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

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.

The project focus has been development of guidelines and methods for upper extremity injury reduction in car crashes. The safety of the central body parts improves which indicates the need to develop methods for avoiding non-life threatening injuries such as fracture of the arms. The purpose of the project was to study the injury mechanisms for the upper extremity in car crashes, and the aim has been to propose methods to reduce the injuries. The project focuses on adult occupants inside the vehicles front seat, and frontal and side impacts. The procedure began with understanding and identifying the injury mechanisms. Studies show that most fractures occur on the forearm (radius and ulna) and on the wrists and hands. To determine which injury mechanisms that were most frequent, data were collected from 29 computer simulations with 29 different crash scenarios. The most common kind of impact was the medial part of the wrist in the central part of the instrument panel, combined with the impact of the elbow in the center consol. The results of the simulations created a basis for the method of the component test, with focus on the injury mechanism i.e. the forward movement of the arms into the instrument panel. The component test consisted of a test rig, on which was mounted with a measuring arm of a 50th percentile male dummy. The arm dropped into a block of expanded polypropylene (EPP-block) for observation and study, and with following variable parameters: the impact angle of the surface, velocity and position of the wrist. Then also an instrumented measuring arm from a 5th percentile female dummy was released into an instrument panel. The project contributes to knowledge about the injury mechanism of the upper extremity in car crashes. The most frequent injury mechanism is a forward movement of the arms resulting in an impact with the interior structure of the car. The most frequent injured region is the distal part of the upper extremity. The project has developed and suggested the first step to a test method for the specific injury mechanism. There is a need of more research on how impact angles and velocity affect the violence on the arm.

Este estudo teve como objetivo implementar um modelo biomecânico, de segmentos articulados, associado à solução inversa que permita a análise em três dimensões das forças de reação proximais e momentos proximais resultantes para diferentes gestos do membro superior. O modelo implementado é composto por cinco segmentos rígidos (mão, antebraço, braço, escápula e tronco) conectados. A resolução das equações de movimento de Newton-Euler é feita através da solução inversa. Para registro cinemático foram utilizadas cinco câmeras digitais, com freqüência de amostragem de 50 campos/seg. O modelo implementado foi avaliado de quatro formas: estimativa da acurácia da medida tridimensional obtida pela cinemetria, comparação quantitativa e qualitativa dos resultados parciais oferecidos pelo modelo implementado com resultados obtidos por instrumentos de mensuração direta (eletrogoniômetro e eletromiografia) e cálculo da propagação do erro nos valores de força de reação resultante e momento proximal líquido. Os resultados sugerem que o modelo apresenta resultados coerentes. A acurácia do sistema de videogrametria estimada foi, em média, de 1,7 (± 1,5) mm. As medidas angulares da cinemetria e eletrogoniometria divergiram em até 36°. O erro propagado no cálculo da força de reação proximal pode chegar até 25% e até 100% no cálculo do momento proximal. O sinal eletromiográfico e o momento proximal apresentaram sincronismo temporal. O modelo foi capaz de avaliar as forças de reação proximal resultantes e momentos proximais líquidos nos diferentes gestos. / The goal of this study was to implement a link segments biomechanical model, associate to the inverse solution for three dimensions analysis of proximal reaction force and proximal net moments during upper limb movement. The implemented model is composed by five connected rigid segments (hand, forearm, arm, scapula and trunk). The resolution of Newton-Euler movement equations is done through the inverse solution. For kinematics acquisition five digital cameras were used, with a frequency sample of 50 fields/sec. The implemented model was evaluated in four ways: accuracy estimation of the three-dimensional measurements, quantitative and qualitative comparison of the partial results offered by the implemented model with results obtained by instruments of direct measurements (electrogoniometer and electromyography) and calculation of the error propagation in proximal reaction force and proximal net moment values. The results suggest that the model presents coherent results. The estimated accuracy videogrammetry system was, on average, of 1.7 (± 1.5) mm. The joint angular values obtained by kinematics system and electrogoniometer diverged in 36°. The error propagation in proximal reaction force values can arrive up to 25% and up to 100% for proximal net moment. The electromyographic sign and the proximal moment presented temporary synchronism. The model was able to evaluate the proximal reaction force and proximal net moment during upper limb movement.

