Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip.

BACKGROUND: Previous studies identified corrosion between the modular tibial components of total knee arthroplasty (TKA) devices. In this study, we investigated the damage modes present in titanium-titanium (Ti-Ti) junctions in the knee. We asked: under typical in vivo cyclic loading conditions, will the same alloy damage modes from TKA devices resemble those documented in the hip? METHODS: A total of 50 paired titanium alloy tibial baseplates and stems were collected and semi-quantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy. RESULTS: Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed four damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting. CONCLUSIONS: Each of the damage modes identified in modular Ti-Ti tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Hybrid Clinics: A New Model for Ambulatory Care to Reduce Infection Risk.

Objectives: To assess the viability of a hybrid clinic model combining in-person examination with video-based consultation to minimize viral transmission risk. Methods: Data were collected prospectively in a pediatric urology clinic for in-person visits from January to April 2018 ("classic") and hybrid visits from October to December 2020 of the COVID-19 pandemic ("hybrid"). Variables included provider, diagnosis, patient type, time of day, prior surgery, postoperative status, and decision-making for surgery. The primary outcome was "room time" or time in-person. The secondary outcome was "total time" or visit duration. Proportion of visits involving close contact (room time ≥15 min) was assessed. Univariate analyses were performed using the Wilcoxon rank-sum test and Fisher's exact test. Mixed models were fitted for visit approach and other covariates as fixed effects and provider as random effect. Results: Data were collected for 346 visits (256 classic, 90 hybrid). Hybrid visits were associated with less room time (median 3 min vs. 10 min, p < 0.001) but greater total time (median 13.5 min vs. 10 min, p = 0.001) as compared with classic visits. On multivariate analysis, hybrid visits were associated with 3 min less room time (95% confidence intervals [CIs]: -5.3 to -1.7, p < 0.001) but 3.8 min more total time (95% CI: 1.5-6.1, p = 0.001). Close contact occurred in 6.7% of hybrid visits, as compared with 34.8% of classic visits (p < 0.001). Conclusions: Hybrid clinic visits reduce room time as compared with classic visits. This approach overcomes the examination limitations of telemedicine while minimizing viral transmission, and represents a viable model for ambulatory care whenever close contact carries infection risk.

Comparing Pediatric Ureteroscopy Outcomes with SuperPulsed Thulium Fiber Laser and Low-Power Holmium:YAG Laser.

PURPOSE: The thulium fiber laser is a promising new lithoptripsy technology never before studied in the pediatric population. Our center adopted the first platform in North America, the SuperPulsed thulium fiber laser (SPTF). We aimed to compare outcomes in pediatric ureteroscopy using the SPTF to those using the gold standard, low-power holmium:yttrium-aluminum-garnet (Ho:YAG) laser. MATERIALS AND METHODS: This is a retrospective, consecutive cohort study of unilateral ureteroscopy with laser lithotripsy performed in pediatric patients from 2016 to 2021 as an early adopter of the SPTF. Thirty-day complications and stone-free status, defined as the absence of a stone fragment on followup imaging within 90 days, were analyzed using logistic regression. Operative times were compared using linear regression. Propensity scores for use of SPTF were used in regression analyses to account for potential cohort imbalance. RESULTS: A total of 125 cases were performed in 109 pediatric patients: 93 with Ho:YAG and 32 with SPTF. No significant difference was noted in age (p=0.2), gender (p=0.6), stone burden (p >0.9) or stone location (p=0.1). The overall stone-free rate was 62%; 70% with SPTF and 59% with Ho:YAG. The odds of having a residual stone fragment were significantly lower with SPTF than with Ho:YAG (OR=0.39, 95% CI: 0.19-0.77, p=0.01). There was no significant difference in operative time (p=0.8). Seven (25%) complications were noted with SPTF and 19 (22%) with Ho:YAG (p=0.6). CONCLUSIONS: The SPTF laser was associated with a higher stone-free rate than the low-power Ho:YAG laser without compromising operative time and safety.

Malignancy Yield of Testis Pathology in Older Boys and Adolescents with Cryptorchidism.

