Thesis (MScPhysio (Physiotherapy))--University of Stellenbosch, 2007. / INTRODUCTION Computer use has been identified as a risk factor for the development of musculoskeletal dysfunction among children and adolescents internationally. Computer exposure has increased in the Western Cape since 2002, with the inception of a project to install computer laboratories in all schools in the province. As musculoskeletal dysfunction experienced during adolescence is predictive of musculoskeletal disorders in adulthood, it is essential to identify all risk and/or associative factors. METHODOLOGY A descriptive study was conducted with the aim to investigate whether the musculoskeletal dysfunction of high school learners in the Cape Metropolitan region was related to their computer use. This study was conducted in two phases. Phase 1 of the study entailed the completion of a new questionnaire, the Computer Usage Questionnaire, by grade 10-12 learners. The learner sample was divided in a computer and a non-computer group depending on their exposure to the school computer. Phase 2 of the study involved the assessment of the ergonomic design of the computer laboratories at randomly selected high schools within the Cape Metropolitan region. RESULTS A total of 1073 learners (65% girls & 35% boys), aged 14-18 years, completed the CUQ in phase 1 of the study. The results indicated that learners in the computer group had greater weekly exposure to computers than the non-computer group. The prevalence of musculoskeletal dysfunction among this learner sample was 74%. The most common body areas of dysfunction were the head, low back and neck. The female gender, playing sport and using the school computer for more than three years were associated with musculoskeletal dysfunction. Weekly computer use of more than seven hours was predictive of general musculoskeletal dysfunction, low back pain and neck pain. Twenty nine computer laboratories within 16 selected high schools were assessed by means of the Computer Workstation Design Assessment (CWDA). Out of a total score of 40, the computer laboratories obtained average scores of less than 45%, indicating compliance with less than half of the standard ergonomic requirements. The average scores for the workspace environment was less than 40%. The design of the desk, chair and computer screen had the poorest compliance to ergonomic guidelines. DISCUSSION AND CONCLUSION The prevalence of musculoskeletal dysfunction among this sample was higher than among other similar samples on the same study topic. The higher prevalence may be attributed to the poor ergonomic design of the computer laboratories in the Cape Metropolitan region. Learners’ reduced participation in activities such as sport and working on a computer due to their musculoskeletal dysfunction, may impact on their choice of a future career. The tendency of learners not to seek medical advice for their musculoskeletal dysfunction may predispose the development of chronic musculoskeletal disorders. Education of related parties on safe computing habits as well as advice on the ergonomic design of computer laboratories is recommended to prevent the progression of adolescent musculoskeletal dysfunction into chronic disorders in adulthood.

Thesis (PhD)--Stellenbosch University, 2012. / Includes bibliography / ENGLISH ABSTRACT: Introduction: The increased prevalence of adolescent upper quadrant musculoskeletal pain (UQMP) is becoming a great concern to health professionals. The risk factors associated with adolescent UQMP are complex and multifactorial, including, among others sitting as a physical risk factor. However, no evidence exists to support sitting postural angles as a potential predictive factor for adolescent UQMP in computing high school students. Thus, the current project aimed to describe the three-dimensional (3D) sitting postural angles of computing South African high school students in a real-life setting, using a well-tested and documented posture measurement instrument. Methodology: This research project is comprised of seven related studies. Part I of the dissertation presents a systematic review describing the reliability and validity testing of posture measurement instruments. This is followed by three primary correlation and repeated measures observational studies aimed at ascertaining the reliability and validity of a newly developed 3D Posture Analysis Tool (3D-PAT) in the measurement of nine sitting postural angles of computing high school students. Part II of the dissertation presents a systematic review, that evaluates the latest published research evidence of whether sitting is related to UQMP, and, if so, to