<p>The aim of this study was to understand injury mechanisms behind fractures of the upper extremities in car accidents. Volvo Car Corporation initiated this project based on the fact that no safety system today focuses on preventing injuries to the upper extremity. A literature study was undertaken focusing on the basic anatomy of the upper extremity, different fracture types and fracture mechanisms. Three subsets, from 1998 – January 2009, were selected from Volvo’s statistical accident database: 1) all occupants involved in an accident 2) all occupants with a MAIS2+ injury 3) all occupants with an upper extremity fracture. These subsets were used in a comparison, using frequency analyses. The comparison analysis showed that frontal impact is the dominating accident type for all three subsets. The comparison analysis also indicated that the risk for upper extremity fractures follows the pattern of MAIS2+ injury risk. An in-depth study using 92 selected cases, including 80 occupants, was also performed. All available information, such as medical records, questionnaires completed by the occupants and photographs from the accident scene was collected and analysed. The analysis of the in-depth study, together with knowledge retrieved from the literature study, resulted in six different mechanism groups that were used to categorise fractures. The groups were then analysed individually in regard to accident type and fractured segment of the upper extremity. Analysis of the mechanism groups showed that frontal impact is the dominating accident type in these subsets as well. It could also be seen that the fractures occurring in the in-depth study are quite evenly distributed along the upper extremities. Upper extremity injuries are relatively infrequent in car accidents but may result in long-term disability, including chronic deformity, pain, weakness and loss of motion. More attention is therefore necessary in order to develop a safer environment for car occupants.</p>

The aim of this study was to understand injury mechanisms behind fractures of the upper extremities in car accidents. Volvo Car Corporation initiated this project based on the fact that no safety system today focuses on preventing injuries to the upper extremity. A literature study was undertaken focusing on the basic anatomy of the upper extremity, different fracture types and fracture mechanisms. Three subsets, from 1998 – January 2009, were selected from Volvo’s statistical accident database: 1) all occupants involved in an accident 2) all occupants with a MAIS2+ injury 3) all occupants with an upper extremity fracture. These subsets were used in a comparison, using frequency analyses. The comparison analysis showed that frontal impact is the dominating accident type for all three subsets. The comparison analysis also indicated that the risk for upper extremity fractures follows the pattern of MAIS2+ injury risk. An in-depth study using 92 selected cases, including 80 occupants, was also performed. All available information, such as medical records, questionnaires completed by the occupants and photographs from the accident scene was collected and analysed. The analysis of the in-depth study, together with knowledge retrieved from the literature study, resulted in six different mechanism groups that were used to categorise fractures. The groups were then analysed individually in regard to accident type and fractured segment of the upper extremity. Analysis of the mechanism groups showed that frontal impact is the dominating accident type in these subsets as well. It could also be seen that the fractures occurring in the in-depth study are quite evenly distributed along the upper extremities. Upper extremity injuries are relatively infrequent in car accidents but may result in long-term disability, including chronic deformity, pain, weakness and loss of motion. More attention is therefore necessary in order to develop a safer environment for car occupants.