The Strain Index (SI) has repeatedly shown high levels of validity for differentiating between safe and hazardous tasks for the distal upper extremity (DUE). One limitation of the SI is the lack of reliability data. This study was designed to evaluate the test-retest repeatability of the SI. Fifteen raters, divided into five teams of three, were asked to use the SI to analyze 73 video AVI files of different job tasks; initially as individuals and then as teams. Several months later, raters were asked to repeat individual and team job task assessments. Raters were instructed to analyze tasks using five of six SI task variables, while the sixth was held constant. For three of these task variables, additional data was collected such as peak force and duration of job cycle. Test-retest repeatability was measured using Pearson's R, Spearman's rho, and tetrachoric correlation according to the nature of the variable. Spearman's rho values for individual and team task variable ratings ranged from 0.68 to 0.96 (0.88 average). Pearson's R for task variable data ranged from 0.76 to 0.99 for both teams and individuals with an average of 0.91. The Strain Index's rho values for individuals and teams were 0.70 and 0.84, respectively. For hazard classification, the tetrachoric correlation for individuals was 0.81 and 0.88 for teams. Results of this study support the conclusion that the Strain Index is repeatable when used by teams as well as individuals.

The main objective of my dissertation was to evaluate the biomedical and psychosocial factors associated with pain and disability in patients following traumatic upper extremity nerve injuries. This was approached by conducting 3 studies. The first study surveyed peripheral nerve surgeons regarding the assessment of pain in patients with nerve injury. The results showed that only 52% of surgeons always evaluate pain in patients referred for motor/sensory dysfunction. Pain assessment frequently includes verbal response and assessment of psychosocial factors is infrequent. The second study was a retrospective review to assess disability, as measured by the Disabilities of the Arm, Shoulder and Hand (DASH), in patients with chronic nerve injury. Results showed substantial disability (mean DASH 52 + 22) and a significantly lower health status (p < 0.001) compared with well-established norms. In the regression model, the factors associated with the DASH (R2 = 44.5%) were pain, older age and nerve injured. The third study was a cross-sectional evaluation of the biomedical and psychosocial factors associated with pain and disability after upper extremity nerve injury in 158 patients. DASH scores were significantly higher in patients with workers’ compensation or litigation (p = 0.03), brachial plexus injuries (p < 0.001) and unemployed patients (p < 0.001). In the multivariable regression analysis, the final model explained 52.7% of the variance with these predictors; pain intensity (Beta = .230, p = 0.006), nerve injured (Beta = -.220, p = 0.000), time since injury (Beta = -.198, p = 0.002), pain catastrophizing (Beta = .192, p = 0.025), age (Beta = .187, p = 0.002), work status (Beta = .179, p = 0.008), cold sensitivity (Beta = .171, p = 0.015), depression score (Beta = .133, p = 0.066), workers’ compensation/litigation (Beta = .116, p = 0.049) and gender (Beta = -.104, p = 0.09). Future investigation regarding treatments of the factors that are associated with disability and chronic pain will assist to improve health related quality of life in patients with traumatic nerve injury.

The main objective of my dissertation was to evaluate the biomedical and psychosocial factors associated with pain and disability in patients following traumatic upper extremity nerve injuries. This was approached by conducting 3 studies. The first study surveyed peripheral nerve surgeons regarding the assessment of pain in patients with nerve injury. The results showed that only 52% of surgeons always evaluate pain in patients referred for motor/sensory dysfunction. Pain assessment frequently includes verbal response and assessment of psychosocial factors is infrequent. The second study was a retrospective review to assess disability, as measured by the Disabilities of the Arm, Shoulder and Hand (DASH), in patients with chronic nerve injury. Results showed substantial disability (mean DASH 52 + 22) and a significantly lower health status (p < 0.001) compared with well-established norms. In the regression model, the factors associated with the DASH (R2 = 44.5%) were pain, older age and nerve injured. The third study was a cross-sectional evaluation of the biomedical and psychosocial factors associated with pain and disability after upper extremity nerve injury in 158 patients. DASH scores were significantly higher in patients with workers’ compensation or litigation (p = 0.03), brachial plexus injuries (p < 0.001) and unemployed patients (p < 0.001). In the multivariable regression analysis, the final model explained 52.7% of the variance with these predictors; pain intensity (Beta = .230, p = 0.006), nerve injured (Beta = -.220, p = 0.000), time since injury (Beta = -.198, p = 0.002), pain catastrophizing (Beta = .192, p = 0.025), age (Beta = .187, p = 0.002), work status (Beta = .179, p = 0.008), cold sensitivity (Beta = .171, p = 0.015), depression score (Beta = .133, p = 0.066), workers’ compensation/litigation (Beta = .116, p = 0.049) and gender (Beta = -.104, p = 0.09). Future investigation regarding treatments of the factors that are associated with disability and chronic pain will assist to improve health related quality of life in patients with traumatic nerve injury.

