Limited knowledge of the neuromechanical response to use of an ankle foot orthosis-footwear combination (AFO-FC) has created a lack of consensus in understanding orthotic motion control as a therapeutic treatment. Lack of consensus may hinder the clinician’s ability to target the motion control needs of persons with movement impairment (e.g., peripheral nerve injury, stroke, etc.). Some evidence suggests a proportional relationship between joint motion and neuromuscular activity based on the notion that use of lower limb orthoses that constrain joint motion may invoke motor slacking and decreasing levels of muscle activity. Use of AFO-FCs likely alters the biomechanical and neuromuscular output as the central control system gradually forms new movement patterns. If there is proportional relationship between muscle activation and joint motion, then it could be examined by quantifying joint motion and subsequent neuromuscular output. Considering principles of neuromechanical adjustment, my general hypothesis examines whether orthotic control of lower limb motion alters neuromuscular output in proportion to the biomechanical output as a representation of the limb’s dynamics are updated by the neural control system. The rationale for this approach is that reference knowledge of the neuromechanical response is needed to inform clinicians about how a person responds to walking with motion controlling devices such as ankle foot orthoses combined with footwear. In the first line of research, I hypothesize that a newly developed AFO which maximizes leverage and stiffness will constrain the talocrural joint and alter joint kinematics and ground reaction force patterns. To answer the hypothesis, I sampled kinematics and kinetics of healthy subjects’ treadmill walking using an AFO-FC in a STOP condition and confirmed that the AFO substantially limited the range of talocrural plantarflexion and dorsiflexion motion to 3.7° and in a FREE condition maintained talocrural motion to 24.2° compared to 27.7° in a CONTROL (no AFO) condition. A follow up controlled static loading study sampled kinematics of matched healthy subjects limbs and cadaveric limbs in the AFO STOP and FREE conditions. Findings revealed healthy and cadaveric limbs in the AFO STOP condition substantially limited their limb segment motion similar to matched healthy subjects walking in the STOP condition and in the AFO FREE condition healthy and cadaveric limbs maintained similar limb segment motion to matched healthy subjects walking in the FREE condition. In a second line of research, I hypothesize that flexibility of a newly developed footwear system will allow normal walking kinetics due to the shape and flexibility of the footwear. To answer the hypothesis, I utilized a curved-flexible footwear system integrated with an AFO in a STOP condition and sampled kinematics and kinetics of healthy subjects during treadmill walking. Results revealed subjects elicited similar cadence, stance and swing duration and effective leg-ankle-foot roll over radius compared to walking in the curved-flexible footwear integrated with the AFO in a FREE condition and a CONTROL (no AFO) condition. To validate rollover dynamics of the curved-flexible footwear system, a follow up study of healthy subjects’ treadmill walking in newly developed flat-rigid footwear system integrated with the AFO in a STOP condition revealed interrupted leg-ankle-foot rollover compared to walking in curved-flexible footwear in STOP, FREE and CONTROL conditions. In a third line of research, I hypothesize that use of an AFO that limits talocrural motion in a STOP condition will proportionally reduce activation of Tibialis Anterior, Soleus, Medial and Lateral Gastrocnemii muscles compared to a FREE and CONTROL condition due to alterations in length dependent representation of the limb’s dynamics undergoing updates to the central control system that modify the pattern of motor output. To answer the question, the same subjects and AFO-footwear presented in the first two lines of research were used in a treadmill walking protocol in STOP, FREE, and CONTROL conditions. Findings revealed the same subjects and ipsilateral AFO-footwear system presented in Aim 1 exhibited an immediate yet moderate 30% decline in EMG activity of ipsilateral Soleus (SOL), Medial Gastrocnemius (MG) and Lateral Gastrocnemius (LG) muscles in the STOP condition compared to the CONTROL condition. The reduction in EMG activity in ipsilateral SOL, MG and LG muscles continued to gradually decline during 15 minutes of treadmill walking. On the contralateral leg, there was an immediate yet small increase of 1% to 14% in EMG activity in SOL, MG, LG muscles above baseline. After 10 minutes of walking, the EMG activity in contralateral SOL, MG and LG declined to a baseline level similar to the EMG activity in the contralateral CONTROL condition. These collective findings provide compelling evidence that the moderate 30% reduction in muscle activation exhibited by subjects as they experience substantial (85%) constraint of total talocrural motion in the AFO STOP condition is not proportionally equivalent. Further, the immediate decrease in muscle activation may be due to a reactive feedback mechanism whereas the continued decline may in part be explained by a feedforward mechanism. The clinical relevance of these findings suggests that short term use of orthotic constraint of talocrural motion in healthy subjects does not substantially reduce muscle activation. These preliminary findings could be used to inform the development of orthoses and footwear as therapeutic motion control treatments in the development of motor rehabilitation protocols.

