers-Danlos syndromes (EDS) are genetic connective tissue disorders affecting multiple organ systems that frequently result in connective tissue hyperlaxity and early osteoarthritis. Short- and long-term outcomes after primary total hip arthroplasty (THA) in this patient population remain poorly characterised. The primary purpose of this study is to compare postoperative outcomes and survivorship after primary THA in patients with and without EDS.

METHODS

The New York Statewide Planning and Research Cooperative System (SPARCS) database was queried for all patients undergoing primary elective THA between September 2009 and December 2020. Patients with EDS were identified using ICD9 and ICD10 diagnosis codes. Given the relatively low incidence of EDS in this patient population, the cohort was propensity-matched 1:10 to patients without diagnosis of EDS based on demographics characteristics and medical comorbidities as measured by the Elixhauser Comorbidity Index.

RESULTS

A total of 66 THA patients with and 660 without EDS were included in each group after 1:10 propensity-matching. There were no significant differences in baseline characteristics or THA indications. Early postoperative outcomes such as length of hospital stay and discharge disposition were similar. Emergency Room visits and inpatient readmission rates at 3 months postoperatively did not significantly differ between groups. Patients with EDS had a higher overall revision rate compared to those without (15.0% vs. 3.2%, p < 0.001). Revision free survival after primary THA in patients with EDS was significantly lower than those without EDS at 9-year follow-up. Cox proportional hazard regression demonstrated EDS patients had 7-times higher risk of revision (hazard ratio [HR] 7.43; 95% CI, 3.46-16.00; p < 0.001). Lastly, revision due to instability insignificantly trended higher in the EDS cohort (HR 2.29; 95% CI, 0.95-5.49; p = 0.063).

CONCLUSIONS

EDS patients undergoing primary THA have increased rate of all cause revision and demonstrate decreased revision free survival compared to non-EDS THA patients.

Post-traumatic Total Hip Arthroplasty After Acetabular Fractures: Benefits of the Hardinge Approach

Post-traumatic arthritis is a common sequelae after undergoing open reduction and internal fixation (ORIF) of acetabular fractures. This often necessitates conversion to total hip arthroplasty (THA) to help alleviate pain and improve function for these patients. Unfortunately, dislocation rates for post-traumatic THA have been alarmingly high especially when the posterior approach has been used. In the setting of prior soft tissue disruption, the theoretical risk of dislocation is even greater. Conversely, the lateral or the abductor-split approach (Hardinge) is associated with decreased dislocation rates. In this retrospective case series, we evaluated the dislocation rate of the Hardinge approach on patients who underwent THA after developing post-traumatic arthritis after acetabulum ORIF. All patients who matched CPT code 27132 (Repair, Revision, and/or Reconstruction Procedures on the Pelvis and Hip Joint), from January 2009 to December 2019, and treated by the senior author, were pulled from the electronic medical record at the University of Pittsburgh Medical Center. Thirty-one of the resultant 110 were treated with THA for post-traumatic arthrosis through a lateral, abductor-splitting Hardinge approach and met the inclusion criteria for further study. Our case series involves 31 patients who underwent post-traumatic THA through a Hardinge approach: the mean age at the time of index acetabular ORIF is 48.5 years, the mean age at the time of THA is 53.5 years, and the mean interval between ORIF and ultimate THA was five years. The mean length of follow-up after THA was 22.4 months. Overall, patients did well with an all-cause revision rate of 9.7%, with no revision performed for loosening of either the acetabular or femoral component. One patient developed an infection. No patient in our group sustained a dislocation, and all implants were stable without evidence of radiographic loosening at the final follow-up. This study found satisfactory results with patients undergoing THA via lateral or abductor split approach (Hardinge) for post-traumatic arthritis after acetabular ORIF. The use of a Hardinge approach for post-traumatic reconstruction of the hip may be protective against dislocation without increasing baseline risks in this difficult patient population.

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

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

Periprosthetic fracture following anterior approach or dislocation after posterior approach: which one is the lesser evil?

INTRODUCTION

The most common approaches in total hip arthroplasty (THA) have different complication profiles; anterior-approach (AA-THA) has an increased risk of periprosthetic fractures (PPF); posterior-approach (PA-THA) is associated with higher dislocation risk. However, the relative severity of one versus the other is unknown. This study aims to compare outcome of patients who suffered PPF after AA-THA with those that sustained dislocation after PA-THA.

METHODS

This is a retrospective, single-center, multi-surgeon, consecutive case-series of primary THA patients. In a cohort of 9867 patients who underwent THA, 79 fulfilled the approach-specific, post-operative complication criteria, of which 44 were PPF after AA-THA and 35 with dislocation after PA-THA (age 67.9 years (range: 38.0-88.1), 58.2% women). Outcome included complication- and revision- rates, and patient-reported outcomes including Oxford Hip Score (OHS).

RESULTS

At 5.8 years follow-up (range: 2.0-18.5), reoperation was more common in the dislocation after PA-THA group (23/35 vs. 20/44; p = 0.072). Change of surgical approach occurred in 15/20 of patients with PPF after AA-THA, but none in those with dislocation after PA-THA. Following re-operation, complication rate was greater in the PPF group (9/20 vs. 4/23; p = 0.049). At latest follow-up, OHS were superior in the PPF after AA-THA group [42.6 (range: 25.0-48.0) vs. 36.6 (range: 21.0-47.0); p = 0.006].

CONCLUSION

Dislocation following PA-THA is more likely to require revision. However, PPF following AA-THA requires more often a different surgical approach and is at higher risk of complications. Despite the increased surgical burden post-operative PROMs are better in the peri-prosthetic fracture group, especially in cases not requiring reoperation.

LEVEL OF EVIDENCE

III, case-control study.

Total Hip Arthroplasty After Proximal Femoral Nailing: Preoperative Preparation and Intraoperative Surgical Techniques

The combination of an aging population and increased utilization of total hip arthroplasty (THA) is leading to a higher incidence of conversion THA, defined as conversion from previous hip fracture surgery to THA. Conversion THA is a more technically challenging, time-consuming, and costly procedure compared to primary THA and frequently involve more medically complex patients. Thus, the aim of this review is to provide a rubric for surgeons to use when preparing for a conversion THA. We have assessed the compatibility of commonly available extraction devices with popular femoral nails. Furthermore, we review technical pearls for conversion THA including equipment planning, operative setup, intraoperative imaging, extraction sequencing, and troubleshooting commonly encountered obstacles.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevalence of groin pain after primary dual-mobility total hip arthroplasty

BACKGROUND

Instability remains a challenging problem following total hip arthroplasty (THA). Dual-mobility (DM) components are used with increasing frequency to mitigate this potential complication. As has been shown with larger metal-on-metal (MoM) THA, the larger size femoral head may pose an increased risk of groin pain. This study aims to evaluate the prevalence of groin pain following primary DM THA compared to other THA constructs.

METHODS

We identified 190 primary THAs (183 patients) performed with DM components at a single academic institution from 2008 to 2017. We retrospectively reviewed standardised patient questionnaires and the electronic medical record to determine the prevalence of groin pain. DM patients were compared to historical controls of 39 MoM hip resurfacing, 26 large-head MoM THA, and 217 conventional THA. Mean age was 64 years, 58% were female, mean body mass index was 30 kg/m², and mean follow-up was 3.5 years (range 2-8 years).

RESULTS

The prevalence of groin pain in patients with DM components was 5%, similar to the prevalence reported by patients with conventional THA (7%). There was a decreased prevalence of groin pain in DM patients compared to hip resurfacing (18%) and MoM THA (15%). Among the 9 DM patients with groin pain, 1 was treated with iliopsoas injection, and 1 underwent radiofrequency ablation of the articular nerve.

CONCLUSIONS

This study documents a relatively low prevalence of groin pain among primary DM THA patients. This is comparable with historical controls of conventional THA and decreased compared to hip resurfacing and large head MoM THA.

