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Gas isotope thermometry using the isotopes of molecular nitrogen and argon has been used extensively to reconstruct past surface temperature change from Greenland ice cores. The gas isotope ratios δ15N and δ40Ar in the ice core are each set by the amount of gravitational and thermal fractionation in the firn. The gravitational component of fractionation is proportional to the firn thickness, and the thermal component is proportional to the temperature difference between the top and bottom of the firn column, which can be related to surface temperature change. Compared to Greenland, Antarctic climate change is typically more gradual and smaller in magnitude, which results in smaller thermal fractionation signals that are harder to detect. This has hampered application of gas isotope thermometry to Antarctic ice cores. Here, we present an analytical method for measuring δ15N and δ40Ar with a precision of 0.002 ‰ per atomic mass unit, a two-fold improvement on previous work. This allows us to reconstruct changes in firn thickness and temperature difference at the South Pole between 30 and 5 kyr BP. We find that variability in firn thickness is controlled in part by changes in snow accumulation rate, which is, in turn, influenced strongly by the along-flowline topography upstream of the ice core site. Variability in our firn temperature difference record cannot be explained by annual-mean processes. We therefore propose that the ice core gas isotopes contain a seasonal bias due to rectification of seasonal signals in the upper firn. The strength of the rectification also appears to be linked to fluctuations in the upstream topography. As further evidence for the existence of rectification, we present new data from the Dome Fuji ice core that are also consistent with a seasonal bias throughout the Holocene. Our findings have important implications for the interpretation of ice core gas records. For example, we show that the effects of upstream topography on ice core records can be significant at flank sites like the South Pole – they are responsible for some of the largest signals in our record. Presumably upstream signals impact other flank-flow ice cores such as EDML, Vostok, and EGRIP similarly. Additionally, future work is required to confirm the existence of seasonal rectification in polar firn, to determine how spatially and temporally widespread rectifier effects are, and to incorporate the relevant physics into firn air models.

A periacetabular osteotomy (PAO) can reduce pain and improve quality of life in patients with hip dysplasia. While its utility for patients without traditional radiographic parameters for hip dysplasia has not been previously established, the PAO may help treat patients with hip instability that does not improve following single or multiple hip arthroscopic procedures, or when such procedures lead to hip instability.A single-surgeon registry of patients at a single institution was queried to identify patients with a lateral center-edge angle (LCEA) of ≥24° and a Tönnis angle of10° who underwent PAO because of hip pain and/or instability that failed treatment with hip arthroscopy. Descriptive summary statistics were reported on patient demographics, mean change in LCEA, and patient-reported outcome measures, including the modified Harris hip score (mHHS) and the International Hip Outcome Tool-33 (iHOT-33), at a minimum of 6 months of follow-up.Among 25 patients (mean age, 27.3 ± 6.9 years; 100% women), the mean LCEA increased from 27.2° (range, 24° to 37°) preoperatively to 39.0° ± 5.1° postoperatively (net increase, 11.8° ± 4.5°). Overall, the mean improvement in the mHHS was 11.5 ± 16.9 (preoperative, 59.4 ± 11.6; postoperative, 70.9 ± 20.6) and the mean improvement in the iHOT-33 was 23.8 ± 23.6 (preoperative, 32.2 ± 17.2; postoperative, 56.0 ± 30.0). Eighteen patients (72%) achieved a minimal clinically important improvement in mHHS (mean improvement, 17.4 ± 12.9) and iHOT-33 (mean improvement, 32.4 ± 19.1) scores. In comparison with 7 patients who did not show improvement, the 18 patients who showed improvement had significantly greater mean baseline patient-reported outcome scores.To our knowledge, these findings provide the first report on outcomes of PAO in patients with hip pain following arthroscopy who do not meet the traditional criteria for acetabular dysplasia. Early benefits in clinical outcomes suggest a novel surgical indication for PAO as a potential salvage option for selected patients; however, longer-term studies are needed.Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Intraoperative neuromonitoring (IONM) has historically been difficult to obtain in patients with Charcot-Marie-Tooth (CMT) disease. Transcranial motor-evoked potentials (TcMEPs) have been found to be safe and effective for other spinal deformity patients. Our objective was to determine the effectiveness of TcMEP monitoring in patients with CMT.An IRB-approved, retrospective review of CMT patients undergoing spinal deformity surgery assessing TcMEP, somatosensory-evoked potential (SSEP), and neurogenic motor evoked potential (NMEP) IONM was performed. A 2:1 matched cohort control group of idiopathic spinal deformity patients was used. A waveform grading system was applied to review baseline TcMEP reliability and quality, which was validated via intraclass correlation coefficient amongst five raters.Twenty-three CMT patients (26 surgical cases) were identified. The use of TcMEP improved the ability to obtain baseline IONM when compared to SSEP (83% vs. 20%; p 0.001) and NMEP (83% vs. 18%; p = 0.003). Baseline monitoring was obtained less often for CMT patients using SSEP (20% vs. 100%; p 0.001) and TcMEP (83% vs. 100%; p = 0.111) compared to idiopathic patients. Sweep length (time from stimulation waveform evaluation) and maximum stimulation voltage were higher in the CMT group (289 ms vs. 111 ms p = 0.007 and 740 V vs. 345 V p = 0.089, respectively).TcMEP monitoring significantly improves the ability to provide IONM for CMT patients undergoing spinal deformity surgery. Utilizing longer sweep lengths enhances the ability to attain baseline TcMEP readings, allowing surgeons to more safely proceed with surgery for these complex patients.Therapeutic-Level III.

