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Published Article / The objective of this study was to examine the relationship between external markers typically used in external motion capturing devices and the true vertebral kinematics in the cervical spine. Twenty one healthy subjects were subjected to low dosage X-rays in five different positions, while radio opaque markers were attached to the skin at each vertebral level. Distance and angle parameters were constructed for vertebral prediction from skin surface markers. The causes of variation in these parameters were identified by investigating the correlations of these parameters with anthropometrical variables. Strong correlations of the parameters were observed in flexion, but in extension, especially full extension, the correlations were poor to insignificant. In neutral, half flexion, and full flexion it is possible to predict the vertebral position from surface markers by using the parameters and anthropometrical variables. In half extension this prediction is less accurate and in full extension alternative methods should be investigated for external motion capturing.

During pregnancy the female body must accommodate the enlarging gravid uterus and increased mass. Therefore the maternal musculoskeletal system is required to adapt in both morphology and functional workload. After childbirth there is a rapid change in both mass and dimensions, requiring further adaptations. The objectives of the study were to investigate seated and standing upper body posture, the kinematics of seated and standing trunk motion, and the three dimensional kinematics and kinetics during rising to stand from a chair, as pregnancy progressed and in the early post-birth period. Nine maternal subjects (aged 28 to 40 years) were tested at less than 16 weeks, 24 weeks, 30 weeks, 38 weeks gestation and at 8 weeks postbirth. The subjects, fitted with 37 retroreflective markers, were filmed during upright sitting, quiet standing, and four trials each of maximum seated and standing trunk forward flexion, side to side flexion and during maximum seated axial rotation. Three trials each of constrained and free rising to stand from a height adjustable stool and with each foot placed on a forceplate were also recorded. An eight-camera motion analysis system was used to record movements of the body segments and synchronised force plate variables in three dimensions. Motion of the ankle, knee and hip joints, pelvic, thoracic and head segments and the thoracolumbar and cervicothoracic spines and shoulder joints were investigated. Twelve nulliparous subjects (aged 21 to 35 years) were used as controls to provide standard descriptive data and to investigate the consistency of the selected biomechanical variables with repeated testing. A repeated measures ANOVA was used to investigate the possibility of linear and quadratic trends showing systematic changes within the maternal group, over the four test sessions during pregnancy for each variable. Two tailed Student t-tests were used to compare the maternal postbirth variable results with the control group. There was no significant effect of pregnancy on the upper body posture during upright sitting and quiet standing. Postbirth, the pelvic segment had a smaller anterior orientation and the thoracolumbar spine was less extended, indicating a flatter spinal curve. The maternal subjects were similar to the control subjects in early pregnancy and postbirth for trunk segment motions during seated and standing forward flexion and side to side flexion and seated axial rotation. Strategies, such as increasing the width of the base of support and reducing obstruction to movements from other body parts, were used in late pregnancy in attempts to minimise the effects of increased trunk mass and circumference. For seated and standing side to side flexion, the strategies were successful and no significant decreases in range of motion were seen. For seated and standing forward flexion and seated axial rotation, motion of the thoracic segment and the thoracolumbar spine were significantly reduced, although movement of the pelvis was less affected. In early pregnancy and postbirth the kinematics and kinetics of the lower limbs and upper body segment kinematics during constrained and free rising were generally similar to the control subjects. As pregnancy progressed there were increases in mass and dimensions of body segments. The effect of increased mass was seen in increased ground reaction forces and sagittal plane lower limb joint external moments. An increased base of support width was found in association with an increased lateral ground reaction force and ankle inversion moment from each foot, which would move the body centre of mass medially. There was little change in the three dimensional kinematics of the thoracolumbar and cervicothoracic spine, although the contribution of the upper body segments differed for each rise condition. There were also few significant changes in the displacement of the ankle, knee and hip, and the angular velocity of ankle and knee joints. The maternal subjects were thus able to flex the upper body forward, raise the body and maintain stability as pregnancy progressed, regardless of whether the rise to stand was performed in a natural manner or under constrained conditions. The overall results show that, contrary to expectations as pregnancy progressed, maternal subjects minimised propulsion rather than increasing it to overcome the increased mass and possibly limited trunk flexion. A fear of postural instability may have made the subjects more cautious and as they were able to adequately flex the trunk forward, propulsion was minimised in favour of maintaining upright terminal balance.