Thesis (MScPhysio)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Aim: The aim of the study was to improve understanding of the hip joint kinematics in cricket fast bowlers and to ascertain whether a relationship exists between hip joint biomechanical parameters, including kinematics, ROM characteristics and lumbar symptoms. Study design: A descriptive cross-sectional study was conducted. Participants: Sixteen adult male fast bowlers between the ages of 18 and 40 years old, playing first-club league, were featured in the study. Main outcome measures: To obtain data with regards to the training history, as well as the nature of lumbar-spine symptoms experienced by the cricket fast bowlers, a newly designed questionnaire was compiled. For analysis of the front foot hip joint ROM and kinematics, the biomechanical equipment used included: a two-dimensional Canon MV950 Digital Video Camcorder, a Kodak EasyShare C310 camera and XSENS Motion Tracking equipment (Xsens Technologies B. V., Enschede, Netherlands). Results: Eight of the sixteen bowlers in our study experienced LBP in the season with seven of these bowlers presenting with recent symptoms most of which are experienced after bowling a spell and described as “tightness” or a “stabbing pain” in the lower back. Intensity of LBP ranged between 1/10 to 8/10. Front foot hip joint kinematics of fast bowlers showed highly individualised patterns of movement between different subjects. Medium amplitude movements in the flexion/extension as well as the rotation plane of movement showed a significant difference in bowlers with- and without LBP. No significant differences between groups with LBP and without LBP were found in the three passive hip ROM measurements. Conclusions: It has proved to be very difficult to improve the understanding of the front foot hip biomechanics in cricket fast bowlers due to the high inter-subject variability. Variability in movement patterns remains under-researched by sports biomechanics. Although decreased hip mobility could alter mechanical forces transmitted to the lumbar spine and therefore predispose or be a causative factor in LBP development, this study found no significant relation between these parameters. The sample size was very small in this study which will influence the validity of results. Our study confirmed the high incidence of LBP and preventative efforts for bowlers should therefore be strongly supported. / AFRIKAANSE OPSOMMING: Doelwit: Die doelwit van die studie was om die heupgewrig kinematika van krieket snelboulers beter te verstaan en om vas te stel of daar ‘n verwantskap bestaan tussen heupgewrig biomeganiese parameters, insluitende kinematika, omvang van beweging karakter en lumbale simptome. Studie ontwerp: ‘n Deursneë beskrywende studie is onderneem. Deelnemers: Sestien volwasse manlike snelboulers tussen die ouderdomme van 18 en 40 jaar oud wat eerste liga speel maak deel uit van die studie. Hoof uitkoms maatreëls: ‘n Nuut ontwerpte vraelys is opgestel om data aangaande oefen geskiedenis sowel as aard van lumbale simptome wat deur krieket snelboulers ervaar word in te samel. Die biomeganiese apparaat wat gebruik is vir die analiese van die voorvoet heup omvang van beweging, sowel as die kinematika, sluit in: ‘n twee dimensionele Canon MV950 Digitale Video Camcorder, ‘n Kodak EasyShare C310 kamera en XSENS beweging volgende apparaat (Xsens Technologies B. V., Enschede, Netherlands). Resultate: Agt van die sestien boulers in ons studie het lae rug pyn in die seisoen ervaar. Sewe van die boulers het gepresenteer met onlangse simptome waarvan die meeste na ‘n bouler se boulbeurt ervaar is en beskryf was as ‘n “styfheid” of “steekpyn” in die lae rug. Die intensiteit van die lae rug pyn het gewissel tussen 1/10 en 8/10. Voorvoet heup kinematika van snelboulers het hoogs individualistiese patrone van beweging getoon tussen verskillende deelnemers. Medium amplitude bewegings in die fleksie/ekstensie sowel as die rotasie plein van beweging het ‘n beduidende verskil tussen boulers met- en sonder lae rug pyn getoon. Geen beduidende verskille tussen die groep met- en sonder rugpyn is gevind met die drie passiewe heup omvang van beweging meetings nie. Gevolgtrekkings: Dit blyk baie moelik te wees om die voorvoet heup biomeganika in krieket snelboulers beter te verstaan a.g.v. die hoë inter-deelnemer veranderlikheid. Veranderlikheid in bewegings patrone is nog nie genoeg nagevors deur sport biomeganici nie. Alhoewel ingekorte heup mobiliteit meganiese kragte wat deur die lumbale werwelkolom gaan kan wysig, en sodoende die ontwikkeling van lae rug pyn kan predisponeer of ‘n oorsakende faktor kan wees, het hierdie studie nie ‘n beduidende verwantskap tussen die parameters gevind nie. Die steekproef groote was baie klein en dit sal die geldigheid van die resultate beïnvloed. Ons studie het die hoë insidensie van lae rug pyn bevestig en pogings tot voorkomende maatreëls moet daarom ten sterkste ondersteun word.

