Continuous modeling of creased annuli with tunable bistable and looping behaviors.

Creases are purposely introduced to thin structures for designing deployable origami, artistic geometries, and functional structures with tunable nonlinear mechanics. Modeling the mechanics of creased structures is challenging because creases introduce geometric discontinuity and often have complex mechanical responses due to local material damage. In this work, we propose a continuous description of the sharp geometry of creases and apply it to the study of creased annuli, made by introducing radial creases to annular strips with the creases annealed to behave elastically. We find that creased annuli have generic bistability and can be folded into various compact shapes, depending on the crease pattern and the overcurvature of the flat annulus. We use a regularized Dirac delta function (RDDF) to describe the geometry of a crease, with the finite spike of the RDDF capturing the localized curvature. Together with anisotropic rod theory, we solve the nonlinear mechanics of creased annuli, with its stability determined by the standard conjugate point test. We find excellent agreement between precision tabletop models, numerical predictions from our analytical framework, and modeling results from finite element simulations. We further show that by varying the rest curvature of the thin strip, dynamic switches between different states of creased annuli can be achieved, which could inspire the design of deployable and morphable structures. We believe that our smooth description of discontinuous geometries will benefit the mechanical modeling and design of a wide spectrum of engineering structures that embrace geometric and material discontinuities.

Civilian national service programs can powerfully increase youth voter turnout.

Low rates of youth voting are a feature of contemporary democracies the world over, with the United States having some of the lowest youth turnout rates in the world. However, far too little is known about how to address the dismal rates of youth voter participation found in many advanced democracies. In this paper, we examine the causal effect of a potentially scalable solution that has attracted renewed interest today: voluntary national service programs targeted at the youth civilian population. Leveraging the large pool of young people who apply each year to participate in the Teach For America (TFA) program-a prominent voluntary national service organization in the United States that integrates college graduates into teaching roles in low-income communities for 2 y-we examine the effect of service participation on voter turnout. To do so, we match TFA administrative records to large-scale nationwide voter files and employ a fuzzy regression discontinuity design around the recommended admittance cutoff for the TFA program. We find that serving as a teacher in the Teach For America national service program has a large effect on civic participation-substantially increasing voter turnout rates among applicants admitted to the program. This effect is noticeably larger than that of previous efforts to increase youth turnout. Our results suggest that civilian national service programs targeted at young people have great promise in helping to narrow the stubborn and enduring political engagement gap between younger and older citizens.

Extended N-centered ensemble density functional theory of double electronic excitations.

A recent work (arXiv:2401.04685) has merged N-centered ensembles of neutral and charged electronic ground states with ensembles of neutral ground and excited states, thus providing a general and in-principle exact (so-called extended N-centered) ensemble density functional theory of neutral and charged electronic excitations. This formalism made it possible to revisit the concept of density-functional derivative discontinuity, in the particular case of single excitations from the highest occupied Kohn-Sham (KS) molecular orbital, without invoking the usual "asymptotic behavior of the density" argument. In this work, we address a broader class of excitations, with a particular focus on double excitations. An exact implementation of the theory is presented for the two-electron Hubbard dimer model. A thorough comparison of the true physical ground- and excited-state electronic structures with that of the fictitious ensemble density-functional KS system is also presented. Depending on the choice of the density-functional ensemble as well as the asymmetry of the dimer and the correlation strength, an inversion of states can be observed. In some other cases, the strong mixture of KS states within the true physical system makes the assignment "single excitation" or "double excitation" irrelevant.

Antenatal corticosteroids and newborn respiratory outcomes in twins: A regression discontinuity study.