During pregnancy the female body must accommodate the enlarging gravid uterus and increased mass. Therefore the maternal musculoskeletal system is required to adapt in both morphology and functional workload. After childbirth there is a rapid change in both mass and dimensions, requiring further adaptations. The objectives of the study were to investigate seated and standing upper body posture, the kinematics of seated and standing trunk motion, and the three dimensional kinematics and kinetics during rising to stand from a chair, as pregnancy progressed and in the early post-birth period. Nine maternal subjects (aged 28 to 40 years) were tested at less than 16 weeks, 24 weeks, 30 weeks, 38 weeks gestation and at 8 weeks postbirth. The subjects, fitted with 37 retroreflective markers, were filmed during upright sitting, quiet standing, and four trials each of maximum seated and standing trunk forward flexion, side to side flexion and during maximum seated axial rotation. Three trials each of constrained and free rising to stand from a height adjustable stool and with each foot placed on a forceplate were also recorded. An eight-camera motion analysis system was used to record movements of the body segments and synchronised force plate variables in three dimensions. Motion of the ankle, knee and hip joints, pelvic, thoracic and head segments and the thoracolumbar and cervicothoracic spines and shoulder joints were investigated. Twelve nulliparous subjects (aged 21 to 35 years) were used as controls to provide standard descriptive data and to investigate the consistency of the selected biomechanical variables with repeated testing. A repeated measures ANOVA was used to investigate the possibility of linear and quadratic trends showing systematic changes within the maternal group, over the four test sessions during pregnancy for each variable. Two tailed Student t-tests were used to compare the maternal postbirth variable results with the control group. There was no significant effect of pregnancy on the upper body posture during upright sitting and quiet standing. Postbirth, the pelvic segment had a smaller anterior orientation and the thoracolumbar spine was less extended, indicating a flatter spinal curve. The maternal subjects were similar to the control subjects in early pregnancy and postbirth for trunk segment motions during seated and standing forward flexion and side to side flexion and seated axial rotation. Strategies, such as increasing the width of the base of support and reducing obstruction to movements from other body parts, were used in late pregnancy in attempts to minimise the effects of increased trunk mass and circumference. For seated and standing side to side flexion, the strategies were successful and no significant decreases in range of motion were seen. For seated and standing forward flexion and seated axial rotation, motion of the thoracic segment and the thoracolumbar spine were significantly reduced, although movement of the pelvis was less affected. In early pregnancy and postbirth the kinematics and kinetics of the lower limbs and upper body segment kinematics during constrained and free rising were generally similar to the control subjects. As pregnancy progressed there were increases in mass and dimensions of body segments. The effect of increased mass was seen in increased ground reaction forces and sagittal plane lower limb joint external moments. An increased base of support width was found in association with an increased lateral ground reaction force and ankle inversion moment from each foot, which would move the body centre of mass medially. There was little change in the three dimensional kinematics of the thoracolumbar and cervicothoracic spine, although the contribution of the upper body segments differed for each rise condition. There were also few significant changes in the displacement of the ankle, knee and hip, and the angular velocity of ankle and knee joints. The maternal subjects were thus able to flex the upper body forward, raise the body and maintain stability as pregnancy progressed, regardless of whether the rise to stand was performed in a natural manner or under constrained conditions. The overall results show that, contrary to expectations as pregnancy progressed, maternal subjects minimised propulsion rather than increasing it to overcome the increased mass and possibly limited trunk flexion. A fear of postural instability may have made the subjects more cautious and as they were able to adequately flex the trunk forward, propulsion was minimised in favour of maintaining upright terminal balance.

The South African Professional Board for Emergency Care prehospital Clinical Practice Guideline (CPG) recommends that emergency medical services (EMS) make use of the National Emergency X Radiography Utilization Study (NEXUS) rule and Canadian C-spine Rule (CCSR) when managing traumatic spinal injury. However, the safety and effectiveness of prehospital clinical spinal clearance or spinal motion restriction (SMR) decision support tools within poorly resourced settings are unclear. We conducted a scoping review on clinical spinal clearance and selective SMR decision support tools which aimed at identifying possible barriers to their implementation, safety, and effectiveness when used by EMS personnel. Studies were included if they described the use of clinical spinal clearance or SMR decision tools in first line management of blunt trauma patients by medical practitioners in the Emergency Department (ED) or by EMS personnel working in a prehospital setting. After screening, 42 documents fulfilled the inclusion criteria. Several selective SMR decision support tools have been implemented in the prehospital setting, the most common of which were those based on the NEXUS and the CCSR tools. Only one study evaluated the safety and efficacy of the NEXUS rule when used by EMS personnel. The limited prehospital literature available investigating either the NEXUS rule or CCSR therefore makes it difficult to determine its appropriateness for adoption and implementation by EMS personnel in other prehospital settings such as that of South Africa. Furthermore, commonly found prehospital NEXUS-based decision tools presented with unique challenges related to the subjective nature of some of the individual components of the decision tool. This leaves the decision tool open to interpretation by examiners and is especially relevant in settings, such as South Africa, where there are many different levels in scope of practices. This increases the risk of the patient being either under-triaged or over-triaged. More studies are therefore needed to definitively assess for the safety, efficacy and effectiveness of clinical spine clearance within the prehospital setting. It is believed that a selective SMR decision tool which has more specific instructions for the prehospital practitioner may be able to accommodate such challenges and is an area which needs further investigation.