Osteochondral lesions of the femoral head in young people are rare and present unique management challenges. Optimal treatment for these lesions is unclear. From 2009 to 2016, clinical and radiographic outcomes were prospectively collected within a series of symptomatic focal osteochondral lesions of the femoral head with a minimum follow-up of 2 years. A surgical hip dislocation followed by implantation of a size-matched fresh osteochondral femoral head allograft was performed. Nine hips in eight patients (6 female patients) underwent surgery at an average of 17 years (11 to 21 years). Individual allograft sizes ranged from 10 to 35 mm in diameter; with 2 of 9 hips receiving two allografts in a stacked or mosaicplasty technique at the time of treatment. The average graft implantation was 3536.5 mm2. Modified Harris hip scores improved by 13.4 (P = 0.018) from preoperative to final follow-up for all patients. Significant improvements in internal rotation (12° versus 23°, P = 0.011), external rotation (32° versus 50°, P = 0.041), and abduction (28° versus 40°, P = 0.042) were also achieved. Three patients (four hips) demonstrated poor radiographic healing (

BACKGROUND: Although p values are standard for reporting statistical significance of patient-reported outcome measures (PROMs), the shift toward clinically important outcome values, including minimal clinically important difference (MCID) and substantial clinical benefit (SCB), necessitates re-evaluation of the current literature. QUESTIONS/PURPOSES: We sought to answer two questions regarding studies on primary hip arthroscopy performed for the treatment of femoroacetabular impingement syndrome (FAIS). (1) Do such studies reporting statistical significance on common PROMs meet published MCID/SCB thresholds? (2) What proportion of such studies report both statistical and clinical significance? METHODS: We identified four papers published in two journals defining MCID/SCB values on the modified Harris Hip Score (mHHS), Hip Outcome Score–Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sport (HOS-Sport), international Hip Outcome Tool (iHOT-33), and its short version (iHOT-12) for different groups of FAIS patients undergoing hip arthroscopy. We reviewed these two journals from the dates of publication to the present to identify papers reporting changes in post-operative PROMs. The difference in pre- and post-operative scores on each PROM was calculated and compared to MCID/SCB thresholds. RESULTS: Twelve studies were included. Ten studies (83%) evaluated mHHS (90% met MCID, 50% met SCB), seven (58%) evaluated HOS-ADL (100% met MCID/SCB) and HOS-Sport (100% met MCID, 57% met SCB), and one (8%) evaluated iHOT-33 (met MCID/SCB) and iHOT-12 (met MCID). Most studies met MCID and SCB at both 1- and 2-year timepoints. Of the studies evaluated, 50% reported clinical relevance. CONCLUSIONS: Nearly all studies evaluated met MCID, while fewer met SCB. Only half discussed these clinical measures. It is proposed that all future studies report both statistical and clinical significance as standard best practice. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11420-020-09759-3) contains supplementary material, which is available to authorized users.

