Injury Biomechanics

There are a variety of parameters that affect injury potential, including, past medical history, weight, age, gender, and the magnitude, duration, location and direction of applied forces. However, the current biomechanical approach to determine injury potential in low-speed rear-end MVCs appears to be relegated to a comparison between the magnitude of experienced forces to injury tolerance metrics. This is despite such tolerance metrics may overestimate the force required to cause injury. It is thus encouraged that future biomechanical analyses consider other parameters – such as loading rate, passive / active muscle contraction, and pre-existing condition – when making conclusions regarding injury potential. Simulation technologies and computational models based on response data obtained from laboratory studies could also help improve the validity of the conclusions made by experts. Further research is also encouraged to determine new neck injury criteria and tolerance limits of cervical discs injuries that consider these parameters.

Anterior cruciate ligament (ACL) injuries have been shown to place a severe burden on the injured athlete and the Australian health care system. Significant research has been dedicated to injury prevention training programs with limited success in reducing ACL injury rates among heterogeneous athletic populations. A contributing factor to unsuccessful injury prevention programs are low athlete attendance, compliance and/or engagement to the training protocol (Donnelly et al, 2012a). Though lower limb injury rates are high among elite level athletes, injury prevention programs are generally considered to be low priority as coaches have a misguided perception that there is an inverse relationship between prophylactic training and athletic performance (ie. speed/agility, aerobic power, and strength). Recent literature has identified the dynamic strength and control of the hip and trunk during dynamic sporting tasks is of paramount importance for reducing an athlete’s peak knee loading and injury risk in sport (Dempsey et al, 2009; Donnelly et al, 2012b; Weir et al, 2014). The purpose of this study was to show that a biomechanically focused ACL injury prevention training protocol is effective in reducing ACL injury rates, while simultaneously having no negative effect on athletic performance.

• Cervical spine injuries sustained during impact events in sport activities such as rugby union can have devastating effects on players' welfare. • Dynamic simulations using musculoskeletal models, driven by in vivo biomechanical data, are effective tools to gain insight into injury mechanisms and can aid injury risk reduction.

Knee abduction/adduction moment and knee internal rotation moment are known surrogate measures of anterior cruciate ligament (ACL) load during tasks like sidestepping and single-leg landing. Previous experimental literature has shown that a variety of kinematic strategies are associated or correlated with ACL injury risk; however, the optimal kinematic strategies needed to reduce peak knee moments and ACL injury are not well understood. To understand the complex, multifaceted kinematic factors underpinning ACL injury risk and to optimize kinematics to prevent the ACL injury, a musculoskeletal modeling and simulation experimental design was used. A 14-segment, 37-degree-of-freedom, dynamically consistent skeletal model driven by force/torque actuators was used to simulate whole-body single-leg jump landing kinematics. Using the residual reduction algorithm in OpenSim, whole-body kinematics were optimized to reduce the peak knee abduction/adduction and internal/external rotation moments simultaneously. This optimization was repeated across 30 single-leg jump landing trials from 10 participants. The general optimal kinematic strategy was to bring the knee to a more neutral alignment in the transverse plane and frontal plane (featured by reduced hip adduction angle and increased knee adduction angle). This optimized whole-body kinematic strategy significantly reduced the peak knee abduction/adduction and internal rotation moments, transferring most of the knee load to the hip.

This paper shows preliminary results of a research aimed to improve passive safety of gymnastic equipments. To assess the impact attenuation performances of protective devices, mainly realized with polymer-based foams, impact testing standards are applied. Due to lack of criticism about test procedures and analysis of experimental results, the choice of the most safe device is not trivial. The first part of the paper shows the main impact testing procedures provided by international standards and defined for gymnastic equipments and playground area. In accordance to these standards the main impact attenuation performances for passive safety assessment are defined. The second part of the paper shows first experimental results obtained using new testing apparatus developed at the Sports Equipment and Technology Lab of Chemnitz University of Technology. Impact attenuation performances of two protective devices realised with polymer-based foams are analysed. The parameter of theoretical drop height is introduced to compare experimental results collected in our laboratory with others previously collected in an accredited laboratory. The comparison of test standards reveals lack of specifications in EN 913, that should be modified. Finally, sources of uncertainty and reasons of unfair comparison are discussed in order to advice managers and technicians about the consequences of their choices in evaluating performances of passive safety devices for gymnastic equipment.

The aim has been to review the literature about the risk factors of hamstring injury in soccer from a biomechanical point of view. METHODOLOGY. Data bases of bibliography references were Medline, Scopus and SportDiscuss. RESULTS AND DISCUSSION. Many prospective studies have shown that the previous injury is the greatest risk factor of sustaining the injury. However the primary causes of the injury are unclear in soccer. A lack of hamstring flexibility has been one of the main injury risk factors with controversies on the results. Imbalance of isokinetic force is a risk factor but electrical coactivation of all muscles participating during knee flexion and extension are unknown in football. While the importance of lumbopelvic-hamstrings muscles synchronization during running seems to be crucial for understanding the risk of injury, no research has been developed in this topic in football. CONCLUSIONS. More research using new data recording procedures as Dynamic Scanners, Surface EMG,...