A Research Report submitted to the Faculty of Health Sciences, University of the Witwatersrand Gauteng, 2017 / Background Soccer is a sport that is gaining in popularity in the elite and non-elite populations worldwide. As a result, the number of injuries in soccer is increasing. Hamstring injuries in particular, with a reported incidence rate as high as 63%, are of significant concern. Most hamstring injuries tend to occur during the swing phase of sprinting when hamstring activity is at its highest. As the speed of sprinting increases, greater mobility in the lumbo-pelvic area is required to maximise sprinting efficiency. Any abnormal or dysfunctional lumbo-pelvic movement during this phase could induce pain and hamstring injury. Lumbo-pelvic movement control dysfunction may therefore indirectly link abnormal lumbar spine movement to lumbo-pelvic pain and hamstring injury. The first aim of this study was to compare the performance of the erector spinae, gluteus maximus, hamstrings (biceps femoris) and quadriceps (rectus femoris) muscles in soccer players, with and without recent hamstring injuries, while performing isometric contractions, a functional squat and sprinting. The study’s second aim was to compare lumbo-pelvic movement control in soccer players with and without recent hamstring injuries. Method Thirty soccer players were selected to participate in this study. Fifteen were assigned to the injured group and 15 to an uninjured group. The injured group comprised players who had sustained a hamstring injury six months prior to the research and who had partially returned to training, and the uninjured group comprised players with no recent hamstring injuries and who were actively involved in full training. Players were matched in respect of age, height, weight and playing position. All players gave informed written consent, completed the physical activity, training and injury questionnaire, and the Oslo hamstring injury questionnaire. Physical tests, which included isometric contraction of the erector spinae, gluteus maximus, hamstrings (biceps femoris) and quadriceps (rectus femoris) muscles, a functional squat and a thirty-metre sprint were done. Muscle activity during these tests was recorded via electromyography (EMG). To determine the lumbo-pelvic movement control of the players, the dorsal pelvic tilt, waiter’s bow, one leg stand and prone knee bend tests were used. Cohen's d (parametric) and Spearman’s correlation coefficient (nonparametric) were used to calculate the effect size, and the Chi-square test and Fisher’s exact to analyse the lumbopelvic movement control data. To establish a statistical significance, the p-value of the study was set at p<0.05. Results EMG muscle activity during isometric contractions was lower in the erector spinae muscles (p=0.04) and biceps femoris muscle (p=0.02) of the injured group. Both these findings were statistically significant. There was no statistically significant difference in muscle activity during the functional squat between the study and uninjured groups. The results of the EMG activity in the thirty-metre sprint were determined to be significant as they demonstrated that the hamstring muscle (p=0.01) activation in the injured group was decreased in comparison with the uninjured group. During the performance of the lumbo-pelvic test, no association was found between the two groups in the dorsal pelvic tilt and one leg stand. The performance of the waiter’s bow (p=0.01) and prone knee bend (p=0.004) revealed statistically significant differences between the study and uninjured groups. The majority of the players in the injured group performed both of these functional tests incorrectly (WB n=10; PKB n=14). Conclusion The study found that the hamstring muscle is at great risk of injury during eccentric contraction of the hamstring muscles. This can be associated with poor lumbo-pelvic movement control, as the load on the hamstring muscle is increased to provide intersegmental stability around the neutral zone, the area of high spinal flexibility. / MT2017

To achieve expressive musical results in violin bowing, performers access wide ranges of combined musical tone loudness and duration variables. By comparison, allowable mechanical variability in bow stroke execution may be limited. Such constraints on string bowing variability similarly might limit variability of bowing limb movement. Constrained variability may carry risk of upper extremity musculoskeletal disorders. Therefore if musical and/or bowing-execution variables influence bowing limb movement variability, they may in turn influence risk of cumulative injury in the player. In two experimental studies we examined the influence of the musical variables of duration and sound intensity (loudness) on variability in both string bowing mechanical variables and bowing limb joint moments (i.e. rotational forces) and joint angle trajectories. Five violinists performed playing tasks in which bow strokes varied across four levels of duration and three levels of loudness. Given a constant-amplitude bow stroke, quiet, brief strokes and loud, long strokes had to be executed close to the lower and upper limits of permissible bow-on-string force (bow force). In Study #1, we computed one- and three-dimensional bow movement variance measures, in both kinematic (bow velocity across violin string, distance from bow-to-bridge) and kinetic (bow force) variables. In Study #2 we computed the cycle-to-cycle standard deviation of joint moments and angles for each moment and angular degree of freedom in the bowing limb. In each study, these variability measures were compared across the 12 experimental conditions. We hypothesized that variability would be lowest when executing quiet/brief and loud/long strokes, compared to strokes that could be executed further from bow force limits. However, it was also anticipated that variability instead could be influenced most strongly by bow and/or limb velocity, magnitude of bow force, and/or bowed-string loudness response properties. Results from both studies indicated that variability in both bow-on-string and limb movement was conditioned on these latter properties: tone duration and loudness exerted consistent effects on variances and standard deviations. Contradicting the main hypothesis, variability was not influenced by proximity to bow force limits. We conclude that bowing variability is constrained mainly by factors not specific to variability tolerance at the bow-violin string interface.