Sarcopenia Is Associated with an Increased Risk of Postoperative Complications Following Total Hip Arthroplasty for Osteoarthritis

Sarcopenia is a state of catabolic muscle wasting prevalent in geriatric patients. Likewise, osteoarthritis is an age-related musculoskeletal disease affecting patients with similar demographics. Late-stage hip osteoarthritis is often treated with total hip arthroplasty (THA). As sarcopenia influences the surgical outcomes, this study aimed to assess the impact of sarcopenia on the outcomes of THA. A 1:3 matched case-control study of sarcopenic to control patients was performed using a large national database. In total, 3992 patients were analyzed. Sarcopenic patients undergoing THA were more likely to experience dislocation (odds ratio (OR) = 2.19, 95% confidence interval (CI) 1.21-3.91) within 1 year of THA. Furthermore, sarcopenic patients had higher urinary tract infection rates (OR = 1.79, CI 1.32-2.42) and a greater risk of 90-day hospital readmission (hazard ratio (HR) = 1.39, CI 1.10-1.77). Sarcopenic patients experienced more falls (OR = 1.62, CI 1.10-2.39) and fragility fractures (OR = 1.77, CI 1.34-2.31). Similarly, sarcopenic patients had higher day of surgery costs (USD 13,534 vs. USD 10,504) and 90-day costs (USD 17,139 vs. USD 13,394) compared with the controls. Ultimately, sarcopenic patients undergoing THA experience higher rates of postoperative complications and incur greater medical costs. Given the potential risks, orthopedic surgeons may consider treating or reducing the severity of sarcopenia before surgery.

How do dislocation rates differ between different approaches to total hip arthroplasty? A systematic review and meta-analysis

Background: Different surgical approaches for total hip arthroplasty (THA) exist, without predisposition when it comes to dislocation risk. The direct anterior approach (DAA) is thought to have reduced risk since soft tissue trauma is minimalized. Therefore, we assessed the dislocation risk for different surgical approaches, and the relative dislocation risk of DAA compared to other approaches. Methods: Six electronic databases were systematically searched for prospective studies reporting dislocation following THA. Proportion meta-analyses were performed to assess the dislocation rate for subgroups of the surgical approach. Meta-analysis for binary outcomes was performed to determine the relative risk of dislocation for the DAA compared to other approaches. Results: Eleven studies with 2025 patients were included (mean age 64.6 years, 44% male, mean follow-up 10.5 months), of which four studies were also used in the risk ratio meta-analysis. Overall dislocation rate was 0.79% (95% CI 0.37–1.69). Subgroup analyses showed that most dislocations occurred in the posterior approaches group (1.38%), however non-significant. Furthermore, the DAA emerged with a non-significant lower risk of dislocation (RR 0.37, 95% CI 0.05–2.46) compared to other surgical approaches. Conclusion: Current literature shows non-significant predisposition for a surgical approach to THA regarding dislocation risk. To what extent patient characteristics influence the risk of dislocation could not be determined. Future research should focus on this, as well as on the influence of a surgeon's experience with a specific approach.

Dissociation of polyethylene liners with the Depuy Pinnacle cup: a report of 26 cases

BACKGROUND

Although the Pinnacle Acetabular Hip System (DePuy Synthes) has demonstrated excellent survivorship results since it was first introduced in 2003, there have been a growing number of cases indicating that Pinnacle liners may be subject to a higher-than-expected rate of early dissociation failure. Between 2006 and 2020, our Centre received 212 retrieved Pinnacle liners from Western Australian hospitals. Of these, 26 were removed due to liner dissociation.

METHODS

To better understand the frequency and cause of this complication we assessed all retrieved Pinnacle acetabular components for type, damage modes and patient demographics. The leverage force required to dissociate Pinnacle liners was also measured and compared with another commonly used acetabular system, the Trident (Stryker Orthopaedics).

RESULTS

The estimated minimum incidence of liner dissociation from our data was 0.35%. Characterisation of dissociated Pinnacle cases (n = 26) revealed 73% were female with an average age of 59 compared to all retrieved Pinnacle cases (n = 212) where 58% were female with an average age of 66. Retrieval analysis indicated plastic deformation of the liner into an ovoid shape, signs of impingement on the rim postero-superiorly and shearing of the liner's anti-rotation tabs was common. Mechanical testing indicated that the dissociation strength of Pinnacle cups decreases at approximately 6.6 N/year in situ (p = 0.01).

CONCLUSION

The survival rate of Pinnacle acetabular cups is exceptional with only 5% revised at 10 years. However, surgeons should be aware of the clinical symptoms and high-risk demographics when assessing patients with polyethylene Pinnacle liners.

Dual Mobility Cup in Fractures of the Femoral Neck in Neuromuscular Disorders and Cognitive Dysfunction Patients above 60 years-old

Objectives

Dislocation rate of total hip arthroplasty (THA) can be as high as 20% for patients with fracture neck of femur, which is a disastrous complication in these vulnerable patients. Numerous techniques, including bipolar arthroplasty and constrained liner, have been adopted to minimize the risk of dislocation. We aimed to evaluate the role of dual mobility Cups in treating patients with fractures of the femoral neck with high risk of postoperative dislocation due to neuromuscular instability disorders.

Methods

A prospective cohort study was conducted (place is blinded as asked during submission), between 2016 and 2019, with a post-operative follow up period of two years. We included skeletally mature patients with femoral neck fractures having neuromuscular disorders and cognitive dysfunction who are candidates for THA above 60 years. Patients were then followed up clinically and radiographically at the clinic using Harris Hip Score (HHS) and x-rays at six weeks, six months, one year and two years postoperatively.

Results

Twenty patients (20 hips) with femoral neck fractures with high risk of postoperative dislocation due to neuromuscular instability disorders undergoing dual mobility cup were included. The mean age of patients was 70.5 ±6.42 years. There is highly significant difference between HHS preoperatively and postoperatively (six weeks, six months and one, two years) p<0.001.Infection occurred in one case (5 %), sciatic nerve injury occurred in one case (5%), and none of the patients had postoperative dislocation.

Conclusion

Dual mobility cup is effective in preventing early dislocation in patients suffered from fracture neck of femur with muscle weakness due to neurologic disorders.

Three dimensional analysis of hip joint reaction force using Q Hip Force (AQHF) software: Implication as a diagnostic tool

Assessment of hip joint reaction force (JRF) is one of the analytical methods that can enable an understanding of the healthy walking index and the propensity towards disease. In this study, we have designed software, Analysis Q Hip Force (AQHF), to analyze the data retrieved from the mathematical equations for calculating the JRF and ground reaction force (GRF) that act on the hip joint during the early part of the stance phase. The stance phase is considered the least stable sub-phase during walking on level ground, and the gait stability is sequentially minimized during walking on elevated ramps. We have calculated the JRF and GRF values of walking stances on varied inclinations. The data obtained from these calculations during walking on elevated ramps were exported from mathematical equations to Q Hip Force software as two separate values, namely the JRF data and GRF data of the hip joint. The Q Hip Force software stores the two reaction force data in a text file, which allows the import and easy readability of the analyzed data with the AQHF application. The input and output data from the AQHF software were used to investigate the effect of different walking ramps on the magnitude of the hip JRF and GRF. The result of this study demonstrates a significant correlation between the JRF/GRF values and healthy walking indices till a ramp elevation of 70°. The software is designed to calculate and extrapolate data to analyze the possibility of stress in the hip joint. The framework developed in this study shows promise for preclinical and clinical applications. Studies are underway to use the results of JRF and GRF values as a diagnostic and prognostic tools in different diseases.

Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation

INTRODUCTION

Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA.

METHODS

A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3).

RESULTS

There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%).

DISCUSSION

Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.

Implant and patient survival rates using Exeter Trauma Stem hemiarthroplasty in fracture neck of femur patients: The largest study to date

INTRODUCTION

Exeter Trauma Stems (ETS) femoral hemiarthroplasties are based on Exeter THR stems with a few design changes. Little has been published on ETS survival rates to justify their high cost compared to other cheaper implants. This is the largest prospective study to assess ETS implant failure-free survival rates in fracture neck of femur patients (NOF). This non-developing-centre study examined whether these design differences have altered implant survival (compared with Exeter THR's published survival data).

METHODS

Data were prospectively collected by independent audit officers. Dislocation, periprosthetic fracture, re-admission with severe hip pain, deep infection and revision surgery were considered events of interest in implant failure-free survival.

