Changes in the Standing Lumbar Spine at Above Bodyweight Loading

Introduction and Objectives: Understanding the mechanical response of the spine and intervertebral disc to various loading situations is vital to predicting its behaviour, to verify computer models of the spine and to gaining insight in to how loading and spinal posture may cause or exacerbate injury. Studies of the lumbar spine and intervertebral disc under compression have typically been carried out in vitro; those which have used in vivo methods have mostly been conducted in the supine position at loading equal to or below static bodyweight. This study measures the lumbar spine response to above bodyweight loading in the standing position at loads equivalent to walking. Methods: Sagittal plane magnetic resonance imaging scans of the spine were taken of nine asymptomatic male subjects (22-32 years of age, 167-195 cm, 66.3-93.2 kg) in the supine and standing positions with a third scan taken in the standing position with additional loading. Additional load was applied by having subjects hold two 6 kg kettlebells, one in each hand, enough to increase loading on the IVD to levels experienced during walking. Disc heights were measured as the average of anterior and posterior distance between adjacent vertebrae in the midsagittal plane. Change in lordosis was measured in two ways; the relative angle between the lumbar spine and pelvis was measured as the posterior angle between L5 and S1 vertebrae whilst change in the upper lumbar spine was measured by the angle between the superior facet of L3 with the vertical plane. Results: Increased axial loading resulted in reduced disc height and lumbar lordosis. Initial disc heights in the supine position for L3/L4, L4/L5 and L5/S1 were found to be 10.7(1.6), 12.0(2.8) and 11.4(1.9) mm respectively (Fig. 1a). These heights were reduced to 10.4(1.9), 11.4(2.1) and 10.8(1.6) mm in the standing position and 10.3(1.4), 11.4(2.0) and 10.4(1.8) mm with additional loading but these changes were not statistically significant (P>0.05). Lumbar angle in supine, standing and with additional loading was found to be 140(9), 145(11) and 145(12) degrees respectively (Fig. 1b) with L3 angled 0.7 (3.5), 4.4 (4.4) and 4.8 (4.2) degrees posteriorly from the horizontal in the three loading positions (Fig. 1c). In all cases disc height change was greater posteriorly as loading increased lumbar lordosis

Experimental Modelling of Viscoelastic Self-Heating in Healthy and Degenerate Bovine Intervertebral Discs

Objectives Low back pain (LBP) is an increasing drain on developed economies due to direct medical costs and lost working days. The majority of medical costs can be attributed to long-term problems resulting from specific physiological conditions. Acute injury and/or chronic degeneration of the intervertebral disc (IVD) has been linked with long term pain with high levels of nerve in-growth in degenerate IVDs. The fact that disc degeneration is a structural failing and not just a pathogenesis of pain may lead to reduced mobility and quality of life (QOL). Degenerate IVDs have elevated levels of heat shock proteins (HSPs) and HSPs elevated temperatures and/or heat shock within the IVD is a potential mechanism for HSP upregulation. Is it possible that high temperatures are a precursor to degeneration? Could activities of daily living (ADL) result in elevated temperatures in the IVD? This study aims to determine if there is a significant generation of heat within the IVD when subjected to cyclic loading at levels and frequencies relevant to ADL and whether this is effected by degeneration. Materials and Methods Bovine coccygeal discs were removed whole from tail sections and half of the discs were injected with a 2mg/ml collagenase solution and incubated at 37°C for 2 hours to simulate moderate degeneration. Discs were then subjected to sinusoidal loading at 2Hz at force levels equivalent to those in the human spine during locomotion. Mechanical data was analysed with MATLAB software to determine the energy dissipated by the discs for each cycle of loading and an idealised thermal model was generated to predict temperature change within the disc. Results Under axial loading equivalent to that in the lumbar spine during walking degenerate discs showed greater average compression than healthy discs (0.108mm and 0.024mm respectively) and therefore substantially lower average stiffness (714N/mm and 3149N/mm). Average heat generation in degenerate IVDs (2.79mW) was lower than that in healthy discs (4.13mW). An idealised 3D model of heat loss from the disc showed no significant increase in disc temperature in either healthy or degenerate disc condition. Conclusions Heat generated due to dissipated energy from axial loading of intervertebral discs at loading equivalent to that in the lumbar spine when walking is not enough to induce significant temperature increases within the disc. If elevated levels of HSPs within degenerate discs are the result of high temperatures, heat generated within the disc due to activities of daily living such as walking are not the cause

