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OBJECTIVE Although 70% of football players in the United States are youth players (6-14 years old), most research on head impacts in football has focused on high school, collegiate, or professional populations. The objective of this study was to identify the specific activities associated with high-magnitude (acceleration > 40g) head impacts in youth football practices. METHODS A total of 34 players (mean age 9.9 ± 0.6 years) on 2 youth teams were equipped with helmet-mounted accelerometer arrays that recorded head accelerations associated with impacts in practices and games. Videos of practices and games were used to verify all head impacts and identify specific drills associated with each head impact. RESULTS A total of 6813 impacts were recorded, of which 408 had accelerations exceeding 40g (6.0%). For each type of practice drill, impact rates were computed that accounted for the length of time that teams spent on each drill. The tackling drill King of the Circle had the highest impact rate (95% CI 25.6-68.3 impacts/hr). Impact rates for tackling drills (those conducted without a blocker [95% CI 14.7-21.9 impacts/hr] and those with a blocker [95% CI 10.5-23.1 impacts/hr]) did not differ from game impact rates (95% CI 14.2-21.6 impacts/hr). Tackling drills were observed to have a greater proportion (between 40% and 50%) of impacts exceeding 60g than games (25%). The teams in this study participated in tackling or blocking drills for only 22% of their overall practice times, but these drills were responsible for 86% of all practice impacts exceeding 40g. CONCLUSIONS In youth football, high-magnitude impacts occur more often in practices than games, and some practice drills are associated with higher impact rates and accelerations than others. To mitigate high-magnitude head impact exposure in youth football, practices should be modified to decrease the time spent in drills with high impact rates, potentially eliminating a drill such as King of the Circle altogether., Competing Interests: The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

In this study, an analytical model is provided to describe the filling dynamics of a capillary filled with a viscous fluid containing spinning particles. The aim is to demonstrate the effect of angular momentum on the capillary filling dynamics of molecular fluids which has not been explored before. The presence of spinning particles generates additional coefficients of viscosity, namely, spin viscosity and vortex viscosity, which couples rotational and translational movements. Three different time stages have been noticed during the capillary filling phenomenon: inertia force dominated, visco-inertial, and viscous-dominated regions. The last two regions are found to be mainly affected by the spinning particles. An increase in the spin and vortex viscosities is found to increase the viscous force and thus reduce the front position of the moving liquid. The results of this study are validated using the literature no-angular-momentum (NAM) base-case results and an excellent agreement is observed., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Energy harvesting has become an increasingly important topic thanks to the advantages in renewability and environmental friendliness. In this paper, a comprehensive study on contemporary portable wind energy harvesters has been conducted. The electrical power generation methods of portable wind energy harvesters are surveyed in three major groups, piezoelectric-, electromagnetic-, and electrostatic-based generators. The paper also takes another view of this area by gauging the required mechanisms for trapping wind flow from ambient environment. In this regard, rotational and aeroelastic mechanisms are analyzed for the portable wind energy harvesting devices. The comparison between both mechanisms shows that the aeroelastic mechanism has promising potential in producing an energy harvester in smaller scale although how to maintain the resonator perpendicular to wind flow for collecting the maximum vibration is still a major challenge to overcome for this mechanism. Furthermore, this paper categorizes the previously published portable wind energy harvesters to macro and micro scales in terms of their physical dimensions. The power management systems are also surveyed to explore the possibility of improving energy conversion efficiency. Finally some insights and research trends are pointed out based on an overall analysis of the previously published works along the historical timeline.

OBJECTIVE Direct impact with the head and the inertial loading of the head have been postulated as major mechanisms of head-related injuries, such as concussion. METHODS This descriptive observational study was conducted to quantify the head impact acceleration characteristics in under-9-year-old junior rugby union players in New Zealand. The impact magnitude, frequency, and location were collected with a wireless head impact sensor that was worn by 14 junior rugby players who participated in 4 matches. RESULTS A total of 721 impacts > 10g were recorded. The median (interquartile range [IQR]) number of impacts per player was 46 (IQR 37-58), resulting in 10 (IQR 4-18) impacts to the head per player per match. The median impact magnitudes recorded were 15g (IQR 12g-21g) for linear acceleration and 2296 rad/sec(2) (IQR 1352-4152 rad/sec(2)) for rotational acceleration. CONCLUSIONS There were 121 impacts (16.8%) above the rotational injury risk limit and 1 (0.1%) impact above the linear injury risk limit. The acceleration magnitude and number of head impacts in junior rugby union players were higher than those previously reported in similar age-group sports participants. The median linear acceleration for the under-9-year-old rugby players were similar to 7- to 8-year-old American football players, but lower than 9- to 12-year-old youth American football players. The median rotational accelerations measured were higher than the median and 95th percentiles in youth, high school, and collegiate American football players.