PURPOSE: We performed a retrospective, single-institution study to characterize the pathological findings of testis tissue specimens from older boys and adolescents with cryptorchidism. MATERIALS AND METHODS: With institutional review board approval, pathology reports were obtained for testicular specimens from patients age 10 years or older at a pediatric hospital from 1994 to 2016. Reports were excluded if they lacked clinical records, lacked testicular parenchyma, were from a descended testis or were from a patient with differences of sexual development. Variables of interest included age, testis location, procedure and pathological findings. Presence of malignancy among intra-abdominal versus extra-abdominal undescended testes was compared using Fisher's Exact Test. RESULTS: Seventy-one patients met inclusion criteria. The median age was 15.3 years (range 10.1-27.7). None had a history of testicular malignancy. Forty-five unilateral orchiectomies, 22 unilateral orchiopexies with biopsy and 4 bilateral procedures were performed. Seventeen testes (22.7%) were intra-abdominal, 42 (56.0%) were in the inguinal canal, 9 (12.0%) were at the external inguinal ring, 3 (4.0%) were in the superficial inguinal pouch and 4 (5.3%) were in the scrotum. Malignancy was detected in 2/71 patients (2.8%). By location, 2/16 patients (12.5%) with intra-abdominal testis and 0/55 patients (0%) with extra-abdominal testis demonstrated malignancy (p=0.048). CONCLUSIONS: Among males with cryptorchidism ages 10 years and older without differences of sexual development, 2/16 patients with intra-abdominal testis and 0/55 patients with extra-abdominal testis demonstrated malignancy. In older boys and adolescents, orchiectomy or biopsy is indicated for intra-abdominal testes but may not be necessary for extra-abdominal undescended testes.

Dietary Risk Factors for Pediatric Kidney Stones: A Case-Control Study.

PURPOSE: Data are scarce regarding dietary risk factors for pediatric nephrolithiasis. Our objective was to perform a case-control study (nonmatched) of the association of dietary nutrients with pediatric urolithiasis. MATERIALS AND METHODS: We obtained dietary information from pediatric urolithiasis patients (from stone clinic in 2013-2016) and healthy controls (well-child visit at primary care in 2011-2012). Survey results were converted to standard nutrient intakes. Children younger than 5 years of age and those with extreme calorie intake values (<500 or >5,000 kcal/day) were excluded. The association of individual nutrients with urolithiasis was assessed by bivariate analysis results and machine-learning methods. A multivariable logistic regression model was fitted using urolithiasis as the outcome. RESULTS: We included 285 patients (57 stones/228 controls). Mean±SD age was 8.9±3.6 years (range 5-20). Of the patients 47% were male. After adjusting for age, sex, body mass index (obese/overweight/normal), calorie intake and oxalate, urolithiasis was associated with higher dietary sodium (OR=2.43 [95% CI=1.40-4.84] per quintile increase, p=0.004), calcium (OR=1.73 [95% CI=1.07-3.00] per quintile increase, p=0.034) and beta carotene (OR=2.01 [95% CI=1.06-4.18] per quintile increase, p=0.042), and lower potassium (OR=0.31 [95% CI=0.13-0.63] per quintile increase, p=0.003). Sensitivity analysis was performed by removing oxalate from the model and limiting the sample to patients aged 5-13 years, with similar results. CONCLUSIONS: In our cohort, higher dietary intake of calcium, sodium and beta carotene, and lower potassium intake were associated with pediatric urolithiasis. This is the first study using a detailed dietary survey to identify dietary risk factors for pediatric urolithiasis. Further research is warranted to delineate the mechanisms and to generate a lower risk diet profile for pediatric urolithiasis.

Pediatric Stone Surgery: What Is Hot and What Is Not.

PURPOSE OF REVIEW: We aim to highlight recent advances in technology and techniques for surgical management of urinary tract calculi in pediatric patients. RECENT FINDINGS: Percutaneous nephrolithotomy (PCNL) is classically performed in the prone position. The supine PCNL was first attempted to overcome the shortcomings of difficult airway access, patient and surgeon discomfort. The supine PCNL, and subsequent modifications, has been successfully described in the pediatric population. Classically, PCNL has also been classically concluded with obligate placement of a nephrostomy tube and bladder catheter. Recently, tubeless and totally tubeless PCNL reduces pain and duration of hospitalization with satisfactory surgical outcomes in children. Finally, we describe the use of thulium laser technology, which offers improved efficacy in stone treatment and may supplant the current dominant technologies in coming years. Recent advances in pediatric stone surgery include supine PCNL, miniaturized PCNL instrumentation, tubeless procedures, and thulium laser technology.