OBJECTIVE: To estimate the effect of antenatal corticosteroids on newborn respiratory morbidity in twins. DESIGN: Regression discontinuity applied to population-based birth registry data. SETTING: British Columbia, Canada, 2008-2018. POPULATION: Twin pregnancies admitted for birth between 31+0 and 36+6 weeks of gestation. METHODS: During our study period, Canadian clinical practice guidelines recommended antenatal corticosteroid administration for imminent preterm birth up to 33+6 weeks. We used a logistic model to compare the predicted risks of our outcomes among pregnancies admitted for birth immediately before this clinical cut-point (higher probability of exposure to antenatal corticosteroids) versus immediately after it (lower probability). MAIN OUTCOME MEASURES: Our primary outcome was a composite of newborn respiratory distress or in-hospital death. Our secondary outcome was a composite of newborn respiratory intervention or in-hospital death. RESULTS: Among 2524 pregnancies (5035 liveborn twins), 47% of admissions before 34+0 weeks of gestation were exposed to antenatal corticosteroids but only 4.2% of admissions after this cut-point were exposed. The risk of newborn respiratory distress or in-hospital mortality increased abruptly at 34+0 weeks, corresponding to a protective effect of treatment (risk ratio [RR] 0.69, 95% CI 0.53-0.90; risk difference [RD] -12 cases per 100 births, 95% CI -20 to -4.1). There was no clear evidence for or against an effect on newborn respiratory intervention or in-hospital death (RR 0.89, 95% CI 0.70-1.13; RD -4.2 per 100, 95% CI -13 to +4.2). CONCLUSIONS: Our findings provide evidence for the effectiveness of antenatal corticosteroids in preventing adverse newborn respiratory outcomes in twins.

Exiting primary care providers.

This article studies the impact of primary care providers (PCPs) exit from the local health care system on patients' health care utilization. I compare patients with each other whose physicians have left the local health care system at different points in time due to retirement, relocation, or other reasons. Estimation results indicate that the imminent exit leads soon-leaving physicians to changing their treatment behavior, which has a significant impact on patients' health care spending. In addition, successors and new PCPs provide significantly more preventive services in the post-exit-period and refer patients more often to specialists for further examinations than the physicians who exit later. The increased inpatient expenditures in the post-exit period are caused by the new PCPs (through referrals). Self-initiated substitution behavior of patients (e.g., less PCP care, more specialist care) after the exit is observed but is low in magnitude. Although an overall increase in health service utilization is observed, mortality in the post-exit periods is significantly increased among affected patients. A possible explanation is the low frequency follow-up care of patients who were referred to hospitals by their former PCP in the notification-period.

The effects of parental retirement on adult children's health: Evidence from China.

Using representative data from China, we examine the causal effects of parental retirement on the health of adult children. To do so, we adopt a fuzzy regression discontinuity design and exploit the mandatory retirement ages in China as cut-off points. We find no evidence that parental retirement has significant effects on the mental health, healthcare utilization, or risky health behaviors of adult children. However, paternal retirement and maternal retirement have different effects on adult children's Self-reported health (SRH). Paternal retirement has a significantly negative effect only on the SRH of sons, while maternal retirement does not induce such effects. Potential mechanisms of intergenerational transfer through which parental retirement might affect adult children's health are also explored.

Age penalties and take-up of private health insurance.

Financial penalties for delayed enrollment could be useful tools to encourage people to enroll earlier in health insurance markets, but little is known about how effective they are. We use a large administrative dataset for a 10% random sample of all Australian tax-filers to study how people respond to a step-wise age-based penalty, and whether the effect has changed over time. Individuals must pay a 2% premium surcharge for each year they delay enrollment beyond age 31. The penalty stops after 10 years of continuous hospital cover. The age-based penalty creates discontinuities in the incentive to insure by age, which we exploit to estimate causal effects. We find that people respond as expected to the initial age-penalty, but not to subsequent penalties. The 2% premium loading results in a 0.78-3.69 percentage points (or 2.1%-9.0%) increase in the take-up rate at age 31. We simulate the penalty impact and implications of potential reforms, and conclude that modest changes around the policy make little difference in the age distribution of insured, premiums or take-up rates. Our study provides important evidence on an understudied area in the literature and offers insights for countries considering financial penalties.

Multi-institutional study of osimertinib dose-optimization in non-small cell lung cancer patients with EGFR activating mutation aged 70 years or older ('MONEY' trial).