identify the elements of sitting that significantly contribute to UQMP. This review is followed by a description of a cohort study, with a prospective period of one year. The 3D-PAT was implemented in a clinical research setting in order to measure the 3D sitting posture of a cohort of asymptomatic computing high school students and in order to assess the outcome, seated-related UQMP, prospectively. The prospective study design enabled the research project to contribute to an understanding of any causative relationship between the exposure (sitting postural angles) and the outcome (seated-related UQMP) in a subgroup of adolescents (computer users). Results: After the first phase of psychometric testing of the 3D-PAT using high school students, the findings indicated that the instrument required modifications prior to further psychometric testing. The second phase of testing revealed that the 3D-PAT compared very well with the reference standard for measurement of the X-, Y- and Z-coordinates of the reflective markers on a mannequin. The findings from the phase three study, again using high school students, indicated that the 3D-PAT compared very well with the reference standard and justified its use for the measurement of six sitting postural angles of the upper quadrant in computing high school students. For the cohort study, a 60% response rate for participation was achieved at baseline, with 98% of the students participating at six-month and 80% at one-year follow up. Of the students, 33.5% complained of seated-related UQMP during the follow-up period. Exposure to increased head flexion (>80°) (ρ=0.0001) and the combination of increased head flexion and decreased cranio-cervical angles (ρ=0.007) were significant predictors of seated-related UQMP for those computing high school students complaining of pain greater than the 90th percentile for such. Conclusion: The project described in the current dissertation is the first research project to assess sitting postural angles in asymptomatic high school students, while they worked on desktop computers in a school computer classroom and to assess UQMP prospectively. The research project reports a causal relationship between increased head flexion and seated-related UQMP as increased head flexion was found to be a predictor of seated-related UQMP developing within six to 12 months for computing high school students with a pain score equal or greater than the 90th percentile for pain. The research project emphasises that further research is warranted to investigate the causal pathway between sitting posture and adolescents’ UQMP. / AFRIKAANSE OPSOMMING: Inleiding: Die stygende voorkoms van boonste-kwadrant muskuloskeletale-pyn (BKMP) onder adolessente is besig om ’n groot bron van kommer vir professionele gesondheidswerkers te word. Die risiko-faktore waarmee adolessente BKMP gepaard gaan, is kompleks en multifaktories. Dit sluit onder andere sit as ’n fisiese risiko-faktor in. Daar is egter nog geen bewyse om sittende posturale hoeke as potensiële voorspeller van adolessente BKMP te ondersteun nie. Dus beoog hierdie projek om die drie-dimensionele (3D) sittende posturale hoeke van Suid-Afrikaanse hoërskoolleerders wat ook rekenaargebruikers is, in ’n werklike omgewing te beskryf, deur gebruik te maak van ’n instrument wat postuur meet en wat goed getoets en gedokumenteerd is. Metodiek: Hierdie navorsingsprojek is saamgestel uit sewe studies. Gedeelte I van die proefskrif bied ’n sistematiese oorsig van betroubaarheids- en geldigheidstoetsing van instrumente wat postuur meet. Dit word gevolg deur drie primêre korrelasie studies en studies vir die waarneming van herhaalde meting wat die betroubaarheid en geldigheid van n nuut-ontwikkelde 3D instrument vir posturale analise (3D-PAT) bepaal, wanneer nege sittende posturale hoeke van hoërskoolleerders wat rekenaars gebruik, gemeet word. Gedeelte II van die proefskrif bied ’n sistematiese oorsig van die jongste gepubliseerde navorsing om te evalueer of daar bewyse is dat sit verband hou met BKMP, en, indien wel, om die elemente van sit wat betekenisvol bydra tot BKMP, te identifiseer. Die sistematiese oorsig word deur ’n beskrywing van ‘n jaarlange kohortstudie gevolg. Die 3D-PAT is gebruik in ’n kliniese-navorsingsraamwerk om die 3D-sitpostuur van ’n kohort simptoomvrye hoërskoolleerders wat rekenaargebruikers is, te meet en sitverwante BKMP as uitkoms in die vooruitsig te stel. Die studie ontwerp het dit vir die navorsingsprojek moontlik gemaak om ’n insiggewende bydrae te lewer tot begrip vir enige oorsaaklikheidsverwantskap tussen die blootstelling (sittende posturale hoeke) en die uitkoms (sitverwante BKMP) in ’n