RESULTS

This study assessed 1,123 ETS stems (36 patients received bilateral ETS) in NOF patients. The mean patient age at the time of operation was 83 years (range; 49 - 102 years). The mean observation period was 2.5 years (range; 0 days - 8 years). Only 29 implants failed. All failure events were reported within the first year. Stem failure-free survival was 97.2% at eight years (CI 95.9% - 98%). Dislocation occurred in 10 patients (1%), periprosthetic femoral fracture in 4 (0.4%), and deep infection in 11 patients (1.2%). Patient survival rates were 75% and 48% at one and five years respectively.

CONCLUSION

ETS has high implant failure-free survival rates when used in hip fractures. ETS design changes have not altered ETS survival when used in hip fractures compared with the published literature of Exeter THR stem when used as a treatment for OA. Exeter Trauma Stems in NOF patients might last these elderly patients their entire short lifetime.

Inpatient dislocation after primary total hip arthroplasty: incidence and associated patient and hospital factors

INTRODUCTION

Inpatient dislocation following total hip arthroplasty (THA) may incur substantial financial penalties for hospitals in the United States. However, limited studies report on current incidence and variability of dislocations. We utilised a large national database to evaluate inpatient hip dislocation trends regarding: (1) yearly incidences; (2) lengths of stay (LOS); (3) demographic factors; and (4) hospital metrics.

METHODS

The National Inpatient Sample was queried from 2012 to2016 for primary THA patients (n = 1,610,155), identifying 2490 inpatient dislocations. Various patient demographics and hospital characteristics were assessed. Multivariate regression analyses were conducted to identify dislocation risk factors.

RESULTS

Dislocation rates increased from 0.11% in 2012 to 0.18% in 2016 (p < 0.001). Dislocated patients experienced significantly longer LOS (p < 0.001). Patient demographic factors associated with dislocation were sex, race, Medicaid insurance, alcohol use disorder, psychosis, hemiparesis/hemiplegia, chronic renal failure, and obesity. Spinal fusion was not associated with inpatient dislocation. Dislocations were likeliest in the South and least likely in teaching hospitals.

CONCLUSION

Inpatient dislocation has increased in recent years. Optimised management and recognition of the patient and hospital factors outlined in this study may help decrease inpatient dislocation risks following THA, thus avoiding hospital reimbursement penalties for this preventable complication.

Novel Measure of Acetabular Cup Inclination and Anteversion During Total Hip Arthroplasty

PURPOSE

The purposes of the present research were to assess the accuracy and usability of the inertial navigation system (INS).

MATERIALS AND METHODS

The accuracy of the device navigation subsystem was assessed using benchtop testing. The usability was assessed through simulated use with surgeons. These results were compared to recent cadaveric results for the same system.

RESULTS

The navigation subsystem had an overall mean absolute error of 1.21° and a maximum absolute error across all devices of 4.79°. The device was found to be usable and to add an estimated 7 minutes to surgery time.

CONCLUSION

The INS uses a novel approach to provide the surgeon with accurate and fast acetabular cup inclination and anteversion angles during THA.

Dual-mobility versus Fixed-bearing in Primary Total Hip Arthroplasty: Outcome Comparison

Purpose

Use of dual mobility (DM) articulations can reduce the risk of instability in both primary and revision total hip arthroplasty (THA). Knowledge regarding the impact of this design on patient-reported outcome measures (PROMs) is limited. This study aims to compare clinical outcomes between DM and fixed bearing (FB) prostheses following primary THA.

Materials and Methods

All patients who underwent primary THA between 2011-2021 were reviewed retrospectively. Patients were separated into three cohorts: FB vs monoblock-D vs modular-DM. An evaluation of PROMs including HOOS, JR, and FJS-12, as well as discharge-disposition, 90-day readmissions, and revisions rates was performed. Propensity-score matching was performed to limit significant demographic differences, while ANOVA and chi-squared test were used for comparison of outcomes.

Results

Of the 15,184 patients identified, 14,652 patients (96.5%) had a FB, 185 patients (1.2%) had a monoblock-DM, and 347 patients (2.3%) had a modular-DM prosthesis. After propensity-score matching, a total of 447 patients were matched comparison. There was no statistical difference in the 90-day readmission (P=0.584), revision rate (P=0.265), and 90-day readmission (P=0.365) and revision rate due to dislocation (P=0.365) between the cohorts. Discharge disposition was also non-significant (P=0.124). There was no statistical difference in FJS-12 scores at 3-months (P=0.820), 1-year (P=0.982), and 2-years (P=0.608) between the groups.

Conclusion

DM bearings yield PROMs similar to those of FB implants in patients undergoing primary THA. Although DM implants are utilized more often in patients at higher-risk for instability, we suggest that similar patient satisfaction may be attained while achieving similar dislocation rates.

Acetabular Component and Liner Selection for the Prevention of Dislocation After Primary Total Hip Arthroplasty

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Primary total hip arthroplasty (THA) is a reproducible and efficacious procedure for patients with end-stage osteoarthritis; however, dislocation remains the most common cause of revision arthroplasty.

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Technological advancements in acetabular component design and liner options, in conjunction with a more comprehensive understanding of the spinopelvic factors that influence dislocation, will likely reduce the risk of dislocation and revision over time.

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The contemporary liner and shell options for primary THA, in order of increasing constraint and stability, include (1) neutral, (2) lateralized, (3) face-changing (oblique), (4) lipped (high-wall) with or without lateralization, (5) modular and anatomic dual-mobility, and (6) constrained options.

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Different liner designs can alter functional anteversion, inclination, and jump distance, and can be used to minimize a single predictable dislocation vector (lipped [high-wall] liners) or multiple vectors of instability risk when the dislocation direction is unpredictable (dual-mobility liners).

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Liner selection should be based on the patient-specific risk of dislocation, including static anatomic (e.g., large anterior inferior iliac spine or greater trochanter morphology), dynamic anatomic (e.g., limited sitting-standing change in the sacral slope), and demographic or medical (e.g., neurocognitive disorders and obesity) risk factors.

Does timing of lumbar fusion affect dislocation rate after total hip arthroplasty?

Introduction

The impact of lumbar spinal fusion (LSF) on pelvic mobility and increased risk for THA dislocation are recognized. However, there is still controversy on whether THA should be performed prior or following LSF. This study aims to compare the rates of hip dislocation in patients undergoing THA prior to or following LSF.

Methods

We retrospectively reviewed 109 primary THA and LSF. There were 34 men and 75 women with a mean age of 66.9. The cohort was divided into 2 groups: 1) THA prior to lumbar fusion (n = 42) and 2) THA following lumbar fusion (n = 67). Radiographic parameters including acetabular component abduction, anteversion, pelvic incidence (PI), sacral slope, standing lumbar lordosis (LL) and PI-LL mismatch were determined for each patient. The surgical approach and THA parameters were also recorded and compared between the 2 groups. Patients with fracture, malignant disease, and prior hip hardware were excluded.

Results

The mean follow up was 14.7 months. Overall, 8 patients (7.3%) had a postoperative hip dislocation (0 in group 1 (0%), and 8 in group 2 (11.9%) (p = 0.022). The mean cup abduction and anteversion in patients that dislocated was 37.7° and 23.4° respectively while patients who did not dislocate had an average cup abduction of 37.6° (p = 0.970) and anteversion of 25.9° (p = 0.367). Patients who dislocated had decreased lumbar lordosis (p = 0.022) and higher PI-LL mismatch (p = 0.0004) compared to that did not dislocate. There were no other significant differences in the spinopelvic parameters between the 2 groups. Neither surgical approach nor dual mobility articulations use had a significant impact on postoperative dislocations.

Conclusion

Higher rates of hip dislocation were observed in patients undergoing primary THA following LSF. Dislocators had decreased lumbar lordosis and increased PI-LL mismatch. Patients who require both spinal fusion and THA should undergo hip arthroplasty first to minimize the risk of postoperative instability.

Instability Is the Most Common Indication for Revision Hip Arthroplasty in the United States: National Trends From 2012 to 2018

Background

As primary total hip arthroplasty volume continues to increase, so will the number of revision total hip arthroplasty (rTHA) procedures. These complex cases represent a significant clinical and financial burden to the health-care system.

Methods

This was a retrospective review using the National Inpatient Sample. International Classification of Diseases, 9th and 10^th revision codes were used to identify patients who underwent rTHA and create cohorts based on rTHA indications from 2012 to 2018. National and regional trends for length of stay (LOS), cost, and discharge location were evaluated.