Optimizing the protective capabilities of helmets is one of several methods of reducing brain injury risk in sports. This paper presents the experimental and analytical development of a hockey helmet evaluation methodology. The Summation of Tests for the Analysis of Risk (STAR) formula combines head impact exposure with brain injury probability over the broad range of 227 head impacts that a hockey player is likely to experience during one season. These impact exposure data are mapped to laboratory testing parameters using a series of 12 impact conditions comprised of three energy levels and four head impact locations, which include centric and non-centric directions of force. Injury risk is determined using a multivariate injury risk function that incorporates both linear and rotational head acceleration measurements. All testing parameters are presented along with exemplar helmet test data. The Hockey STAR methodology provides a scientific framework for manufacturers to optimize hockey helmet design for injury risk reduction, as well as providing consumers with a meaningful metric to assess the relative performance of hockey helmets.

Purpose: The purpose of this study was to compare intraoperative stress radiography and ankle arthroscopy in the evaluation of distal tibiofibular syndesmosis disruption in acute ankle fracture. Type Of Study: Prospective study. Methods: We treated 53 Weber type B or C ankle fractures without radiographic evidence of frank syndesmosis diastasis. Intraoperative stress radiography and ankle arthroscopy were performed. Syndesmotic screws were inserted in those patients with syndesmosis diastasis. Screws were removed 12 weeks later and second-look ankle arthroscopy was performed at the same time. Results: Sixteen cases (30.2%) had positive intraoperative stress radiographs; 35 cases (66.0%) had positive arthroscopic findings of syndesmosis diastasis, including various combinations of coronal, sagittal, and rotational planes of instability. During second-look arthroscopy, 31 of 34 patients with syndesmotic screws showed healing of the syndesmotic ligaments and the syndesmosis became stable. Conclusions: Ankle arthroscopy excels intraoperative stress radiography in detecting syndesmosis disruption. It also provides assessment of different planes of instability and assists anatomic reduction of the syndesmosis. Intraoperative radiography still does play an important role in assessing fracture reduction and proper restoration of fibular length and longitudinal orientation of the syndesmosis. Level Of Evidence: Level 2. [ABSTRACT FROM AUTHOR]

Background: Direct impacts with the head (linear acceleration or pressure) and inertial loading of the head (rotational acceleration or strain) have been postulated as the 2 major mechanisms of head-related injuries such as concussion. Although data are accumulating for soccer and American football, there are no published data for nonhelmeted collision sports such as rugby union., Purpose: To quantify head impacts via instrumented mouthguard acceleration analyses for rugby union players over a season of matches., Study Design: Descriptive epidemiology study., Methods: Data on impact magnitude and frequency were collected with molded instrumented mouthguards worn by 38 premier amateur senior rugby players participating in the 2013 domestic season of matches., Results: A total of 20,687 impacts >10g (range, 10.0-164.9g) were recorded over the duration of the study. The mean ± SD number of impacts per player over the duration of the season of matches was 564 ± 618, resulting in a mean ± SD of 95 ± 133 impacts to the head per player, per match over the duration of the season of matches. The impact magnitudes for linear accelerations were skewed to the lower values (Sp = 3.7 ± 0.02; P < .001), with a mean linear acceleration of 22.2 ± 16.2g. Rotational accelerations were also skewed to the lower values (Sp = 2.0 ± 0.02; P < .001), with a mean rotational acceleration of 3902.9 ± 3948.8 rad/s(2)., Conclusion: The acceleration magnitudes and number of head impacts in amateur rugby union players over a season of matches, measured via instrumented mouthguard accelerations, were higher than for most sports previously reported. Mean linear acceleration measured over a season of matches was similar to the mean linear accelerations previously reported for youth, high school, and collegiate American football players but lower than that for female youth soccer players. Mean rotational acceleration measured over a season of matches was similar to mean rotational accelerations for youth, high school, and collegiate American football players but less than those for female youth soccer players, concussed American collegiate players, collegiate American football players, and professional American football players., (© 2014 The Author(s).)