1-Chromonyl-5-Imidazolylpentadienone Demonstrates Anti-Cancer Action against TNBC and Exhibits Synergism with Paclitaxel.

Curcumin has been well studied for its anti-oxidant, anti-inflammatory, and anti-cancer action. Its potential as a therapy is limited due to its low bioavailability and rapid metabolism. To overcome these challenges, investigators are developing curcumin analogs, nanoparticle formulations, and combining curcumin with other compounds or dietary components. In the present study, we used a 1-chromonyl-5-imidazolylpentadienone named KY-20-22 that contains both the pharmacophore of curcumin and 1,4 benzopyrone (chromone) moiety typical for flavonoids, and also included specific moieties to enhance the bioavailability. When we tested the in vitro effect of KY-20-22 in triple-negative breast cancer (TNBC) cell lines, we found that it decreased the cell survival and colony formation of MDA-MB-231 and MDA-MB-468 cells. An increase in mitochondrial reactive oxygen species was also observed in TNBC cells exposed to KY-20-22. Furthermore, KY-20-22 decreased epithelial-mesenchymal formation (EMT) as evidenced by the modulation of the EMT markers E-cadherin and N-cadherin. Based on the fact that KY-20-22 regulates interleukin-6, a cytokine involved in chemotherapy resistance, we combined it with paclitaxel and found that it synergistically induced anti-proliferative action in TNBC cells. The results from this study suggested that 1-chromonyl-5-imidazolylpentadienone KY-20-22 exhibited anti-cancer action in MDA-MB-231 and MDA-MB-468 cells. Future studies are required to evaluate the anti-cancer ability and bioavailability of KY-20-22 in the TNBC animal model.

Why Does Prevention of Recurrent Urinary Tract Infection not Result in Less Renal Scarring? A Deeper Dive into the RIVUR Trial.

PURPOSE: The RIVUR (Randomized Intervention for Children with Vesicoureteral Reflux) trial reported that antibiotic prophylaxis reduced recurrent urinary tract infection but antibiotic prophylaxis was not associated with decreased new renal scarring. However, the original reports did not assess the relationship among recurrent urinary tract infection, new renal scarring and antibiotic prophylaxis in detail. Therefore, we investigated the relationship among these issues. MATERIALS AND METHODS: We included subjects with dimercaptosuccinic acid scan within 6 months of enrollment and at least 1 followup dimercaptosuccinic acid scan from the RIVUR trial. The primary outcome was recurrent urinary tract infection associated new renal scarring, defined as recurrent urinary tract infection and new changes on dimercaptosuccinic acid scan. Due to a low number of events, propensity score was used to adjust for confounders. Multivariate logistic regression was fitted to investigate the associations between the covariates and the outcome. RESULTS: A total of 489 patients (91% female, mean age 20.3 months) were included in the study. Any new renal scarring was more common among those with recurrent urinary tract infection (OR 4.1, 95% CI 2.0-8.5, p <0.01) after adjusting for age, sex, index urinary tract infection, duplication, bowel bladder dysfunction and antibiotic prophylaxis. Recurrent urinary tract infection associated new renal scarring occurred in 5 of 244 (2%) patients on antibiotic prophylaxis and 13 of 245 (5%) on placebo. Compared to antibiotic prophylaxis, placebo was associated with a higher risk of recurrent urinary tract infection associated new renal scarring (OR 3.1, 95% CI 1.0-8.8, p=0.04) after adjusting for age, sex, race, index urinary tract infection, bowel bladder dysfunction, duplication, hydronephrosis, vesicoureteral reflux grade and baseline renal scarring. There were no differences in scar severity at final dimercaptosuccinic acid scan (p=0.88) or change from baseline (p=0.53) between antibiotic prophylaxis and placebo. CONCLUSIONS: Recurrent urinary tract infection was associated with new renal scarring in the RIVUR trial. When limited to recurrent urinary tract infection associated new renal scarring, antibiotic prophylaxis was associated with a decreased risk of this outcome. It remains unclear why new renal scarring developed in a proportion of subjects without recurrent urinary tract infection. The results should be carefully interpreted due to the inherent limitations.

The Use of Telemedicine for the Postoperative Urological Care of Children: Results of a Pilot Program.