Results

A total of 292,250 rTHA procedures were identified. The annual number of rTHA procedures increased by 28.1% from 2012 to 2018 (37,325 to 47,810). The top 3 indications for rTHA were instability (20.4%), aseptic loosening (17.8%), and infection (11.1%). Over the study period, the proportion of patients discharged to skilled nursing facility decreased from 44.2% to 38% (P < .001). Hospital LOS decreased on average from 4.8 to 4.4 days (P < .001). Infections had the highest average LOS (7.3 days) followed by periprosthetic fractures (6.5 days). Hospital costs decreased over the study period, from $25,794 to $24,555 (P < .001). The proportion of rTHA cases performed at urban academic centers increased (58.0% to 75.3%, P < .001) while the proportion performed at urban nonacademic centers decreased (35.5% to 19.4%, P < .001).

Conclusion

Instability was the most common indication for rTHA between 2012 and 2018. The proportion of rTHA performed in urban academic centers has increased substantially, away from urban nonacademic centers. While cost and LOS have decreased, significant geographic variability exists.

Assessment of Acetabular Component Anteversion after Total Hip Arthroplasty: Comparison of Anteroposterior and Cross-Table Lateral Radiographs with Computed Tomography Scans

Background

Several methods of measurement of anteversion of acetabular components after total hip arthroplasty (THA) have been described in the literature using plain radiographs or computed tomography (CT) scans. None of these have proved to be the gold standard. We aimed to study the correlation between the CT and radiographic methods of calculation of acetabulum anteversion.

Methods

CT scans of the pelvis, anteroposterior (AP) and cross-table lateral (CL) radiographs were obtained in 60 patients who underwent THA two weeks after surgery. Anteversion was measured using Widmer method and Liaw method on AP radiographs, and the ischiolateral method on CL radiographs. Anteversion measured on the CT scan was taken as the reference anteversion and the above measurements were analysed for correlation with the measurements on CT scan. Intraclass correlation coefficients (ICCs) were calculated for both intra- and interobserver reliability.

Results

Mean acetabular version on CL radiographs was 53.1 ± 10.7. Mean version on AP radiographs by Widmer method was 21.4 ± 3.6 and by Liaw method was 20.3 ± 4.8. Mean version on CT scans was 26.02 ± 6.8. There was a good correlation between the acetabular version on CT scans with the version on AP radiographs by Widmer method (r = 0.78, p < 0.001) and Liaw method (r = 0.87, p < 0.001). Good correlation was seen between the acetabular version on CL radiographs and CT scans (r = 0.91, p < 0.001). Also, a good correlation was observed between the acetabular version measurements on CL radiographs and AP radiographs by Widmer method (r = 0.81, p < 0.001) or Liaw method (r = 0.70, p < 0.001). Excellent inter- and intraobserver reliability were seen for all the measurements.

Conclusions

Calculation of acetabular component version on AP views as well as CL views of plain radiographs showed a strong correlation with the version measurements on CT scans. Good correlations were observed between different techniques of measurement on radiographs. Therefore, all these measurements can be valid methods for assessment of anteversion.

Use of elevated liners in primary total hip arthroplasty: a systematic review of the literature

PURPOSE

Instability remains one of the most frequent complications requiring revision surgery after primary total hip arthroplasty (THA). Elevated liners are often utilized to reduce the risk of dislocation; however, the literature is inconclusive, with no systematic reviews summarizing the data. Thus, this systematic review aimed to establish a consensus for the efficacy of elevated liners in primary THA by determining rates of overall revision and revision specifically for recurrent dislocation.

MATERIALS AND METHODS

This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eligible randomized-controlled trials and observational studies reporting on the use of elevated liners in primary total hip arthroplasty were identified through May 2020. A random effects model meta-analysis was conducted, and the I² statistic was used to assess for heterogeneity.

RESULTS

Eight studies met inclusion criteria, and overall, 26,507 patients undergoing primary THA with use of an elevated liner were included. In aggregate, the most common cause of revision was recurrent hip dislocation (1.3%, N = 82/6,267) followed by joint infection (1.2%, N = 45/3,772) and acetabular loosening (0.3%, N = 10/3,772). Notably, elevated liners were associated with a lower risk of revision for recurrent dislocation compared to neutral liners (HR: 0.74; 95% CI: 0.55-1.00; p = 0.048).

CONCLUSION

This review found that after primary THA with the use of elevated liners, hip dislocation and prosthetic joint infection continued to be the most frequent reasons for revision surgery. However, elevated liners had a lower risk of revision for recurrent dislocation compared to neutral liners.

Risk Factors for Revision After Early and Delayed Total Hip Arthroplasty Dislocation. An Analysis of Lithuanian Arthroplasty Register

Introduction: Despite relatively low incidence, dislocation remains one of the main reasons for total hip arthroplasty (THA) revision. It is a devastating complication for a patient and a surgeon, and has high burden on the healthcare system. The aim of the present study was to assess and compare the risk factors for revision after early and delayed THA dislocations.

Methods: Some 3403 THA through posterior approach for primary osteoarthritis were retrospectively studied in the Lithuanian Arthroplasty Register from 2011 to 2018. Three months after THA was the splitting time between the first event of early and delayed dislocations. Revision was set as outcome measure. Gender, affected side, number of dislocations, femoral head and neck size, and prosthesis fixation type were tested as risk factors for revision after early and delayed THA dislocations.

Results: Dislocation occurred in 108 patients (3.2%), and 26 cases (0.8%) required revision. Men had statistically significant higher risk for revision due to early dislocation [hazard ratio (HR) 4.7; 1.3-17.7 confidence interval (CI)] and considerably lower risk for revision due to delayed dislocation (HR 0.5; 0.1-1.7 CI). The left side THA had twice the risk as compared to the right in the early settings (HR 2.1; 0.6-6.9 CI) which equalized after three months (HR 1.1; 0.4-3.1 CI). Some 32 mm femoral head had significantly lower risk in the early group as compared to 28 mm head (HR 0.3; 0.1-0.5 CI). Short head was associated with increased risk for revision after early dislocation, although, not statistically significant. Prosthesis fixation type was not a risk factor for revision surgery neither after early nor after delayed dislocation.

Conclusion: The unique finding of gender separation was found -- men tend for revision after early dislocation and women after delayed dislocation. In early stage, additional precautions should be considered when 28 mm short metal heads are used.

Acetabular and Femoral Component Positioning Using Direct Anterior Approach Versus Posterior Approach in Total Hip Arthroplasty

PURPOSE

Direct anterior approach (DAA) has recently become popular in total hip arthroplasty (THA). However, irrespective of the surgical approach used, component malposition is an important factor affecting function and complications after THA. This study aims to compare component positioning on the femoral and acetabular side between DAA and posterior approach (PA) to the hip joint. We hypothesized that the two approaches are similar in terms of component positioning.

METHODS

We prospectively studied 50 patients, matched according to age, sex, and body mass index, undergoing THA, divided non-randomly into 2 groups. Group 1 comprised 25 patients (35 hips) undergoing THA using DAA and group 2 comprised 25 patients (25 hips) undergoing THA using PA. Ten patients from group 1 had simultaneous bilateral THA. Radiological parameters studied were acetabular inclination (AI), coronal femoral stem alignment (CFA), leg length difference (LLD), acetabular cup version (AV), and femoral stem version (FV).

RESULTS

There was no significant difference in AI, CFA, LLD, AV, and FV between the two groups. Excellent to good inter and intra-observer reliability expressed in terms of intraclass correlation coefficient (ICC) was noted for all the radiographic measurements.

CONCLUSION

Both DAA and PA for THA achieve comparable radiological component positioning. DAA may not provide any advantage over PA in terms of positioning of the prosthesis.

LEVEL OF EVIDENCE

Level II, non-randomized comparative study.

Outcomes of total hip arthroplasty using dual-mobility cups for femoral neck fractures: a systematic review and meta-analysis

OBJECTIVES

Femoral neck fractures (FNFs), with up to 15% mortality, are prominent orthopaedic emergencies. After treating FNFs, dislocation is another challenge increasing morbidity, mortality and treatment costs substantially. The emerging dual-mobility cup (DMC) may decrease dislocation rates following total hip arthroplasty (THA) for FNFs. We performed a systematic review of literature reporting dislocation and mortality rates with DMC-THA for the treatment of FNFs.