Purpose: There is a paucity of data defining safe transport protocols for children treated with hip spica casting. No current restraint device has been tested using casted anthropomorphic test devices (ATDs). Our goal was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD. Methods: Using an ATD simulating a 3-year-old child, dynamic crash sled tests simulating a frontal crash were performed in accordance with Federal Motor Vehicle Safety Standards 213 (FMVSS 213). Sensors within the ATD recorded: HIC36 (Head Injury Criterion score; predictive of skull fracture), neck injury assessment (Nij), chest compression, chest acceleration, and pelvic injury assessment. Test crash video visual assessment was performed (Figures 1&2). The ATD was casted in a double-leg spica. Five restraint devices were tested: seat designed for spica-casted children (Merrit Wallenberg), modified restraint harness (Modified EZ-On-Vest), commercially available booster seat (Britax Parkway SGL Booster), and two commercially available forward-facing car seats able to accommodate the casted ATD (Diono Radian R100, Graco Nautilus 65 LX). One test was performed for each restraint system. All tests were performed at 30 MPH on a deceleration sled. Results: Although the presence of the cast increased many of the injury metrics measured, all 5 seats that were tested passed current FMVSS 213 federal guidelines for the head and chest. However, there were marked differences between the 5 restraint options (Figures 3-5). No single seat performed best in all metrics. Additionally, visual analysis of the video from the test crash of the EZ-On-Vest demonstrated that the face and upper extremities of the ATD are impacted during the crash. The ATD does not have a way to record injury to the extremities, thus this is not captured in the quantitative data. Conclusions: Per the FMVSS 213 standard, these results suggest safe transport in the five evaluated restraint systems is possible with the child properly fitted and restrained. However, the Nautilus and Diono were found to have both the lowest HIC36 and chest acceleration values, suggesting casted children may not need specially designed seats. Additionally, review of the video of the EZ-On Vest appears to demonstrate that the vest may expose the casted child to additional facial and extremity injuries compared to systems that allow the child to sit upright. Significance: Parents should not assume a restraint system is automatically appropriate for use with their child. While there were differences in the performances of the tested restraint systems, each child is unique and a trained healthcare provider should be consulted to ensure the child is properly restrained.

Since 1985, one-third of all US all-terrain vehicle (ATV)-related injuries and one-quarter of deaths involved victims16 years of age. ATV safety education of youth could help reduce these tragedies.To assess the efficacy of the Safety Tips for ATV Riders (STARs) school-based programme targeting adolescents.A survey was anonymously administered before and after the programme to determine demographics, knowledge and reported likelihood of using the information learned.Over 4600 students in 30 Iowa schools participated from November 2010 to April 2013. Initially, 52% knew most ATVs are designed for one rider, 25% knew the recommended vehicle size for their age range and 42% knew riding on Iowa's roads was legal only for agricultural purposes. After the programme, this increased to 92%, 82% and 76%, respectively (p0.0001 in each case), with 61% of students correct on all three. Better preintervention scores were associated with being males, higher riding frequency and being from isolated rural communities. After the programme, 48% and 32% said they were likely/very likely versus unlikely/very unlikely to use the safety information learned, respectively; younger students, females and infrequent riders reported higher likelihoods.STARs increased short-term ATV safety knowledge and almost half the participants reported they would use the safety information presented. Males and frequent riders seemed more resistant, but some groups that may be more vulnerable to potential ATV crash and injury appeared amenable to the training with higher increases in postprogramme scores and greater intention of improving safety behaviours.

