Bakgrund:  Simning är en populär sport. De extrema repetitiva rörelserna som ingår i sporter med majoriteten av rörelserna över huvudet, som exempelvis simning, och otillräcklig stabilitet i axelleden resulterar ofta i överansträngning och skador. Ett vanligt syndrom är impingement och det har rapporterats att 40-91 % av alla simmare har eller upplever problem i axelleden eller de omkringliggande strukturerna. Syfte: Att undersöka om en intervention bestående av övningar för scapulas närliggande muskler i fyra veckor kan påverka upplevd smärta i axel och nacke hos unga simmare. Deltagare: Sexton unga simmare mellan åldrarna (13±2), bestående av (10 flickor och 6 pojkar) deltog. Alla deltagare utförde minst fyra simpass i veckan. Alla deltagare i studien upplever problematik i axel och/eller nacke. Metod: Deltagarna fick fylla i ett (SRQ-S) formulär och genomgå ett Beighton-test. Alla deltagare instruerades i fyra olika övningar, syftet med övningarna var att öka neuromuskulär kontroll och styrka i axelns stabiliserande muskler. Alla övningar skulle utföras innan träningspass, minst en gång om dagen, i fyra veckor. Efter fyra veckors interventionen fick deltagarna fylla i ett nytt (SRQ-S) formulär, den totala poängen innan och efter jämfördes. Resultat:  (SRQ-S) formulären resulterade i en signifikant skillnad (p=0,0005) mellan innan och efter interventionen. Majoriteten av deltagarna rapporterade ett högre välmående i axel och/eller nacke. Konklusion : Majoriteten av deltagarna upplevde minskad problematik i axel och/eller nacke efter fyra veckors interventionen. Det visar på att det finns ett samband mellan ökad axel stabilisering och minskad upplevd smärta i axel/nacke. Dock kan denna studie inte komma till en säker konklusion då vidare undersökning måste göras i detta område. / Background : Competitive swimming is a popular sport. The extreme repetitive motions that overhead-sports implies, like swimming, and inadequate stability in the shoulder joint often results in overexertions and injuries. A common condition is impingement syndrome and it has been reported that 40-91% of all swimmers have or experience problems in the shoulder joint or in the surrounding structures. Purpose : To investigate whether an intervention consisting of exercises for scapulas nearby muscles for four weeks can affect perceived distress in the shoulders and neck of young swimmers. Participants : Sixteen young swimmer between the age of (13±2), consisting of (10 females and 6 males) volunteered to participate. All the participants are performing at least four sessions of swimming a week. All the participants in the study are experiencing trouble in their neck or/and shoulders. Method : The participants had to fill in a (SRQ-S) form and do a Beighton-test. Participants were instructed in four different exercises, the purpose of the exercises were to increase neuromuscular control and strength in the shoulder stabilizing muscles. All exercise were to be performed before every session of swimming, at least once a day, for four weeks. After the four weeks of intervention the participants had to fill in a new (SRQ-S) form, the before and after score were compared. Results : The (SRQ-S) formulas resulted in a significant difference (p=0,0005) between before and after the intervention. The majority of the participants reported also a higher prosperous in their shoulder and/or neck area. Conclusion: The majority of the participant experienced less discomfort in their shoulder and neck area after the four weeks of intervention. There seems to be a relationship between increased shoulder stability and decrease in discomfort in the shoulder/neck. However this study can not come to a secure conclusion and further investigation has to be made in this area.