METHODS

2 authors independently searched PubMed (MEDLINE), Google Scholar and Cochrane library for studies reporting dislocation and mortality rates for FNFs treated with DMC-THA since inception up to January 2019. Data on outcomes of interest was extracted from all studies and assessed for eligibility for a meta-analysis.

RESULTS

Out of 522 search results, 18 studies were included in the systematic review and 4 in the meta-analysis. The mean rate of dislocation following DMC-THA for FNFs was found to be 1.87% ± 2.11, with a 1-year mortality rate of 14.0% ± 10.55. Results of meta-analysis showed that dislocation and 1-year postoperative mortality rates were significantly lower for DMC-THA with a risk ratio 0.31 (95% CI, 0.16-0.59; I² = 0%, p = 0.0003) and 0.55 (0.40, 0.77; I² = 0%, p = 0.003) respectively when compared to biploar hemiathroplasty (BHA).

CONCLUSIONS

The mean dislocation and mortality rates in DMC-THA are lower than previously reported rates for THA with single cup and comparable to unipolar and bipolar hemiarthroplasty. Further research involving randomised control trials to assess differences in outcomes, longevity and cost-effectiveness needs to be conducted to make recommendations for the use of DMC in treating FNFs.

Does Prosthetic or Bony Impingement Occur More Often in Total Hip Arthroplasty: A Dynamic Preoperative Analysis

BACKGROUND

Impingement is a leading cause for instability resulting in revision total hip arthroplasty (THA). Impingement can be prosthetic, bony, or soft tissue. The purpose of this study is to investigate, using a virtual simulation, whether bony or prosthetic impingement presents first in well-positioned THAs.

METHODS

Twenty-three patients requiring THA were planned for a ceramic-on-poly cementless construct using dynamic planning software. Cups were orientated at 45° inclination and 25° anteversion when standing. Femoral components and neck lengths were positioned to reproduce native anteversion and match contralateral leg length and offset. The type and location of impingement was then recorded with recreation of anterior and posterior impingement during standard and extreme ranges of motion (ROM).

RESULTS

In standard ROM, flexion produced both prosthetic and bony impingement and extension resulted in prosthetic impingement in models with lipped liners. In extreme ROM, anterior impingement was 78% bony in 32-mm articulations, and 88% bony in 36-mm articulations. Posterior impingement was 65% prosthetic in 32-mm articulations, and 55% prosthetic in 36-mm articulations. Dual mobility cups showed the greatest risk of posterior prosthetic impingement in hyperextension (74%).

CONCLUSION

In standard ROM, both bony and prosthetic impingement occurred in flexion, while prosthetic impingement occurred in extension in models with lipped liners. In hyperextension, prosthetic impingement was more common than bony impingement, and was exclusively the cause of impingement when a lip was used. In flexion, impingement was primarily bony with the use of a 36-mm head. The risk of posterior prosthetic impingement was greatest with dual mobility cups.

LEVEL OF EVIDENCE

3.

Posterior approach, fracture diagnosis, and American Society of Anesthesiology class III-IV are associated with increased risk of revision for dislocation after total hip arthroplasty: An analysis of 33,337 operations from the Finnish Arthroplasty Register

Background and objective:

Dislocation is one of the most common reasons for revision surgery after primary total hip arthroplasty. Both patient related and surgical factors may influence the risk of dislocation. In this study, we evaluated risk factors for dislocation revision after total hip arthroplasty based on revised data contents of the Finnish Arthroplasty Register.

Methods:

We analyzed 33,337 primary total hip arthroplasties performed between May 2014 and January 2018 in Finland. Cox proportional hazards regression was used to estimate hazard ratios with 95% confidence intervals for first dislocation revision using 18 potential risk factors as covariates, such as age, sex, diagnosis, hospital volume, surgical approach, head size, body mass index, American Society of Anesthesiology class, and fixation method.

Results:

During the study period, there were 264 first-time revisions for dislocation after primary total hip arthroplasty. The hazard ratio for dislocation revision was 3.1 (confidence interval 1.7–5.5) for posterior compared to anterolateral approach, 3.0 (confidence interval 1.9–4.7) for total hip arthroplasties performed for femoral neck fracture compared to total hip arthroplasties performed for osteoarthritis, 2.0 (confidence interval 1.0–3.9) for American Society of Anesthesiology class III–IV compared to American Society of Anesthesiology class I, and 0.5 (0.4–0.7) for 36-mm femoral head size compared to 32-mm head size.

Conclusions:

Special attention should be paid to patients with fracture diagnoses and American Society of Anesthesiology class III–IV. Anterolateral approach and 36-mm femoral heads decrease dislocation revision risk and should be considered for high-risk patients.

Mid-Term Survivorship of a Novel Constrained Acetabular Device

BACKGROUND

Recurrent instability after total hip arthroplasty is a difficult complication. In certain cases, a constrained acetabular device is needed to address these issues. The purpose of this study is to report the midterm outcomes and survivorship of a single novel constrained liner device.

METHODS

A retrospective review as performed on all procedures (except first stage exchange for infection) in which a Freedom Constrained (Zimmer Biomet, Warsaw, IN) liner was used between December 2003 and November 2016. Patients with 2-year minimum follow-up or failure were included, yielding a cohort of 177 patients. Procedures were 130 aseptic revisions, 40 reimplantations following infection eradication, and 7 complex primaries. The constrained mechanism was implanted in 46 hips (26%) to treat active instability and 131 hips (74%) for increased risk of instability and intraoperative instability. Patients had on average 3.4 previous surgeries.

RESULTS

With an average 7.1-year follow-up, 11 hips dislocated (6.2%), and 13 hips (7.3%) were revised for acetabular aseptic loosening, resulting in an overall constrained aseptic or mechanical failure rate of 13.6%. Nineteen hips (10.7%) failed from infection with 58% of these having had a previous infection. Patients with active instability had significantly higher failure for dislocation than patients who were at risk (15.2% vs 3%, P = .01). All-cause survival rate at 7 years was 74.8%, aseptic survival was 83.6%, and survival for instability was 91.8%.

CONCLUSION

Revision for instability remains challenging as many patients have had numerous previous surgeries and at-risk anatomy. Constrained inserts are one option to manage instability, but a high rate of recurrence can still occur.

Are Lipped Polyethylene Liners Associated with Increased Revision Rates in Patients with Uncemented Acetabular Components? An Observational Cohort Study

BACKGROUND

Recurrent dislocation after THA remains a serious complication that carries with it a high risk of revision surgery. Previous studies have shown reduced dislocation rates with the use of lipped polyethylene (PE) liners in modular uncemented acetabular components, but there may be increased wear because of impingement, which may lead to aseptic loosening in the longer term; whether the aggregate benefit of lipped PE liners outweighs the risks associated with their use remains controversial.

QUESTIONS/PURPOSES

We used data from the New Zealand Joint Registry to (1) compare Kaplan-Meier survival rates, (2) rates of revisions for dislocation between neutral and lipped PE liners, and (3) revision rates for aseptic loosening for the four most commonly used modular uncemented cups.

METHODS

We used data from the New Zealand Joint Registry (NZJR) to identify 31,247 primary THAs using the four most commonly used uncemented modular acetabular implants from January 1, 1999 to December 31, 2018. The lipped liner group comprised 49% males (9924 of 20,240) compared with 42% (4669 of 11,007) in the neutral group (p < 0.001); 96% (19,382 of 20,240) of patients in the liner group had OA versus 95% (10,450 of 11,007) in the neutral group (p < 0.001). There was no difference in other patient characteristics such as age (mean 66.9 years), BMI (mean 29 ± 6 kg/m) and American Society of Anesthesiologists grade. The mean follow-up was 5.1 years (SD 3.9) and longest follow-up 19.3 years. The NZJR has more than 96% capture rate and data entry is a mandatory requirement of members of the New Zealand Orthopaedic Association. Kaplan-Meier survival rates were compared between 20,240 lipped and 11,007 neutral PE liners. Highly cross-linked polyethylene was used in 99% of lipped liner cups and 85% of neutral liner cups. Associated hazard ratios were calculated using a Cox regression analysis with a Kaplan-Meier revision-free estimates plot.

