High Complication Rate After Percutaneous Screw Fixation for Valgus-Impacted Femoral Neck Fractures Without Sagittal Malalignment.

OBJECTIVES: To evaluate the rate of reoperation in patients without sagittal plane malalignment who underwent percutaneous screw fixation of a valgus-impacted femoral neck fracture. DESIGN: Retrospective case series. SETTING: Two Level 1 academic trauma centers. PATIENTS AND INTERVENTION: Two hundred seven patients >50 years of age with valgus-impacted femoral neck fractures treated with at least 3 large-diameter (>6.5 mm) cancellous screws from 2013 to 2019. Patients were excluded if there was a sagittal plane fracture deformity. MAIN OUTCOME MEASUREMENTS: The primary outcome was reoperation. Secondary outcomes considered "major complications" included: avascular necrosis, varus collapse or implant cutout, nonunion, deep infection, and hematoma requiring reoperation. Surgical fixation strategies (screw configuration, aim) and implant type (partial vs. fully threaded cancellous screws) were secondarily compared. RESULTS: Average patient age was 77 years, and median clinical follow-up was 658 days. Thirty-one patients (15%) required reoperation, and the major complication rate was 17.3% (36 complications in 33 patients). Logistic regression analysis demonstrated a higher risk of reoperation with constructs consisting of all partially threaded screws (17.0%) compared with the use of at least 1 fully threaded screw (7.5%) when an inverted triangle configuration was used (odds ratio, 2.50; 95% CI, 0.81-7.77). CONCLUSIONS: This study demonstrated a relatively high rate of reoperation and major complications in patients with valgus-impacted femoral neck fractures without sagittal malalignment treated with in situ percutaneous screw fixation. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A cross-sectional investigation of SARS-CoV-2 seroprevalence and associated risk factors in children and adolescents in the United States.

BACKGROUND: Pediatric SARS-CoV-2 data remain limited and seropositivity rates in children were reported as <1% early in the pandemic. Seroepidemiologic evaluation of SARS-CoV-2 in children in a major metropolitan region of the US was performed. METHODS: Children and adolescents ≤19 years were enrolled in a cross-sectional, observational study of SARS-CoV-2 seroprevalence from July-October 2020 in Northern Virginia, US. Demographic, health, and COVID-19 exposure information was collected, and blood analyzed for SARS-CoV-2 spike protein total antibody. Risk factors associated with SARS-CoV-2 seropositivity were analyzed. Orthogonal antibody testing was performed, and samples were evaluated for responses to different antigens. RESULTS: In 1038 children, the anti-SARS-CoV-2 total antibody positivity rate was 8.5%. After multivariate logistic regression, significant risk factors included Hispanic ethnicity, public or absent insurance, a history of COVID-19 symptoms, exposure to person with COVID-19, a household member positive for SARS-CoV-2 and multi-family or apartment dwelling without a private entrance. 66% of seropositive children had no symptoms of COVID-19. Secondary analysis included orthogonal antibody testing with assays for 1) a receptor binding domain specific antigen and 2) a nucleocapsid specific antigen had concordance rates of 80.5% and 79.3% respectively. CONCLUSIONS: A much higher burden of SARS-CoV-2 infection, as determined by seropositivity, was found in children than previously reported; this was also higher compared to adults in the same region at a similar time. Contrary to prior reports, we determined children shoulder a significant burden of COVID-19 infection. The role of children's disease transmission must be considered in COVID-19 mitigation strategies including vaccination.

Intracrystalline proteins and urolithiasis: a synchrotron X-ray diffraction study of calcium oxalate monohydrate.

UNLABELLED: The existence of intracrystalline proteins and amino acids in calcium oxalate monohydrate was demonstrated by X-ray synchrotron diffraction studies. Their presence has implications for the destruction of calcium oxalate crystals formed in the urinary tract and the prevention of kidney stones. INTRODUCTION: Although proteins are present in human kidney stones, their role in stone pathogenesis remains unknown. This investigation aimed to characterize the nature of the relationship between the organic and mineral phases in calcium oxalate monohydrate (COM) crystals grown in human urine and in aqueous solutions of proteins and amino acids to clarify the function of proteins in urolithiasis. METHODS: COM crystals were grown in human urine and in aqueous solutions containing either human prothrombin (PT), Tamm-Horsfall glycoprotein (THG), aspartic acid (Asp), aspartic acid dimer (AspAsp), glutamic acid (Glu), glutamic acid dimer (GluGlu), or gamma-carboxyglutamic acid (Gla). Controls consisted of COM crystals precipitated from pure inorganic solutions or from human urine that had been ultrafiltered to remove macromolecules. Synchrotron X-ray diffraction with Rietveld whole-pattern peak fitting and profile analysis was used to determine nonuniform crystal strain and crystallite size in polycrystalline samples. RESULTS: Crystals precipitated from ultrafiltered urine had lower nonuniform strain than those grown in urine or in aqueous PT solution. Nonuniform strain was much lower in crystals grown in distilled water or in the presence of THG. For the amino acids, the highest nonuniform strain was exhibited by crystals grown in Gla solution, followed by Glu. Crystallite size was inversely related to nonuniform strain, with the effect being significantly less for amino acids than for macromolecules. CONCLUSIONS: Selected proteins and amino acids associated with COM crystals are intracrystalline. Although their incorporation into the mineral bulk would be expected to affect the rate of crystal growth, they also have the potential to influence the phagocytosis and intracellular destruction of any crystals nucleated and trapped within the renal collecting system. Crystals impregnated with protein would be more susceptible to digestion by cellular proteases, which would provide access to the crystal core, thereby facilitating further proteolytic degradation and mineral dissolution. We therefore propose that intracrystalline proteins may constitute a natural form of defense against renal stone formation.