Osimertinib is the standard of care for patients with epidermal growth factor receptor-activating mutation-positive non-small cell lung cancer. Dose-toxicity has been previously reported, but no dose-response data within the range of 20-240 mg daily (mg/d). Thus, the current 80 mg/d dosing might be too high for elderly Japanese patients with an average body weight of only 50 kg, resulting in excessive toxicity and cost. We therefore initiated a study to investigate whether osimertinib at 40 mg/d is non-inferior to 80 mg/d in patients with advanced or recurrent epidermal growth factor receptor-activating mutation-positive non-small cell lung cancer aged ≥70 years, using a regression discontinuity design. Osimertinib is administered at 40 mg/d for body weight ≤50 kg, and 80 mg/d for body weight >50 kg. The primary endpoint is progression-free survival. Sample size is 550 patients, based on a non-inferiority margin of the progression-free survival hazard ratio 1.333, 0.10 one-sided type I error and 80% power.

Surgical options in retrosternal oesophageal reconstruction.

BACKGROUND: Retrosternal oesophageal reconstructions with collar anastomoses can become necessary when the stomach is either unavailable for oesophageal replacement, or orthotopic reconstruction is deemed impractical. Our aim was to analyse our results regarding technical approaches and outcomes. MATERIALS AND METHODS: All patients undergoing primary and secondary oesophageal retrosternal reconstructions with collar anastomoses at our centre (2019-2023) were retrospectively analysed and individual surgical reconstruction options were presented. RESULTS: Overall, twelve patients received primary (n = 5; 42.7%) or secondary (n = 7; 58.3%) reconstructions; ten with colonic interposition and two with gastric pull-up. Male/female ratio was 4:8; median age 66 years (30-87). Charlson-Comorbidity-Score (CCS) was 5 (1-7); 8/12 patients (67%) had ASA-classification score ≥ 3. We observed no conduit necrosis, but one patient (8.3%) with a leakage of the oesophago-colonostomy which was successfully treated by endoscopic vacuum therapy. Four patients (33.3%) acquired nosocomial pneumonia. Additional drainages for pleural fluid collections were necessary in three patients (25%). Overall comprehensive-complication-index (CCI) was 26.2 (0-44.9). Length-of-stay (LOS) was 22 days median (15-40). There was no 90-days mortality. Overall, CCI during the follow-up (FU) period at median 26 months (16-50) was 33.7 (0-100). 10 out of 12 patients were on sufficient oral nutrition at 12 months FU. CONCLUSION: Primary and secondary oesophageal retrosternal reconstructions encompass diverse entities and typically requires tailored decision-making. These procedures, though rare, are feasible with acceptable complication rates and positive functional outcomes when performed in experienced hands.

Examining the impact of a change in maternity leave policy in Canada on maternal mental health care visits to the physician.

PURPOSE: Maternity leave is a critical employee benefit that allows mothers to recover from the stress of pregnancy and childbirth and bond with their new baby. We aimed to examine the association between the extension of a maternity leave policy and maternal use of mental health services and prescription drugs in a universal public healthcare system. METHODS: This study uses administrative medical records from 18,000 randomly selected women who gave birth three months before and after an extension of the maternity leave policy. More specifically, mothers who gave birth after January 1st 2001, were entitled to 50 weeks of paid maternity leave, while mothers who gave birth before that date were entitled to only 26 weeks of paid maternity leave. Medical records were analyzed over a seven-year period (i.e., from October 1998 to March 2006). We examined the number and costs of mothers' medical visits for mental health care in the five years following delivery, as well as maternal use of prescribed medication for mental health problems. RESULTS: We found that mothers with extended maternity leave had - 0.12 (95%CI=-0.21; -0.02) fewer medical visits than mothers without a more generous maternity leave and that the cost of mental health services was Can$5 less expensive per women. These differences were found specifically during the extended maternity leave period. CONCLUSIONS: The extra time away from work may help mothers to balance new family dynamics which may result in less demand on the healthcare system.

