Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 6 uppsatser.

Injuries to the neck, or cervical region, are very importantsince there is a potential risk of damage to the spinal cord.Any neck injury can have devastating if not life threateningconsequences. High-speed transportation as well as leisure-timeadventures have increased the number of serious neck injuriesand made us increasingly aware of its consequences.Surveillance systems and epidemiological studies are importantprerequisites in defining the scope of the problem. Thedevelopment of mechanical and clinical tools is important forprimary prevention of neck injuries. Thus, the main objectives of the present doctoral thesisare:- To illustrate the dimension of cervical injuries inSweden,- To develop a Finite Element (FE) model of the uppercervical spine, and- To study spinal stability for cervical injuries. The incidence studies were undertaken with data from theinjury surveillance program at the Swedish National Board ofHealth and Welfare. All in-patient data from Swedish hospitals,ranging over thirteen years from 1987 to 1999, were analyzed.During this period 14,310 nonfatal and 782 fatal cervicalinjuries occurred. The lower cervical spine is the mostfrequent location for spinal trauma, although, this changeswith age so that the upper cervical spine is the most frequentlocation for the population over 65 years of age. The incidencefor cervical fractures for the Swedish population decreased forall age groups, except for those older than 65 years of age.The male population, in all age groups, has a higher incidencefor neck fractures than females. Transportation relatedcervical fractures have dropped since 1991, leaving fallaccidents as the sole largest cause of cervical trauma. An anatomically detailed FE model of the human uppercervical spine was developed. The model was validated to ensurerealistic motions of the joints, with significant correlationfor flexion, extension, lateral bending, axial rotation, andtension. It was shown that an FE-model could simulate thecomplex anatomy and mechanism of the upper cervical spine withgood correlation to experimental data. Three studies wereconducted with the FE model. Firstly, the model of the uppercervical spine was combined with an FE model of the lowercervical spine and a head model. The complete model was used toinvestigate a new car roof structure. Secondly, the FE modelwas used for a parameter study of the ligament materialcharacteristics. The kinematics of the upper cervical spine iscontrolled by the ligamentous structures. The ligaments have tomaintain spinal stability while enabling for large rotations ofthe joints. Thirdly, the FE-model was used to study spinalinjuries and their effect on cervical spinal stability inflexion, extension, and lateral bending. To do this, the intactupper cervical spine FE model was modified to implementruptures of the various spinal ligaments. Transection of theposterior atlantooccipital membrane, the ligametum flavum andthe capsular ligament had the most impact on flexion, while theanterior longitudinal ligament and the apical ligamentinfluenced extension. It is concluded that neck injuries in Sweden is a problemthat needs to be address with new preventive strategies. It isespecially important that results from the research on fallaccidents among the elderly are implemented in preventiveprograms. Secondly, it is concluded that an FE model of thecervical region is a powerful tool for development andevaluation of preventive systems. Such models will be importantin defining preventive strategies for the future. Lastly, it isconcluded that the FE model of the cervical spine can increasethe biomechanical understanding of the spine and contribute inanalyses of spinal stability.