Dance sport is the competitive aspect of social dancing, and encompasses 5 genres of Latin dance: Cha Cha, Samba, Rumba, Paso Doble, and Jive. Education of technique focuses predominantly on foot positions and directions, and there is a lack of information regarding technical aspects of the dance, such as timing, position in space, and rhythm. This knowledge gap limits the potential for optimal skill development and progression. This study examined the centre of balance trajectory in the basic walks and cucaracha steps of Rumba dance using foot scan, gaining preliminary insight on weight placement and movement patterns in one professional and three novice ballroom dancers. The professional dancer performed the steps on the Foots can, while novices were given two 30 minute sessions to learn the steps. Results showed that novice dancers made various compensations in balance trajectory and weight distribution on their feet, in response to teaching cues for the Walks and Cucarachas. The professional dancer was in greater accordance of the described foot trajectory as it was traditionally taught, though still had more deviations in balance, and used more foot volume than the literal technique described. The findings of this study provide an improved understanding of the biomechanics in Latin dancing, and is a starting point for developing improved teaching techniques for performance enhancement and injury prevention for Ballroom dance.

The study of the injury caused by Pickup vehicle-teenage cyclist crash is presented in this paper. The vehicle has high frontal part, in order to compare the results with those obtained previously in the sedan and SUV-teenage cyclist crash. No variation is executed on the model of the teenage cyclist and the bike. Three different positions are analyzed: front, rear and lateral position. The injury on the cyclist head is examined by HIC criterion, in the way indicated in the rules. Correlation HIC – AIS is used to calculate the lethality of the injuries. A comparison is made between the results of the simulations for Pick up, SUV and sedan, concluding that the injury of the head is more dangerous for Pickup impact than SUV and the sedan, but only at the maximum speed (50 km/h). This value of the speed can be considered critical, since HIC values are very high for all the three vehicles. The more dangerous injury is the side impact. A further comparison is done between the impact points of the three vehicles concluding that both the shape of the bonnet that the height of the front part must be studied carefully in order to reduce the damage to cyclists and pedestrians.

Soccer is the world's most popular sport and unique in that players use their unprotected heads to intentionally deflect, stop, or redirect the ball for both offensive and defensive strategies. Headed balls travel at high velocity pre-and postimpact. Players, coaches, parents, and physicians are justifiably concerned with soccer heading injury risk. Furthermore, risk of long-term neurocognitive and motor deficits caused by repetitively heading a soccer ball remains unknown. We review the theoretical concerns, the results of biomechanical laboratory experiments, and the available clinical data regarding the effects of chronic, subconcussive head injury during heading in soccer.

BACKGROUND:

A better coupling of the occupant to the car seat in the early phase of a frontal or far side impacts using pretensioner systems may reduce the likelihood of the submarining effect or increases the likelihood of seat belt engaging the shoulder, respectively. However, the high belt forces may also increase the risk of upper body injuries to the vehicle occupant (especially in abdominal region). It was hypothesized that human body characteristics, such as body mass index (BMI) influence the biomechanical response and injury outcome to the abdominal regions during static pretensioning deployment tests.

METHODS:

Four postmortem human specimens (PMHS), in a BMI range from 15.6 to 31.2, were positioned in production seats in a normal passenger position and were restrained using a standard three-point belt system. The pretension forces in the belts were generated at two points (retractor and right anchorage) or at all three locations (retractor, left anchorage, and right anchorage). An optical motion capture system and acceleration cubes mounted to the lumbar spine were used to measure the abdomen deformation during testing.

RESULTS:

The normalized deflections of the thorax recorded at the level of fourth rib were under 10% (noninjury level). Two different patterns were observed in the time histories of abdominal penetration rate in the four PMHSs associated with lower and higher BMI. Abdominal injuries (spleen lacerations) were observed only in the two PMHS with highest BMI.

CONCLUSION:

Based on data from this study and similar data from the literature, belt velocity and FmaxCmax were shown to be the best injury predictors for injury risk analysis for Abbreviated Injury Scale 2+ and for Abbreviated Injury Scale 3+ injuries, respectively.

BACKGROUND:

A better coupling of the occupant to the car seat in the early phase of a frontal or far side impacts using pretensioner systems may reduce the likelihood of the submarining effect or increases the likelihood of seat belt engaging the shoulder, respectively. However, the high belt forces may also increase the risk of upper body injuries to the vehicle occupant (especially in abdominal region). It was hypothesized that human body characteristics, such as body mass index (BMI) influence the biomechanical response and injury outcome to the abdominal regions during static pretensioning deployment tests.