The impact of pension on the health behavior of elderly rural residents: evidence from China.

BACKGROUND: Unhealthy behavior is an important factor threatening the health of older rural residents in China. We examine the effects of receiving pension on elderly rural residents' health behavior (namely conscious control of sugar, salt, and edible oil intake, as well as learning health or wellness knowledge), also including effect heterogeneity by income level and gender. METHODS: Using China Rural Revitalization Survey (CRRS) in 2020, we used the policy rule of the China's New Rural Pension Scheme that only those people who are over 60 years old can have access to pension as the natural experiment, and explore the causal effect of receiving pensions on the health behaviors by using regression discontinuity design method. RESULTS: Having access to pension can improve the health behavior of rural elderly residents, including increasing the probability of rural residents' conscious control of sugar (p < 0.1) and conscious control of salt intake (p < 0.1), which is still valid after a series of robustness tests. Heterogeneity analysis finds that access to pensions is more likely to improve the health behavior of low-income families and male rural elderly residents. CONCLUSIONS: The research has expanded the discussion on the correlation between the pension and the health of rural elderly residents, and the conclusion provides important policy implications for optimizing the rural elderly insurance system and leveraging pension to improve the health behavior of rural elderly residents.

The impact of retirement on blood pressure: evidence from a nationwide survey in China.

INTRODUCTION: The health impact of retirement is controversial. Most previous studies have been based on self-reported health indicators or the endpoints of some chronic diseases (e.g., morbidity or mortality), but objective physiological indicators (e.g., blood pressure) have rarely been used. The objective of this study is to elucidate the health effects of retirement on blood pressure, thereby offering empirical evidence to facilitate the health of retirees and to optimize retirement policies. METHODS: From 2012 to 2015, 84,696 participants of the Chinese Hypertension Survey (CHS) were included in this study. We applied the fuzzy regression discontinuity design (FRDD) to identify retirement's causal effect on systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure. We also explored the heterogeneity in the effects of retirement across different sex and education level groups. RESULTS: Based on the fully adjusted model, we estimated that retirement increased SBP by 5.047 mm Hg (95% CI: -2.628-12.723, P value: 0.197), DBP by 0.614 mm Hg (95% CI: -3.879-5.108, P value: 0.789) and pulse pressure by 4.433 mm Hg (95% CI: -0.985-9.851, P value: 0.109). We found that retirement led to a significant increase in male participants' SBP and pulse pressure as well as a possible decrease in female participants' blood pressure. Additionally, the blood pressure levels of low-educated participants were more vulnerable to the shock of retirement. CONCLUSION: Retirement is associated with an increase in blood pressure level. There is a causal relationship between the increase in blood pressure levels of men and retirement. Policy-makers should pay extra attention to the health status of men and less educated people when adjusting retirement policies in the future.

The effect of retirement on physical and mental health in China: a nonparametric fuzzy regression discontinuity study.

BACKGROUND: With the rapid aging of the domestic population, China has a strong incentive to increase the statutory retirement age. How retirement affects the health of the elderly is crucial to this policymaking. The health consequences of retirement have been debated greatly. This study aims to investigate the effects of retirement on physical and mental health among Chinese elderly people. METHODS: The data we use in this study comes from four waves (2011, 2013, 2015, and 2018) of the Harmonized China Health and Retirement Longitudinal Study (Harmonized CHARLS), a prospective cohort. We use the nonparametric fuzzy regression discontinuity design to estimate the effects of retirement on physical and mental health. We test the robustness of our results with respect to different bandwidths, kernel functions, and polynomial orders. We also explore the heterogeneity across gender and education. RESULTS: Results show that retirement has an insignificant effect on a series of physical and mental health outcomes, with and without adjusting several sociodemographic variables. Heterogeneity exists regarding gender and education. Although stratified analyses indicate that the transition from working to retirement leaves minimal effects on males and females, the effects go in the opposite direction. This finding holds for low-educated and high-educated groups for health outcomes including depression and cognitive function. Most of the results are stable with respect to different bandwidths, kernel functions, and polynomial orders. CONCLUSIONS: Our results suggest that it is possible to delay the statutory retirement age in China as retirement has insignificant effects on physical and mental health. However, further research is needed to assess the long-term effect of retirement on health.