subgroup van adolessente (rekenaargebruikers). Resultate: Na afloop van die eerste psigometriese toesting van die 3D-PAT, waarin hoërskoolleerders gebruik is, het bevindings daarop gedui dat die instrument verander moet word voordat toetsing kan voortgaan. Die tweede fase van toetsing het getoon dat die 3D-PAT baie goed vergelyk met die verwysingstandaard vir die meet van die X-, Y- en Z-koördinate van die reflektiewe merkers op ’n mannekyn. Die bevindings van die derde fase van die studie, waartydens hoërskoolleerders weer gebruik is, het aangedui dat die 3D-PAT baie goed vergelyk met die verwysingstandaard. Dit het die gebruik van die instrument om ses sittende posturale hoeke van die boonste kwadrant van hoërskoolleerders wat rekenaars gebruik te meet, bevestig. Die kohortstudie het ’n 60%-reaksiesyfer vir deelname behaal tydens die basislynmetings, waarvan 98% leerders deelgeneem het aan die sesmaande-opvolgmetings en 80% aan die eenjaaropvolgmetings. ’n Totaal van 33.5% van die leerders het gekla van sitverwante BKMP gedurende die eenjaar opvolgperiode. Blootstelling aan ’n vergrootte kopfleksie-hoek (>80°) (ρ = 0.0001) en die kombinasie van ’n vergrootte kopfleksie- en verminderde kranio-servikale hoek (ρ = 0.007) was betekenisvolle voorspellers van sitverwante BKMP vir die hoërskoolleerders wat rekenaars gebruik en kla van groter pyn as die 90ste persentiel daarvan. Gevolgtrekking: Hierdie projek is die eerste navorsing wat sittende posturale hoeke van simptoomvrye hoërskoolleerders wat op tafelrekenaars in die skool se rekenaarklaskamer werk, meet en BKMP voorspel. Die navorsingsprojek rapporteer ‘n oorsaaklikheidsverwantskap tussen ‘n vergrootte kopfleksie-hoek en sitverwante BKMP omdat vergrootte kopfleksie ‘n voorspeller is van sitverwante BKMP wat binne ses tot 12 maande by hoërskoolleerders wat rekenaars gebruik, met ‘n pyntelling gelyk of groter as die 90ste persentiel van pyn, ontwikkel. Die navorsingsprojek beklemtoon dat verdere navorsing om die oorsaaklikheidsroete tussen sitpostuur en adolessente BKMP te ondersoek, geregverdig is. / Medical Research Council of South Africa / National Research Fund / Division of Research Development and Support of Stellenbosch University

Indiana University-Purdue University Indianapolis (IUPUI) / Aromatase inhibitors (AIs) are the current standard of care for the treatment of hormone receptor positive breast cancer in postmenopausal women. Nearly one-half of patients receiving AI therapy develop musculoskeletal toxicity that is characterized by joint and/or muscle pain and approximately one-fourth of patients discontinue their therapy as a result of musculoskeletal pain. Since there are no effective strategies for prevention or treatment, insight into the mechanisms of AI-induced pain is critical to improve treatment. However, there are few studies of AI effects in animal models of nociception. To determine whether AIs produce hypersensitivity in animal models of pain, I examined the effects of AI administration on mechanical, thermal, and chemical sensitivity in rats. The results demonstrate that (1) repeated injection of 5 mg/kg letrozole in male rats produces mechanical, but not thermal, hypersensitivity that extinguishes when drug dosing is stopped; (2) administering a single dose of 1 or 5 mg/kg letrozole in ovariectomized (OVX) rats also induces mechanical hypersensitivity, without altering thermal sensitivity and (3) a single dose of 5 mg/kg letrozole or daily dosing of letrozole or exemestane in male rats augments flinching behavior induced by intraplantar ATP injection. To determine whether the effects of AIs on nociceptive behaviors are mediated by activation or sensitization of peptidergic sensory neurons, I determined whether letrozole exposure alters release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons and from sensory nerve endings in rat spinal cord slices. No changes in basal, capsaicin-evoked or high extracellular potassium-evoked CGRP release were observed in sensory neuronal cultures acutely or chronically exposed to letrozole. Furthermore, letrozole exposure did not alter the ability of ATP to augment CGRP release from sensory neurons in culture. Finally, chronic letrozole treatment did not augment neuropeptide release from spinal cord slices. Taken together, these results do not support altered release of this neuropeptide into the spinal cord as mediator of letrozole-induced mechanical hypersensitivity and suggest the involvement of other mechanisms. Results from this dissertation provide a new experimental model for AI-induced hypersensitivity that could be beneficial in delineating mechanisms mediating pain during AI therapy.