Thesis (MScPhysio)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Introduction-Groin injuries are among the top six most cited injuries in soccer and account for 10-18 per cent of all injuries reported in contact sport. Groin pain can result from a variety of pathologies, but according to literature, 63 per cent of groin pain is due to adductor pathology. Objective-The objective of this study was to explore if there are kinematic differences in the hip joint in sports participants with groin pain compared to matched healthy controls. Study design A cross sectional, descriptive study was conducted. Study setting-The study was conducted at the FNB -3D motion analysis laboratory at the University of Stellenbosch, South Africa. Outcome variables-The dependent variables included hip kinematics in the sagittal, frontal and transverse planes at foot strike, lowest vertical point of the pelvis and total range of hip motion during a single leg drop landing. Methodology-The study sample comprised 20 male club level soccer-and, rugby players, running and cycling participants between the ages of 18-55 years of age. Ten of the subjects had chronic groin pain and the other ten were healthy matched controls. An eight-camera Vicon system was used to analyse the kinematics of the hip joint during single leg drop landing. For the purpose of comparison, the data was analysed for participants with unilateral groin pain and matched controls (n=14) and participants with bilateral groin pain and controls (n=6). The full set of data was subdivided for analysis into three distinct sub-groups. Unilaterally injured groin cases (n=7) were matched with seven healthy controls for analysis. Bilaterally injured groin cases (n=3) were matched with three healthy controls. Results-Cases with unilateral groin pain at initial contact had significantly more abduction of the hip joint when compared to controls (p<0.05). The effect size of this difference was large (0.94). Cases with unilateral groin pain also demonstrated greater hip internal rotation while the controls had external rotation (p<0.05) during a drop landing activity. Bilaterally injured groin cases landed with significantly (p=?) greater ranges of hip flexion as well as in significantly (p=?) more hip abduction during a drop landing activity. They also demonstrated greater total range of motion in the frontal plan when compared to controls. Groin pain cases overall demonstrated greater ranges of motion and tended to land in more abduction compared to controls. Conclusion-This study found that during a single leg drop landing, sports participants with unilateral chronic groin pain landed with significantly greater hip abduction and exhibited larger total range of motion in the transverse plane, which may indicate impaired stability of the hip complex when compared to controls. / AFRIKAANSE OPSOMMING: Inleiding-Liesbeserings is een van die top ses mees prominente sokker beserings. Dit beloop 10-18 persent van alle beserings wat in kontaksport aangemeld word. Liespyn kan die gevolg wees van ‘n verskeidenheid patologië, maar volgens die literatuur is 63 persent van liespyn as gevolg adduktor patologie. Doelwitte-Die doelwit van hierdie studie was om ondersoek in te stel of daar enige kinematiese veranderinge in die heupgewrig is in spelers met liespyn in vergelyking met dieselfde vergelykbare spelers sonder liespyn. Studie Ontwerp-‘n Deursnit, beskrywende studie was onderneem. Studie Omgewing-Die studie was uitgevoer by die FNB-3D bewegingsanalise laboratorium van die Stellenbosch Universiteit, Suid-Afrika. Uitkomsveranderlikes-Die afhanklike veranderlikes het in gesluit die heup kinematika in die sagitale, frontale en transvers vlakke met