RESULTS

The Kaplan-Meier survival at 10 years for lipped PE liners was 96% (95% confidence interval 95.4 to 96.2) and for neutral liners 95% (95% CI 94.7 to 95.9). After controlling for age, gender approach, femoral head size, and the use of image guidance, the all-cause revision risk was greater for neutral PE liners than that for lipped PE liners (HR 1.17 [95% CI 1.06 to 1.36]; p = 0.032). There was a higher risk of revision for dislocation in those with neutral PE liners than in those with lipped liners (HR 1.84 [95% CI 1.41 to 2.41]; p < 0.001) but no difference in the revision rate for aseptic acetabular component loosening (HR 0.85 [95% CI 0.52 to 1.38]; p = 0.511).

CONCLUSIONS

The use of a lipped PE liner is not associated with a higher rate of aseptic loosening in patients who undergo primary THA compared with a neutral PE liner. Lipped PE liners are associated with lower rates of dislocation and lower all-cause revision rates without any increased association with revision rates for wear and aseptic loosening.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Implant Survival of Constrained Acetabular Device in Primary Total Hip Arthroplasty Based on Data From the Finnish Arthroplasty Register

BACKGROUND

Constrained acetabular devices were developed to prevent dislocations after total hip arthroplasty (THA). However, the data on their success have been contradictory. In this study, we aimed to assess implant survival of the constrained acetabular device in primary THA based on the Finnish Arthroplasty Register data.

METHODS

A total of 373 primary THAs with constrained acetabular devices inserted from 2006 to 2017 were included. A reference group was formed on a 1:3 basis and matched for age, sex, and diagnosis, consisting of 1118 conventional THAs. Implant survival estimates using death as a competing risk were assessed with revision for any reason and for any aseptic reason as the endpoints. The Cox multiple regression models were adjusted for age, sex, and diagnosis. The mean follow-up time was 3.3 (0-12.4) years for the constrained device group and 3.8 (0-12.0) years for the reference group.

RESULTS

Overall, there were 21 revisions in the constrained device group and 49 in the reference group. The 8-year survivorship for any reason was 94% (confidence interval [CI]: 91-96) for the constrained device group and 93% (CI: 89-97) for the reference group. With revision for any aseptic reason as the endpoint, the 8-year survivorships were 97% (CI: 95-99) and 94% (CI: 90-98), respectively. During the first 1.5 years, the constrained acetabular device group had a similar revision risk (hazard ratio: 1.09 [CI: 0.57-2.07], P = .8) to that of the reference group.

CONCLUSION

The constrained acetabular device had good survival in primary THA, and our results support its continued use even in high-risk patients.

Radiological Imaging Evaluation of the Failing Total Hip Replacement

Total hip replacements (THR) have been performed in the UK from the 1960s and since then we have seen surgical techniques, the design of implants, and imaging modalities rapidly develop. This paper will aim to review the different complications and imaging appearance which help to evaluate each problem. As for all investigations for bone and joints, a radiograph is the first imaging to be performed for any patient with a THR and can detect a majority of complications. CT is relatively low-cost, simple to perform and easily available making it an excellent tool to supplement radiographs when trying to evaluate a hip prosthesis. Single photon emission computed tomography with CT (SPECT-CT) is an emerging modality which has shown to combine the sensitivity that bone scintigraphy offers with the high specificity of CT. SPECT imaging also has the advantage of showing the bone's metabolic activity and is less prone to metal artifact than Magnetic resonance imaging (MRI). MRI has evolved to become an important diagnostic tool for the evaluation of THR in the post-operative period. Optimized pulse sequences and metal artifact reduction techniques have made MRI a useful tool in diagnosis of soft tissue abnormalities and is particularly useful in identifying adverse local tissue reactions in metal on metal implants. CT and MRI are accurate in identifying the diagnosis of most causes of THR complications except infection. Research confirms that leukocyte-marrow scintigraphy is the modality of choice for accurately diagnosing prosthetic joint infection and reassures us of its superiority over other nuclear medicine imaging. However, due to the limited availability and increased costs when performing leukocyte-marrow scintigraphy, CT and SPECT-CT would be a more preferred option when suspecting prosthesis infection. Ultrasound (US) has a limited role in the assessment of most THR complications but can be useful to identify peri-prosthetic fluid collections and the presence of soft tissue sinus tracts. Being aware of the imaging modalities that are available to orthopedic surgeons, and discussing these challenging cases with specialist radiologists will enable optimal management of THR complications.

Is Parkinson's Disease Associated with Increased Mortality, Poorer Outcomes Scores, and Revision Risk After THA? Findings from the Swedish Hip Arthroplasty Register

BACKGROUND

Neurological conditions such as Parkinson's disease are commonly accepted as a risk factor for an increased likelihood of undergoing revision surgery or death after THA. However, the available evidence for an association between Parkinson's disease and serious complications or poorer patient-reported outcomes after THA is limited and contradictory.

QUESTIONS/PURPOSES

(1) Do patients with a preoperative diagnosis of Parkinson's disease have an increased risk of death after elective THA compared with a matched control group of patients? (2) After matching for patient- and surgery-related factors, do revision rates differ between the patients with Parkinson's disease and the matched control group? (3) Are there any differences in patient-reported outcome measures for patients with Parkinson's disease compared with the matched control group?

METHODS

Data were derived from a merged database with information from the Swedish Hip Arthroplasty Register and administrative health databases. We identified all patients with Parkinson's disease who underwent THA for primary osteoarthritis between January 1, 1999 and December 31, 2012 (n = 490 after exclusion criteria applied). A control group was generated through exact one-to-one matching for age, sex, Charlson comorbidity index, surgical approach, and fixation method. Risk of death and revision were compared between the groups using Kaplan-Meier and log-rank testing. Patient-reported outcome measures (PROMs), routinely recorded as EQ-5D, EQ VAS, and pain VAS, were measured at the preoperative visit and at 1-year postoperatively; mean absolute values for PROM scores and change in scores over time were compared between the two groups.

RESULTS

The risk of death did not differ at 90 days (control group risk = 0.61%; 95% CI = 0.00-1.3; Parkinson's disease group risk = 0.62%; 95% CI = 0.00-1.31; p = 0.998) or 1 year (control group = 2.11%; 95% CI = 0.81-3.39; Parkinson's disease group = 2.56%, 95% CI = 1.12-3.97; p = 0.670). At 9 years, the risk of death was increased for patients with Parkinson's disease (control group = 28.05%; 95% CI = 22.29-33.38; Parkinson's disease group = 54.35%; 95% CI = 46.72-60.88; p < 0.001). The risk of revision did not differ at 90 days (control group = 0.41%; 95% CI = 0.00-0.98; Parkinson's disease group = 1.03%; 95% CI = 0.13-1.92; p = 0.256). At 1 year, the risk of revision was higher for patients with Parkinson's disease (control group = 0.41%; 95% CI = 0.00-0.98; Parkinson's disease group = 2.10%; 95% CIs = 0.80-3.38; p = 0.021). This difference was more pronounced at 9 years (control group = 1.75%; 95% CI = 0.11-3.36; Parkinson's disease group = 5.44%; 95% CI = 2.89-7.91; p = 0.001) when using the Kaplan-Meier method. There was no difference between the control and Parkinson's disease groups for level of pain relief at 1 year postoperatively (mean reduction in pain VAS score for control group = 48.85, SD = 20.46; Parkinson's disease group = 47.18, SD = 23.96; p = 0.510). Mean change in scores for quality of life and overall health from preoperative measures to 1 year postoperatively were smaller for patients in the Parkinson's disease group compared with controls (mean change in EQ-5D scores for control group = 0.42, SD = 0.32; Parkinson's disease group = 0.30, SD = 0.37; p 0.003; mean change in EQ VAS scores for control group = 20.94, SD = 23.63; Parkinson's disease = 15.04, SD = 23.00; p = 0.027).

CONCLUSIONS

Parkinson's disease is associated with an increased revision risk but not with short-term mortality rates relevant to assessing risk versus benefit before undergoing THR. The traditional reluctance to perform THR in patients with Parkinson's disease may be too conservative given that the higher long-term risk of death is more likely due to the progressive neurological disorder and not THR itself, and patients with Parkinson's disease report comparable outcomes to controls. Further research on outcomes in THR for patients with other neurological conditions is needed to better address the broader assumptions underlying this traditional teaching.Level of Evidence Level III, therapeutic study.