A literatura indica que os profissionais de enfermagem possuem alto risco de adquirir doenças osteomusculares devido aos problemas ergonômicos e posturais presentes na rotina hospitalar. A satisfação no trabalho é considerada um dos indicadores de qualidade de vida e pode influenciar na saúde física e mental do trabalhador. A dor no ombro em profissionais de enfermagem, apesar de menos comum que a dor lombar, é uma importante causa de morbidade, podendo acarretar limitação das atividades diárias e ocupacionais e interferir na qualidade de vida. Dentre as patologias do ombro, a desordem do manguito rotador é a patologia mais comum, e tratamentos conservadores ou cirúrgicos podem ser indicados. O tratamento fisioterapêutico tem-se mostrado uma importante ferramenta na reabilitação dos sujeitos com distúrbios do manguito rotador. Os objetivos deste estudo foram comparar o efeito da aplicação de dois programas fisioterapêuticos diferenciados pelos exercícios de propriocepção, em trabalhadores de enfermagem com desordem do manguito rotador, segundo indicadores de qualidade de vida e satisfação no trabalho. Trata-se de um estudo experimental, randomizado, prospectivo e comparativo, com análise quantitativa dos dados. A coleta de dados foi realizada, no período de junho de 2010 a julho de 2011, por meio da aplicação de um questionário contendo informações sociodemográficas, profissionais e relativas à fisiopatologia do ombro, por um instrumento de qualidade de vida (The Western Ontário Rotador Cuff Index - WORC) e pela Escala de Satisfação no Trabalho (Occupational Stress Indicator - OSI). A partir da randomização, os sujeitos foram alocados em dois grupos. No Grupo 1 (controle), foram aplicados exercícios de alongamento, fortalecimento e crioterapia. No Grupo 2 (experimental), foram realizados os mesmos exercícios que no Grupo 1 acrescidos de exercícios de propriocepção. Os dados foram analisados por meio do Statistical Package for the Social Science (SPSS) versão 16.0 for Windows. Após a aplicação dos programas fisioterapêuticos, foi verificado que houve melhora significativa da dor nos sujeitos dos dois grupos e melhora significativa da qualidade de vida nos trabalhadores do Grupo 2. A prescrição de exercícios proprioceptivos tem se mostrado importante no tratamento dos distúrbios osteomusculares, no entanto, os resultados não permitem inferir a melhor efetividade dos exercícios de propriocepção, pois não houve diferença significativa entre os grupos. Em relação à satisfação no trabalho, não houve alteração dos indicadores de satisfação, após aplicação dos tratamentos fisioterapêuticos nos dois grupos. Estudos clínicos de maior valor amostral são necessários para dar continuidade às pesquisas referentes ao tratamento fisioterapêutico a portadores de desordens de manguito rotador, com vistas à melhoria da qualidade de vida dos trabalhadores de enfermagem. / The literature indicates that nursing professionals possess high risks of developing musculoskeletal disorders due to ergonomical or postural problems which are present within the hospital routine. Work satisfaction is considered one of the indicators of quality of life and can influence the physical and mental wellbeing of workers. Shoulder pain in nursing professionals, although less common than low back pain, is an important cause of morbidity, and may lead to limitations in occupational and daily activities and consequently interfere with quality of life. Among the various shoulder pathologies, rotator cuff disorders are the most common and conservative or surgical treatment can be indicated. Physical therapy treatment has been proven to be a fundamental tool in the rehabilitation of persons with rotator cuff disorders. The objective of this study was to compare the effects of two physical therapy programs which differed in the proprioceptive exercises utilized on the nursing professionals with rotator cuff disorder, according to quality of life and work satisfaction indicators. This study was an experimental, randomized, prospective, and comparative trial, with quantitative analysis of the data. The data sampling was realized between the months of June 2010 and July 2011, by means of a questionnaire containing socio-demographic and professional information, the Western Ontario Rotator Cuff Index (WORC), and the Occupational Stress Indicator (OSI). Based on randomization, the subjects were divided into two groups. Group 1 (control) was submitted to stretching and strengthening exercises, and cryotherapy. Group 2 (experimental) was treated with the same protocol as group control, with the addition of proprioception exercises. The data was analyzed by means of the Statistical Package for the Social Science (SPSS) version 16.0 for Windows. After physical therapy intervention, significant reduction in pain levels occurred in both groups, with a significant improvement in quality of life for Group 2. The utilization of proprioceptive exercises was shown to be important in musculoskeletal care; however, the results do not permit the researchers to infer the influence of these exercises since no significant differences were seen between groups. In relation to work satisfaction, no changes were observed in the satisfaction indicators after the two types of physical therapy interventions. Other clinical trials with greater samples are needed in order to give continuity to research regarding physical therapy care for patients with rotator cuff disorder while aiming toward an improvement in the quality of life of nursing professionals.

Musculoskeletal Injuries are the most common cause of severe long-term pain and physical disability. Push-Ups and Pull-Ups are effective dynamic exercises that mimic high level function activities, such as those used in the military. The model developed allows for researchers to analyze the forces and moments associated with the shoulder, elbow and wrist, to further assess function in military personnel, athletes and the active population. The model also follows the guidelines set forth by the International Society of Biomechanics (ISB).

