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The aim of this study was to use video evidence of tackles in elite level rugby union to identify ball carrier proficiency characteristics, for both lower and upper body tackles, that have a higher propensity to result in Head Injury Assessments(HIA) for the tackler. HIA (n = 74) and non-HIA tackles (n = 233) were categorised as either front-on or side-on upper or lower body tackles and scored for ball carrying proficiency characteristics. Side-on tackles included tackles from behind. A Chi-Square test (p < 0.05) and Cramer's V were calculated to compare proficiency characteristics in HIA and non-HIA cases. For front-on upper body tackles, the ball carrier "fending into contact" (p < 0.01;ES = Moderate) and "explosiveness on contact" (p = 0.04;ES = Moderate) had a higher propensity to result in a HIA for the tackler. Fending into contact was exhibited in 47% of all upper body Tackle front-on HIA cases. The fending arm contacted the tackler's head in 67% of these cases. Fending into contact can potentially be dangerous and therefore emphasis should be placed on safe fending during tackle-based training drills. Referees should also be alert to arm-to-head contact during the fend. Given the low number of ball carrier characteristics identified, focus should be placed on tackler characteristics for HIA prevention strategies. [ABSTRACT FROM AUTHOR]

Background: The mechanisms of ACL injury in rugby are not well defined.Aim: To describe the mechanisms of ACL injury in male professional rugby players using systematic video analysis.Methods: 36 cases from games played in top professional leagues and international matches were analysed. 5 analysts independently assessed all videos to record the estimated frame/time of initial ground contact, frame/time of ACL tear and a range of play specific variables. This included contact versus non-contact ACL injuries, injury timing, joint flexion angles and foot contact with the ground. 37 side-stepping manoeuvres from a control game were analysed to allow comparison of non-injury versus injury situations.Results: 57% of ACL injuries occurred in a contact manner. 2 main scenarios were identified: (1) offensive running and (2) being tackled, indicating that the ball carrier might be at higher risk of ACL injury. The majority of non-contact ACL injuries resulted from a side-stepping manoeuvre. In most non-contact cases, initial ground contact was through heel strike. Statistical assessment of heel strike at initial ground contact versus non-heel strike cases showed a significant difference in injury versus non-injury outcomes, with heel strike associated with higher injury risk. Non-contact ACL injuries had lower median knee flexion angles and a more dorsiflexed ankle when compared with a control group (10° vs 20°, p≤0.001 and 10° vs 0°, p=0.033 respectively).Conclusions: Over half of ACL injuries in rugby in our analysis resulted from a contact mechanism. For non-contact injuries, lower knee flexion angles and heel-first ground contact in a side-stepping manoeuvre were associated with ACL injury. [ABSTRACT FROM AUTHOR]

In rugby union, effective defensive play is highly technical and essential for game outcomes. Therefore, the aim of this study was to identify tackle heights, for given tackle types, that had a greater propensity to result in tackle gainline success for the tackler using match video evidence. The results indicated that tackling the upper legs of the ball carrier had a greater propensity to result in tackler success for both front-on (OR = 3.27; 95% CI = 1.34–7.95; p < 0.01) and side-on (OR = 5.31; 95% CI = 2.08–13.6; p < 0.01) arm tackles. For shoulder tackles, tackling at the lower trunk for front-on tackles (OR = 1.70; 95% CI = 1.04-2.79; p = 0.03) and the mid trunk for side-on tackles (OR = 3.11; 95% CI = 1.31–7.37; p < 0.01) had a greater propensity to result in tackler success. For smother tackles, tackling at the mid trunk had a greater propensity to result in tackler success during front-on (OR = 3.49; 95% CI = 1.81–6.74; p < 0.01) and side-on (OR = 5.11; 95% CI = 2.42–10.8; p < 0.01) tackles. The results highlight the importance of tackle height when coaching the tackle. The findings also suggest that technically proficient players can advance to more challenging contact techniques than aiming for the ball carrier’s centre of gravity. [ABSTRACT FROM AUTHOR]

