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Introduction: The Modified Mallampati Tongue Score (MMT) is commonly used in anesthesiology for the pre-anesthetic assessment of the airway in patients. This score roughly estimates the size and position of the tongue relative to the oral cavity, with higher scores associated with difficult intubation and increased incidence of breathing interferences, such as obstructive sleep apnea. The distance from the tongue base to roof of the mouth decreases from MMT-I to MMT-IV. The tongue shape and position impact the airway patency in the hypopharynx, contributing to changes in craniofacial head posture followed by changes in craniofacial morphology. This present study examines the pattern of associations between the Modified Mallampati Tongue Score positions and 1) the postural relationship of the cranium, hyoid bone, cervical column, and tongue 2) size, shape, and position of the craniofacial components, as depicted in a lateral cephalogram. Methods: This retrospective study was performed on 200 subjects (145 female, 55 male) prior to starting orthodontic treatment. MMT was assessed from one photograph of maximum mouth opening and tongue protrusion. Pretreatment cephalograms were analyzed to evaluate craniocervical posture, resting tongue position, hyoid bone position, or sagittal and vertical skeletal relationships. MMT (I-IV) was also compared to basic demographics (age, gender, race/ethnicity). One-way ANOVA, Chi-square test, and correlation analysis were used for statistical analysis. Probability values <0.05 were accepted as significant. Results: A total of 200 patients (72.5% Female, 27.5% Male, 54% African American), with a mean age of 20 (Range 7-73), were included for the study. MMT-III was most prevalent (34%). MMT was not associated with age, gender, or race/ethnicity. Mean cephalometric measurements of hyoid position (p=0.06-0.03), mandibular position (p=0.006), ANB (p=0.009), and SNB (p=0.023, were shown to have significant differences with MMT. MMT positively correlated with the ANB (p=0.001), Wits (p=0.016), vertical position of the hyoid bone to neck (p=0.004) and mandible (p=0.048); and inversely correlated with the SNB (p=0.003) and Pog:Na-Perp (p=0.045). Conclusion: A higher MMT correlates to a Class II skeletal morphology and extended craniofacial posture. Preliminary results suggest high tongue position influences Class II craniofacial morphology, enhancing maxillary prognathic growth and mandibular deficiency. This indicates that MMT can be a potential predictor of craniofacial growth patterns, strengthening the prognosis and long-term stability of orthodontic treatment. / Oral Biology

This diploma thesis is focused on the vestibular system and its influence on postural musculature. The theoretical section contains an overview of modern findings concerning the vestibular system and its impact on other parts of the organism. Besides anatomical and physiological findings, the theoretical section also contains a research section which includes studies on the vestibular system, posture, stretching and their mutual effects. The main focus of the practical section is to prove the influence of the vestibular system on musculature, mainly the extensors and flexors of the lower limbs. Affecting the vestibular system causes lengthening of the ischiocrural muscles and shortening of the hip flexors (musculus rectus femoris). In this study, we tested 39 probands and measured their results after rotational vestibular stimulation. The measurements were taken goniometrically in the hip and knee joints. Dynamic parameters of the spine were also measured, along with Thomayers distance in metric values. The results have been statistically and graphically evaluated. It was proven that the vestibular system has a large statistical impact on the ischiocrural muscles as well as the frontal thigh muscles. An influence of the vestibular system on the paravertebral muscles was however not proven. In the...