Dislocation of large-diameter head metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty

INTRODUCTION

Dislocation of large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA) is a rare complication. This study aimed to determine the incidence and risk factors for dislocation of LDH MoM THAs and HRAs.

METHODS

This retrospective analysis considered 4038 cementless LDH MoM THAs and HRAs, 3207 THAs in 2912 patients and 831 HRAs in 757 patients. The end of follow-up was revision due to dislocation. Incidence of dislocation was evaluated from this study population of 4038, and study groups were formed. The study was designed as a case-control study, and a threefold stratified randomised control group was formed. Demographic data were collected and radiological analyses were performed in the study groups.

RESULTS

There were 26/3207 (0.8%) early dislocations in the THA group, and 6/831 (0.7%) in the HRA group ( p = 0.9). Most LDH THA dislocations occurred in a group with head size ⩽ 38 mm (18/26) ( p < 0.001). In dislocated hips, there were more dysplastic acetabula and post-traumatic hips than in the control group ( p = 0.036). In the dislocation group, the mean acetabulum component anteversion angle was 19.6° (standard deviation [SD] 13.4°) and in the control group it was 23.2° (SD 10.4°) ( p = 0.006); 7/32 (21.8%) of dislocated THAs needed revision surgery, and mean time to revision from the index surgery was 1.2 (SD 2.6) years.

DISCUSSION

Dislocations occurred more often in THAs of head size ⩽ 38 mm and with a smaller anteversion angle of the acetabulum component. Hip dysplasia and post-traumatic osteoarthritis were more common in patients with dislocation.

Inflammatory demyelinating polyneuropathy after total hip arthroplasty

Inflammatory demyelinating polyneuropathy is a rare but devastating condition. Guillain-Barré syndrome is the most common cause with acute inflammatory demyelinating polyneuropathy being the most common subtype that follows a monophasic course and does not recur. Chronic inflammatory demyelinating polyneuropathy occurs when symptoms persist for greater than 8 weeks. With many proposed etiologies, few reports have described acute inflammatory demyelinating polyneuropathy after total joint arthroplasty. To our knowledge, this is the first case report of chronic inflammatory demyelinating polyneuropathy developing after total hip arthroplasty that was further complicated by dislocation.

Optimal position of lipped acetabular liners to improve stability in total hip arthroplasty-an intraoperative in vivo study

BACKGROUND

Lipped or elevated acetabular liners are frequently used in total hip arthroplasty to improve stability. However, the optimal position of the lip is not known. The purpose of this study was to determine the optimal position of lipped acetabular liners in total hip arthroplasty performed with a posterior approach.

METHODS

In 14 hips, lipped trial liners were placed intraoperatively in various positions around the posterior clock-face of the implanted acetabular shell component. For each liner position, stability of the hip was tested at maximal hip flexion with gradually increasing internal rotation until subluxation occurred, at which point the position of the hip was measured using smartphone accelerometer-based goniometers. Smartphone goniometers were first validated against a computer-assisted navigation system. Post-operative radiographs were analyzed for cup inclination angle, cup anteversion angle, and femoral offset.

RESULTS

Mean cup inclination angle in our series was 31° ± 6°. The most common liner position that imparted the greatest stability to posterior subluxation was posteriorly and inferiorly (4 o'clock position for left hip, or 8 o'clock position for right hip). The range for most stable liner position for different patients varied from postero-superior (11 o'clock/1 o'clock position) to directly inferior (6 o'clock position). Comparing a non-lipped liner to a lipped liner placed in the optimal position, the average difference in internal rotation gained before dislocation was 23°. There was no association between cup inclination or anteversion angle with liner position of greatest stability.

CONCLUSION

In hip replacements performed through a posterior approach and with mean cup inclination angle of 31° ± 6°, placing the lip of the elevated liner in the postero-inferior quadrant may impart more stability than in the postero-superior quadrant.

Effect of changing femoral head diameter on bony and prosthetic jumping angles

BACKGROUND

In THA, using a larger femoral head can increase the oscillation angle and jumping distance. However, there have been no reports which indicate precisely how increasing the jumping distance leads to an increase in the angle from impingement to dislocation (jumping angle). In this study, we clarified the jumping angle of various head diameters and its relationship with pelvic morphology.

METHODS

Using a three-dimensional templating system, virtual THA and ROM simulations were performed in 82 patients. We investigated the distance between bony and prosthetic impingement points and the head centre and calculated the jumping angle for various head diameters. We measured various pelvic shapes and length to clarify the relationship between pelvic morphology and impingement distance.

RESULTS

Jumping angles were 7.7° ± 3.2°, 12.1° ± 1.6°, 15.4° ± 2.5° and 10.0° ± 3.0° with flexion, internal rotation with 90° flexion (IR), extension and external rotation (ER), respectively, when we used a 22-mm head diameter. Bony jumping angle increased about 0.5°, 0.8°, 1.0° and 0.7° per 2-mm increase in head diameter with flexion, IR, extension and ER. On the other hand, prosthetic jumping angle remained almost stable at about 31°. Impingement distance was related to pelvic morphology in all directions. Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. On the other hand, bony jumping angle was less than prosthetic jumping angle in all cases.

CONCLUSION

Bony jumping angles differed with ROM; the biggest was seen with extension, followed by IR, ER and flexion. Prosthetic impingement angles were stable. In addition, the bony jumping angle was less than the prosthetic jumping angle in all cases.

Dislocation of the Hip: A Review of Types, Causes, and Treatment

Background

Dislocation of the hip is a well-described event that occurs in conjunction with high-energy trauma or postoperatively after total hip replacement.

Methods

In this review, the types, causes, and treatment modalities of hip dislocation are discussed and illustrated, with particular emphasis on the assessment, treatment, and complications of dislocations following total hip replacement.

Results

Hip dislocations are commonly classified according to the direction of dislocation of the femoral head, either anterior or posterior, and are treated with specific techniques for reduction. Generally, closed reduction is the initial treatment method, usually occurring in the emergency room. Bigelow first described closed treatment of a dislocated hip in 1870, and since then many reduction techniques have been proposed. Each method has unique advantages and disadvantages. Anterior hip dislocation is commonly reduced by inline traction and external rotation, with an assistant pushing on the femoral head or pulling the femur laterally to assist reduction. Posterior hip dislocations are the most common type and are reduced by placing longitudinal traction with internal rotation on the hip.

Conclusion

Patients with hip dislocations must receive careful diagnostic workup, and the treating physician must be well versed in the different ways to treat the injury and possible complications. Timely evaluation and treatment, including recognizing the potential complications, are necessary to offer the best outcome for the patient.

The impact of capsular repair on the risk for dislocation after revision total hip arthroplasty - a retrospective cohort-study of 259 cases

BACKGROUND

Dislocation following total hip arthroplasty has to date not been resolved satisfactorily. Previous work has shown that using a less-invasive adaption of Bauer's lateral transgluteal approach with capsular repair significantly reduces dislocation rates in primary total hip arthroplasty. The aim of this retrospective cohort study was to assess whether this approach also helps to reduce the dislocation rate in revision total hip arthroplasty.

METHODS

We analyzed revision total hip arthroplasty cases performed between 10/2005 and 12/2013 in our department, classifying capsular repair cases as study group and capsular resection cases as control group. The WOMAC score, the dislocations and the revisions were observed.

RESULTS

A total of 259 cases were included, 100 in the study group and 159 in the control group. In the 12-month follow-up, dislocation rates were significantly lower in the study group (3%, n = 3) compared to the control group (21.4%, n = 34; p = 0.001). Overall follow-up periods were 49 and 79 months, revision frequencies were 10 and 29%, pain improvements were 5.5 compared to 4.4 and the WOMAC global scores averaged 2.0 ± 2.1 and 2.9 ± 2.6 for the study group and the control group, respectively.

CONCLUSION

The modified, less-invasive, lateral transgluteal approach with capsular repair was accompanied by an 86% reduction in dislocation rates when compared to the conventional technique with capsular resection via the anterolateral Watson-Jones-approach. Capsular repair is possible in about 60% of the revision total hip arthroplasty cases, may be considered as beneficial to avoid dislocation and can therefore be recommended.

