A three dimensional analysis of soft tissue and bone changes following orthognathic surgery

Introduction: This report investigates the ability of surgeons to achieve predicted surgical movements in five different groups of patients, and analyses both the predictions and the changes in two dimensions using scale space analyses (Campos 1991). The report then progresses to the three dimensional analysis of the bone, the soft tissues and the ratio of soft tissue to bone following surgery, using a colour coded techniques (Fright and Linney, 1991) to illustrate the changes. The average soft tissue scans from each group of patients were averaged and compared to a control group at the preoperative, three months and 1 year postoperative stages (Fright, 1991) Data Acquisition: Bone measurements were recorded from lateral skull radiographs preoperatively and 48 hrs postoperatively, and CT scans preoperatively and 1 year postoperatively. Soft tissue measurements from an optical scanner, preoperatively, three months and 1 year postoperatively. Patients 1) Control group: 30 females and 30 males 2) Skeletal class 2 patients: 15 Females and 2 Males 3) Skeletal class 3 patients: 9 Females and 7 Males 4) Cleft Palate Patients a) Unilateral cleft lip and palate: I 6 Females: 2 left and 4 right sided clefts 7 Males: 3 left and 4 right sided clefts b) Bilateral cleft lip and palate: 5 Males and 1 Female c) Clefts of the Hard and Soft palate: 5 Females. Results: Prediction: There was a surprisingly poor match between the predicted and achieved movements in both the horizontal and vertical direction in all patient groups. The scale space analysis provided an efficient method of illustrating profile changes. Soft tissue movements There were definite patterns of change and relapse in the patient groups. The relapse being most marked in the cleft palate patients. Bone movements and soft tissue to bone ratios Definite patterns of movement for the maxilla and the mandible became apparent for both the bone and soft tissue to bone ratio of movement in each group. For maxillary impactions in the skeletal 2 group there was a 1:1 ratio of movement of the soft tissue to bone in the midline increasing to 1.25:1 in the canine region and 1.5:1 in the paranasal region. Conclusions: There is a need to develop a technique to aid the the surgeons in carrying out planned surgical movements. The colour coded method was shown to be a simple, efficient and easily understandable way of analysing surgical change. Diagnosis of surgical requirements was aided by the ability to objectively compare the individual to a control group. The prediction of surgical change should be greatly aided by adapting the current database to include the distinct patterns of movement in the bone and ratio of movements of the soft tissues to the bone

Elite rowing : technique and performance

In elite rowing competition the difference between Gold and Silver is often less than one second, and there is a high incidence of injury amongst the sport’s athletes. Previous studies into rowing have described kinetic and kinematic profiles, commented on the effects of factors such as fatigue and training status, and identified some aspects of rowing technique that may be associated with improvements in performance, or with injury mechanisms. However, such work has often been subject to significant errors and limitations, such as: restricting kinematic analysis to two-dimensions, small sample sizes, and lack of clinical and performance relevance. Furthermore there has been no one body of work to date that has published a comprehensive analysis of elite rowers’ technique and described its relevance to performance. This represents a gap in the performance literature. The primary aim of this thesis was to describe and analyse the kinetic output and three-dimensional kinematics of elite rowers. It was hypothesised that a comprehensive and explicit description of athletes’ technique could be compiled, and that aspects of this technique would be influenced by exercise intensity and longitudinal training. Furthermore, it was thought that discrete aspects of technique could be used to predict high levels of athletic performance, and individual’s risk of spinal and knee injuries. A custom experimental methodology was developed and several pilot studies optimised and validated the method. More than eleven hundred rowing trials were completed by members of the Great Britain elite rowing squad over a period of twenty six months. This provided kinetic and kinematic data that was treated and analysed using custom written software, and subjected to statistical modelling. The thesis described the method and kinematic model that was utilised. A detailed description of elite athletes’ rowing technique and kinematics was produced. Increasing exercise intensity influenced some of the measured parameters, and longitudinal feedback, and coaching interventions were effective in influencing the elite participants. Adopting a kyphotic posture in the lumbar region of the spine at any point in the rowing stroke was found to be detrimental to rowing performance, and may be linked to an increased risk of lumbar injury. Rapid extension of the lumbar spine was also thought to pose an injury risk, however it was found that athletes who extended the lumbar spine at the finish of the stroke exhibited better performance than those who did not. The kinematic characteristics of the lower limbs may positively influence rowers’ performance, and provide protection against spinal injury.Open acces

b Quark Tagging Performance and Higgs Detection via Top Production Using the ATLAS Detector

The single particle response of the ATLAS Inner Detector has been simulated. The impact parameter resolution was parameterised as sigma (d0) = 11 ⊕ 59/pT mum and sigma(z0) = 85 ⊕ 94/pT mum with pT in GeV. The b-tagging performance was evaluated, for a b-tagging efficency eb = 0.5, the light quark rejection Ru = 83 +/- 6 for 97% silicon microstrip and pixel detector efficiency and Ru = 61 +/- 4 for 90% detector efficiency for 200 GeV jets. The viability for a Higgs boson search using the channel ttH → bW+bW-bb was examined. For a total integrated luminosity of 3 . 10e4pb-1 and a Higgs boson of mass mH = 80 GeV the signal significance was 11.7, for MH = 100 GeV 6.5, above mH = 110 GeV the signal significance fell below the 5sigma level