The deformation associated with a ballistic shield defeating a projectile can interact with the user’s upper extremity, resulting in the release of the shield, placing those behind the device at risk. This injury mechanism is known as behind-shield blunt trauma (BSBT). Previous studies investigating these interactions have used testing conditions not representative of those present during these behind-shield events and lacked sufficient testing to determine statistically relevant outcomes. In the present work, the loading present during ballistic shield deformation was characterized through testing using an Anthropomorphic Test Device (ATD) upper extremity placed behind a level III ballistic shield. Digital image correlation (DIC) and post-impacting X-ray imaging were used to assess the ballistic shield’s deformation. The data collected from ballistic testing informed the development of a projectile used with a pneumatic impactor for the application of BSBT in a lab-based setting. Using the projectile, ballistic impacts were replicated on the ATD upper extremity and translated to 5th and 95th percentile cadaveric arms. Load data were collected for the hand and forearm using piezoelectric force sensors embedded in the projectile. Similarly, PMHS were impacted in a stepwise fashion of increasing energy until fractures were identified using X-ray imaging. A novel scaling technique was developed where Partial Least Squares (PLS) was used to determine critical variables relating donor anthropometrics to peak impact force. The scaling equations generated using this technique offer future researchers the opportunity to employ a larger range of specimens when determining injury thresholds for the hand and forearm. Through the characterization of the conditions present during BSBT, the injury thresholds to these mechanisms were assessed for understudied populations. Additionally, this work presents scaling techniques that could reduce the number of specimens required to determine future upper extremity injury limits. The information presented within this work provides an important step in developing new standards for ballistic shields to better protect users from BSBT. / Thesis / Master of Applied Science (MASc) / The deformation of a ballistic shield associated with stopping a bullet can interact with the user’s arm, causing them to drop the shield and placing the user in further danger. This work aimed to assess the risks to the hand and forearm over a range of male sizes using mechanical and biomedical tools. Ballistic loading was characterized using a crash test dummy arm to understand the conditions present during the event. The injuries associated with this loading were assessed using cadaveric specimens and a custom projectile for replicating the impacts. Mathematical techniques were used to translate the injury thresholds to the exact user sizes – providing relevant metrics for future ballistic shield standards. The results of this work present methods for recreating ballistic testing in a lab-based setting and for scaling forces associated with the hand and forearm, allowing future researchers to use a broader range of specimens for injury assessment.

No description available.

This paper describes a three part analysis to characterize the interaction between the female upper extremity and a helicopter cockpit side airbag system and to develop dynamic hyperextension injury criteria for the female elbow joint. Part I involved a series of 10 experiments with an original Army Black Hawk helicopter side airbag. A 5th percentile female Hybrid III instrumented upper extremity was used to demonstrate side airbag upper extremity loading. Two out of the 10 tests resulted in high elbow bending moments of 128 Nm and 144 Nm. Part II included dynamic hyperextension tests on 24 female cadaver elbow joints. The energy source was a drop tower utilizing a three-point bending configuration to apply elbow bending moments matching the previously conducted side airbag tests. Post-test necropsy showed that 16 of the 24 elbow joint tests resulted in injuries. Injury severity ranged from minor cartilage damage to more severe joint dislocations and transverse fractures of the distal humerus. Peak elbow bending moments ranged from 42.4 Nm to 146.3 Nm. Peak bending moment proved to be a significant indicator of any elbow injury (p=0.02) as well as elbow joint dislocation (p=0.01). Logistic regression analyses were used to develop single and multivariate injury risk functions. Using peak moment data for the entire test population, a 50% risk of obtaining any elbow injury was found at 56 Nm while a 50% risk of sustaining an elbow joint dislocation was found at 93 Nm for the female population. These results indicate that the peak elbow bending moments achieved in Part I are associated with a greater than 90% risk for elbow injury. Subsequently, the airbag was re-designed in an effort to mitigate this as well as the other upper extremity injury risks. Part III assessed the enhanced side airbag module to ensure injury risks had been reduced prior to implementing the new system. To facilitate this, 12 enhanced side airbag deployments were conducted using the same procedures as Part I. Results indicate that the re-designed side airbag has effectively mitigated elbow injury risks induced by the original side airbag design. It is anticipated that this study will provide researchers with additional injury criteria for assessing upper extremity injury risk caused by both military and automotive side airbag deployments. / Master of Science