METHODS:

Four postmortem human specimens (PMHS), in a BMI range from 15.6 to 31.2, were positioned in production seats in a normal passenger position and were restrained using a standard three-point belt system. The pretension forces in the belts were generated at two points (retractor and right anchorage) or at all three locations (retractor, left anchorage, and right anchorage). An optical motion capture system and acceleration cubes mounted to the lumbar spine were used to measure the abdomen deformation during testing.

RESULTS:

The normalized deflections of the thorax recorded at the level of fourth rib were under 10% (noninjury level). Two different patterns were observed in the time histories of abdominal penetration rate in the four PMHSs associated with lower and higher BMI. Abdominal injuries (spleen lacerations) were observed only in the two PMHS with highest BMI.

CONCLUSION:

Based on data from this study and similar data from the literature, belt velocity and FmaxCmax were shown to be the best injury predictors for injury risk analysis for Abbreviated Injury Scale 2+ and for Abbreviated Injury Scale 3+ injuries, respectively.

Anthropomorphic dummies for crash and escape system testing have been used by military and civilian agencies for many
years to assess, develop and standardize safer occupant protective systems for land and air vehicles. The automotive industry
has spent considerable effort in designing crash test dummies that are biofidelic; i.e., dummies that duplicate the properties of
a representative human subject on which injury risk is to be assessed. The major adult crash test dummies currently in use are
the Hybrid II and its development into the Hybrid III for frontal impacts, and Side Impact Dummy (SID), Biofidelic Side
Impact Dummy (BIOSID) and European Side Impact Dummy (EUROSID 1) for side impact tests. The US Air Force
developed the Advanced Dynamic Anthropomorphic Manikin (ADAM) to test advanced ejection systems. More recently,
biodynamic analytical models such as MAthematical DYnamical MOdel (MADYMO) and Articulated Total Body (ATB)
model have been developed to simulate human responses and injuries associated with vehicular impacts.

Restraint system parameter configurations encouraged by the current legislative or consumer crash tests cannot provide tailored protection to occupants with different statures under various crash severities. The restraint system parameters should be adapted to different circumstances. In this study, a restraint system optimization framework was built to explore optimal configurations for 5 different sizes of occupants in 2 crash severities. Seat position was treated as a variable in the design space. The optimization results showed that, optimal seat positions had clear patterns for the 2 crash severities. In high crash severity, dummies tended to sit closer to the knee bolster to achieve better contacts of airbag and knee bolster. In low crash severity, optimal seat positions were farther from knee bolster. With aggressively tuned pretensioner and stature dependent load limiting values, the dummies were efficiently restrained by the seatbelt. Tailored protections to the 10 cases were achieved after the optimization, compared to the fixed parameter restraint system.

PERCOBAAN 2 GAYA TEKANAN PADA SEGMEN L5/S1 Adiratna Ciptaningrum (081311733058) Dosen Pembimbimbing : Endah Purwanti, S.Si, M.T. Program Studi S1 Teknobiomedik Fakultas Sains dan Teknologi, Universitas Airlangga Surabaya ABSTRAK Sistem gerak pada tubuh manusia dibagi menjadi dua, yaitu sistem gerak aktif dan sistem gerak pasif. Sistem gerak aktif yang dimaksud adalah otot, sedangkan yang pasif adalah tulang atau rangka. Selain tulang dan otot juga terdapat jaringan pembantu dalam proses gerak yaitu jaringan penghubung (connective tissue). L5/S1 merupakan pengertian dari lumbar 5 dan sacrum 1, bagian yang merupakan titik rawan dalam sistem rangka. Pada segmen L5/S1 dari kegiatan pengangkatan dalam satuan Newton yang distandarkan oleh NIOSH (National Instiute of Occupational Safety and Health) tahun 1981. Besar gaya tekannya adalah di bawah 6500 N pada L5/S1. Sedangkan batasan gaya angkatan normal (the Action Limit) sebesar 3500 pada L5/S1. Sehingga, apabila Fc < AL (aman), AL < Fc < MPL (perlu hati-hati) dan apabila Fc > MPL (berbahaya). Batasan gaya angkat maksimum yang diijinkan , yang direkomendasikan NIOSH (1991) adalah berdasarkan gaya tekan sebesar 6500 N pd L5/S1 , namun hanya 1% wanita dan 25% pria yang diperkirakan mampu melewati batasan angkat ini. Kata kunci : L5/S1, Fc 1. PENDAHULUAN Sistem gerak pada tubuh manusia dibagi menjadi dua, yaitu sistem gerak aktif dan sistem gerak pasif. Sistem gerak aktif yang dimaksud adalah otot, sedangkan yang pasif adalah tulang atau rangka. Selain tulang dan otot juga terdapat jaringan pembantu dalam proses gerak yaitu jaringan penghubung (connective tissue). Tulang adalah alat untuk meredam dan mendistribusikan gaya/tegangan yang ada padanya.Tulang yang besar dan panjang berfungsi untuk memberikan perbandingan terhadap beban yang terjadi pada tulang tersebut. Mungkin dalam aplikasinya, biomekanika selalu berhubungan dengan kerangka manusia (Eko Nurmianto, 1996). Berikut ini adalah gambar kerangka manusia: Gambar 1. Kerangka tubuh manusia