voet kontak endie laagste vertikale punt van die pelvis sowel as die totale heup omvang van beweging gedurende een been landing. Metodologie-Die studie populasie het bestaan uit 20 manlike sokker- en, rugbyspelers, hardlopers en fietsryers tussen die ouderdomme van 18 en 55 jaar. Tien van die deelnemers het kroniese liespyn gehad en die ander tien in die gelyke gesonde groep was sonder liespyn. Die agt kamera Vicon sisteem was gebruik om die kinematika van die heupgewrig te analseer tydens een been landing. Vir die doel om ‘n vergelyking te kan maak, was die data geanaliseer van deelnemers met unilaterale liespyn en die vergelykende groep sonder liespyn (n=14) en deelnemers met bilaterale liespyn en hulle vergelykende groep sonder liespyn (n=6).. Die volledige stel data was onderverdeel in drie afsonderlike sub groepe. Vir die analiese was unilaterale liesbeserings (n=7) vergelyk met sewe deelnemers sonder liespyn in die kontrolegroep. Deelnemers met bilaterale liesbeserings (n=3) was vergelyk met drie in die kontrolegroep. Resultate-Die deelnemers met unilaterale liespyn het met eerste kontak beduidend meer abduksie van die heupgewrig gehad in vergelyking met die kontrolegroep (p<0.05). Die effek van hierdie verskil was groot (0.94). Die deelnemers met unilaterale liespyn het ook ‘n grooter interne rotasie getoon, terwyl die kontrole groep meer eksterne rotasie gedemonstreer het (p<0.05) met landing. Deelnemers met bilaterale liespyn het beduidend (p=?) meer heup fleksie en abduksie omvang van beweging tydens landing. Hulle het ook ‘n groter totale heup omvang van beweging in die frontale vlak gehad in vergelyking met die kontrolegroep. Deelnemers met liespyn het oor die algemeen ‘n grooter omvang van beweging getoon, en was geneig om met meer abduksie van die heup te land as die kontrolegroep. Gevolgtrekking-Die studie toon dat deelnemers met kroniese unilaterale liespyn, tydens een been landing, beduidende meerheup abduksie toon en dat die heup in die transverse vlak meer totale omvang van beweging gebruik wat kan dui op onstabiliteit in die heupkompleks in vergelyking met die kontrolegroep.

For a general J wheeled mobile platform capable of up to 3-Degrees-Of-Freedom (DOF) planar motion, there are up to 2J independent input parameters yet the output of the planar platform is specified with only three independent parameters. Currently, the motion synthesis for such platforms is done with a Jacobian based “pseudo” inverse that uses a rectangular matrix for Jacobian. However, a mobile platform is a parallel mechanism and has a more direct solution to the inverse kinematics problem. To this effect, we propose a physical methodology for kinematic modeling of multi-wheeled mobile platforms using Instant Centers (IC) to describe the kinematic state of all system points up to the kth order using a generalized algebraic formulation. This is achieved by using a series of ICs (velocity, acceleration, jerk, etc.) where each point in the system has a time state with its magnitude proportional to the radial distance of the point from the associated IC and at a constant angle relative to that radius. The use of IC’s for mobile platform kinematics is not new, however we present a completely generalized and extensive formulation that also treats the higher order kinematics. To the best of our knowledge, this is the first time the third and higher order ICs have been presented in the literature. The components of this research effort are: (i) extension of the theory of instantaneous invariants to the higher order motion by generalizing the theory to any order, (ii) studying some special case 1-DOF, 2-DOF motions to understand the physical nature of the higher order ICs, (iii) applying the results of (i) and (ii) to the motion synthesis of planar, wheeled mobile platforms by first categorizing them into four distinct categories, and (iv) studying the dynamic model of a representative mobile platform to emphasize the importance of wheel dynamics and traction parameters on the performance of the mobile platform. The IC based formulation presents a concise expression for a general order time state of a general point on the rigid body with the magnitude and direction separated and identified. We showed that the method based on instant centers provides a straightforward and yet physically intuitive way to