<p>Injuries to the neck, or cervical region, are very importantsince there is a potential risk of damage to the spinal cord.Any neck injury can have devastating if not life threateningconsequences. High-speed transportation as well as leisure-timeadventures have increased the number of serious neck injuriesand made us increasingly aware of its consequences.Surveillance systems and epidemiological studies are importantprerequisites in defining the scope of the problem. Thedevelopment of mechanical and clinical tools is important forprimary prevention of neck injuries.</p><p>Thus, the main objectives of the present doctoral thesisare:- To illustrate the dimension of cervical injuries inSweden,- To develop a Finite Element (FE) model of the uppercervical spine, and- To study spinal stability for cervical injuries.</p><p>The incidence studies were undertaken with data from theinjury surveillance program at the Swedish National Board ofHealth and Welfare. All in-patient data from Swedish hospitals,ranging over thirteen years from 1987 to 1999, were analyzed.During this period 14,310 nonfatal and 782 fatal cervicalinjuries occurred. The lower cervical spine is the mostfrequent location for spinal trauma, although, this changeswith age so that the upper cervical spine is the most frequentlocation for the population over 65 years of age. The incidencefor cervical fractures for the Swedish population decreased forall age groups, except for those older than 65 years of age.The male population, in all age groups, has a higher incidencefor neck fractures than females. Transportation relatedcervical fractures have dropped since 1991, leaving fallaccidents as the sole largest cause of cervical trauma.</p><p>An anatomically detailed FE model of the human uppercervical spine was developed. The model was validated to ensurerealistic motions of the joints, with significant correlationfor flexion, extension, lateral bending, axial rotation, andtension. It was shown that an FE-model could simulate thecomplex anatomy and mechanism of the upper cervical spine withgood correlation to experimental data. Three studies wereconducted with the FE model. Firstly, the model of the uppercervical spine was combined with an FE model of the lowercervical spine and a head model. The complete model was used toinvestigate a new car roof structure. Secondly, the FE modelwas used for a parameter study of the ligament materialcharacteristics. The kinematics of the upper cervical spine iscontrolled by the ligamentous structures. The ligaments have tomaintain spinal stability while enabling for large rotations ofthe joints. Thirdly, the FE-model was used to study spinalinjuries and their effect on cervical spinal stability inflexion, extension, and lateral bending. To do this, the intactupper cervical spine FE model was modified to implementruptures of the various spinal ligaments. Transection of theposterior atlantooccipital membrane, the ligametum flavum andthe capsular ligament had the most impact on flexion, while theanterior longitudinal ligament and the apical ligamentinfluenced extension.</p><p>It is concluded that neck injuries in Sweden is a problemthat needs to be address with new preventive strategies. It isespecially important that results from the research on fallaccidents among the elderly are implemented in preventiveprograms. Secondly, it is concluded that an FE model of thecervical region is a powerful tool for development andevaluation of preventive systems. Such models will be importantin defining preventive strategies for the future. Lastly, it isconcluded that the FE model of the cervical spine can increasethe biomechanical understanding of the spine and contribute inanalyses of spinal stability.</p>

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 153-165).

Cervical spine injuries are a serious threat, as they may damage the central nervous system. In the elderly, cervical fractures due to falls are very frequent. The overall weakening of the bony and ligamentous spine decreases the resistance to fractures. Fractures of the dens of the second cervical vertebra (C2) are the most frequent individual fractures in the upper spine. Osteoporosis and impaired conditions play the main role in increasing the fracture risk. Several mechanisms may induce dens fractures: hyper-extension, lateral bending, shear, torsion, but the mechanisms of fractures have not been fully understood. Osteoporosis reduces overall bone strength. Cortical bone thinning occurs in the vertebræ, and there is a general loss of bone mass. Trabecular micro-architecture of bones loses integration, leading an increasing porosity. Mechanical properties worsen, and failure occurs more easily. In this study the role of osteoporosis on the genesis of dens fractures was investigated. An existing finite element (FE) model of the human spine was employed to simulate the effect of parameters associated with osteoporosis on the loading conditions of the dens. A baseline case was first simulated. Then, cortical thickness, cortical and trabecular bulk modulus and shear modulus were decreased in steps. Three impact scenarios were simulated: a lateral fall, a backward fall, and a forward fall. Effects of osteoporotic variations on the ligamentous spine deformations were studied. A mesh convergence analysis was performed to assess the influence of mesh size on the stresses in vertebra C2. The effect of reduced cortical and trabecular bulk moduli alone on stress distribution was not that apparent. In the dens, a reduced cortical thickness, in lateral and backward fall, caused