Anterior cruciate ligament (ACL) rupture is a serious and debilitating injury that usually results in an athlete undergoing reconstructive surgery and remaining out of sport for an extended period.  Therefore the incidence of this injury although only moderate (approximately one per professional Australian football team per year) when considered from a social and sporting cost perspectives is of serious concern.  However, the non-contact nature of the majority of occurrences of this injury indicates that it may be possible to reduce the incidence with interventions aimed at modifying the movement and/or physical characteristics of individual athletes.  Previous research aimed at reducing the risk of non-contact ACL injury has focused on improving support of general knee loads, particularly valgus and internal rotation moments, which are known to load the ACL, during sporting tasks through the utilisation of balance and plyometric training.  While technique cues have been included in a number of these training programs there has been no research that has investigated training to change isolated aspects of sidestep cutting and landing techniques and their effect on valgus and internal rotation moments at the knee, the moments thought to cause non-contact ACL injury.  This was the overarching theme of this thesis.

Most non-contact ACL injuries occur during either sidestep cutting or landing tasks, as such, the relationship between technique and knee loads was investigated within these two tasks.  The first study presented in this thesis investigated how performing sidestep cuts with various extreme postures affected knee moments.  It was identified that peak valgus loads during the weight acceptance phase of the sidestep cut were increased when performed with either increased torso lean over the support leg or wide placement of the support leg.  Wide foot placement also resulted in increase peak internal rotation moments.  Sidestep cuts, with torso rotation towards the support leg also increased peak knee internal rotation moments.  As these postures were reflective of those observed during actual non-contact ACL injuries it was concluded that these three postures should be avoided when performing a sidestep cut.
The next study investigated the effectiveness of a six week technique modification program aimed at avoiding the three high loading techniques, identified in the first study, for reducing knee moments during sidestep cutting.  Following the intervention participants performed the sidestep cut with a foot placement closer to the midline of the body and a more upright torso.  These kinematic changes were accompanied by a reduction in the peak valgus moment occurring during the weight acceptance phase of the sidestep cut.  This intervention may then reduce at least one factor identified as being a risk for an athlete of sustaining a non-contact ACL injury.

Studies three and four investigated the relationship between technique and knee loads during landing tasks.  The first of these two studies investigated the effect of ball positioning in a functional landing task on both full body kinematics and knee moments.  When participants were required to take possession of a ball during flight that was swinging towards their support leg they demonstrated increased valgus moments compared with when the ball was swung away from the support leg.  The whole body segmental kinematics of the high loading ball movement reflected body postures observed when injury occurs in a game situation.  However, the high loading task exhibited a more flexed knee posture, contrary to the results expected from the literature.  The second of these two studies further investigated the relationship between whole body kinematics and knee moments. Intra-participant correlations were performed between all kinematics and each knee joint moment, with the intention of identifying mean correlations significantly different from zero.  Increased valgus moments were significantly correlated with increased knee flexion, hip flexion, torso lean and torso rotation towards the support leg, and foot and knee external rotation. Increase internal rotation moments were significantly correlated with reduced hip abduction and external rotation, increased ankle inversion, knee external rotation and torso lean away from the support leg.  Again these results reflected joint positions observed in injury, except for knee flexion and hip flexion angles.  It was identified that while there may be statistically significant effects for knee angle the difference in magnitude may not result in functional differences.

The final study investigated the effect of a six week technique modification program on landing tasks.  The technique modification aimed at bringing athletes’ torsos upright and forward facing, based upon the results of the previous studies.  It also aimed to increase knee flexion angle, as this is still the current literature recommendation.  Post-intervention participants displayed an increase in maximal knee flexion angles but no change in torso positioning.  This kinematic change was correlated to a significant increase in peak internal rotation moments, with no change in valgus or flexion moments.  Although, due to the angle at which the peak internal rotation moment occurred it was identified that this increase in moment may not increase the risk of non-contact ACL injury risk, due to the increased potential for muscular support and decreased transmission of the moment to the ACL.  However, it was concluded that the technique modification program may not be appropriate for reducing the risk of non-contact ACL injury, within the particular landing task chosen.

Overall this thesis identified that whole body kinematics are related to knee moments during sidestep cutting and landing.  Kinematics associated with increase valgus and internal rotation moments at the knee tended to reflect joint posture observed during actual non-contact ACL injuries.  Secondly a six week technique modification program is capable of modifying both sidestep cutting and landing technique.  Technique changes result in changed knee moments.  However, the complex nature of the relationship between technique and knee loads indicates that any potential intervention aimed at reducing the risk of non-contact ACL injury, should be tested in the laboratory utilising tools such as neuromuscular modelling and stochastic modelling to ensure the planned intervention has the potential to be successful prior to implementing the protocol in an epidemiological testing scenario.

