The Influence of neck muscle characteristics on head kinematics during lateral impacts : a simulation based analysis

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dc.contributor.advisorVan der Merwe, Johanen_ZA
dc.contributor.advisorDe Jongh, Cornelen_ZA
dc.contributor.advisorDerman, Wayneen_ZA
dc.contributor.authorBergh, Oloff Charles Wesselen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Institute of Biomedical Engineering.en_ZA
dc.date.accessioned2023-03-02T08:02:37Z
dc.date.accessioned2023-05-18T07:02:56Z
dc.date.available2023-03-02T08:02:37Z
dc.date.available2023-05-18T07:02:56Z
dc.date.issued2023-03
dc.descriptionThesis (MEngSc)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH SUMMARY: The skull contains the most critical component of the human body, the brain. Large changes in the velocity and acceleration of the skull, specifically in an angular manner, have been associated with an increased risk of concussion or mild traumatic brain injuries. Modifiable risk factors can be defined as intrinsic characteristics that can be altered to decrease the risk of head injury. Previous studies have investigated neck muscle strength as a potential modifiable risk factor in sports research. However, literature appears to be divided regarding the influence of neck muscle strength on head kinematics and injury risk. Additionally, research associated with individuals who demonstrate a decline in neck muscle strength compared to control subjects appears to be scarce, potentially due to ethical concerns. This project aims to contribute to current literature and evaluate the influence of neck muscle characteristics, such as the maximum isometric and eccentric strength, on the kinematics of the skull during laterally induced head collisions through a simulation-based approach. Multibody dynamic computer models were used to determine the influence of neck muscle characteristics on head kinematics and subsequent head injury risks. The models were based on the original Hyoid model in OpenSim by Mortensen, Vasavada and Merryweather (2018), which has been verified and validated against experimental responses with similar total neck muscle strength values. The Normal model in this project demonstrated the same muscle characteristics as the original Hyoid model. The two stronger models, referred to as the Intermediate and Max models, have increases in maximum isometric and eccentric muscle strength compared to the Normal model. The Intermediate model has realistic achievable neck muscle characteristics of an individual who has undergone specific neck training, while the Max model represents a highly trained athlete with significantly strengthened neck musculature. The Decreased model has lower total neck muscle strength compared to the Normal model and is based on the reductions in muscle characteristics of elderly individuals. The static optimization tool within the OpenSim environment was used to determine the optimal muscular activations of the different models. These activations were subsequently used in the forward dynamic tool to determine the influence of the neck muscle characteristics on head kinematics during increasing lateral impacts. The head kinematics were then used to calculate the head injury criterion (HIC15), a commonly used metric to determine the extent of head injuries based on empirical data. The stronger models consistently showed lower head kinematic and HIC15 values compared to the Normal model, while the Decreased model always demonstrated higher kinematics with a greater risk of injury. At a low external force there was a considerable influence of the neck muscle characteristics on head kinematics and injury risk. However, a non-linear trend indicated that the influence of the neck muscles declined as the external force increased. This could indicate that the influence of the neck muscle characteristics might be overshadowed by large external forces, but could still play a role in reducing head kinematics and injury-risk at lower forces.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die skedel bevat die mees belangrikste komponent van die menslike liggaam, naamlik die brein. Groot veranderinge in die snelheid en versnelling van die skedel, spesifiek in rotasie, is geassosieer met 'n verhoogde risiko van harsingskudding of ligte traumatiese breinbeserings. Veranderbare risikofaktore kan gedefinieer word as intrinsieke eienskappe wat verander kan word om die gevare van kopbesering te verminder. Vorige studies het al nekspiersterkte as 'n potensiele veranderbare risikofaktor in sportnavorsing ondersoek. Literatuur blyk egter verdeeld oor die invloed van nekspiersterkte op kopkinematika en beseringsrisiko. Daarbenewens blyk navorsing wat verband hou met individue wat 'n afname in nekspiersterkte in vergelyking met kontrole-persone toon, skaars te wees, moontlik as gevolg van etiese uitdagings. Hierdie projek mik om by te dra tot huidige literatuur en die invloed van nekspier eienskappe, soos die maksimum isometriese en eksentriese sterkte, op die kinematika van die skedel tydens laterale kopbotsings deur middel van 'n simulasie-gebaseerde benadering te evalueer. Multiliggaam dinamiese rekenaarmodelle is gebruik om die invloed van nekspier eienskappe op kopkinematika en daaropvolgende kopbeserings risiko's te bepaal. Die modelle is gebaseer op die oorspronklike Hyoid-model in OpenSim deur Mortensen, Vasavada en Merryweather (2018), wat gestaaf en bekragtig is teen eksperimentele reaksies met soortgelyke totale nekspier sterkte-waardes. Die Normale model in hierdie projek het dieselfde spier eienskappe as die oorspronklike Hyoid-model gedemonstreer. Die twee sterker modelle word na verwys as die Intermediere en Maks modelle, het toenames in maksimum isometriese en eksentriese spierkrag in vergelyking met die Normale model. Die Intermediere model dui realistiese haalbare nekspier eienskappe van 'n individu wat spesifieke nek oefening ondergaan het. Die Maks model verteenwoordig 'n hoogs opgeleide atleet met buitegewone versterkte nekspiere. Die Verlaagde model het laer totale nekspier-sterktes in vergelyking met die Normale model en is gebaseer op die afname in nekspier eienskappe van bejaarde individue. Die statiese optimaliserings instrument binne die OpenSim-sagteware is gebruik om die optimale spieraktiverings van die verskillende modelle te bepaal. Hierdie aktiverings is dan in die voorwaartse dinamiese instrument gebruik om die invloed van die nekspier eienskappe op kopkinematika tydens toenemende laterale impakte te bepaal. Die kopkinematika is dan gebruik om die hoofbeserings kriterium (HIC15) te bereken, 'n algemeen gebruikte maatstaf om die omvang van kopbeserings op grond van empiriese data te bepaal. Die sterker modelle het konstante laer kopkinematiese en HIC15 waardes getoon in vergelyking met die Normale model. Die Verminderde model het altyd hoer kinematika en 'n groter risiko van besering getoon. By 'n lae eksterne krag was daar 'n groot invloed van die nekspier eienskappe op kopkinematika en beserings risiko’s. 'n Nie-lineere neiging het egter aangedui dat die invloed van die nekspiere blyk te daal soos die eksterne krag toeneem. Dit kan aandui dat die invloed van die nekspier eienskappe deur hoer eksterne kragte oorskadu kan word, maar steeds 'n rol kan speel in die vermindering van kopkinematika en beseringsrisiko by laer kragte.af_ZA
dc.format.extentxiii, 121 pages : illustrations
dc.identifier.urihttp://hdl.handle.net/10019.1/127073
dc.language.isoen_ZAen_ZA
dc.subject.lcshNeck -- Wounds and injuriesen_ZA
dc.subject.lcshHead -- Wounds and injuriesen_ZA
dc.subject.lcshNeck -- Musclesen_ZA
dc.subject.lcshMuscle strengthen_ZA
dc.titleThe Influence of neck muscle characteristics on head kinematics during lateral impacts : a simulation based analysisen_ZA
dc.typeMastersen_ZA
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