SPECT/CT in Postoperative Painful Hip Arthroplasty

Consecutive milestones in hip arthroplasty design and surgical technique have contributed to the successful and cost-effective intervention this procedure has become today in maintaining mobility and quality of life in patients with osteoarthritis, fracture, or other hip conditions. With the increasing prevalence of hip joint replacements, the need for improved diagnostic imaging tools to guide revision surgery has risen in parallel. Over the last few years, promising data have emerged on the potential role of bone SPECT/CT imaging in the assessment of patients with recurrent pain after arthroplasty. This review summarizes the trends in hip arthroplasty surgery (partial vs total arthroplasty; cemented vs cementless arthroplasty; resurfacing arthroplasty) and prosthesis design (bearing materials; stem designs) over the last decade. In particular, the impact on the biomechanics and interpretation of bone SPECT/CT findings is discussed, with emphasis on integrative reporting in the following frequently encountered conditions: lysis/aseptic loosening, septic loosening, heterotopic ossification, periprosthetic fracture, tendinopathies, and adverse local tissue reactions. Based on the available literature data, bone SPECT/CT is increasingly being used as second-line imaging modality when conventional investigations are nondiagnostic. Further outcome research is warranted to examine whether this technique could be used earlier in patient management.

Functional outcome and health related quality of life after dual mobility cup total hip replacement for displaced femoral neck fractures in middle aged Egyptian patients

AIM

This study was done to assess the functional and clinical results after one year of cemented THR with dual mobility cup for the treatment of fracture neck femur in active middle-aged patients in Egypt (Middle Eastern population).

PATIENTS AND METHODS

This study included 31 patients (32 hips) with displaced femoral neck fractures that were admitted to El Hadara University Hospital, Alexandria, Egypt. Their mean age was 66.4 ± 5.9 years. Fifteen patients were females. All the patients were treated with total hip replacement using a cemented dual mobility cup (Ecofit^® 2 M, Implantcast GmbH, Germany) total hip replacement through the standard posterior approach. Functional assessment was done using Harris Hip Score (HHS), SF-36 questionnaire for health related quality of life (HRQoL) with assistance of a physiotherapist.

RESULTS

The mean HHS improved over the follow up period from 79.04 ± 7.9 at 12 weeks to an average of 92.8 ± 11.1 at 1 year follow up. HRQoL measures showed a pattern of initial drop at 3 months postoperatively, then a steady rise to be restored at 1 year as compared to the preoperative baseline measures. There were no dislocations encountered in this series over one year follow up. The following complications were encountered; 1 deep infection, 2 deep vein thrombosis, 2 heterotopic ossifications, and 1 patient died within one year after surgery.

CONCLUSIONS

Dual mobility cup total hip replacement is an acceptable method for treatment of displaced femoral neck fracture in active middle aged patients in Egypt as it provides pain relief and good function without compromising the stability.

Outcomes of Modular Dual Mobility Acetabular Components in Revision Total Hip Arthroplasty

BACKGROUND

There is a high rate of dislocation after revision total hip arthroplasty. This study evaluated the outcomes of 1 modular dual mobility component in revision total hip arthroplasty in patients at high risk of dislocation.

METHODS

We reviewed 64 revisions performed in 27 (42%) patients for recurrent dislocation, 16 (25%) for adverse local tissue reaction, 11 (17%) for reimplantation infection, and 10 (16%) for aseptic loosening, malposition, or fracture. Complications, reoperations, and survivorship were evaluated.

RESULTS

Three-year survival was 98% with failure defined as aseptic loosening and 91% with failure as cup removal for any reason. With mean follow-up time of 38 months, there were 14 complications, including 2 dislocations treated with closed reduction, 9 infections, and 12 reoperations. All complications occurred in patients revised for instability, adverse local tissue reaction, or infection.

CONCLUSION

The early results of this component are promising, with good overall survival and low rate of dislocation.

Dislocation following total hip arthroplasty using dual mobility acetabular components: a systematic review

AIMS

The aim of this systematic review was to report the rate of dislocation following the use of dual mobility (DM) acetabular components in primary and revision total hip arthroplasty (THA).

MATERIALS AND METHODS

A systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines was performed. A comprehensive search of Pubmed/Medline, Cochrane Library and Embase (Scopus) was conducted for English articles between January 1974 and March 2016 using various combinations of the keywords "dual mobility", "dual-mobility", "tripolar", "double-mobility", "double mobility", "hip", "cup", "socket". The following data were extracted by two investigators independently: demographics, whether the operation was a primary or revision THA, length of follow-up, the design of the components, diameter of the femoral head, and type of fixation of the acetabular component.

RESULTS

In all, 59 articles met our inclusion criteria. These included a total of 17 908 THAs which were divided into two groups: studies dealing with DM components in primary THA and those dealing with these components in revision THA. The mean rate of dislocation was 0.9% in the primary THA group, and 3.0% in the revision THA group. The mean rate of intraprosthetic dislocation was 0.7% in primary and 1.3% in revision THAs.

CONCLUSION

Based on the current data, the use of DM acetabular components are effective in minimising the risk of instability after both primary and revision THA. This benefit must be balanced against continuing concerns about the additional modularity, and the new mode of failure of intraprosthetic dislocation. Longer term studies are needed to assess the function of these newer materials compared with previous generations. Cite this article: Bone Joint J 2017;99-B(1 Supple A):18-24.

Revision Total Hip Arthroplasty Using an Acetabular Reinforcement Ring With a Hook: A Precise Follow-Up, at Average 11.4 Years, of a Previous Report

BACKGROUND

This study aims at determining the average long-term result of revision total hip arthroplasty (THA) using the acetabular reinforcement ring with a hook (ARRH) and bone grafting in severe acetabular bony defect. Expected 15-year survival of ARRH in revision THA is included in the study.

METHODS

Retrospective review of 48 patients (48 hips) with follow-up duration of average 11.4 years (range, 6.1-21.4 years) was conducted. At each follow-up, Harris hip score was used to assess functional outcome, and radiographic acetabular component osteolysis was measured by DeLee and Charnley classification. Bone defects were assessed preoperatively and intraoperatively using American academy of orthopedic surgeons and Paprosky classification. The common modes of ARRH failures were evaluated. Bone consolidation, presence of heterotopic ossification, and complications such as infection and dislocation were recorded.

RESULTS

The bone defects were varied and included cavitary, segmental, and combined defects without any pelvic discontinuity. Mean Harris hip score improved from 52.6 points preoperatively to 82.0 points postoperatively. Nine acetabular revisions and 3 stem revisions (2 concurrent with acetabular revisions and 1 isolated stem revision) were performed. There were 5 infected cases and 1 patient with recurrent dislocation. The 11.4-year survival of revision THA with ARRH was 71% as the end point for acetabular revision surgery for any reason. The expected 15-year survival of revision THA with ARRH was 60%. The most common failure mode of ARRH was superomedial migration followed by lateral migration.

CONCLUSION

ARRH combined with bone grafting produces relatively good average long-term clinical results.

Short-term outcome after total hip arthroplasty using dual-mobility cup: report from Lithuanian Arthroplasty Register

PURPOSE

The purpose of the study was to investigate how the use of dual-mobility cups (DMCs) affected the risk of revision due to dislocation as well as overall risk of revision compared with a conventional total hip arthroplasty (THA) system in the short term.

METHODS

A total of 12,657 primary THAs were registered from the start of 2011 to the end of 2014. 620 THAs were with DMCs. For comparison, we included all registered THAs with Exeter cup and a cemented Exeter stem combined with 28-mm femoral head. Patients were followed up with respect to revision and/or death until 1 January 2016. For survival analysis, we used revision as an endpoint. Cox proportional hazards models were used to analyse the influence of various covariates (age, gender, surgical approach, THA model and pre-operative diagnosis).

RESULTS

Of the 620 dual-mobility THAs and 2170 Exeter THAs, 100 had been revised. The overall unadjusted cumulative revision rate (CRR) for any reason of revision at five years after surgery was 3.9% in the dual-mobility group and 5.2% in the Exeter group. Cox regression analysis, adjusting for age, gender, THA type, surgical approach and pre-operative diagnosis, showed that the risk of revision was less in patients operated with DMCs and in patients having their operation for osteoarthritis.

CONCLUSION

The DM implant had a lower short-term complication rate than a conventional well defined THA. Low dislocation rate suggests that it is a good choice for high risk patients.