Epidemiological evidence suggests an association between exposure to non-neutral working postures and work-related musculoskeletal disorders (MSDs) of the low back and shoulder. Accurate and precise quantitative estimation of exposure to non-neutral working postures is, therefore, essential for evaluating worker risk, developing and testing ergonomic interventions, and improving worker health and well-being. Current methods used to directly estimate occupational exposure to non-neutral postures may be obtrusive, often lack sufficient portability for field use, and have limited accuracy and precision when used to measure dynamic or complex motions. Inertial measurement units (IMUs) are emerging instrumentation devices that measure and report an object's orientation and motion characteristics using multiple electromechanical sensors (i.e., accelerometers, gyroscopes, and/or magnetometers). They have been observed to accurately monitor body kinematics over periods of relatively short duration in comparison to laboratory-based optical motion capture systems. Limited research, however, has been performed comparing exposure information obtained with IMUs to exposure information obtained with other field-capable direct measurement exposure assessment methods. Furthermore, insufficient information on the repeatability of IMU-based estimates over a substantial time period (e.g., a full work shift) and inadequate knowledge regarding the effects of different IMU sensor configurations and processing methods on the accuracy and repeatability of estimates of exposure obtained with IMU systems contributes to a lack of their use in epidemiological field studies. This thesis was designed to address these issues and expand upon the current scientific literature regarding the use of IMU sensors as direct measurement devices for assessing exposure to non-neutral working postures in the field. Chapter I provides a background and justification for the work. Chapter II presents the findings of a laboratory-based, manual material handling study that was performed to compare estimates of thoracolumbar trunk motion obtained with a commercially available IMU system with estimates of thoracolumbar trunk motion obtained with a field-capable reference system, the Lumbar Motion Monitor (LMM). The effects of alternative sensor configurations and processing methods on the agreement between LMM and IMU-based estimates of trunk motion were also explored. Chapter III presents the results of a study performed to evaluate the accuracy and repeatability of estimates of trunk angular displacement and upper arm elevation obtained with the IMU system examined in Chapter II over the course of an eight-hour work shift in both a laboratory and field-based setting. The effects of alternative sensor configurations and processing methods on the accuracy and repeatability of estimates of trunk angular displacement and upper arm elevation obtained with the IMU system were also studied. Chapter IV presents the results of a randomized, repeated measures intervention that demonstrates the utility of the IMU system examined in Chapters II and III as a direct measurement instrument for comparing "ergonomic" and conventional examination equipment commonly used by ophthalmologists. Finally, Chapter V summarizes the major findings, discusses their practical implications, and provides suggestions for future research.

Friction stir welding (FSW) is a relatively new solid-state welding technology invented at The Welding Institute of UK in 1991. It is versatile and has been widely adopted to join various materials. There has been strong research activity on revealing the details of the material flow pattern in the nugget zone induced by the conventional shoulder tool. However, there is insufficient understanding on the aspects of the scroll shoulder tool design and the shoulder flow zone formation utilizing this type of tool. The major objective of this study was to conduct experiments, analyse results and then reveal the shoulder flow zone forming mechanism for the scroll shoulder tool. The method used was to identify the flow pattern in the shoulder flow zone using a ‘marker insert’ technique, and then to suggest the forming mechanism of the shoulder flow zone based on the obtained flow pattern; although the ‘marker insert’ technique has never been used to study the shoulder flow zone flow pattern induced by the scroll shoulder tool. Experiments were conducted to examine the thick sections 6061 aluminium ‘marker insert’ welds, which were welded using a scroll shoulder tool at a range of welding parameters. These were followed by quantifying the mass of the accumulated work piece material within the scroll groove (pick up material-PUM), evaluating the effect of welding parameters on the shoulder flow zone formation, and documenting the shoulder flow zone flow pattern. The major finding was that there is a simple banded structure which forms in a layer to layer manner in the bottom portion of the shoulder flow zone, but it disappears in the top portion of the shoulder flow zone. Accordingly, the forming mechanism of the shoulder flow zone for the scroll shoulder tool was suggested as follows. Firstly, the tool pin is plunged into the work piece; the work piece material is extruded by the pin and pushed up into the scroll groove forming the PUM. Secondly, after the tool shoulder is plunged into the work piece to a certain depth, the scroll groove is fully filled up with the PUM. Finally, during the forward movement of the tool, the central portion of PUM is driven downward by the root portion of the pin and then detaches from the pin (tip portion) in a layer to layer manner. It has also found that the thickness of the shoulder flow zone varies with a thicker on the advancing side than on the retreating side, and there is a positive linear relationship between the mass of PUM and the weld quality. This study has revealed for the first time the forming mechanism of the shoulder flow zone, and has improved the understanding of the shoulder flow zone formation using a scroll shoulder tool. It is recommended that a ‘shoulder-breaking’ technique is developed to break the rotating shoulder suddenly and hence embed it into the work piece during FSW, in which a real-time shoulder-work piece couple could be produced for a better three-dimensional examination of the shoulder flow zone.