Background: To determine the safety and effectiveness of full thickness eyelid reconstructions using a semicircular rotational flap without reconstructing the posterior lamella., Methods: The charts of all patients undergoing semicircular flap closure of full thickness eyelid defects by one surgeon (JDP) at the Cole Eye Institute between March 2000 and October 2012 were reviewed. Charts were reviewed for patient demographic information, as well as for the size of the defect, the type of flap used, length of follow-up and complications., Results: Fifty eyelids of 50 patients underwent a semicircular flap repair without posterior lamellar reconstruction during the study period, and 41 charts were available for review. Average patient age was 74 years (range, 40-92 years). Average follow-up was 9.8 months (range, 1-84 months). Average defect size was 19.1 mm (range, 14-30 mm, SD 4.6). Complications included pyogenic granuloma (10 patients, 24.4%), exposure keratopathy (7 patients, 17.1%) lagophthalmos (5 patients, 12.2%), ectropion (6 patients, 14.6%), lateral canthal dystopia (2 cases, 4.9%), eyelid notch (2 cases, 4.9%) and trichiasis (4 cases, 9.8%). Two patients underwent subsequent tarsorrhaphy and one patient underwent ectropion repair. There were no cases of wound dehiscence, diplopia or fornix inadequacy, and the recruited aspect of the eyelid healed well in each case. No case required reconstruction of the eyelid margin or fornix., Conclusions: Semicircular flap repair of full thickness eyelid defects without flap or graft repair of the posterior lamella results in an adequate fornix and a low rate of secondary surgery.

Objective: Sports people always strive to avoid injury. Sports shoe designs in many sports have been shown to affect traction and injury rates. The aim of this study is to demonstrate the differing stiffness and torque in rugby boots that are designed for the same effect., Methods: Five different types of rugby shoes commonly worn by scrum forwards were laboratory tested for rotational stiffness and peak torque on a natural playing surface generating force patterns that would be consistent with a rugby scrum., Results: The overall internal rotation peak torque was 57.75±6.26 Nm while that of external rotation was 56.55±4.36 Nm. The Peak internal and external rotational stiffness were 0.696±0.1 and 0.708±0.06 Nm/deg respectively. Our results, when compared to rotational stiffness and peak torques of football shoes published in the literature, show that shoes worn by rugby players exert higher rotational and peak torque stiffness compared to football shoes when tested on the same natural surfaces. There was significant difference between the tested rugby shoes brands., Conclusion: In our opinion, to maximize potential performance and lower the potential of non-contact injury, care should be taken in choosing boots with stiffness appropriate to the players main playing role., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Cervical fractures can result in severe neurological compromise and even death. One of the most commonly injured segments is the C2 vertebrae, which most frequently involves the odontoid process. In this report, we present the unusual case of a 28-year-old female who sustained a C2 vertebral body fracture (comminuted transverse fracture through the body and both transverse processes) that had both a significant distractive and rotational component, causing the fracture to be highly unstable. Application of halo bracing was unsuccessful. The patient subsequently required a C1-C4 posterior spinal fusion. Follow-up computer tomography imaging confirmed fusion and the patient did well clinically thereafter.

Large lateral facial defects as a result of trauma or head and neck oncologic surgery can present a challenging reconstructive dilemma for the operating surgeon. A number of options currently exist for reconstructing such defects, including skin grafts, myocutaneous flaps, and free vascularized flaps. The decision to utilize one approach versus another depends largely on the nature of the defect, anatomical location, and the experience of the surgeon. This article describes our experience utilizing cervicopectoral rotation flaps with and without myocutaneous flaps to reconstruct large lateral facial defects after head and neck oncologic surgery.