Player-to-player contact inherent in many unhelmeted sports means that head impacts are a frequent occurrence. Model-Based Image- Matching (MBIM) provides a technique for the assessment of three-dimensional linear and rotational motion patterns from multiple camera views of a head impact event, but the accuracy is unknown for this application. The goal of this study is to assess the accuracy of the MBIM method relative to reflective marker-based motion analysis data for estimating six degree of freedom head displacements and velocities in a staged pedestrian impact scenario at 40 km/h. Results showed RMS error was under 20 mm for all linear head displacements and 0.01-0.04 rad for head rotations. For velocities, the MBIM method yielded RMS errors between 0.42 and 1.29 m/s for head linear velocities and 3.53-5.38 rad/s for angular velocities. This method is thus beneficial as a tool to directly measure six degree of freedom head positional data from video of sporting head impacts, but velocity data is less reliable. MBIM data, combined in future with velocity/acceleration data from wearable sensors could be used to provide input conditions and evaluate the outputs of multibody and finite element head models for brain injury assessment of sporting head impacts. [ABSTRACT FROM AUTHOR]

Tackling is a major component of rugby union and effective attacking and defensive play are essential for game outcomes. In this study, a number of pre-contact, contact and post-contact tackle characteristics that had an influence on tackle gainline success for the ball carrier and tackler were identified using match video evidence from European Rugby Champions Cup games. A total of 122 front-on tackles and 111 side-on tackles were analysed. For each ball carrier and tackler characteristic, the Odds Ratio and 95% Confidence Interval were calculated based on a gainline success outcome. A Chi-Square and Phi and Cramer’s V calculation was also conducted. A Chi-Square test then identified any statistically significant differences (p < 0.05) for proficiency characteristics between playing position. For both the ball carrier and tackler, tackle characteristics that were indicative of strong and powerful tackle technique such as ‘explosiveness on contact’ and ‘leg drive on contact’ were effective for achieving the desired gainline outcome. Playing position had an influence on only two proficiency characteristics that were statistically significant for gainline success: ‘fending into contact’ for ball carriers and ‘straight back, centre of gravity forward of support base’ for tacklers. [ABSTRACT FROM AUTHOR]

The stress–strain behaviour of skeletal muscle is affected by many factors, leading to varied results reported in the literature. This article examines how the physical dimension of samples in in vitro compression tests affects the muscle stress for a given stretch ratio, in both quasi-static and dynamic loading. It is proposed that physically larger samples display a higher stress response due to the greater inclusion of complete muscle fascicles and also a reduction in percentage fluid exudation during compression. In the case of quasi-static loading, this was evaluated by testing nominally cubic samples of fresh and aged porcine tissue of characteristic lengths between 10 and 40 mm in compression at 0.05%/s strain in the fibre and cross-fibre directions using a Zwick Z005 universal testing rig. For the dynamic tests, a custom instrumented drop tower test rig was used to achieve average strain rates of 12,500%/s, and the stress responses at stretch ratios of λ = 0.8 and λ = 0.5 of nominally cubic samples of aged porcine tissue of characteristic lengths between 10 and 30 mm compressively loaded in the cross-fibre direction were evaluated. Both static and dynamic results clearly indicate that the muscle stress for a given stretch ratio of aged skeletal muscle tissue increases as the characteristic sample dimension increases from 10 to 30 mm. The effect was somewhat stronger for the dynamic tests. In the case of quasi-static testing, the strain rate of 0.05%/s limited the influence of the viscoelastic properties of the muscle, and sample dimension effects in the static tests are mostly attributable to the greater proportion of complete fascicles in the physically larger samples. In dynamic testing, in addition to the proportion of complete fascicle inclusion, the smaller percentage of fluid exudation for the larger samples compared to the smaller samples may also influence the size effect. [ABSTRACT FROM AUTHOR]

This paper evaluates the potential of gabions as roadside safety barriers. Gabions have the capacity to blend into natural landscape, suggesting that they could be used as a safety barrier for low-volume road in scenic environments. In fact, gabions have already been used for this purpose in Nepal, but the impact response was not evaluated. This paper reports on numerical and experimental investigations performed on a new gabion barrier prototype. To assess the potential use as a roadside barrier, the optimal gabion unit size and mass were investigated using multibody analysis and four sets of 1:4 scaled crash tests were carried out to study the local vehicle–barrier interaction. The barrier prototype was then finalised and subjected to a TB31 crash test according to the European EN1317 standard for N1 safety barriers. The test resulted in a failure due to the rollover of the vehicle and tearing of the gabion mesh yielding a large working width. It was found that although the system potentially has the necessary mass to contain a vehicle, the barrier front face does not have the necessary stiffness and strength to contain the gabion stone filling and hence redirect the vehicle. In the EN1317 test, the gabion barrier acted as a ramp for the impacting vehicle, causing rollover. [ABSTRACT FROM PUBLISHER]

