Evaluation of strategies to improve measurement, evaluation, and force requirements of the spine during manual materials handling tasks

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Before researchers can address person-specific causal factors related to back injuries, we must first develop instrumentation, methodologies, and statistical analysis techniques. We are especially interested in developing strategies to measure predisposing areas of weakness before a back injury or between acute episodes of a chronic back injury. First, lifting technique remains elusive as a predisposing factor to low back injury. We plan to examine the impact of load and gender on lifting technique and inter-joint coordination using Principal Components Analysis (PCA) and Functional Data Analysis (FDA). Then, we will examine workers in an industrial plant who lift 15 kg boxes approximately 1000 times per day to determine if changes have occurred in technique due to fatigue and non-acute low back pain. We hypothesize that gender and load will affect both lifting technique and inter-joint coordination and that both fatigue and previous low back pain will also be evident though PCA and FDA strategies. Second, we wish to establish a reliable dynamic spinal stability protocol in terms of: i) movement patterns and ii) muscular activity, and then iii) examine healthy individuals' responses to the same variables during a perturbation test. These data will help us establish a normative database as a comparator for those who have spinal instability. Together, these studies will provide a better understanding of movement patterns and changes in movement patterns that may contribute to low back disability. Our last objective is to develop a cumulative loading measurement system to determine the effects of wearing an on-body personal lift assistive device (PLAD) over extended periods of time. This objective requires the construction and validation of two hardware components that can be integrated into the PLAD, namely: a load-in-hands microprocessor and a PLAD spring measurement tool, which can be used to calculate the forces and moments at the L4/L5 disc. We have proven PLAD to be effective for short term use and it is currently undergoing user-acceptability trials. By developing a valid measurement system, we will be able to determine if PLAD can reduce the incidence of onset or recurrence of back injuries in manual handling tasks.