The supraspinatus tendon is an important structure of the rotator cuff. Subacromial impingement is a common reason for shoulder pain. Despite extensive scientific work in this field, the cause of impingement syndrome is still not fully understood. The general aim of the present thesis was to generate new knowledge with respect to pathogenesis and treatment of impingement syndrome. A combination of animal and clinical studies were performed. Different methods were used such as histology, immunohistochemistry, development and assessment of a novel measuring device and clinical and radiological assessment. Thirty rats were injected with triamcinolone or saline into the subacromial bursa. After five corticosteroid injections, we found focal inflammation, degradation and fragmentation of collagen bundles in the supraspinatus tendon, whereas the control specimens were normal (p=0.035). Subacromial bursitis was induced by injections of carrageenan into the subacromial space (n=28). Fibrocartilaginous metaplasia and bony metaplasia were found in the supraspinatus tendon. Even in specimens with no histologic changes of the collagen bundles the staining for fibronectin was significantly increased. The distance between the anterolateral acromion and the supraspinatus tendon was measured in patients with impingement syndrome intraoperatively (n=30) and in controls (instability, n=15). The mean value of the subacromial distance in controls was 16 mm, the 95% mean confidence limits between 14 and 18 mm. The mean value in the group of patients with impingement syndrome was 8 mm before and 16 mm after the decompression. Fifty patients were reviewed after arthroscopic subacromial decompression. Twenty-five showed calcific deposits in the rotator cuff on radiographs preoperatively. In 13 patients the calcific deposits totally disappeared postoperatively. In another six patients the calcifications had decreased in size. Four patients still showed calcifications, which were 5 mm or greater in size. The postoperative results measured by the Constant score were almost identical in the calcific and the non-calcific groups. Tillander 010916 8 Human surgical supraspinatus tendon specimens were studied from patients with impingement (n=16), ruptured supraspinatus tendons (n=7) and controls (n=10). Degradation of tendinous tissue and fibrin were found only in some specimens from ruptures. The difference in fibronectin staining was significant between controls and patients with a rupture (p=0.002). Fibrosis and thinning of fascicles seemed to be a more non-specific finding, appearing in control, impingement and rupture specimens. In conclusion, subacromial corticosteroid injections may cause rupture of the supraspinatus tendon. Metaplasia of the supraspinatus tendon may play a role in the pathogenesis of impingement and rupture of the supraspinatus tendon. The subacromial distance can be measured intraoperatively and was shown to be lower in patients with impingement than in patients with instability. Calcifications disappear or decrease in size after arthroscopic subacromial decompression and do not seem to influence the postoperative outcome in patients with impingement. Degradation of tendon tissue, fibrin and fibronectin appear to be signs of tendon degeneration, whereas fibrosis and thinning of fascicles were found also in controls.