PURPOSE: For postoperative visits, which are often brief interactions between family and clinician, patients may prefer the convenience of receiving postoperative care from home. We evaluated the feasibility of telemedicine for postoperative encounters in pediatric urology. MATERIALS AND METHODS: We performed a prospective telemedicine pilot study during an implementation period from November 10, 2017 to March 22, 2018. All postoperative patients deemed eligible by 1 of 4 urologists were offered enrollment in the telemedicine program. Enrollees underwent at least 1 virtual visit within 6 weeks of surgery. Technical difficulties and the number of unscheduled visits and readmissions were noted. After each virtual evaluation the family and clinician were prompted to complete a survey pertaining to perceptions of the telemedicine experience, including how effective the virtual visit was in delivering care. For each virtual visit with a urologist we estimated roundtrip travel cost and time. RESULTS: There was 96% technical success when using the software. A total of 125 postoperative virtual visits were completed in 83 patients. Median age of the children was 3.4 years and 87% were boys. Clinicians found that the virtual visit was "very effective" in 86% of cases, delivering the same care that they would have provided during a visit in person. Families were estimated to have saved a mean $150 travel cost and a median of 113 minutes of travel time per visit. No adverse postoperative outcomes were observed. CONCLUSIONS: This pilot study demonstrates that telemedicine can be successfully implemented in the postoperative care of pediatric urology patients.

The effect of various tax and redistribution models on the Gini coefficient of simple exchange games.

The Bennati-Dragulescu-Yakovenko (BDY) game is an agent-based simple exchange game that models a basic economic system. The BDY game results in the agents' wealth following a Boltzmann-Gibbs distribution. In other words, the result of the game is many "poor" agents and few "wealthy" agents. In this paper, we apply several tax and redistribution models to study their effect on the population's wealth distribution by computing the resulting Gini coefficient of the system. We find that income taxes, both flat and progressive, that evenly redistributed taxed monies do little to change the Gini coefficient from the Boltzmann-Gibbs distribution. However, income taxes that are redistributed to the poorest agents can significantly lower the Gini coefficient, resulting in a more evenly distributed wealth distribution. Furthermore, we find that a very small wealth tax can lead to significant decreases in the Gini coefficient.

Advances in paediatric urology.

Paediatric urological surgery is often required for managing congenital and acquired disorders of the genitourinary system. In this Series paper, we highlight advances in the surgical management of six paediatric urological disorders. The management of vesicoureteral reflux is evolving, with advocacy ranging from a less interventional assessment and antimicrobial prophylaxis to surgery including endoscopic injection of a bulking agent and minimally invasive ureteric reimplantation. Evidence supports early orchidopexy to improve fertility and reduce malignancy in boys with undescended testes. A variety of surgical techniques have been developed for hypospadias, with excellent outcomes for distal but not proximal hypospadias. Pelvi-ureteric junction obstruction is mostly detected prenatally; indications for surgery have been refined with evidence, and minimally invasive pyeloplasty is now standard. The outlook for patients with neurogenic bladder has been transformed by a combination of clean intermittent catheterisation, algorithms of diagnostic investigations, and innovative medical and surgical therapies. Posterior urethral valves are associated with considerable mortality; fetal diagnosis allows stratification of candidates for intervention, but ongoing bladder dysfunction in patients after valve ablation remains a cause of long-term morbidity.

Blunt Abdominal Trauma from Motor Vehicle Collisions from 2007 to 2011: Renal Injury Probability and Severity in Children versus Adults.

PURPOSE: There are sparse data directly comparing the probability of renal injury in children and adults. The kidney of the child is believed to be more susceptible to blunt injury for a variety of anatomical reasons. In a large cohort we tested the hypothesis that the pediatric kidney is more susceptible to any renal injury and to higher grade injury. MATERIALS AND METHODS: We queried the NTDB® (National Trauma Data Bank®) on all hospital admissions following motor vehicle collisions in a pediatric population (age less than 21 years) and a referent adult population (age 30 to 50 years). Of 111,172 children who were admitted after motor vehicle collisions 1,093 had renal injury. RESULTS: Of the 111,172 children admitted to the hospital following motor vehicle collisions 59,385 had abdominal trauma and 1,093 had renal injury. In a multivariate logistic model adjusting for overall ISS (Injury Severity Score), region, year, driver/passenger status, presence of restraint or an airbag, we found that children had 48% higher odds of renal injury compared to adults ages 30 to 50 years (OR 1.48, 95% CI 1.32-1.66, p <0.001). Furthermore, children were at 33% higher risk for high grade renal injury (OR 1.33, 95% CI 1.05-1.69, p = 0.919). The effect remained when restricting analysis to patients with concomitant liver and spleen injuries (p <0.001). CONCLUSIONS: In a large national cohort of children, blunt renal injury following motor vehicle collisions is rare but substantially more common than in adults. The odds of high grade renal injury are approximately 50% higher in children. A greater index of suspicion and a lower threshold for renal imaging is prudent for children with blunt abdominal trauma from motor vehicle collisions.