synthesize a general kth order planar motion of mobile platforms. The study of special case 1-DOF/2-DOF motions emphasized the geometric nature of the higher order ICs and also helped understand the influence of instantaneous kinematic states (such as angular velocity _, angular acceleration, _, etc.) on the various ICs. The application of this theory to planar mobile platform allowed us to categorize the platforms based on their dexterity and to generalize the motion synthesis to some extent. The study of the dynamic model of a representative mobile platform showed us that the redundant inputs (2J inputs versus 3 outputs) in this case may be employed to sustain and manage the uncertainties and nonlinearities in the wheel ground interaction. / text

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L'épaule est souvent affectée par des troubles musculo-squelettiques. Toutefois, leur évaluation est limitée à des mesures qualitatives qui nuisent à la spécificité et justesse du diagnostic. L'analyse de mouvement tridimensionnel pourrait complémenter le traitement conventionnel à l'aide de mesures quantitatives fonctionnelles. L'interaction entre les articulations de l'épaule est estimée par le rythme scapulo-huméral, mais la variabilité prononcée qu'il affiche nuit à son utilisation clinique. Ainsi, l'objectif général de cette thèse était de réduire la variabilité de la mesure du rythme scapulo-huméral. L'effet de la méthode de calcul du rythme scapulo-huméral et des conditions d'exécution du mouvement (rotation axiale du bras, charge, vitesse, activité musculaire) ont été testées. La cinématique des articulations de l'épaule a été calculé par chaîne cinématique et filtre de Kalman étendu sur des sujets sains avec un système optoélectronique. La méthode usuelle de calcul du rythme scapulo-huméral extrait les angles d'élévation gléno-humérale et de rotation latérale scapulo-thoracique. Puisque ces angles ne sont pas co-planaires au thorax, leur somme ne correspond pas à l'angle d'élévation du bras. Une nouvelle approche de contribution articulaire incluant toutes les rotations de chaque articulation est proposée et comparée à la méthode usuelle. La méthode usuelle surestimait systématiquement la contribution gléno-humérale par rapport à la méthode proposée. Ce nouveau calcul du rythme scapulo-huméral permet une évaluation fonctionnelle dynamique de l'épaule et réduit la variabilité inter-sujets. La comparaison d'exercices de réadaptation du supra-épineux contrastant la rotation axiale du bras a été réalisée, ainsi que l'effet d'ajouter une charge externe. L'exercice «full-can» augmentait le rythme scapulo-huméral et la contribution gléno-humérale ce qui concorde avec la fonction du supra-épineux. Au contraire, l'exercice «empty-can» augmentait la contribution scapulo-thoracique ce qui est associé à une compensation pour éviter la contribution gléno-humérale. L'utilisation de charge externe lors de la réadaptation du supra-épineux semble justifiée par un rythme scapulo-huméral similaire et une élévation gléno-humérale supérieure. Le mouvement de l'épaule est souvent mesuré ou évalué en condition statique ou dynamique et passive ou active. Cependant, l'effet de ces conditions sur la coordination articulaire demeure incertain. La comparaison des ces conditions révélait des différences significatives qui montrent l'importance de considérer les conditions de mouvement pour l'acquisition ou la comparaison des données. / The shoulder is often afflicted by musculo-skeletal diseases. However, shoulder evaluation is limited to qualitative measures affecting the specificity and accuracy of diagnosis. Three-dimensional motion analysis could complement conventional treatment with quantitative functional measures. The interaction between shoulder joints is estimated by the scapulo-humeral rhythm, but its pronounced variability of measurement ampers appropriate clinical use. Hence, the main objective of the thesis was to reduce the variability in the measure of the scapulo-humeral rhythm. The effect of the calculation method and conditions of motion (arm axial rotation, load, velocity, muscular activity) were tested on healthy subjects. Shoulder joints kinematics were obtained with an optoelectronic system using a kinematical chain and an extended Kalman filter. The common method of scapulo-humeral