higher maximum stresses than in the baseline. Conversely, in forward fall, reduced cortical thickness caused lower stresses than in the baseline. The effect of reducing trabecular bulk and shear moduli altogether was to decrease the stresses in dens trabecular bone. In lateral and backward fall, by reducing cortical bulk and shear moduli altogether, stresses in dens cortex decreased; whereas, in forward fall, stress decreased in dens neck cortex, and increased in dens apex and waist. It is concluded that cortical thinning, and reduced bulk and shear moduli of bone compartments considerably alter the stress distribution in C2, as well as the ligamentous spine response. The extent of such variations depends also on the impact scenarios. Finally, stresses in the model were found to be sensitive to the mesh size currently used in the human spine FE model. / Halsryggsskador är ett allvarligt problem, eftersom de kan orsaka skador på det centrala nervsystemet. Bland äldre är halskotfrakturer på grund av fall väldigt frekventa. Med åldern kommer en generell försvagning av benen och förändringar av ligamenten som leder till minskad motståndskraft mot frakturer. Densfrakturer av andra halskotan (C2) är den mest frekventa individuella frakturen av övre ryggraden. Osteoporos och annan nedsättning spelar en stor roll i den ökade frakturrisken. Flera mekanismer kan orsaka densfrakturer: hyper-extension, lateral böjning, skjuvning, vridning, men fortfarande saknas en full förståelse för frakturmekanismen. Osteoporos reducerar benstyrkan. Förtunning av det kortikala benet uppkommer i koterna, och en generell minskning av benmassan. Mikroarkitekturen av det trabekulära benet förändras och leder till en ökad porositet. Mekaniska egenskaper försämras, och frakturrisken ökar. I denna studie har inverkan av osteoporos i densfrakturer undersökts. En existerande finit element modell av den mänskliga ryggraden har använts för att studera effekten på dens av olika parameter associerade med osteoporos. En referenssimulering gjordes först som skulle representera en normal halsrygg. Därefter reducerades den kortikala tjockleken, kortikala och trabekulära bulk- och skjuvmodulen stegvis. Resultatet jämfördes sedan med referenssimuleringen. Tre olika situationer simulerades: lateralt fall, fall bakåt och fall framåt. En konvergensanalys gjordes också för att undersöka inverkan av mesh-storleken på spänningarna i C2. Effekten av en reduktion av bulkmodulen av kortikala och trabekulära benet enbart var inte så uppenbar. En reduktion av den kortikala tjockleken i fall lateralt eller bakåt skapade högre spänningar jämfört med referenssimuleringarna. Däremot, i fall framåt skapade samma parameter förändring en minskning av spänningarna. Effekten av att reducera både bulk- och skjuvmodulen för det trabekulära benet sänkte spänningarna i det trabekulära benet. I fall lateralt och bakåt, en reduktion av både bulk- och skjuvmodulen av det kortikala benet gav en sänkning av spänningar i det kortikala benet. Fall framåt minskade spänningarna i det kortikala benet för halsen av dens men ökade spänningarna för apex och midjan. Studien visade att den kortikala förtunningen och reducerad bulk- och skjuvmodul av benet förändrade spänningsfördelningen i C2. Storleken av förändringen berodde också på olyckssituation. Till sist, spänningarna visade sig vara känslig mot mesh-storleken i FE modellen som användes i studien.

Objective: To investigate the potential etiology of a loss of neck control injury in female standard ballroom dancers. The median frequency (MF) as measured by electromyography (EMG) of the left upper trapezius (UT), left splenius capitius (SPL), and right sternocleidomastoid (SCM) of injured dancers was compared to non-injured dancers. This comparison was performed to identify whether dancers with a history of loss of neck control have a greater amount of fatigue than those with no history of this particular injury. Design and Setting: A 2 x 6 factorial design was used for this investigation. The independent variables were group (injured vs. non-injured) and time (before and after the three rounds of dancing). The dependent variables were MF as measured by EMG, range of motion, and neck length. All testing was performed at the university biomechanics laboratory and ballroom dance studio. Subjects: Twenty female subjects (10 injured group {mean height 167.40 ± 4.12 cm and weight 59.30 ± 5.41 kg}, 10 non-injured group {mean height 166.76 ± 4.62 cm and weight 58.93 ± 5.30 kg}), with at least one year experience in competitive ballroom dancing, in the standard division participated in this study. All subjects competed at a Dancesport competition either in the novice, pre-championship, and/or amateur standard classifications. Inclusion criteria for the injured group included female ballroom dancers who had a loss of neck control episode. Measurements: Surface EMG activity was recorded from the left UT, left SPL, and right SCM muscles before and after dancing the five standard dances. Results: The decrease in EMG MF was not significant between groups. There was no difference in neck lengths from the external occipital protuberance to inferior angle of the scapula between groups. There were also no significant differences in range of motion of left and right lateral flexion and extension in either group from pre to post dancing. Conclusions: Based on the results of this study, subjects with a history of neuromuscular neck injury did not appear to have acute fatigue of the three muscles studied here following the routine used in this study.