Existing rigid body dynamics and finite element computer codes do not have adequate databases for manikin neck structures to properly model head/neck system dynamics occurring in crash or ejection testing. This report describes measured static stiffness and dynamic damping and stiffness characteristics of the Hybrid II and Hybrid III manikin necks and uses these data to improve the current manikin neck data sets of the Articulated Total Body (ATB) model and the Head Spine Model (HSM). The Hybrid II and Hybrid III manikin necks are used extensively throughout the automotive industry, the Department of Transportation, and the Department of Defense for safety testing.

Background: In taekwondo (TKD), the incidence of concussion is four times greater than in American gridiron football. Biomechanical studies of concussion in taekwondo are scarce. Research question: To assess the effect of head impact biomechanics as a result of taekwondo kicks. Type of study: Between-groups design. Methods: Two male (22.0±0.0 years, 184±0.0cm, 81.3±1.8 kg) and two female (0.0±2.8 years, 171.0±1.4 cm, 63.0±5.2 kg) elite taekwondo athletes participated in this study. Head linear acceleration (RLA) and head injury criterion (HIC) data were collected from five different head kicks randomly performed five times. A Hybrid II Crash Dummy head (H2D) was instrumented with a tri-axial accelerometer. Results: Significant differences were found between kicks in RLA (eta2=3.8) and HIC (eta2=4.6) in the men and women (RLA, eta2=4.5 and HIC, eta2=4.7). Post-hoc analyses showed differences in RLA between the jump back kick (61.6±31.0 g) and clench axe kick (33.3±11.1 g) in males (ES=0.9). HIC analysis revealed differences between the jump back kick (556.8±679.2) and jump hook kick (191.0±37.2) (ES=0.7) and in head velocity between the turning kick (5.0±0.5 m.s-1) and jump hook kick (3.2±1.3 m.s-1, ES=1.1) in the males. In the females, there was a difference between the jump back (HIC: 236.8±104.3) and clench axe kicks (22.2±11.2) (ES=1.2) and in foot velocity between the turning (15.7±1.2 m.s-1) and clench axe kicks (9.1±2.3 m.s-1) (ES=1.2). Conclusions: Previous research reported RLA values of 67.0 g (HIC=167) in boxing compared to 72.8 g (HIC=667) in TKD. These high magnitudes of injury-related measures highlight the need for the implementation of more safety precautions. Keywords: taekwondo, head injury criterion, acceleration, concussion, kick

Using exercise to enhance occupational performance and injury prevention is well documented. In recent years the use of labile suspension exercise devices (i.e. TRX) has become a popular means of exercise used in both performance enhancement and rehabilitative settings. Firefighting is known to be a physically demanding occupation that is associated with a high prevalence of lower back injury. Exercise intervention, namely the inclusion of core training, is a commonly used strategy for injury prevention, performance enhancement, and rehabilitation of the low back. Biomechanical analysis can provide insight to the efficacy of several different dynamic labile suspension exercises. The purpose of this study was to measure the kinematics and electromyographical differences in (EMG) activity of the rectus abdominis (RA), external obliques (EO), and lumbar erector spinae (LES) of firefighters when comparing a TRX Straight Arm Plank to several different TRX core exercise conditions. Six healthy male firefighters were recruited from local fire departments. Each subject performed several different TRX core exercises in randomized order. Mean ± SD EMG activity at the peak phase (p-phase) and Peak EMG was recorded bilaterally for the RA, EO, and LES and compared between a control condition and several other exercise conditions. Dependent samples t-tests were used to detect differences between the exercise conditions. The results indicated that there were significant differences (p < 0.015) identified in the %MVC at the p-phase of the right EO between the control and both the TRX Alternating Knee Tuck (p = 0.007) and TRX Pike (p = 0.0008). Additionally, each TRX suspension exercise elicited significant differences (p < 0.015) in Peak %MVC between left EO (KT, p = 0.006; AKT, p = 0.005; Pike, p = 0.003) and right EO (KT, p = 0.008; AKT, p = 0.006; Pike, p = 0.0002) when compared to the control condition. The TRX pike elicited the highest mean Peak %MVC for the LE (19% ± 12%), LO (64% ± 19%), RO (84% ± 30%), and RRA (58% ± 17%). The findings of this study support the notion that labile suspension exercises in general produce moderate to high levels of abdominal challenge, particularly in the EO. Exercise prescription should take into account and match an individual’s level of fitness, injury history, and training goals. The data collected in this study can help govern exercise selection for the firefighter. The information provided in this research indicates that the TRX suspension exercises can be used as a viable means for strengthening the abdominal wall of firefighters.