Syftet med avhandlingen var att beskriva diagnostiken och utvärdera handläggningen i primärvård av patienter med subacromial smärta. Avhandlingen omfattar fyra studier. I den första studien användes ett frågeformulär och resultaten beskriver hur distriktsläkare och distriktssjukgymnaster i ett svenskt län diagnosticerar och handlägger primärvårdspatienter med subacromial smärta. Den andra studien beskriver distriktsläkares och distriktssjukgymnasters tilltro till effekten av olika behandlingsmetoder för dessa patienter. Med utgångspunkt från de tilltrodda behandlingsmetoderna genomfördes en systematisk litteraturöversikt. Den tredje studien utvärderar intra- och interbedömar reliabilitet för ett styrketest som ingår i ett utvärderingsinstrument ‘the Constant-Murley shoulder assessment’. Den avslutande studien är en randomiserad klinisk studie som utvärderar och jämför effekten av två behandlingsstrategier, akupunktur och ultraljud, båda i kombination med hemträning. Distriktsläkare och distriktssjukgymnaster visade sig använda en likartad diagnostik. Det troligaste valet av behandling för distriktsläkare var antiinflammatoriska läkemedel och kortisoninjektion i den subacromiala bursan och för distriktssjukgymnaster rörelseträning samt ergonomiska åtgärder. Dock var de flesta behandlingsalternativen troliga val, vilket tolkas som en osäkerhet om behandlingarnas effekt. Med utgångspunkt från de behandlingsmetoder som distriktsläkare och distriktssjukgymnaster tilltrodde som effektiva för patienter med subacromial smärta, genomfördes en systematisk kritisk litteraturöversikt. Fyrtio studier inkluderades och deras evidensnivå utvärderades. Endast kortisoninjektion i den subacromiala bursan visade sig ha definitiva bevis för effekt. Akupunktur visade sig ha troliga bevis för effekt och ultraljudsbehandling konkluderades som ineffektivt för patienter med subacromial smärta. Det förelåg en låg grad av samstämmighet mellan tilltro och tillgängliga vetenskapliga bevis. En digital dynamometer kan ersätta den konventionella fjädervågen i det standardiserade styrketestet. En nästan perfekt överensstämmelse vad gäller både intra- och interbedömarreliabilitet vid test av unga skulderfriska personer, oberoende av om en ”håll emot-” eller ”dragteknik” användes eller om medel- eller maxvärden användes vid beräkningen av överensstämmelse. I den randomiserade kliniska studien inkluderades 85 patienter. Tre utvärderingsinstrument, kombinerade i resultatanalysen, utvärderade förändringen under en uppföljningsperiod på 12 månader tillsammans med patienternas subjektiva skattning av resultatet. Resultaten visade att akupunktur i kombination med hemträning är att föredra. Båda behandlingsgrupperna förbättrades signifikant och fortsatte förbättras över tid oberoende av behandling. De flesta patienter uppnådde ett tillfredställande behandlingsresultat efter 12 månader. Åtminstone tre fjärdedelar i varje behandlingsgrupp skattade sig mycket förbättrade eller helt återställda. Detta tolkas som en behandlingseffekt i kombination med naturalförloppet. Avhandlingen har beskrivit handläggningen i primärvård av patienter med subacromial smärta och har bidragit med vetenskapliga bevis för distriktsläkare att behandla med kortisoninjektion i subacromiala bursan och för distriktssjukgymnaster att behandla med akupunktur kombinerat med hemträning. / The aim of the thesis was to describe the diagnostic approach and evaluate primary care management of patients with subacromial pain. The thesis includes four different studies, a questionnaire study describing attitudes among general practitioners and physiotherapists in a Swedish county toward the diagnostic approach and management of primary care patients with subacromial pain; a combination of a systematic review and general practitioners and physiotherapists beliefs in interventions for patients with subacromial pain; a study of intra- and inter-observer reliability for the strength test in the Constant-Murley shoulder assessment; and a randomised clinical trial to evaluate and compare the efficacy of two treatment strategies for patients with subacromial pain, acupuncture combined with home exercises and continuous ultrasound combined with home exercises. In the questionnaire study we described that general practitioners and physiotherapists have a uniform diagnostic approach. The most probable choice of treatment was non-steroidal anti-inflammatory drugs and corticosteroid injection into the subacromial bursa for general practitioners and movement exercises together with ergonomics/adjustments at work for physiotherapists, but most treatments were probable choices, reflecting an uncertainty about their effectiveness. The treatments trusted by general practitioners and physiotherapists were systematically reviewed. Forty studies were included and the level of evidence was summarised. Only corticosteroid injections into the subacromial bursa, had definitive evidence for efficacy. Acupuncture had tentative evidence for efficacy and therapeutic ultrasound was concluded as ineffective for patients with subacromial pain. The association between trusted treatments and available scientific evidence was weak. A digital dynamometer can replace the conventional spring-balance in the standardised strength test. An almost perfect agreement was found for intra- and inter-observer reliability in young shoulder-healthy persons, regardless of whether a 'resisted-force' or a 'pull-force' was used or if calculated with mean or maximum values. Eighty-five patients were included in the randomised clinical trial. Three shoulder scores, combined in the analysis, measure change during a 12 months follow-up together with a ‘patient self-evaluation’ of the experienced result. The results favoured acupuncture combined with home exercises. Both groups improved significantly and continued to improve over time independent of treatment and most of the patients reached a satisfactory result at 12 months. At least three fourths of the patients, in each treatment group, reported large improvements or felt completely recovered. This is interpreted as a combination of treatment effect and the natural course. This thesis has described the primary care management of patients with subacromial pain and provided scientific evidence for general practitioners to use corticosteroid injection and for physiotherapists to use acupuncture combined with home exercises, when treating these patients. / On the day of the defence date the status on article III was Accepted and article IV was Submitted.