The required fidelity of synthetic materials in surgical simulators to teach tissue handling and repair requirements should be as accurate as possible. There is a poor understanding of the relationship between choice of muscle surrogates and training outcome for trainee surgeons. To address this, the mechanical characteristics of several candidate synthetic muscle surrogates were measured, and their subjective biofidelity was qualitatively assessed by surgeons. Silicone was selected after assessing several material options and 16 silicone-based surrogates were evaluated. Three of the closest samples to muscle (Samples 1.1, 1.2, 1.3) and one with inserted longitudinal fibres (1.2F) were mechanically tested in the following: compression and tension, needle puncture force and suture pull-out in comparison with real muscle. The four samples were evaluated by 17 Plastic and Orthopaedic surgeons to determine their views of the fidelity with regard to the handling properties, needle insertion and ease of suture pull-out. The mechanical testing showed the surrogates exhibited varying characteristics that matched some of the properties of muscle, though none recreated all the mechanical characteristics of native muscle. Good biofidelity was generally achieved for compression stiffness and needle puncture force, but it was evident that tensile stiff was too low for all samples. The pull-out forces were variable and too low, except for the sample with longitudinal fibres. In the qualitative assessment, the overall median scores for the four surrogate samples were all between 30 and 32 (possible range 9–45), indicating limited differentiation of the samples tested by the surgeons. The surrogate materials showed a range of mechanical properties bracketing those of real muscle, thus presenting a suitable combination of candidates for use in simulators to attain the requirements as set out in the learning outcomes of muscle repair. However, despite significant mechanical differences between the samples, all surgeons found the samples to be similar to each other. [Display omitted] • Four silicone based muscle surrogates tested for suitability for a simulator. • Surrogates tested in tension, compression, puncture and suture pull-out force. • Surrogates mimicked muscle in compression and puncture force. • Surgical experts rated the samples compared to that during in-vivo muscle repair. [ABSTRACT FROM AUTHOR]

Methods to estimate the pre-impact pedestrian speed from limited post-accident measurements are required both for biomechanics research and for legal applications following vehicle–pedestrian collisions, but none is currently available. Such a method is presented in this paper. A constant-inertial-property pedestrian model based on the conservation of momentum is first shown to predict satisfactorily the transverse offset of a pedestrian between the primary and secondary impacts in wrap-trajectory vehicle–pedestrian collisions and is then used in a Monte Carlo environment to predict the pedestrian pre-impact speed distribution utilizing an estimate of the vehicle speed based on the pedestrian projection distance, the ratio of the longitudinal offset to the transverse offset for the pedestrian primary and secondary contact locations on the vehicle (indicated by the primary and secondary vehicle damage locations) and, where available, information on the pedestrian gait stance at impact (derived from the injury location on the head). Separate analysis of recently published Fourier relationships between the transverse offset and the contact location on the head derived from modelling with Mathematical Dynamic Models (MADYMO) software is used to show that the gait stance is related to the location on the head of head injuries from the vehicle contact, and that contact locations significantly anterior or posterior of the coronal plane are predominant. Results from the constant-inertial-property pedestrian model show that significant differences occur between the ratio of the transverse offset to the longitudinal offset with the struck leg leading and the corresponding ratio with the struck leg lagging. The special case of nominally zero transverse offset between the primary and secondary damage locations from the contacts of the pedestrian with the vehicle is considered, and pedestrian speed confidence limits for accident reconstruction purposes are provided. Regression equations relating the pedestrian speed to the pedestrian projection distance and the ratio of the transverse offset to the longitudinal offset of the damage location on the vehicle are presented. These provide the first means to predict the pedestrian speed from limited post-accident damage locations on the vehicle and the pedestrian projection distance. [ABSTRACT FROM AUTHOR]

Magnetic Resonance (MR) imaging-based motion and deformation tracking techniques combined with finite element (FE) analysis are a powerful method for soft tissue constitutive model parameter identification. However, deriving deformation data from MR images is complex and generally requires validation. In this paper a validation method is presented based on a silicone gel phantomcontaining contrasting sphericalmarkers. Tracking of thesemarkers provides a directmeasure of deformation. Validation of in vivo medical imaging techniques is often challenging due to the lack of appropriate reference data and the validation method may lack an appropriate reference. This paper evaluates a validation method using simulated MR image data. This provided an appropriate reference and allowed different error sources to be studied independently and allowed evaluation of the method for various signal-to-noise ratios (SNRs). The geometric bias error was between 0-5.560×10-3 voxels while the noisy magnitudeMR image simulations demonstrated errors under 0.1161 voxels (SNR: 5-35). [ABSTRACT FROM AUTHOR]