INTRODUCTION: While strengthening and aerobic exercise have been shown to decrease chronic knee and hip pain, little is known about the effectiveness of Egoscue corrective exercises, which are intended to reduce musculoskeletal pain by bringing the body into postural alignment. PURPOSE: An experimental study to determine the acute effect following one treatment and the short-term effect after a 2 week program of Egoscue corrective exercises on knee pain, hip pain, and whole-body postural alignment. METHODS: Forty participants with chronic knee and/or hip pain (defined as pain on most days of the week for at least the previous 12 weeks) were randomly assigned and equally divided between an exercise group (n = 20) and a control group (n = 20). The exercise group completed a corrective exercise routine, as per the Egoscue Method, at least 5 d/wk for two weeks. The control group simply maintained their current lifestyle for the 2-week duration of the study. All participants kept a daily log of their average pain levels at rest and during movement using a Visual Analog Scale (VAS). Standing posture was assessed using PostureScreen Mobile® and pain and function were recorded using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) at baseline and at the end of week 1 and 2. RESULTS: The exercise group experienced a significant decrease in pain during everyday movement as reported in daily VAS logs (p = 0.019). After controlling for age, BMI, past surgeries, arthritis status, and location of pain, there was a significant group x time interaction in WOMAC scores (p = 0.015). At week 2, WOMAC scores were significantly lower in the exercise group (p = 0.001) but not the control group (p > 0.05). Pain was not significantly different after one treatment. No significant changes in posture were observed in this study. CONCLUSION: Two weeks of corrective exercises significantly decreased knee and hip pain and improved function. Although an observable change in posture was not detected, further research is warranted to investigate the effects of Egoscue corrective exercises on posture over longer periods of time.

The purpose of this dissertation was to explore methods for generating neuroplastic changes in healthy individuals using transcutaneous spinal cord stimulation (TSCS) and perturbation-based training in order to improve balance performance. This was done to gain an understanding of their effects on healthy individuals, which could then be used in designing treatments for both healthy and motor-impaired subjects. Three studies were undertaken. First, we set out to show that the Robotic Upright Stand Trainer (RobUST) could generate improvements in balance after perturbation balance training (PBT). In this same study, we showed that the assist-as-needed support of RobUST generates postural control improvements. Balance performance metrics including (i) margin of stability (MOS), (ii) metrics based on the center of pressure (COP) and center of mass (COM) excursions, (iii) postural muscle activations, (iv) balance strategy selection (between ankle and hip strategies) were used in this study. Electromyographic data were also collected from 11 subjects who participated in this study. Subjects were split into a RobUST assisted group (FF) and a non-assisted group (NF). An analysis of variance (ANOVA) was carried out to identify the main effects of the two factors, i.e., training and grouping. We also studied the interaction effects between the two factors in the performance variables. After training, the threshold of the forces that destabilize balance increased for all participants. In addition, the area within which they could withstand perturbations without falling also increased. Muscle activation decreased in most muscles for subjects in both groups indicating that subjects improved balance while demonstrating more energetically efficient strategies. The post-training behavior of the two groups differed in the following way: the NF group adapted towards faster reactions to perturbations, greater use of the hip strategy, and more use of the erector spinae muscle, while the FF group adapted towards slower responses and less MOS. These results show that although balance adaptations with RobUST-assisted PBT are not the same as without RobUST, it is still a platform capable of improving balance performance. Second, the effect of TSCS as a means of boosting neuroplasticity and a replacement for epidural stimulation were tested. Eight subjects were given TSCS for 30 mins while lying supine, and their neurophysiological and balance performance measures were tested before and after the intervention. T-tests were used to assess the difference in performance, and it was found that TSCS caused hypopolarisation of the sensory neurons, which increased the synaptic efficacy of sensory afferent–motoneuron synapses. This change was evidenced by increased H-reflex recovery and a leftward shift of the H-reflex recruitment curve. No improvement in fall frequency was observed, although balance adjustments were made that reduced muscle activity. This experiment showed that TSCS could be used to modulate the excitability of the spinal cord in healthy subjects. Third, TSCS was combined with a training intervention in order to study how these two sources of plasticity interact. TSCS was applied to eleven subjects while they underwent a training intervention in which they played a game in virtual reality (VR) while their balance was perturbed by forces applied by RobUST. Balance characteristics were measured both with and without TSCS, before and after the intervention. It was found that TSCS initially caused an increase in muscle activity and an increase in fall frequency for perturbations in the forward direction. With more practice, though, muscle activity decreased. It was postulated that the CNS adjusted to the initial elevated levels of muscle activity caused by TSCS by suppressing muscle activity in order to ensure successful motor control. These results suggest that TSCS can be used to elevate the resting potential of neurons in the dorsal (close to the back of the body) root, making them more easily excited by cortical signals. These changes induced by TSCS can be beneficial to spinal cord injury patients.