Effects of double-dose algebra on college persistence and degree attainment.

In 2003, Chicago Public Schools introduced double-dose algebra, requiring two periods of math-one period of algebra and one of algebra support-for incoming ninth graders with eighth-grade math scores below the national median. Using a regression discontinuity design, earlier studies showed promising results from the program: For median-skill students, double-dose algebra improved algebra test scores, pass rates, high school graduation rates, and college enrollment. This study follows the same students 12 y later. Our findings show that, for median-skill students in the 2003 cohort, double-dose significantly increased semesters of college attended and college degree attainment. These results were not replicated for the 2004 cohort. Importantly, the impact of the policy on median-skill students depended largely on how classes were organized. In 2003, the impacts on college persistence and degree attainment were large in schools that strongly adhered to the cut-score-based course assignment, but without grouping median-skill students with lower-skill peers. Few schools implemented the policy in such a way in 2004.

Positioning adolescence in the developmental timeline.

Adolescence, the second decade of life, bridges childhood and adulthood, but also represents a host of unique experiences that impact health and well-being. Lifespan theories often emphasize the continuity of individual characteristics and their contexts from childhood to adolescence, underscoring the distal influence of childhood experiences. Yet, adolescence is marked by transitions that may provoke discontinuities, particularly within individuals, their contexts, and their interactions within those contexts. These discontinuities occur at varied times, orders, and intensities for individual youth, suggesting that adolescence may be a developmental turning point where earlier life experiences may be mediated, reversed, or transformed by proximal events. This perspective piece emphasizes the importance of considering transitions, discontinuities, and developmental turning points in adolescence as well as their potential to explain heterogeneity in adolescent and adult outcomes. We explore one biological and one contextual transition in adolescence and highlight innovative theories and methods for investigating continuity and discontinuity dynamics across development, which could lead to new insights related to the adolescent period and its importance in shaping future life trajectories.

Japan's intensive health guidance program has limited effects on cardiovascular risk factors: a regression discontinuity analysis.

OBJECTIVES: It is uncertain whether the effects of health counselling programs differ depending on their intensity. This study compared the effectiveness of intensive health guidance (IHG) and less intensive motivation-enhancing guidance (MEG) on cardiovascular risk factors. STUDY DESIGN: A regression discontinuity design (RDD) was applied. METHODS: In Japan's specific health checkup (SHC) and guidance program, those with a high risk of metabolic syndrome are assigned to IHG or MEG. An RDD was applied using an SHC results database. Four groups were created in which IHG or MEG assignment was solely determined by single cut-off values of the running variables of triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), or haemoglobin A1c (HbA1c) measured during SHC. Outcomes were one year's changes in body mass index (BMI), waist circumference (WCF), systolic and diastolic blood pressure, HDL-C, low-density lipoprotein cholesterol, FBG, and HbA1c. RESULTS: A total of 541,809 observations among 225,115 people from 2008 to 2017 were analysed. Men assigned to IHG had a significantly but slightly lower BMI and WCF than those assigned to MEG the next year, only when TG or FBG was a running variable. There were no significant differences between IHG and MEG for women's BMI and WCF and other cardiovascular risk factors for both sexes. CONCLUSION: Since IHG has limited additional effects on cardiovascular risk factors compared with MEG, abolishing IHG may have little negative impact on the general public's health.

Validity of endoscopic ossiculoplasty immediately after its introduction for ossicular chain disruption.