Spontaneous vertebral fractures are a large and growing health care problem. Biomechanical factors, specifically, abnormal posture or gait‐related spinal motion may interact with age‐weakened bone to induce altered spinal biomechanics that in turn increase the likelihood of vertebral body fracture. This research takes steps towards the goal of reducing the number of vertebral fractures in two phases: 1) Validation of a noninvasive spinal motion measurement system in cadaver torsos and 2) Application of the measurement system in human subjects. The cadaver study compared vertebral motion at 4 levels (T7,T12,L3,L5) as measured by adhesive skin markers versus motion measured by bone pins implanted into the vertebrae. Cadaver torsos were tested in lateral‐bending, flexion and axialrotation. Mean differences in vertebral body angular motion between skin markers and bone pin markers were <0.5° around the anterior‐posterior and medial‐lateral axes and <0.9° around the superior‐inferior axis. This measurement method was able to accurately quantify vertebral body motion in cadaver torsos thus allowing for application to human subject testing. X‐rays and 3D motion capture were employed to quantify spinal posture and motion parameters during gait in 12 older and 12 younger normal, females. Vertebral motion around 3 axes was measured at 4 levels (T7,T10,T12,L2) using noninvasive retroreflective markers during treadmill gait at 3 speeds (0.5,0.7,0.9m/s). The average angular motion of all gait cycles at each speed was determined for each level. The triplanar ranges of motion and variability of motion were compared as a function of age. Older subjects had 31.7% larger frontal Cobb angles and up to 30.9% and 33.5% smaller ranges of spinal motion in the frontal and sagittal planes. Variability of motion in the sagittal plane was up to 42.9% less in older subjects. Decreased ranges of motion and variability of spinal motion observed in older subjects may imply that vertebral loading in these subjects may not be as uniformly distributed across the vertebrae as in younger subjects. Greater stresses may result from the abnormal motion, thus increasing fracture risk. Confirmation of this hypothesis requires a longitudinal study, but if verified, may lead to the development of inexpensive countermeasures to prevent fractures.

Objective - To investigate the effects of injected protease solution on the mechanical advancement of disc degeneration, and to establish test protocol for future pre-clinical validation of spinal arthroplasty devices. The hypothesis that injection of a protease into a cadaveric lumbar disc will mimic advanced degeneration mechanics was the subject of this study. Summary of Background Information - Spinal disc degeneration is a universal condition that progresses in adults due to aging, disease, or injury. Stages of disc degeneration have been categorized in cadaver specimens, with each degeneration level exhibiting characteristic changes in flexibility parameters. Spinal disc tissue can be compromised through introduction of proteolytic enzymes into the collagenous fibers of the annulus fibrosus. Methods - 18 motion segments from 8 human lumbar spines were subjected to flexibility testing. Each specimen was either injected with 0.600 mL of trypsin solution in the annulus fibrosus, 0.600 mL of phosphate-buffed saline, or a fluid-less needle-stick. Motion testing followed with rotations applied in all three major spinal motions. Test sections were transected mid-disc after testing to characterize initial degeneration severity, and acquired motion data was analyzed to show flexibility traits over time. Results - Trypsin, saline, and control injections all caused changes in motion from pre-injection baselines. Saline injections were slightly more effective at mimicking the mechanics of higher grades of degeneration with more fidelity than trypsin injections. All motion parameters were altered by the study treatments, with hysteresis and neutral zone parameters experiencing changes similar to that seen in natural degeneration with greater fidelity. Lateral Bending motion showed the greatest magnitude response to injections, with Flexion-Extension tests showing the smallest change. Discussion - Unexpectedly, fluid-less control injections caused changes to hysteresis and neutral zone parameters, suggesting an alteration to viscoelastic properties due to simple needle puncture. Fluid injections (Trypsin and Saline) caused an immediate transient post-injection change to biomechanics that dissipated over time, except in Axial Rotation. Saline injections provided the highest fidelity in mimicking the motion of more advanced stages of degeneration.