The Dilemma of Adolescent Varicoceles: Do They Really Have to Be Repaired?

The primary indication for varicocele repair in adults, that of failed paternity, must be substituted in the adolescent population with surrogate parameters of testicular size differential and semen analysis. Making recommendations based on these two parameters is incredibly difficult because studies often have contradictory findings, different patient populations, and lack of long-term follow up of the key endpoint, paternity. Therefore, it is not a surprise that recommendations for adolescent varicocele repair are general (with some exceptions) and necessarily so because of limitations in quality of evidence. Apart from pain, all indications for varicocele repair in adolescence remain controversial. This highlights the most important task for future studies: to prevent pediatric urologists from allowing a potentially damaging process to go untreated, while at the same time avoiding unnecessary intervention on a highly prevalent condition.

Factors associated with fetal shunt dislodgement in lower urinary tract obstruction.

OBJECTIVE: To identify factors associated with fetal shunt dislodgement in lower urinary tract obstruction (LUTO). METHODS: We conducted a retrospective study of 42 consecutive fetuses with a diagnosis of LUTO in a tertiary fetal center between April 2013 and November 2015. Possible factors associated with prenatal shunt dislodgment were evaluated in fetuses who underwent shunt placement, including gestational age at diagnosis, gestational age at procedure, presence of 'keyhole sign', initial fetal bladder volume and wall thickness, prenatal ultrasonographic renal characteristics, amniotic fluid volume, presence of ascites prior to shunting, and type of fetal shunt. RESULTS: Nineteen (46.3%) fetuses underwent shunt placement at a median gestational age of 19 (range: 16.3-31.1) weeks. Shunt dislodgement occurred in 10 (52.6%) patients. A total of 35 procedures were performed; among which 16 (45.7%) were repeat procedures. The only prenatal factor associated with shunt dislodgement was the type of the shunt; Kaplan-Meier analysis indicated that the Rocket was associated with increased likelihood of remaining orthotopic (p = 0.04). CONCLUSION: Fetal shunt dislodgement occurs in approximately half of the patients and appears to be associated with the type of the shunt. Future research is necessary to develop better shunt systems and to investigate different fetal therapeutic approaches. © 2016 John Wiley & Sons, Ltd.

Imaging after urinary tract infection in older children and adolescents.

PURPOSE: There are few guidelines and little data on imaging after urinary tract infections in older children. We determined the clinical yield of renal and bladder ultrasound, and voiding cystourethrogram in older children and adolescents after urinary tract infection. MATERIALS AND METHODS: We analyzed findings on voiding cystourethrogram, and renal and bladder ultrasound as well as the clinical history of patients who underwent the 2 studies on the same day between January 2006 and December 2010. We selected for study patients 5 to 18 years old who underwent imaging for urinary tract infection. Those with prior postnatal genitourinary imaging or prenatal hydronephrosis were excluded from analysis. RESULTS: We identified a cohort of 153 patients, of whom 74% were 5 to 8 years old, 21% were 8 to 12 years old and 5% were 12 to 18 years old. Of the patients 77% were female, 78% had a febrile urinary tract infection history and 55% had a history of recurrent urinary tract infections. Renal and bladder ultrasound findings revealed hydronephrosis in 7.8% of patients, ureteral dilatation in 3.9%, renal parenchymal findings in 20% and bladder findings in 12%. No patient had moderate or greater hydronephrosis. Voiding cystourethrogram showed vesicoureteral reflux in 34% of cases and bladder or urethral anomalies in 12%. Reflux was grade I, II-III and greater than III in 5.9%, 26% and 2% of patients, respectively. For any voiding cystourethrogram abnormality the sensitivity and specificity of any renal and bladder ultrasound abnormality were 0.49 (95% CI 0.37-0.62) and 0.76 (95% CI 0.66-0.84), respectively. Positive and negative predictive values were 0.58 (95% CI 0.44-0.71) and 0.69 (0.59-0.77), respectively. CONCLUSIONS: In older children with a history of urinary tract infection the imaging yield is significant. However, imaging revealed high grade hydronephrosis or high grade vesicoureteral reflux in few patients. Renal ultrasound is not reliable for predicting voiding cystourethrogram findings such as vesicoureteral reflux.