Material Behaviours of Healthy, Degenerate and Hydrogel Injected Bovine Intervertebral Discs

Objectives Low back pain (LBP) is an increasing drain on developed economies due to direct medical costs and lost working days. The majority of medical costs can be attributed to long-term problems resulting from specific physiological conditions. Acute injury and/or chronic degeneration of the intervertebral disc (IVD) has been linked with long term pain with high levels of nerve in-growth in degenerate IVDs. The fact that disc degeneration is a structural failing and not just a pathogenesis of pain may lead to reduced mobility and quality of life (QOL). Mesenchymal stem cell (MSC) interventions have been proposed as a treatment for degenerate IVDs but little is known about how the injection of a hydrogel matrix required by such interventions affects the material properties of the intervertebral disc and what effects this might have on disc health. This study aims to determine the difference in material behaviours of healthy, degenerate and hydrogel injected IVDs subjected to cyclic loading simulating activities of daily living (ADL). Materials and Methods Bovine coccygeal discs were dissected whole from tail sections and split in to three equal test groups; healthy, degenerate and hydrogel injected. Degenerate and hydrogel injected groups were injected with a 2 mg/ml collagenase solution and incubated at 37°C for 2 hours to simulate moderate degeneration, the hydrogel injected group then received a hydrogel injection. All discs were then subjected to sinusoidal loading at 2Hz at force levels equivalent to those in the human spine during walking and mechanical data analysed to determine respective material behaviours of each group. Results Under axial loading simulating walking in the lumbar spine compression (absolute and relative strain) and stiffness of discs varied across all three test groups. Conclusions Cyclic loading simulating activities of daily living was found to result in different material behaviours in bovine intervertebral discs that were moderately degenerated and/or injected with hydrogel relative to healthy discs

Assessing participatory practices in community-based natural resource management: experiences in community engagement from southern Africa

The emphasis on participatory environmental management within international development has started to overcome critiques of traditional exclusionary environmental policy, aligning with shifts towards decentralisation and community empowerment. However, questions are raised regarding the extent to which participation in project design and implementation is meaningful and really engages communities in the process. Calls have been made for further local-level (project and community-scale) research to identify practices that can increase the likelihood of meaningful community engagement within externally initiated projects. This paper presents data from three community-based natural resource management (CBNRM) project case studies from southern Africa, which promote Joint Forest Management (JFM), tree planting for carbon and conservation agriculture. Data collection was carried out through semi-structured interviews with key stakeholders, community-level meetings, focus groups and interviews. We find that an important first step for a meaningful community engagement process is to define 'community' in an open and participatory manner. Two-way communication at all stages of the community engagement process is shown to be critical, and charismatic leadership based on mutual respect and clarity of roles and responsibilities is vital to improve the likelihood of participants developing understanding of project aims and philosophy. This can lead to successful project outcomes through community ownership of the project goals and empowerment in project implementation. Specific engagement methods are found to be less important than the contextual and environmental factors associated with each project, but consideration should be given to identifying appropriate methods to ensure community representation. Our findings extend current thinking on the evaluation of participation by making explicit links between the community engagement process and project outcomes, and by identifying further criteria that can be considered in process and outcome-based evaluations. We highlight good practices for future CBNRM projects which can be used by project designers and initiators to further the likelihood of successful project outcomes