Car collisions are, unfortunately, not uncommon and cause 1.35 million deaths each year worldwide. Children are often occupants in cars and to ensure their safety, child restraint systems (CRSs) have been developed. However, CRSs need to be used correctly to be efficient. Several studies, such as field investigations and Q-dummy tests, have shown that a misuse of a CRS can increase the risk of injuries. Typical misuses for a forward-facing CRS and a booster seat, with two real accident parameters, were constructed and simulated using the PIPER child human body model. The kinematics of each case were compared with injury parameters of the head, neck and abdomen. Comparing the parameters to existing injury criteria showed that most of the cases end in AIS3+ head injury, even cases with no misuse. When comparing the results of misuses to the cases where the CRS was correctly used, the dominant result was that misuse resulted in being less effective to protect the child. Moreover, results of chosen misuses compared to Q-dummy tests correlated with their results. Results from this thesis illustrate how important it is for parents to restrain children and route the belt correctly.

INTRODUÇÃO: Estenose do canal cervical consiste na diminuição do diâmetro sagital do canal cervical e está associada com maior risco de lesões neurológicas decorrentes de trauma cervical. Nos esportes de colisão, a estenose do canal cervical consiste em um importante parâmetro na decisão de retorno ao esporte após neuropraxia da medula cervical e após determinadas lesões do plexo braquial. Os métodos atualmente disponíveis para avaliação de estenose do canal cervical em atletas são muito caros (ex: por ressonância nuclear magnética) ou pouco precisos (métodos radiográficos). Este estudo avaliou um novo método radiográfico para determinação de estenose do canal cervical, comparando-o com medições realizadas em cadáveres, medida por ressonância nuclear magnética do canal cervical e do espaço disponível para a medula (SAC/SACD) e com o método radiográfico consagrado na literatura para determinação de estenose do canal cervical, o índice de Torg (IT). MÉTODOS: A população do estudo foram 20 homens entre 16 e 35 anos de idade. Os sujeitos realizaram uma ressonância nuclear magnética da coluna cervical para determinação do SAC/SACD e radiografias cervicais em perfil e antero-posterior para determinação do IT e do novo método radiográfico proposto, o diâmetro corrigido do canal cervical (DCCC). Para determinar o DCCC, foi utilizada uma barra de metal de 100 mm, acoplada verticalmente na linha média cervical, utilizando os processos espinhosos das vertebras cervicais como referência. Obtidos o diâmetro sagital da imagem do canal cervical e o comprimento da imagem da barra de metal na radiografia, e conhecendo o tamanho real da barra de metal, o diâmetro real do canal medular pôde ser estimado matematicamente com o uso do teorema de Tales. Os resultados obtidos para o DCCC foram comparados com valores encontrados em estudos com cadáveres, foi avaliada a concordância entre DCCC e o diâmetro médio-sagital do canal cervical aferido por ressonância magnética (DCRM) e os métodos radiográficos (DCCC e IT) foram correlacionados com o SAC/SACD. Os cálculos foram realizados nos níveis C3 a C7, além das médias de C3 a C6 [DCCC (MDCCC), IT (MTorg) e SAC/SACD (MSAC/MSACD)]. RESULTADOS: Os valores obtidos pelo DCCC (média do MDCCC: 15.29 mm) foram compatíveis com os valores descritos em estudos de medida direta. A correlação entre DCCC e SAC/SACD foi superior à correlação entre IT e SAC/SACD, sendo de 0.7025 para MDCCC e MSACD contra 0.5473 para MTorg e MSACD. O teste de concordância entre os valores absolutos para DCCC e DCRM evidenciou valores mais elevados na medida por DCCC, sendo média de 1.84 mm maior para MDCCC em relação a média de C3 a C6 pelo DCRM. CONCLUSÕES: O Diâmetro Corrigido do Canal Cervical apresentou valores semelhantes aos encontrados em estudos com medida direta em cadáveres e apresentou correlação com SAC/SACD superior ao IT / INTRODUCTION: Cervical spinal stenosis is the diminution