BACKGROUND: Transcanal endoscopic ear surgery (TEES) reportedly requires a long learning curve and may be associated with more complications and longer operative times than microscopic ear surgery (MES). In this study, we aimed to examine the usefulness and validity of TEES for ossicular chain disruption in the early stages of its introduction in our institution. METHODS: TEES was performed on 11 ears (10 with congenital ossicular chain discontinuity and 1 with traumatic ossicular chain dislocation), and MES was performed with a retroauricular incision on 18 ears (6 with congenital ossicular chain discontinuity and 12 with traumatic ossicular chain dislocation) in a tertiary referral center. Postoperative hearing results, operative times, and postoperative hospital length of stay were retrospectively reviewed. The Mann-Whitney U test and Fisher's exact test was performed to compare variables between the TEES and MES groups. Pre- and postoperative air- and bone-conduction thresholds and the air-bone gap of each group were compared using the Wilcoxon signed-rank test. The Mann-Whitney U test and Wilcoxon signed-rank was performed to compare the pre- and postoperative air-bone gaps between the diagnoses. RESULTS: No significant differences in the postoperative air-conduction thresholds, bone-conduction thresholds, air-bone gaps, or incidence of air-bone gap ≤ 20 dB were observed between the TEES and MES groups. The air-conduction thresholds and air-bone gaps of the TEES group significantly improved postoperatively. The air-conduction thresholds and air-bone gaps of the MES group also significantly improved postoperatively. No significant difference was observed in the operative times between the groups (TEES group: median, 80 min; MES group: median, 85.5 min). The TEES group had a significantly shorter postoperative hospital stay (median, 2 days) than the MES group (median, 7.5 days). CONCLUSIONS: TEES was considered appropriate for the treatment of ossicular chain disruption, even immediately after its introduction at our institution. For expert microscopic ear surgeons, ossicular chain disruption may be considered a suitable indication for the introduction of TEES.

Trainee-supervisor collaboration, progress-visualisation, and coaching: a survey on challenges in assessment of ICU trainees.

BACKGROUND: Assessing trainees is crucial for development of their competence, yet it remains a challenging endeavour. Identifying contributing and influencing factors affecting this process is imperative for improvement. METHODS: We surveyed residents, fellows, and intensivists working in an intensive care unit (ICU) at a large non-university hospital in Switzerland to investigate the challenges in assessing ICU trainees. Thematic analysis revealed three major themes. RESULTS: Among 45 physicians, 37(82%) responded. The first theme identified is trainee-intensivist collaboration discontinuity. The limited duration of trainees' ICU rotations, large team size operating in a discordant three-shift system, and busy and unpredictable day-planning hinder sustained collaboration. Potential solutions include a concise pre-collaboration briefing, shared bedside care, and post-collaboration debriefing involving formative assessment and reflection on collaboration. The second theme is the lack of trainees' progress visualisation, which is caused by unsatisfactory familiarisation with the trainees' development. The lack of an overview of a trainee's previous achievements, activities, strengths, weaknesses, and goals may result in inappropriate assessments. Participants suggested implementing digital assessment tools, a competence committee, and dashboards to facilitate progress visualisation. The third theme we identified is insufficient coaching and feedback. Factors like personality traits, hierarchy, and competing interests can impede coaching, while high-quality feedback is essential for correct assessment. Skilled coaches can define short-term goals and may optimise trainee assessment by seeking feedback from multiple supervisors and assisting in both formative and summative assessment. Based on these three themes and the suggested solutions, we developed the acronym "ICU-STAR" representing a potentially powerful framework to enhance short-term trainee-supervisor collaboration in the workplace and to co-scaffold the principles of adequate assessment. CONCLUSIONS: According to ICU physicians, trainee-supervisor collaboration discontinuity, the lack of visualisation of trainee's development, and insufficient coaching and feedback skills of supervisors are the major factors hampering trainees' assessment in the workplace. Based on suggestions by the survey participants, we propose the acronym "ICU-STAR" as a framework including briefing, shared bedside care, and debriefing of the trainee-supervisor collaboration at the workplace as its core components. With the attending intensivists acting as coaches, progress visualisation can be enhanced by actively collecting more data points. TRIAL REGISTRATION: N/A.

Cup-Cage Construct for Treatment of Severe Acetabular Bone Loss in Revision Total Hip Arthroplasty: Clinical and Radiographic Outcomes at a Mean Follow-Up of 7.7 Years.