Semen parameters in adolescents with varicocele: association with testis volume differential and total testis volume.

PURPOSE: We evaluated the relationship between testicular volume differential, total testis volume and total motile sperm count in adolescents with varicocele. Prior reports have been inconclusive regarding the association of testis volume with semen analysis parameters. MATERIALS AND METHODS: We retrospectively reviewed a single institution database of Tanner 5 adolescents with nonoperated left varicocele with at least 1 semen analysis available. Patients were included in analysis if they had clinical left varicocele, ultrasound measurement of testis volume and no prior inguinal or scrotal surgery. RESULTS: We analyzed the records of 100 patients. Mean ± SD age at presentation was 15.2 ± 3.5 years. The mean testicular volume differential was 8% ± 23% and 31 patients (31%) had a greater than 20% testicular volume differential. Mean total testis volume was 30.4 ± 13.3 cc. Varicocele was grade 3 in 39 patients, grade 2 in 50, grade 1 in 8 and ungraded in 3. Median total motile sperm count in the cohort was 42.0 (IQR 9.2, 105.8). ROC analysis with the Youden index indicated an optimal total testis volume cutoff of 30 cc to predict the total motile sperm count. In a multivariable logistic model accounting for age and varicocele grade a testicular volume differential of greater than 20% was associated with twice the odds of a total motile sperm count of less than 20 million per cc (OR 2.1, 95% CI 1.02-4.12, p = 0.04). Total testis volume less than 30 cc more than quadrupled the odds of a total motile sperm count of less than 20 million per cc (OR 4.2, 95% CI 1.8-9.7, p <0.001). CONCLUSIONS: Total testis volume and the testicular volume differential are associated with semen analysis outcomes in adolescents with varicocele. A testicular volume differential of greater than 20% doubles the odds of a low total motile sperm count. A total testis volume of less than 30 cc quadruples the odds of a low total motile sperm count.

Fretting and Fretting Corrosion Behavior of Additively Manufactured Ti-6Al-4V and Ti-Nb-Zr Alloys in Air and Physiological Solutions.

Additive manufacturing (AM) of orthopedic implants has increased in recent years, providing benefits to surgeons, patients, and implant companies. Both traditional and new titanium alloys are under consideration for AM-manufactured implants. However, concerns remain about their wear and corrosion (tribocorrosion) performance. In this study, the effects of fretting corrosion were investigated on AM Ti-29Nb-21Zr (pre-alloyed and admixed) and AM Ti-6Al-4V with 1% nano yttria-stabilized zirconia (nYSZ). Low cycle (100 cycles, 3 Hz, 100 mN) fretting and fretting corrosion (potentiostatic, 0 V vs. Ag/AgCl) methods were used to compare these AM alloys to traditionally manufactured AM Ti-6Al-4V. Alloy and admixture surfaces were subjected to (1) fretting in the air (i.e., small-scale reciprocal sliding) and (2) fretting corrosion in phosphate-buffered saline (PBS) using a single diamond asperity (17 µm radius). Wear track depth measurements, fretting currents and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis of oxide debris revealed that pre-alloyed AM Ti-29Nb-21Zr generally had greater wear depths after 100 cycles (4.67 +/- 0.55 µm dry and 5.78 +/- 0.83 µm in solution) and higher fretting currents (0.58 +/- 0.07 µA). A correlation (R2 = 0.67) was found between wear depth and the average fretting currents with different alloys located in different regions of the relationship. No statistically significant differences were observed in wear depth between in-air and in-PBS tests. However, significantly higher amounts of oxygen (measured by oxygen weight % by EDS analysis of the debris) were embedded within the wear track for tests performed in PBS compared to air for all samples except the ad-mixed Ti-29Nb-21Zr (p = 0.21). For traditional and AM Ti-6Al-4V, the wear track depths (dry fretting: 2.90 +/- 0.32 µm vs. 2.51 +/- 0.51 µm, respectively; fretting corrosion: 2.09 +/- 0.59 µm vs. 1.16 +/- 0.79 µm, respectively) and fretting current measurements (0.37 +/- 0.05 µA vs. 0.34 +/- 0.05 µA, respectively) showed no significant differences. The dominant wear deformation process was plastic deformation followed by cyclic extrusion of plate-like wear debris at the end of the stroke, resulting in ribbon-like extruded material for all alloys. While previous work documented improved corrosion resistance of Ti-29Nb-21Zr in simulated inflammatory solutions over Ti-6Al-4V, this work does not show similar improvements in the relative fretting corrosion resistance of these alloys compared to Ti-6Al-4V.