Most manual wheelchair users will experience upper extremity injury and pain during their lifetime, which can be partly attributed to the high load requirements, repetitive motions and extreme joint postures required during wheelchair propulsion. Recent efforts have attempted to determine how different propulsion techniques influence upper extremity demand using broad measures of demand (e.g., metabolic cost). However studies using more specific measures (e.g., muscle stress), have greater potential to determine how altering propulsion technique influences demand. The goal of this research was to use a musculoskeletal model with forward dynamics simulations of wheelchair propulsion to determine how altering propulsion technique influences muscle demand. Three studies were performed to achieve this goal. In the first study, a wheelchair propulsion simulation was used with a segment power analysis to identify muscle functional roles. The analysis showed that muscles contributed to either the push (i.e. delivering handrim power) or recovery (i.e. repositioning the hand) subtasks, with the transition period between the subtasks requiring high muscle co-contraction. The high co-contraction suggests that future studies focused on altering transition period biomechanics may have the greatest potential to reduce upper extremity demand. The second study investigated how changing the fraction effective force (i.e. the ratio of the tangential to total handrim force, FEF) influenced muscle demand. Simulations maximizing and minimizing FEF both had higher muscle work and stress relative to the nominal simulation. Therefore, the optimal FEF value appears to balance increasing FEF with minimizing upper extremity demand and care should be taken when using FEF to reduce demand. In the third study, simulations of biofeedback trials were used to determine the influence of cadence, push angle and peak handrim force on muscle demand. Although minimizing peak force had the lowest total muscle stress, individual stresses of many muscles were >20% and the simulation had the highest cadence, suggesting that this variable may not reduce demand. Instead minimizing cadence may be most effective, which had the lowest total muscle work and slowest cadence. These results have important implications for designing effective rehabilitation strategies that can reduce upper extremity injury and pain among manual wheelchair users. / text

Introduction: Baseball pitching is considered one of the most intense aspects within the game of baseball, as well as the most complicated dynamic throwing task in all of sports. The biomechanics of pitching have been heavily investigated in an attempt to identify optimal pitching mechanics in terms of pitching performance. Previous quantified upper body kinetics research has concluded that improved muscle strength is needed in attempting to achieve adequate upper body kinetics and efficient pitching performances. Therefore, it is the purpose of this research study to compare the lower extremity muscle and upper extremity muscle activation patterns and kinematic variables associated with the curveball pitch and the fastball pitch when pitching from the wind-up and stretch position. Methods: Twelve skilled (competed at the NCAA collegiate level) baseball pitchers volunteered to be research subjects for this study. The participants were fitted with six surface electromyography (EMG) bipolar electrodes (Delsys Inc., Boston, Massachusetts) on the stride leg biceps femoris, medial gastrocnemius, ipsilateral side (throwing arm side) lower trapezius, upper trapezius, triceps brachii and biceps brachii. Each participant underwent maximum voluntary isometric contraction (MVIC) testing and then performed a pitching analysis. All EMG variables of interest were normalized using MVIC data and then compared between pitching types and pitch delivery. Shoulder rotation, shoulder abduction, elbow flexion and extension, elbow angular velocity and pelvis rotation were determined using motion capture (Motion Analysis Corp., Santa Rosa, SA) and Visual 3D software (C-Motion Inc., Germantown, MD). Paired t-tests and factorial analyses were performed using SPSS (p ≤ 0.05). Results and Discussion: Significant differences in the peak and mean muscle activity for the fastball and curveball pitched from wind-up and stretch position were observed. Significant differences in the kinematic variables between the fastball and curveball from the wind- up and stretch were also observed. These findings suggest that upper and lower muscle activity could be associated with enhanced pitching technique and pitching performance. Pitching kinematic differences associated with the diverse pitch types as well as the multiple pitch deliveries may impact the overall “wear and tear” on a pitcher’s health and pitching arm. Conclusions: Many differences were found, between both the pitching type and the pitching delivery as well as the kinematic variables. These findings suggest that upper and lower muscle activity could be associated with enhanced pitching technique and pitching performance to keep a baseball pitcher healthy and on the pitching mound longer into the season, decreasing the rate of injury. Shoulder rotation and pelvis rotation, as well as the elbow angular velocity and elbow flexion-extension, have an impact on the pitcher’s ability to stay off the disabled list and in the game longer. Determining pitch types along with delivery types that enhance the pitcher’s ability to stay active without injury will provide a way to make the game of baseball safer for the future generation of all stars.

The occurrence of work related musculoskeletal disorders (WRMD) has been a focus of much research and the prevalence of upper extremity disorders (UED) has also been explored. Most of the studies addressing WRMD among hairstylists considered the biomechanical demands of the industry, with a few studies acknowledging the psychosocial risk factors as precipitators of the upper extremity pain. This qualitative study contributes to an understanding of the biopsychosocial factors linked to the experience of pain, and how the process of adjustment to pain impacted the performance of roles at work and home of female hairstylists. The PEO model (Law et al., 1996) was used to describe the impact of pain on roles and the adjustment process in the management of roles, and facilitated an understanding of the occupational performance issues face by the stylists experiencing upper extremity pain.