BACKGROUND: Acetabular reconstruction in the context of massive acetabular bone loss is challenging. Achieving implant stability in these situations requires special considerations. The cup-cage construct is a treatment option that addresses this issue. This study evaluates survivorship, complications, and functional outcomes using the cup-cage construct. METHODS: A total of 131 cup-cage implants (129 patients) were identified from our retrospective review of revision total hip arthroplasties from January 2003 to January 2022. Among these cases, 100 (76.3%) were women, the mean age at the time of surgery was 68 years (range, 29 to 92; SD [SD], 12.4), and the mean follow-up was 7.7 years (range, 0.02 to 20.3; SD, 5.1). Kaplan-Meier survivorship analysis was conducted with failure defined as revision surgery and/or failure of the cup-cage reconstruction. RESULTS: At a mean follow-up of 7.7 years, the cup-cage construct survivorship due to all-cause failure was 83.9% (95% CI [confidence interval]: 77.6 to 90.2) at 5 years with 88 hips at risk, 74.8% (95% CI: 66.2 to 83.4) at 10 years with 38 hips at risk, and 69.8% (95% CI: 59.4 to 80.2) at 15 years with 11 hips at risk. The survivorship due to failure from aseptic loosening was 96.7% (95% CI: 93.6 to 99.8) at 5 years with 88 hips at risk and 95.5% (95% CI: 91.6 to 99.4) at 10 and 15 years with 38 and 11 hips at risk, respectively. The revision rate for aseptic loosening of the cup and/or cage, infection, dislocation, and aseptic loosening of the femoral stem was 5 of 131 (3.8%), 12 of 131 (9.1%), 10 of 131 (7.6%), and 2 of 131 (1.5%). CONCLUSIONS: The cup-cage construct is a reliable treatment option for the treatment of various acetabular defects. There are favorable survivorship, clinical, and radiographic outcomes, with a satisfactory complication rate.

Highly Porous Acetabular Cup and Augment Constructs in Complex Revision Total Hip Arthroplasty: What Predicts 10-Year Implant Survivorship?

BACKGROUND: Porous tantalum acetabular cup and augment constructs have demonstrated favorable outcomes up to 5 years postsurgery despite severe bone loss during revision total hip arthroplasty (THA). Prior literature lacks long-term studies with substantial case numbers. This study aims to assess long-term clinical and radiographic outcomes 10 years postsurgery in patients undergoing revision THA with porous tantalum acetabular cup-augment constructs and determine factors associated with long-term survivorship. METHODS: Between 2000 and 2012, 157 revision THAs were performed in cases with major acetabular defects (mainly Paprosky type IIIA and IIIB) utilizing porous tantalum cup-augment constructs. Pelvic discontinuity was noted intraoperatively in 17 hips (11%). Postoperative radiographs were evaluated at regular intervals for implant stability and radiolucent lines. There were 49 patients who had complete radiographic follow-up at 10 years or longer postsurgery. RESULTS: The 10-year survivorship free of revision of the cup-augment construct for aseptic loosening was 93%, free of any acetabular construct revision was 91%, free of any hip rerevision was 77%, and free of any reoperation was 75%. Pelvic discontinuity was associated with increased risk of reoperation (hazard ratio [HR] = 2.8), any hip rerevision (HR = 3.2), any cup-augment construct revision (HR = 11.8), and aseptic construct revision (HR = 10.0). Of unrevised cases with radiographs at 10 years, 4 hips showed radiographic loosening. Mean Harris hip scores improved from 47 preoperatively to 79 at 10 years. CONCLUSIONS: Porous tantalum acetabular cup-augment constructs used in revision THA with severe acetabular bone loss provide excellent implant survivorship at 10 years when the acetabulum is intact. Due to lower survivorship of cup-augment constructs in cases of pelvic discontinuity, additional construct fixation or stabilization methods are recommended, when a discontinuity is present. LEVEL OF EVIDENCE: IV.