Urology Mythbusters: Does prevalence of vesicoureteral reflux in children vary by race?

In this edition of Mythbusters, we examine the premise that prevalence of vesicoureteral reflux (VUR) in children varies by race. Specifically, we consider whether there is evidence supporting the contention that VUR is more common in White children and less common in Black children. Statements regarding the lower prevalence of VUR in Black children are ubiquitous in both research papers and reviews. Many of the references cited in support of these statements do not actually support the existence of racial variation in VUR, due to uncontrolled single-arm study designs, highly selected samples at risk for bias, or simply not addressing VUR prevalence at all. There is a small group of studies which directly compared VUR prevalence among children undergoing cystography, and these studies have found VUR to be less common among Black children compared to White children. However, the results of such papers can only be considered in the context of a system in which systemic bias and racism may impact access and care delivery in profound ways. Given that race is a social construct that bears little relationship to shared genetic ancestry or underlying biological characteristics, these findings must be approached with extreme caution. The goals of pediatric urological care should be to confer equitable care to all young children regardless of race.

Reactive Oxygen Species, Electrode Potential and pH Affect CoCrMo Alloy Corrosion and Semiconducting Behavior in Simulated Inflammatory Environments.

Crevice corrosion in modular taper junctions of hip or knee replacements using cobalt-chrome-molybdenum (CoCrMo) alloys remains a clinical concern. Non-mechanically-driven corrosion has been less explored compared to mechanically assisted crevice corrosion. This study hypothesized that solution chemistry within crevices, inflammation, and cathodic electrode potential shifts during fretting result in low pH and generate reactive oxygen species (ROS), affecting oxide film behavior. This study investigated how resistance and capacitance of the CoCrMo oxide film (i.e., corrosion resistance) are modified in simulated in vivo crevice environments of modular taper junctions. Six solutions were evaluated (two pH levels: 1 and 7.4 and four hydrogen peroxide (H2O2) concentrations: 0, 0.001, 0.01 and 0.1 M). Rp versus voltage and Mott-Schottky plots were created from symmetry-based electrochemical impedance spectroscopy (sbEIS). At pH 1, the semiconductor transition to p-type occurs at more anodic potentials and higher flat band potentials were found. H2O2 decreased the flat band potential and slope in the Mott-Schottky plot. Higher H2O2 in pH 7.4 solution significantly modified the oxide film, leading to increased donor density (p = 0.0004) and a 150-fold reduction in Rp in the cathodic potential range at -1 V (p = 0.0005). The most unfavorable condition (0.1 M H2O2 pH 1) resulted in a 250-fold lower resistance compared to phosphate buffered saline (PBS) pH 7.4 at -1 V (p = 0.0013). This study highlights the corrosion susceptibility of CoCrMo under adverse chemical and potential conditions, identifying increased defects in the oxide film due to ROS, hydrogen ions and electrode potential. STATEMENT OF SIGNIFICANCE: : Corrosion of cobalt chrome molybdenum alloy caused by direct chemical attack in the crevice region of hip replacements, such as modular taper junctions, remains a clinical concern. The junction environment contains adverse chemical compositions, including high acidity and reactive oxygen species (ROS) due to inflammatory responses against the corrosion products. We simulate inflammatory environments with different pH levels and hydrogen peroxide, representative of ROS. We employ electrochemical impedance spectroscopy and apply stepwise voltage over the range induced by tribocorrosion processes. We relate the effect of adverse chemical components on corrosion and semiconducting behavior of the oxide film using Mott-Schottky analysis. This study shows how pH and ROS concentration compromises the oxide film potentially leading to non-mechanically induced corrosion.