There are numerous indications of possible involvement of the autonomic nervous system in the genesis of chronic pain. The possibility exists that sympathetic activation is related to motor dysfunction and changes in sensory processing, which have otherwise been implicated in musculoskeletal disorders. The primary aim of the thesis has been to investigate autonomic regulation at rest and in response to laboratory tests of autonomic function in subjects suffering from chronic pain in different localisations (lower back, neck-shoulder and neck-jaw), as well as to study the relations between autonomic regulation, proprioceptive acuity and clinical data. Secondary aim has been to assess autonomic regulation in fit, pain-free subjects in response to experimentally induced pain and in occupationally relevant settings. A total of 194 subjects suffering from chronic pain participated [low back pain (LBP) n=93; non-traumatic neck pain (NT) n=40, Whiplash associated disorder (WAD) n=40, Whiplash with temporomandibular dysfunction (WADj) n=21]. Each chronic pain group was subjected to a battery of autonomic function tests combining cognitive (Stroop Colour-Word conflict tests), physical (handgrip), sensory (unpleasant sound) and motor tasks (chewing tests) as well as the activation of reflex pathways (paced breathing and the orthostatic test) and compared to an age- and gender balanced control group. Autonomic regulation was also assessed in exposure to experimentally induced muscle pain in healthy subjects (n=24) in order to describe acute pain reaction. Further assessment was carried out during monotonous repetitive work and dynamic work in healthy subjects (n=10) and in a three-day monitoring of ambulance personnel (n=26) in occupational settings. Autonomic regulation was evaluated using cardiovascular (heart rate and heart rate variability, local blood flow and blood pressure), respiratory (breathing rate) electrodermal (skin conductance), muscular (trapezius and masseter EMG) and biochemical (insulin, cortisol, catecholamines) variables. Proprioceptive acuity was assessed using active-active repositioning tests. Pain levels were assessed using Visual-analogue or Numerical Rating scales. General health was evaluated through the Short-Form SF-36 Health Related Quality of Life questionnaire and Self-Efficacy Score questionnaires, whereas dysfunction was evaluated using the Oswestry Low Back Pain questionnaire, Pain Disability and Neck Disability Index questionnaires, the McKenzie evaluation and primary healthcare diagnoses. Self-reports of pain, stress and exertion were acquired prior to, during and post-testing. Chronic pain subjects were characterised by increased sympathetic and decreased parasympathetic activity as reflected in heart rate (LBP, WAD, WADj), heart rate variability (LBP, WAD, WADj), blood pressure (WADj) and electrodermal activity (LBP). In general, WAD showed more pain and dysfunction than NT, with lower self-efficacy and health-related quality of life. Differential reactivity was observed only in WAD, with increased responsiveness to sensory stimuli (heart rate variability, electrodermal activity), and motor tasks (heart rate) and a decreased response to cognitive challenge (heart rate variability, electrodermal activity). A significant part of WADj subjects showed sensorimotor impairment and low endurance in chewing tests, concomitant with a cardiovascular response that correlated with pain levels. Proprioceptive acuity was not found to be impaired among subjects suffering from chronic pain, and there were no indications of significant individual response specificity. Response to experimentally induced muscle pain in healthy subjects was also characterised by a prominent cardiovascular component. In simulated occupational settings autonomic activation and transient insulin resistance were detected in healthy subjects following monotonous repetitive work, with no similar effects following dynamic exercise. Modest deviations in circadian heart rate variability patterns during workdays were detected in ambulance personnel reporting more pronounced musculoskeletal symptoms, with no such effects on work-free days. Autonomic balance observed in chronic pain subjects was characterised by a trend towards increased sympathetic activity in comparison with pain-free controls. Moderate signs of affected reactivity to autonomic function tests were observed in patients with WAD, however no specific reaction patterns have been observed in any chronic pain group. Correspondence between the intensity of pain and autonomic activity was observed in acute pain and in chronic pain groups characterised by higher pain levels. As indicated by autonomic and neurohormonal changes in the recovery from real and simulated work, further studies with physiological monitoring of the effects of work-related stress are warranted for better understanding of the mechanism of musculoskeletal disorders.