This study aimed to develop a 2-dimensional (2D) video screening tool capable of predicting an athlete's peak 3-dimensional (3D) knee moments during unplanned sidestepping. 2D video-based kinematic measures were simultaneously captured with 3D peak knee moments for 30 female field hockey players (15 junior, 15 senior). Intra- and intertester repeatability of 2D kinematic measures was performed. Then, linear regression models were used to model 3D knee moments from 2D kinematic variables utilizing 80% of the sample (n=24). Regression equations were then validated on the remaining 20% of the sample (n=6). Angular 2D measures had good-excellent intra- (ICC=0.936-0.998) and intertester (ICC=0.662-0.949) reliability. Displacement measures had poor-excellent intra- (ICC=0.377-0.539) and inter-tester (ICC=0.219-0.869) reliability. Significant independent predictors of peak knee moments were dynamic knee valgus, knee flexion angle at foot strike, trunk flexion range of motion (ROM), trunk lateral flexion, hip abduction and knee flexion ROM (P<0.05). Regression equations generated from these models effectively predicted peak knee extension, valgus and internal rotation moments (i. e., were not different from measured values P>0.05, ES<0.4) in the 20% subsample. 2D video-based measurements of an athlete's full body kinematics during unplanned sidestepping provide a reliable, specific, sensitive and cost-effective means for screening female team sport athletes.

The kinematics and kinetics of head impact due to a standing fall onto a hard surface are summarized. Head injury due to impact from falls represents a significant problem, especially for older individuals. When the head is left unprotected during a fall, the impact severity can be high enough to cause significant injury or even death. To ascertain the range of head impact parameters, the dynamic response was captured for the pedestrian version of the 5th percentile female and 50th percentile male Hybrid III anthropomorphic test dummies as they were dropped from a standing position with different initial postures. Five scenarios of falls were considered including backward falls with/without hip flexion, forward falls with/without knee flexion and lateral falls. The results show that the head impact parameters are dependent on the fall scenario. A wide range of impact parameters was observed in 107 trials. The 95% prediction interval for the peak translational acceleration, peak angular acceleration, peak force, impact translational velocity and peak angular velocity are 146-502 g, 8.8-43.3 krad/s(2), 3.9-24.5 kN, 2.02-7.41 m/s, and 12.9-70.3 rad/s, respectively.

The Hybrid III 50th percentile male anthropomorphic test device (ATD) is the most widely used human impact testing surrogate and has historically been used in automotive or military testing. More recently, this ATD is finding use in applications evaluating athletic helmet protectivity, quantifying head impact dosage and estimating injury risk. But ATD head-neck response has not been quantified in omnidirectional athletic-type head impacts absent axial preload. It is probable that headgear injury reduction that can be quantified in a laboratory, including in American football, boxing, hockey, lacrosse and soccer, is related to a number of interrelated kinetic and kinematic factors, such as head center of gravity linear acceleration, head angular acceleration, head angular velocity, occipito-cervical mechanics and neck stiffness. Therefore, we characterized ATD head-neck dynamic response to direct head impacts in a series of front, oblique front and lateral head impacts.

The increased number of women participating in sports has led to a higher knee injury rate in women compared with men. Among these injuries, those occurring to the ACL are commonly observed during landing maneuvers. The purpose of this study was to determine gender differences in landing strategies during unilateral and bilateral landings. Sixteen male and 17 female recreational athletes were recruited to perform unilateral and bilateral landings from a raised platform, scaled to match their individual jumping abilities. Three-dimensional kinematics and kinetics of the dominant leg were calculated during the landing phase and reported as initial ground contact angle, ranges of motion (ROM) and peak moments. Lower extremity energy absorption was also calculated for the duration of the landing phase. Results showed that gender differences were only observed in sagittal plane hip and knee ROM, potentially due to the use of a relative drop height versus the commonly used absolute drop height. Unilateral landings were characterized by significant differences in hip and knee kinematics that have been linked to increased injury risk and would best be classified as “stiff” landings. The ankle musculature was utilized more for impact absorption during unilateral landing, which required increased joint extension at touchdown and may increase injury risk during an unbalanced landing. In addition, there was only an 11% increase in total energy absorption during unilateral landings, suggesting that there was a substantial amount of passive energy transfer during unilateral landings.