The foot/ankle complex (particularly the hindfoot) is frequently injured in a wide array of debilitating events, such as car crashes. Numerical models have been used to assess injury risk, but most are minimally validated and do not account for variations in ankle posture that frequently occur during these events. The purpose of this study was to develop an accurate finite element (FE) model of the foot and ankle that accounts for these positional changes. The bone positions and load path in the foot and ankle were quantified throughout its natural range of motion. CT scans were taken of a male cadaveric leg in five postures in which fractures are commonly reported, while strains were recorded by strain gauges attached to the hindfoot bones in response to quasi-static, sub-failure loading. Substantial variations in bone displacements, rotations and strains were observed for all postures tested, highlighting the need for an FE model that accounts for these positional changes. The CT scans were used as the basis of an FE model of the foot and ankle that was developed using TrueGrid® and LS-Dyna® software. The model met rigorous mesh quality criteria, and its properties were optimized to best represent the experimental plantar tissue compression and surface strains. The model was evaluated by comparing its bone position and strain responses to the experimental results in each posture. The fracture thresholds and locations in each posture were estimated and were similar to those reported in the literature. The least vulnerable posture was neutral, and the talus and calcaneus exhibited the lowest fracture thresholds in all postures. This work will be useful in developing improved injury limits for the ankle and postural guidelines to minimize injury. The model can be used to evaluate new protective systems to reduce the occurrence of lower leg injuries. / Thesis / Master of Applied Science (MASc) / Ankle fractures are common occurrences that can lead to severe disability. Safety evaluations of the lower leg are often performed using computer models in a neutral ankle posture, which may underestimate the fracture tolerance in altered postures. The purpose of this study was to develop a computer model of the ankle that accounts for these changes. A cadaveric leg was used to determine how the locations of and strains in the bones of the foot and ankle varied as ankle posture was adjusted. A computer model of the lower leg and ankle was developed, and its accuracy was evaluated by comparison with the experimental results. The least vulnerable posture was neutral, and the hindfoot bones were the most likely to experience fracture in all postures. This model can be used in the future to evaluate new protective systems and develop comprehensive injury criteria for these altered postures.

The tibia is a frequent site of injury in frontal automotive collisions. The bulk of experimental cadaveric studies on injury tolerance assume load is applied in line with the leg’s long axis, leaving non-standard postures largely uninvestigated. The purpose of this work was to study the effects of non-standard postures on the tibia’s injury tolerance. A pneumatic system was designed to facilitate impact testing. This system allows the user to fire a projectile of variable mass towards a specimen at a range of velocities by varying the supplied air pressure. Impact tests were performed using pairs of isolated cadaveric tibias. Within each pair of specimens, two postures were compared by varying the angle of the bone’s long axis relative to the direction of impact, representing knee extension and corresponding plantarflexion. It was found that the specimens held further from the axial posture sustained injury at lower forces. Two commonly-used Anthropomorphic Test Device legforms were impacted in these non-standard postures. New load limits were proposed for the use of these devices in off-axis impact testing. In order to compare directly with the loads measured by the legforms, it was necessary to measure forces and moments internal to the bone’s long axis. A non-invasive load estimation method was developed and tested using strain measured from the surface of four specimens. The method performed poorly under impact conditions, but may be refined in the future. Quantifying the effect of posture on injury risk in the tibia allows for the refinement of existing injury criteria. Ultimately, this can be used to enhance the design of protective devices to reduce the incidence of tibia fractures in automotive collisions. / Thesis / Master of Applied Science (MASc) / Fractures of the tibia (the shin bone) are common in automotive collisions, and often lead to long-term impairment. Experimental studies on these kinds of injuries are usually performed with the lower leg aligned with the direction of impact, which does not reflect the range of postures an occupant may assume during a crash. Cadaveric tibias were subjected to impact loading in two different postures. It was found that the specimens held further from an axial posture sustained fractures at lower forces. Two commonly-used crash test dummy legs were also impacted in these non-standard postures to test their performance. Suggestions were made for new load limits to be used with these devices in non-standard postures. The finding that leg posture has an effect on injury risk in the tibia can be used in the future to design and evaluate better protective devices and ultimately reduce the incidence of these injuries.

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