As the work force ages and workers retirement age increases, the number of workers suffering from Work-related Musculoskeletal Disorders (WMSDs) has increased. In a recent study, the U.S Bureau of Labor reported that 6.9% of all WMSDs affected shoulders. Electricians, carpenters, and related construction crafts appear to experience higher incidence of these injuries due the nature of their work that require them often to use Awkward shoulder postures. This research aims to develop a new monitoring system that measure the amount of time workers spend in awkward shoulder postures to help decrease the prevalence of cumulative shoulder injuries and to reduce the number of cases of shoulder WMSDs among construction workers. The monitoring system was designed and a feasibility study was conduct to compare the monitoring system with a state of the art motion tracking system. Overall the monitoring system was able to count the time spent in awkward posture as a discrete state sensor and it can be implemented in the field. However, results showed that the monitoring system in its current configuration require some future work for it to produce quantitatively precise results that can be used in the fields of biomechanics, robotics, and ergonomics.

Debilitating shoulder pain is prevalent among wheelchair users, however the causes remain unknown. Shoulder pain is reported to be greater among those who began wheeling after skeletal maturity (adulthood-onset, AO) than among those who began wheeling prior to skeletal maturity (childhood-onset, CO). It is unclear whether functional load-bearing from manual wheelchair use affects glenohumeral bone and cartilage morphology. Bone is known to adapt to loading, however the literature is conflicting regarding cartilage’s capacity to adapt to loading. We performed a pilot study to quantify bone and cartilage morphology at the glenohumeral joint of manual wheelchair users (nCO=3, nAO=5) and age- and gender-matched able-bodied controls (nC=8). Bone morphology (volumetric bone mineral density (vBMD) and normalized cross-sectional area (nCSA)) was evaluated using quantitative computed tomography. Bone density distribution was assessed across the glenoid and, for the first time, across the humeral head using a novel quantitative CT-Osteoabsorptiometry method. Cartilage morphology (thickness, volume, and surface area) was evaluated using quantitative magnetic resonance imaging, in the first assessment at 3T MRI. This novel combination of methods provides complementary quantitative data of glenohumeral bone and cartilage morphology. Compared to the AO, the CO in our study had significantly higher (p<0.05) glenoid subchondral nCSA, non-significantly lower glenoid subchondral vBMD, and non-significantly higher humeral head and glenoid trabecular vBMD. A reasonable cross-sectional study (n=22) would likely show higher humeral head and glenoid trabecular vBMD and glenoid subchondral nCSA in CO subjects but would not find differences in nCSA of humeral head total, trabecular, and cortical bone, or glenoid trabecular bone. Surprisingly, vBMD was (non-significantly) lower in the wheelchair users than in the able-bodied controls, however activity levels varied considerably. Significant correlations were found between humeral head and glenoid trabecular vBMD (r=0.94), and between humeral head trabecular vBMD and physical activity scores (r=0.84). Given the small effect sizes and the large variance in humeral head and glenoid cartilage thickness, volume, and surface area, it is not likely that further study of these parameters would provide insight into wheelchair users’ shoulder pain. Gaining a better understanding of how glenohumeral bone and cartilage respond to wheelchair use would allow for rehabilitation programs and wheelchair-design to be tailored to childhood-onset and adulthood-onset wheelchair users.