Introduction Every year over 200,000 anterior cruciate ligament (ACL) injuries occur in the US [1]. Out of these, approximately 60% are non-contact in nature, with >90% occurring during single leg landing or sidestepping [2]. Anterior tibial force in conjunction with non-sagittal plane (valgus, varus and internal rotation) knee moments during the weight acceptance phase has been shown to place the maximum strain on the ACL [3, 4]. We used OpenSim's forward dynamics residual reduction algorithm (RRA) to identify optimal whole-body kinematics that would reduce non-sagittal plane knee moments during side-stepping and single leg jump landing (SLJL) [5, 6]. This process involved two steps: 1) optimise model parameters (all actuators and tracking weights) to generate simulations with near zero residuals and 2) reduce non-sagittal plane knee moments and tracking weights to identify associated optimal kinematic patterns. Each of these steps used RRA and an outer level optimization routine [7, 8]. Although this technique is powerful, it is computationally expensive. Therein, it can take as long as 13 hours to run a single 70 ms simulation, with approximately 90% of the time spent on reducing residuals. The use of direct collocation [9] is a known method capable of improving the speed of musculoskeletal simulations. OpenSim Moco [10] is a novel software package built to reduce the computational complexity of direct collocation technique. Both RRA and OpenSim Moco find control trajectories of a model's actuators over time, but they use different methodologies to solve for them. RRA finds controls at each time frame and numerically integrates model state derivatives to step forward in time, while direct collocation finds controls simultaneously with model states over an entire movement trajectory, which drastically reduces computational time. This approach also removes the need for model residuals to generate a stable simulation. The purpose of this study was to a) use OpenSim Moco to predict the optimal kinematics linked to reduced non-sagittal plane knee moments during SLJL and b) compare the optimal kinematics generated by OpenSim Moco to those generated using the RRA approach.

The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n=6) and females (n=6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantarflexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantarflexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.

H istorically, linear acceleration has been the main parameter by which to measure athletic head injury risk; however, combinations of linear and rotational impact dosage have been widely acknowledged as contributors to head injury. Current standard head injury metrics-the GSI 9 and HIC 35 -are based on resul-tant linear head center of gravity acceleration and cannot be used to quantify rotational injury risk. These injury metrics were developed from laboratory head impact studies conducted decades ago and were correlated to severe skull fracture and brain injury, but not less-severe brain injuries like concussion. As HIC, GSI, and resultant linear head center of gravity acceleration are the most widely used and only currently mandated injury metrics for athletic head-padding impact testing, 1,19,28 little research has been conducted on boxing and mixed martial arts (MMA) padding effects on rotational or combined impact dosage injury risk. Therefore, while boxing and MMA padding may be capable of reducing linear impact dosage (for example, GSI, HIC, linear acceleration, and impact force), the effects of padding on rotationally in-Object. In spite of ample literature pointing to rotational and combined impact dosage being key contributors to head and neck injury, boxing and mixed martial arts (MMA) padding is still designed to primarily reduce cranium linear acceleration. The objects of this study were to quantify preliminary linear and rotational head impact dosage for selected boxing and MMA padding in response to hook punches; compute theoretical skull, brain, and neck injury risk metrics; and statistically compare the protective effect of various glove and head padding conditions.

Objective: Previous researches on sports injuries primarily focused on specific games or sports or on specific types of injuries. None of them had tried to explore the injury patterns of games and sports altogether. The current study tried to explore the injury patterns of sportspersons over 16 different types of games and sports. Materials and methods: Total of 1008 injury cases (649 male and 369 female, age 21.07±2.78 and 20.81± 3.01 years) between the academic sessions 2008 to 2017 were analysed. Injury data were extracted from the institute injury record book. Apart from age and gender, ' Body site of injury ', ' Types of injury ' and ' Recurring of injury ' were selected as variables for the study. Descriptive statistics, bar and pie diagram were generated using crosstabs function of IBM SPSS. Results: An average 101.80±12.59 injury was reported per year. Footballers were found to be the highest injured sportsperson (19.5%). Injury percentage of male players (63.75%) was higher compared to female (36.25%) counterparts. Lower limb area (45.28%) was found to be the highest affected body site of injury followed by upper limb area (29.47%). Acute injury constituted 50.39% of overall injuries. Most injuries were non-recurring in nature (63.65%). Further different combinations of analysis revealed more insight of injury patterns of sportspersons.

A scenario plays out every day in America. A collision occurs, the party is transported by EMS, or sees the Doctor soon afterwards, and a chain of medical treatment ensues. The medical providers report objective findings and opine that the treatments are necessary and reasonable. Despite this, when reimbursement is sought, a report appears from an engineer/scientist and without scientific or engineering basis the author claims that the injury is not related to the event. To support the opinions of the hired analyst, a series of assertions are made in an attempt to discredit the treating providers’ opinions. While not predicated upon any valid engineering or science, the medical providers may have trouble being reimbursed for the reasonable and necessary services. This article looks at many of the common misconceptions regarding traumatic events and provides the reader with the knowledge necessary to address the inaccurate claims. In the field of biomechanics, the key issue is; were there forces, loads and moments applied in the areas where the medical providers have found the injuries. Engineers should not be used to discount medical treatments, let Doctors be Doctors. There  are  often  discussions  of  limits  of  exposure  in  the  epidemiological  community  and  disease  vectors  are  commonly  studied.  However,  from  a  biomechanical  standpoint  the  issue  of  threshold  and  injury  are  less  clear.  An  injury  threshold  can  be  described as a level of damage or force above which an injury will occur. However, failure of biological material is not linear and often not  repeatable.  As  an  example,  SAE  J885  discusses  the  failure  of  a  femur under loading and notes femur fractures from forces as little as  4,230N  while  other  trials  have  femurs  withstanding  a  force  of  17,130N with no damage.