of the anteroposterior diameter of the spinal canal and it is associated with increased risk of neurological injury from cervical trauma. In collision sports, the cervical canal stenosis is an important parameter in the return to play decision after cervical cord neuropraxia and after some brachial plexus injuries. The methods currently available for evaluation of cervical canal stenosis in athletes are expensive (eg, nuclear magnetic resonance) or imprecise (radiographic methods). This study evaluated a new radiographic method for determination of cervical canal stenosis, comparing it to measurements performed on cadavers, measurement by magnetic resonance imaging of the cervical canal and space available for the cord (SAC/SACD) and the consecrated radiographic method for determining cervical spinal stenosis, Torg ratio(TI). METHODS: The study population were 20 men between 16 and 35 years. The subjects underwent a magnetic resonance imaging of the cervical spine to determine the SAC/SACD and cervical radiographs to determine the IT and the proposed new radiographic method, called corrected cervical canal diameter (DCCC). To determine the DCCC, a 100 mm metal bar was used vertically over the cervical midline, using the spinous processes of the cervical vertebrae as reference. Got the radiographic diameter of the medullary canal and the length of the metal bar image on the radiograph , and knowing the actual size of the metal bar , the actual diameter of the spinal canal could be estimated mathematically with the simple use of the theorem of Thales. The results for the DCCC were compared with values found in cadavers studies, the agreement between DCCC and the mid-sagittal diameter of the cervical canal measured by magnetic resonance imaging (DCRM) was calculated and radiographic methods (DCCC and IT) were correlated with SAC/SACD. Calculations were performed individually for C3 to C7 and averages of C3 to C6 [DCCC (MDCCC), IT (MTorg) and SAC/SACD (MSAC/ MSACD)]. RESULTS: The values obtained by DCCC (average MDCCC: 15:29 mm) were consistent with the values described in studies using direct measurement. The correlation between DCCC and SAC/SACD was higher than the correlation between IT and SAC/SACD, being 0.7025 for MDCCC and MSACD and 0.5473 for MTorg and MSACD. The agreement between absolute values for DCCC and DCRM showed higher values for DCCC, which average 1.84 mm greater for MDCCC compared to the average of C3 to C6 for DCRM. CONCLUSIONS: The Fixed Diameter of the Cervical Canal showed similar values to those found in studies with direct measurement from cadavers and correlated with SAC/SACD better than IT

INTRODUÇÃO: Estenose do canal cervical consiste na diminuição do diâmetro sagital do canal cervical e está associada com maior risco de lesões neurológicas decorrentes de trauma cervical. Nos esportes de colisão, a estenose do canal cervical consiste em um importante parâmetro na decisão de retorno ao esporte após neuropraxia da medula cervical e após determinadas lesões do plexo braquial. Os métodos atualmente disponíveis para avaliação de estenose do canal cervical em atletas são muito caros (ex: por ressonância nuclear magnética) ou pouco precisos (métodos radiográficos). Este estudo avaliou um novo método radiográfico para determinação de estenose do canal cervical, comparando-o com medições realizadas em cadáveres, medida por ressonância nuclear magnética do canal cervical e do espaço disponível para a medula (SAC/SACD) e com o método radiográfico consagrado na literatura para determinação de estenose do canal cervical, o índice de Torg (IT). MÉTODOS: A população do estudo foram 20 homens entre 16 e 35 anos de idade. Os sujeitos realizaram uma ressonância nuclear magnética da coluna cervical para determinação do SAC/SACD e radiografias cervicais em perfil e antero-posterior para determinação do IT e do novo método radiográfico proposto, o diâmetro corrigido do canal cervical (DCCC). Para determinar o DCCC, foi utilizada uma barra de metal de 100 mm, acoplada verticalmente na linha média cervical, utilizando os processos espinhosos das