The Poisson’s ratio of the nucleus pulposus is strain dependent

Part of the Soft Tissue Biomechanics Session this presentation is to characterise the true Poisson’s ratio of the nucleus pulposus is strain dependen

Poisson’s ratio of nucleus pulposus tissue : comparison of experimental results with a biphasic poroviscoelastic finite element model

This presentation looks at Poisson’s ratio of nucleus pulposus tissue, comparison of experimental results with a biphasic poroviscoelastic finite element mode

Effect of indenter velocity on the stiffness of articular cartilage

This presentation looks at the effect of indenter velocity on the stiffness of articular cartilag

Gait and trunk movement patterns of low back pain patients and healthy volunteers during supported and conventional treadmill walking

This study investigates the effects of body weight supported and conventional treadmill walking on gait and trunk motion of asymptomatic people and low back pain (LBP) patients. Forty participants, 19 LBP patients and 21 asymptomatic individuals were recruited. Significant differences were found in gait and trunk kinematic parameters between the two walking conditions, in both participant groups

Haversian canal structures can be associated with size effects in cortical bone

Prediction of periprosthetic failure may be improved by an improved model of bone elasticity which includes microstructural information. Micropolar theory facilitates such information to be included in a continuum model. We assessed the extent of bone’s micropolar behaviour in bending both numerically and experimentally. The numerical model was consistent with micropolar behaviour, and experimental results exhibited size effects that may have been confounded by surface roughness effects, as predicted numerically

Modelling micropolar behaviour in cortical bone

This presentation looks at modelling micropolar behaviour in cortical bon

Non-invasive assessment of lower limb alignment is accurate for pre-operative planning and post-operative follow up

Knee alignment is a fundamental measurement in the assessment, monitoring and surgical management of patients with OA. In spite of extensive research into the consequences of malalignment, there is a lack of data regarding the potential variation between supine and standing (functional) conditions. The purpose of this study was to explore this relationship in asymptomatic, osteoarthritic and prosthetic knees. Our hypothesis was that the change in alignment of these three groups would be different. Infrared position capture was used to assess knee alignment for 30 asymptomatic controls and 31 patients with OA, before and after TKA. Coronal and sagittal mechanical femorotibial (MFT) angles in extension (negative values varus/hyperextension) were measured supine and in bi-pedal stance and changes analysed using a paired t-test. To quantify this change in 3D, vector plots of ankle centre displacement relative to the knee centre were produced. Alignment in both planes changed significantly from supine to standing for all three groups, most frequently towards relative varus and extension. In the coronal plane, the mean±SD(°) of the supine/standing MFT angles was 0.1±2.5/−1.1±3.7 for asymptomatic (p=0.001), −2.5±5.7/−3.6±6.0 for osteoarthritic (p=0.009) and −0.7±1.4/ −2.5±2.0 for prosthetic knees (p<0.001). In the sagittal plane, the mean±SD(°) of the supine/standing MFT angles was −1.7±3.3/−5.5±4.9 for asymptomatic (p<0.001), 7.7±7.1/1.8±7.7 for osteoarthritic (p<0.001) and 6.8±5.1/1.4±7.6 for prosthetic knees (p<0.001). The vector plots showed that the trend of relative varus and extension in stance was similar in overall magnitude and direction between the groups. The similarities between each group did not support our hypothesis. The consistent kinematic pattern for different knee types suggests that soft tissue restraints rather than underlying joint deformity may be more influential in dynamic control of alignment from lying to standing. This potential change should be considered when positioning TKA components on supine limbs as post-operative functional alignment may be different

Assessment of seating forces imparted through daily activity by children with special needs

Extensor spasms regularly occur in spastic Cerebral Palsy (CP) children making their bodies unbalanced and causing wheelchair instability. Furthermore the child may be uncomfortable as a result of the high contact forces potentially causing pain and injury, which will impair their functional ability. Dynamic seating systems have been designed to absorb the energy associated with these spasms. For people with physical disabilities, especially patients who have strong extensor spasticity, the dynamic design prevents pressure ulcers and injury from impact. However, the quantitative effectiveness and impact of using dynamic components has yet to be established. Therefore our objective is to compare the imparted forces on equivalent rigid and dynamic seating systems, to understand the interactions between force, wheelchair compliance and physical activity throughout a four hour session of non-laboratory based daily living

Brief 7: Building an International Court for the Environment: A Conceptual Framework

This issue brief considers the role and nature of existing and potential international dispute resolution fora in relation to international environmental law. It addresses impediments at the international level, such as limited access to justice by non-state actors and the lack of technical and scientific capability. As a conceptual paper, it highlights two possible remedial options: an international environmental tribunal and an international environmental court

Controlling the variable of pressure in the production of test footwear impressions

Footwear impression lifting and enhancement techniques may be affected by several variables introduced during the production of test footwear impressions, thus limiting the usefulness of enhancement technique comparisons and the results obtained. One such variable is the force applied when the impressed mark is being made. Producing consistent test impressions for research into footwear enhancement techniques would therefore be beneficial. This study was designed to control pressure in the production of test footwear impressions when mimicking a stamping action. Twenty-seven volunteers were asked to stamp on two different surfaces and the average stamping force was recorded. Information from the data obtained was used to design and build a mechanical device which could be calibrated to consistently deliver footwear impressions with the same force onto a receiving surface. Preliminary experiments using this device and different contaminants on the footwear sole have yielded consistent and repeatable impressions. Controlling the variable of pressure for the production of test impressions in this study demonstrated that the differences observed were visual (due to the amount of contaminant transferred and subsequent enhancement) and did not affect the replication of outer sole characteristics. This paper reports the development of the device and illustrates the quality of the impressions produced