Three-dimensional assessment of dentofacial deformity in children with clefts

Background: Changes in clinical management; advances in non-invasive three-dimensional imaging; developments in methods of shape analysis. Aim: To assess three-dimensional dentofacial deformity with a view to early appraisal of primary surgical outcome. Results: Significant differences in upper lip morphology were found between the cleft children and their unaffected peers; nasal asymmetry that became more obvious in function was noted in cleft children; the maxillary dental arches of the children with repaired cleft palate were shallow, short and narrow; and the dental arch, deformity and the facial soft tissue deformity were unrelated. Contributions to the field: It has been shown that deviation from normal could be detected as young as 3 years of age using computerised stereophotogrammetry; preliminary, objective, three-dimensional analysis of facial function has been completed in young children; the accuracy of three-dimensional CT scanning of dentate study models and the time cost of data collection were quantified; and this study has produced a body of three-dimensional data that can test and support analytical advances

Problems related to lattice points in the plane

In the first part of this research we find an improvement to Huxley and Konyagin's current lower bound for the number of circles passing through five integer points. The improved lower bound is the conjectured asymptotic formula for the number of circles passing through five integer points. We generalise the result to circles passing through more than five integer points, giving the main theorem. In the second part of the research we consider questions linked to the distribution of different configurations of integer points of the circle passing through the unit square. We show that different configurations of points are distributed uniformly throughout the unit square for circles of fixed radius. Results are obtained by looking at the distribution of the crossing points of circles, where the circles form the boundaries of domains. The domain of a configuration is the set of possible positions of the centre of the circle within the configuration. We choose a rectangle within the unit square and then count the number of regions of the rectangle which are formed by domain boundaries

3D soft-tissue, 2D hard-tissue and psychosocial chantes following orthognathic surgery

A 3D imaging system (C3D®), based on the principles of stereophotogrammetry, has been developed for use in the assessment of facial changes following orthognathic surgery. Patients’ perception of their facial appearance before and after orthognathic surgery has been evaluated using standardised questionnaires, but few studies have tried to link this perception with the underlying two-dimensional cephalometric data. Comparisons between patients’ subjective opinions and 3D objective assessment of facial morphology have not been performed. Aims: (1) To test the reliability of the 3D imaging system; (2) to determine the effect of orthognathic surgery on the 3D soft-tissue morphology; (3) to assess skeletal changes following orthognathic surgery; (4) to evaluate soft-tissue to hard-tissue displacement ratios; (5) to ascertain the impact of orthognathic surgery on patients’ perception of their facial appearance and their psychosocial characteristics, (6) to explore the dentofacial deformity, sex and age on the psychosocial characteristics; (7) to evaluate the extent of compatibility between the cephalometric and the three-dimensional measurements and (8) to determine if the magnitude of facial soft-tissue changes affects the perception of facial changes at six months following surgery. Results and Conclusions: C3D imaging system was proved to be accurate with high reproducibility. The reproducibility of landmark identification on 3D models was high for 24 out of the 34 anthropometric landmarks (SD£0.5 mm). One volumetric algorithm in the Facial Analysis Tool had an acceptable accuracy for the assessment of volumetric changes following orthognathic surgery (mean error=0.314 cm3). The error of cephalometric method was low and the simulation of mandibular closure proved to be reproducible. 2D soft-tissue measurements were compatible with 3D measurements in terms of distances, but angular measurements showed significant differences (p<0.05)

The mechanics of twisting somersaults

Twisting movements are categorised into three mechanical types, named as DIRECT, COUNTER-ROTATION and TILT TWIST. Twisting techniques are studied using mathematical models. A mathematical inertia model is constructed to enable the determination of segmental inertia parameters from anthropometric measurements. A film analysis program is developed so that the angles, which specify the orientation and configuration of the body, may be derived from digitised film data. A computer simulation model, comprising 11 segments and 17 degrees of freedom, is constructed to represent the human body in free fall. The combined use of the three computer programs results in maximum errors of 3% for somersault and 9% for twist in ten filmed movements. The mechanics of twisting techniques are explained using simple mathematical models. An analysis of rigid body motions shows that there are two distinct modes of motion, named as the ROD MODE and the DISC MODE. It is shown that it is possible to change from one mode to the other by varying the angle of pike and this permits the twist to be increased or stopped or even reversed. The capacities of twisting techniques are determined using simulations. For twists from a piked position, delaying the extension from the pike can increase the twist rate although this does depend upon the particular technique used and the initial direction of somersault. The contributions of twisting techniques used in the filmed movements are determined using simulations based upon modifications of the film data. It is found that counter-rotation techniques made small contributions and that aerial techniques, which increased the angle of tilt, were the major contributors, even in movements where the twist was apparent at take off. Using the simulation model it is shown that the build up of twist in the unstable double layout somersault may be controlled by means of small asymmetrical arm movements during flight