Over the past 30 years, treatment advances and the addition of neoadjuvant chemotherapy have led to improved 5-year survival in patients with osteosarcoma. More recent literature suggests the overall prognosis remains highly variable, with little improvement since the introduction of neoadjuvant chemotherapy. Tumor necrosis is an important predictor of patient prognosis. Necrosis of more than 90% correlates with overall survival (OS) approaching 75%. We reviewed the history of osteosarcoma treatment and survival and performed a meta-analysis of the 2000-2011 literature. Forty articles were included in the study. Five-year OS was 63% (95% confidence interval, 60%-66%) in studies that included patients with metastatic and nonmetastatic disease and 71% (95% confidence interval, 67%-76%) in studies that included only patients with nonmetastatic disease. Fifty percent of the patients in the studies of those with nonmetastatic osteosarcoma achieved 90% necrosis on histology. Five-year OS and number of patients achieving 90% necrosis are consistent with previous reports. Research is needed to improve treatment regimens and patient outcomes.

PURPOSE: More youth are killed every year in the United States in all-terrain vehicle (ATV) crashes than on bicycles, and since 2001, one-fifth of all ATV fatalities have involved victims aged 15 years or younger. Effectively preventing pediatric ATV-related deaths and injuries requires knowledge about youth riding practices. Our objective was to examine ATV use, crash prevalence, and riding behaviors among adolescent students in a rural state. METHODS: We administered a cross-sectional survey to 4,684 youths aged 11 to 16 years at 30 schools across Iowa from November 2010 to April 2013. Descriptive and comparative analyses were performed. RESULTS: Regardless of rurality, at least 75% of students reported having been on an ATV, with 38% of those riding daily or weekly. Among ATV riders, 57% had been in a crash. Most riders engaged in risky behaviors, including riding with passengers (92%), on public roads (81%), or without a helmet (64%). Almost 60% reported engaging in all 3 behaviors; only 2% engaged in none. Multivariable modeling revealed male youth, students riding daily/weekly, and those reporting both riding on public roads and with passengers were 1.61 (95% CI, 1.36-1.91), 3.73 (95% CI, 3.10-4.50), and 3.24 (95% CI, 2.09-5.04) times more likely to report a crash, respectively. CONCLUSIONS: Three-fourths of youths surveyed were exposed to ATVs. The majority of riders had engaged in unsafe behaviors and experienced a crash. Given this widespread use and the potentially considerable morbidity of pediatric ATV crashes, prevention efforts, including anticipatory guidance by primary care clinicians serving families at risk, should be a higher priority. Language: en

Objectives— To (1) determine bone contact with the outer surface and ingrowth into the perforated outer shell of the Kyon acetabular component at 2, 6, and 12 months after total hip replacement (THR) and (2) determine correlation between radiographic lucency surrounding the cup–bone interface and bone contact and ingrowth. Study Design— Experimental study. Animals— Large breed dogs (n=11) with and without hip dysplasia. Methods— Force platform gait analysis was performed preoperatively and 2, 6, and 12 months after THR. Curvilinear length of lucency (CLL) was measured on pelvic radiographs. Tissue contact with the outer cup and ingrowth into the cup were determined histomorphometrically at 2, 6, and 12 months. Results— Peak vertical force and vertical impulse of the treated and control hind limb were not significantly different at any time. Median bone contact with the outer cup surface was 77%, 48%, and 76% at 2, 6, and 12 months, respectively. Median bone ingrowth into the cup perforations was 50%, 20%, and 44% at 2, 6, and 12 months, respectively. Median bone ingrowth to the inner cup surface was minimal at any time. CLL did not correlate with bone ingrowth. Conclusions— Bone ingrowth into cup perforations occurred in each dog and was already present 2 months after THR, but most of the inner cup space remained vacant. Clinical Relevance— Radiographic lucency surrounding the cup–bone interface does not allow assessment of bone contact with the outer surface or bone ingrowth into the Kyon cup in dogs without clinical problems.

This article discusses a case in which a patient who sustained an anterior cruciate ligament (ACL) injury returned with anterior knee pain in the same knee approximately 20 years later. He underwent reconstruction at the time of the injury and had a revision reconstruction performed 10 years later. The case highlights the long-term consequences of ACL injury and subsequent reconstruction for the knee joint, as this patient has developed anterior knee pain during his mid-40s. Additionally, non-operative management of knee osteoarthritis is discussed.

Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O{sub 2} composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO{sub 2}.