The Strain Index (SI) has repeatedly shown high levels of validity for differentiating between safe and hazardous tasks for the distal upper extremity (DUE). One limitation of the SI is the lack of reliability data. This study was designed to evaluate the test-retest repeatability of the SI. Fifteen raters, divided into five teams of three, were asked to use the SI to analyze 73 video AVI files of different job tasks; initially as individuals and then as teams. Several months later, raters were asked to repeat individual and team job task assessments. Raters were instructed to analyze tasks using five of six SI task variables, while the sixth was held constant. For three of these task variables, additional data was collected such as peak force and duration of job cycle. Test-retest repeatability was measured using Pearson's R, Spearman's rho, and tetrachoric correlation according to the nature of the variable. Spearman's rho values for individual and team task variable ratings ranged from 0.68 to 0.96 (0.88 average). Pearson's R for task variable data ranged from 0.76 to 0.99 for both teams and individuals with an average of 0.91. The Strain Index's rho values for individuals and teams were 0.70 and 0.84, respectively. For hazard classification, the tetrachoric correlation for individuals was 0.81 and 0.88 for teams. Results of this study support the conclusion that the Strain Index is repeatable when used by teams as well as individuals.

Diss. (sammanfattning) Göteborg : Göteborgs universitet , 2007. / Härtill 5 uppsatser.

Este estudo teve como objetivo implementar um modelo biomecânico, de segmentos articulados, associado à solução inversa que permita a análise em três dimensões das forças de reação proximais e momentos proximais resultantes para diferentes gestos do membro superior. O modelo implementado é composto por cinco segmentos rígidos (mão, antebraço, braço, escápula e tronco) conectados. A resolução das equações de movimento de Newton-Euler é feita através da solução inversa. Para registro cinemático foram utilizadas cinco câmeras digitais, com freqüência de amostragem de 50 campos/seg. O modelo implementado foi avaliado de quatro formas: estimativa da acurácia da medida tridimensional obtida pela cinemetria, comparação quantitativa e qualitativa dos resultados parciais oferecidos pelo modelo implementado com resultados obtidos por instrumentos de mensuração direta (eletrogoniômetro e eletromiografia) e cálculo da propagação do erro nos valores de força de reação resultante e momento proximal líquido. Os resultados sugerem que o modelo apresenta resultados coerentes. A acurácia do sistema de videogrametria estimada foi, em média, de 1,7 (± 1,5) mm. As medidas angulares da cinemetria e eletrogoniometria divergiram em até 36°. O erro propagado no cálculo da força de reação proximal pode chegar até 25% e até 100% no cálculo do momento proximal. O sinal eletromiográfico e o momento proximal apresentaram sincronismo temporal. O modelo foi capaz de avaliar as forças de reação proximal resultantes e momentos proximais líquidos nos diferentes gestos. / The goal of this study was to implement a link segments biomechanical model, associate to the inverse solution for three dimensions analysis of proximal reaction force and proximal net moments during upper limb movement. The implemented model is composed by five connected rigid segments (hand, forearm, arm, scapula and trunk). The resolution of Newton-Euler movement equations is done through the inverse solution. For kinematics acquisition five digital cameras were used, with a frequency sample of 50 fields/sec. The implemented model was evaluated in four ways: accuracy estimation of the three-dimensional measurements, quantitative and qualitative comparison of the partial results offered by the implemented model with results obtained by instruments of direct measurements (electrogoniometer and electromyography) and calculation of the error propagation in proximal reaction force and proximal net moment values. The results suggest that the model presents coherent results. The estimated accuracy videogrammetry system was, on average, of 1.7 (± 1.5) mm. The joint angular values obtained by kinematics system and electrogoniometer diverged in 36°. The error propagation in proximal reaction force values can arrive up to 25% and up to 100% for proximal net moment. The electromyographic sign and the proximal moment presented temporary synchronism. The model was able to evaluate the proximal reaction force and proximal net moment during upper limb movement.