ABSTRACT – Dating to Colonel John Paul Stapp MD in 1975, scientists have desired to measure live human head impacts with accuracy and precision.  But no instrument exists to accurately and precisely quantify single head impact events.  Our goal is to develop a practical single event head impact dosimeter known as “Intelligent Mouthguard” and quantify its performance on the benchtop, in vitro and in vivo. 
In the Intelligent Mouthguard hardware, limited gyroscope bandwidth requires an algorithm-based correction as a function of impact duration.  After we apply gyroscope correction algorithm, Intelligent Mouthguard results at time of CG linear acceleration peak correlate to the Reference Hybrid III within our tested range of pulse durations and impact acceleration profiles in American football and Boxing in vitro tests: American football, IMG=1.00REF-1.1g, R2=0.99; maximum time of peak XYZ component imprecision 3.6g and 370rad/s2; maximum time of peak azimuth and elevation imprecision 4.8° and 2.9°; maximum average XYZ component temporal imprecision 3.3g and 390rad/s2.  Boxing, IMG=1.00REF-0.9g, R2=0.99, R2=0.98;  maximum time of peak XYZ component imprecision 3.9g and 390rad/s2, maximum time of peak azimuth and elevation imprecision 2.9° and 2.1°; average XYZ component temporal imprecision 4.0g and 440rad/s2.  In vivo Intelligent Mouthguard true positive head impacts from American football players and amateur boxers have temporal characteristics (first harmonic frequency  from 35Hz to 79Hz) within our tested benchtop (first harmonic frequency <180Hz) and in vitro (first harmonic frequency <100Hz) ranges. 
Our conclusions apply only to situations where the rigid body assumption is valid, sensor-skull coupling is maintained and the ranges of tested parameters and harmonics fall within the boundaries of harmonics validated in vitro.  For these situations, Intelligent Mouthguard qualifies as a single event dosimeter in American football and Boxing.

There is strong evidence linking an athlete's movement technique during sidestepping with anterior cruciate ligament (ACL) injury risk. However, it is unclear how these injurious postures are influenced by prior movement. We aim to describe preparatory trunk and thigh kinematics at toe‐off of the penultimate‐step and flightphase angular momenta, and explore their associations with frontal‐plane risk factors during unplanned sidestepping maneuvers. We analyzed kinematic and kinetic data of 33 male Australian Football players performing unplanned sidestepping tasks (103 trials). Linear mixed models tested for reliable associations between ACL injury risk during weight acceptance of the execution‐step, with preparatory kinematics and angular momenta of the trunk and thigh during the penultimate‐step. Multi‐planar flight‐phase trunk momenta along with hip abduction angle at penultimate‐step toeoff were significantly associated with peak knee valgus moments during the execution‐step (R2 = .21, P < .01). Execution‐step trunk lateral flexion was significantly predicted by frontal and sagittal‐plane preparatory trunk positioning at toe‐off of the penultimate‐step (R2 = .44, P < .01). Multi‐planar flight‐phase trunk momenta as well as multi‐planar trunk and hip positioning at penultimate‐step toe‐off were associated with hip abduction during the execution‐step (R2 = .53, P < .01). Preparatory positioning of the trunk and hip, along with flight‐phase trunk momentum adjusting this positioning are linked to known ACL injury risk factors. We recommend that during the penultimate‐step athletes maintain an upright trunk, as well as minimize frontal‐plane trunk momentum and transverse‐plane trunk momentum toward the sidestep direction to reduce risk of ACL injury during unplanned sidesteps.

Medial migration or cutout of the neck helical blade has commonly occurred in the treatment of tro-chanteric fracture of the femur. The position of the helical blade within the femoral head is one of the influencing factors that cause the blade to perforate the intact joint surface; however, the ideal placement of the helical blade is not currently known. A finite element model of a femur/ nail construct was utilized to analyze five possible blade positions in the femoral head. Normal strain at the fracture surface, the minimum principal strain in the cancel-lous bone, and the von Mises stress in the implant itself were calculated and compared between different blade positions. The results showed that a large area of normal compressive strain at the fracture surface was observed in the inferior and posterior blade positions. The volume of cancellous bone strained to yielding in the femoral head and neck was lower for the inferior and posterior positions , whereas it was the highest for the superior position. The inferior and posterior positions had lower von Mises stress in the implant itself. The inferior and posterior positions may be the ideal position for the intramedullary nail with a helical neck blade.

We hereby approve the thesis/dissertation of ____________________________________________________ candidate for the ______________________________degree *. (signed) ______________________________________________ (chair of the committee) ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ (date) _______________________