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<p> This pilot study was performed in order to examine the potential beneficial effects of cervical spinal manipulative therapy on volunteers suffering from post-concussive neck syndrome. The study of concussions and post-concussive neck syndrome is still a relatively new topic in the existing literature. Little research has been done in the area of spinal manipulation and the treatment of volunteers suffering from post-concussive neck syndrome, from a biomechanical standpoint.</p> <p> Forty-one volunteers who were suffering from post-concussive neck syndrome were recruited from McMaster University in Hamilton, Ontario to participate in the study. In order to assess the severity of neck complaints, the severity of their post-concussive symptoms and overall general health, the volunteers completed the Neck Disability Index, the Visual Analog Scale, the Standardized Assessment of Concussion and the Short Form-36 Health Survey. During testing sessions, volunteers were fitted with several light emitting markers placed strategically on the head, mid-back, sacrum and heels of the volunteers' footwear. Each volunteer would then walk on a treadmill for four separate five minute trials, after an initial familiarization period. The 3D position of these markers during gait were recorded by a rear-mounted kinematic data acquisition system (Optotrak 3020). After the initial five minute walk (trial 1), the volunteer was treated with a cervical spinal manipulation, and immediately resumed walking for the second trial on the treadmill. The volunteers performed four walking trials in total.</p> <p> Both manual and automated procedures were used to identify the multiple right-heel treadmill surface contacts during each five minute walk. Objective biomechanical outcome measures used in the study included relative phase measurements between the head and thorax in the transverse plane, the Biomechanical Efficiency Quotient and the Neck-Walk Index.</p> <p> Clinically significant results in relative measurements, post-intervention, were found when certain volunteers were removed (due to slow walking velocity). These differences can be attributed to the intervention of spinal manipulation which caused a significant increase in cervico-thoracic spinal motion, which appeared to decrease again at 35 minutes. This is clinically significant because it poses the theory that initial short-term biomechanical changes in the cervical spine are caused by SMT.</p> <p> Clinically significant results in the Biomechanical Efficiency Quotient were found when specific volunteers were removed. The results however, were in the opposite direction than was previously hypothesized. The reason for the increase in BEQ post-manipulation compared to pre-manipulation could be a result of the familiarization walking period before the initial trial. By allowing volunteers several minutes to get accustomed to walking on the treadmill, a learning effect had taken place, decreasing the variability in their gait in the initial pre-intervention trial. Although BEQ increased in the second and third trials, it decreased again at 35 minutes post-intervention, meaning the walking economy had once again increased.</p> <p> The specific intervention of cervical spinal manipulative therapy was hypothesized to change the variability of head movement disturbances during gait (Neck-Walk Index). No reference in the literature is made in relation to Neck-Walk Index and how it evaluates change in head carriage, post-intervention. This study suggests however, that although results approached significance, cervical manipulative therapy did not change biomechanical head carriage in this volunteer population.</p> <p> With respect to future studies, several recommendations have been made in this thesis which are aimed at increasing the clinical significance of the results. This would be done through the incorporation of more affected volunteers (increase in functional disability due to post-concussive neck syndrome), the incorporation of a more lengthy and specific treatment protocol (to sustain biomechanical and physical changes), and an increased treadmill walking velocity (to assess antiphasic movements more easily).</p> / Thesis / Master of Science (MSc)

The work presented in this thesis has two distinct parts: (i) development of a spinal motion measurement technique and (ii) incorporation of the spinal motion measurement with galvanic vestibular stimulation (GVS) technology, acting as a balance assist device hereafter referred to as a galvanic vestibular stimulation device (GVSD). The developed spinal motion measurement technique fulfills seven desired attributes: accuracy, portability, real-time data capture of dynamic data, non-invasive, small device footprint, clinically useful and of non-prohibitive cost. Applications of the proposed system range from diagnosis of spine injury to postural and balance monitoring, on-field as well as in the lab setting. The system is comprised of three inertial measurement sensors, respectively attached and calibrated to the head, torso and hips, based on the subject’s anatomical planes. Sensor output is transformed into meaningful clinical parameters of rotation, flexion-extension and lateral bending of each body segment with respect to a global reference space, then collected and visualized via an interactive graphical user interface (GUI). The accuracy of the proposed sensing system has been successfully verified with subject trials using a VICON optical motion measurement system. Next, the proposed motion measurement system and technique has been used to record a standing iv subject’s motion response to GVS. The data obtained allows the development of a new GVSD with the attributes of: eligibility for commercial licensing, portability, and capable of safely providing controlled stimulating current to the mastoid bones at varying levels and frequencies. The successful combination of the spinal motion measurement technique and GVSD represents the preliminary stage of a balance prosthesis.