The influence of whole-body vibration and axial rotation on musculoskeletal discomfort of the neck and trunk

Elements of an individuals occupational exposure, such as their posture can affect their comfort during work, and also their long term musculoskeletal health. Knowledge as to the extent of the influence of particular aspects of the exposures can help in providing guidance on risk evaluation, and direct future technical design focus. In many situations the exposures interact, and even if the effects of individual exposures are understood, the interactions are often less so. This is certainly the case with off-road driving exposures. Specific investigations have focussed on the effects of vibration exposure, resulting in the development of international standards and guidelines on measurement and evaluation of exposure. Consideration of the posture of the operator can be accomplished through postural assessment tools, although none of the currently available methods are developed specifically for use within a vehicle environment. The issues of both the posture of the operator and the seated vibration exposure are particularly apparent in off-road agricultural driving environments, where the driving task dictates that operator is often required to maintain specific postures whilst also exposed to whole-body vibration. In agriculture, many of the tasks require the operator to maintain axially rotated postures to complete the task effectively. The analysis of the combined effects of the axial rotation of the operator and the whole-body vibration exposure has been limited to a few studies within the literature, and is currently poorly understood. The overall aim of the thesis was to assess the influence of axial rotation and whole-body vibration on the musculoskeletal discomfort of the neck and trunk, in order that the true extent of the exposure risk may be evaluated. A field study was conducted to determine the common characteristics of some typical exposures, to provide a basis for the laboratory studies. A survey of expert opinion was conducted, examining the knowledge and experience of experts in assessing the relative influence of axial rotation and whole-body vibration on operators musculoskeletal health. The main investigations of the thesis are focussed in the laboratory, where the objective and subjective effects of axial rotation (static and dynamic) and whole-body vibration were investigated. Objective measures included the investigation of muscular fatigue in response to exposures. The tasks investigated in the field study indicated that the exposures often exceed the EU Physical Agents Exposure Limit Value, and that the axial rotation is a large component of the postures required. The survey of expert opinion concluded that combined exposure to axial rotation and whole-body vibration would increase the risks of lower back pain, and that acknowledgement of combined exposures should be included when assessing for risk. The results of the laboratory studies indicated that the greatest discomfort was present when subjects were exposed to axial rotation in the neck and shoulders. Out of the 8 muscles investigated, at most 6 of the 8 indicated fatigue during an experimental exposure. The muscle group which was affected most by the exposures was the m. trapezius pars decendens. Findings demonstrated that when subjects were exposed to axial rotation and whole-body vibration they indicated discomfort and their muscles fatigued. However, there was poor correlation between the sites of discomfort and the location of muscular fatigue. The discomfort findings suggest that there is an increased risk of discomfort from experiencing axial rotation together with whole-body vibration. Investigations of muscular fatigue do not substantiate this finding

The Safer Delivery of Surgical Services Program (S3): Explaining Its Differential Effectiveness and Exploring Implications for Improving Quality in Complex Systems

Objective: To analyze the challenges encountered during surgical quality improvement interventions, and explain the relative success of different intervention strategies. Summary Background Data: Understanding why and how interventions work is vital for developing improvement science. The S3 Program of studies tested whether combining interventions addressing culture and system was more likely to result in improvement than either approach alone. Quantitative results supported this theory. This qualitative study investigates why this happened, what aspects of the interventions and their implementation most affected improvement, and the implications for similar programs. Methods: Semistructured interviews were conducted with hospital staff (23) and research team members (11) involved in S3 studies. Analysis was based on the constant comparative method, with coding conducted concurrently with data collection. Themes were identified and developed in relation to the program theory behind S3. Results: The superior performance of combined intervention over single intervention arms appeared related to greater awareness and ability to act, supporting the S3 hypothesis. However, we also noted unforeseen differences in implementation that seemed to amplify this difference. The greater ambition and more sophisticated approach in combined intervention arms resulted in requests for more intensive expert support, which seemed crucial in their success. The contextual challenges encountered have potential implications for the replicability and sustainability of the approach. Conclusions: Our findings support the S3 hypothesis, triangulating with quantitative results and providing an explanatory account of the causal relationship between interventions and outcomes. They also highlight the importance of implementation strategies, and of factors outside the control of program designers