vertebras cervicais como referência. Obtidos o diâmetro sagital da imagem do canal cervical e o comprimento da imagem da barra de metal na radiografia, e conhecendo o tamanho real da barra de metal, o diâmetro real do canal medular pôde ser estimado matematicamente com o uso do teorema de Tales. Os resultados obtidos para o DCCC foram comparados com valores encontrados em estudos com cadáveres, foi avaliada a concordância entre DCCC e o diâmetro médio-sagital do canal cervical aferido por ressonância magnética (DCRM) e os métodos radiográficos (DCCC e IT) foram correlacionados com o SAC/SACD. Os cálculos foram realizados nos níveis C3 a C7, além das médias de C3 a C6 [DCCC (MDCCC), IT (MTorg) e SAC/SACD (MSAC/MSACD)]. RESULTADOS: Os valores obtidos pelo DCCC (média do MDCCC: 15.29 mm) foram compatíveis com os valores descritos em estudos de medida direta. A correlação entre DCCC e SAC/SACD foi superior à correlação entre IT e SAC/SACD, sendo de 0.7025 para MDCCC e MSACD contra 0.5473 para MTorg e MSACD. O teste de concordância entre os valores absolutos para DCCC e DCRM evidenciou valores mais elevados na medida por DCCC, sendo média de 1.84 mm maior para MDCCC em relação a média de C3 a C6 pelo DCRM. CONCLUSÕES: O Diâmetro Corrigido do Canal Cervical apresentou valores semelhantes aos encontrados em estudos com medida direta em cadáveres e apresentou correlação com SAC/SACD superior ao IT / INTRODUCTION: Cervical spinal stenosis is the diminution of the anteroposterior diameter of the spinal canal and it is associated with increased risk of neurological injury from cervical trauma. In collision sports, the cervical canal stenosis is an important parameter in the return to play decision after cervical cord neuropraxia and after some brachial plexus injuries. The methods currently available for evaluation of cervical canal stenosis in athletes are expensive (eg, nuclear magnetic resonance) or imprecise (radiographic methods). This study evaluated a new radiographic method for determination of cervical canal stenosis, comparing it to measurements performed on cadavers, measurement by magnetic resonance imaging of the cervical canal and space available for the cord (SAC/SACD) and the consecrated radiographic method for determining cervical spinal stenosis, Torg ratio(TI). METHODS: The study population were 20 men between 16 and 35 years. The subjects underwent a magnetic resonance imaging of the cervical spine to determine the SAC/SACD and cervical radiographs to determine the IT and the proposed new radiographic method, called corrected cervical canal diameter (DCCC). To determine the DCCC, a 100 mm metal bar was used vertically over the cervical midline, using the spinous processes of the cervical vertebrae as reference. Got the radiographic diameter of the medullary canal and the length of the metal bar image on the radiograph , and knowing the actual size of the metal bar , the actual diameter of the spinal canal could be estimated mathematically with the simple use of the theorem of Thales. The results for the DCCC were compared with values found in cadavers studies, the agreement between DCCC and the mid-sagittal diameter of the cervical canal measured by magnetic resonance imaging (DCRM) was calculated and radiographic methods (DCCC and IT) were correlated with SAC/SACD. Calculations were performed individually for C3 to C7 and averages of C3 to C6 [DCCC (MDCCC), IT (MTorg) and SAC/SACD (MSAC/ MSACD)]. RESULTS: The values obtained by DCCC (average MDCCC: 15:29 mm) were consistent with the values described in studies using direct measurement. The correlation between DCCC and SAC/SACD was higher than the correlation between IT and SAC/SACD, being 0.7025 for MDCCC and MSACD and 0.5473 for MTorg and MSACD. The agreement between absolute values for DCCC and DCRM showed higher values for DCCC, which average 1.84 mm greater for MDCCC compared to the average of C3 to C6 for DCRM. CONCLUSIONS: The Fixed Diameter of the Cervical Canal showed similar values to those found in studies with direct measurement from cadavers and correlated with SAC/SACD better than IT