rhythm calculation extracts the angles of gleno-humeral elevation and scapulo-thoracic lateral rotation. Since these angles are not co-planar, their sum does not correspond to the arm elevation angle. A novel approach of joint contribution including all the rotations of each joint was developed and compared to the common method. The common method systematically overestimated gleno-humeral contribution in comparison to the proposed method. The new scapulo-humeral rhythm calculation allows a dynamic functional evaluation of the shoulder and reduces inter-subject variability. Shoulder coordination was compared on typical supraspinatus rehabilitation exercises contrasting in arm axial rotation, and the effect of adding external load was tested. The ''full-can'' exercise increased the scapulo-humeral rhythm and gleno-humeral contribution, which correspond to supraspinatus function. In contrast, the ''empty-can'' exercise increased scapulo-thoracic contribution, which is associated to compensation to avoid gleno-humeral contribution. The use of external load in supraspinatus rehabilitation seems justified by a similar scapulo-humeral rhythm and superior gleno-humeral elevation. Shoulder motion is often measured or evaluated in static or dynamic and passive or active conditions. However, the effect of these conditions on shoulder coordination remains uncertain. The comparison of these conditions revealed significant differences on shoulder kinematics showing the importance to consider conditions of motion for acquisition or comparison of data.

Différents dessins d’implants de prothèse totale de genou (PTG) sont utilisés en pratique clinique et chacun présente des caractéristiques biomécaniques spécifiques. Aucun implant n’a réussi à ce jour à reproduire parfaitement la biomécanique du genou naturel. Les objectifs de cette étude sont de comparer les résultats cliniques et biomécaniques tridimensionnels (3D) de deux types de PTG chez le même patient, puis de comparer la cinématique des PTG à celle d’un groupe de genoux asymptomatiques. Une cohorte de quinze patients avec un implant traditionnel dans un genou et un implant de nouvelle génération permettant un pivot dans le genou contralatéral a été étudiée. Le groupe contrôle était composé de trente-cinq genoux asymptomatiques. L’analyse de la cinématique 3D a été réalisée avec l’outil KneeKG (Emovi Inc. Canada) lors de la marche sur tapis roulant. L’évaluation clinique comprenait l’amplitude de mouvement ainsi que les questionnaires de perception articulaire, KOOS, Womac et SF-12. La comparaison de la cinématique des deux types de PTG a démontré quelques différences statistiquement significatives dans les plans sagittal et frontal alors que la comparaison des PTG et des genoux asymptomatiques a révélé plusieurs différences significatives dans les trois plans. Les scores cliniques des deux PTG ne comportaient pas de différence significative. Dans notre cohorte de patients, le design de l’implant a eu peu d’influence sur les résultats biomécaniques et cliniques. Les PTG n’ont pas reproduit une cinématique normale de genou. Beaucoup de travail et de recherche dans le développement de nouveaux implants sont encore nécessaires afin d’améliorer les résultats cliniques et de mieux reproduire la cinématique du genou naturel. / Various implants of total knee arthroplasty (TKA) are used in clinical practice and each presents specific biomechanical characteristics. No implant managed this day to reproduce perfectly the biomechanics of the natural knee. The objectives of this study are to compare the clinical and tridimensional (3D) biomechanical data of two different designs of TKA on the same patients and to compare the resulting 3D biomechanical data with those of asymptomatic knees. A cohort of fifteen patients with a traditional implant in one knee and an implant of new generation allowing a pivot in the contralateral knee was studied. The control group was composed of thirty-five asymptomatic knees. Assessment of 3D knee kinematics analysis was realized with the KneeKG (Emovi Inc. Canada) during treadmill gait. Clinical evaluation included range of motion as well as questionnaires of joint perception, KOOS, Womac and SF-12. Results showed some statistically significant differences in knee 3D kinematics of both TKAs in sagittal and frontal planes while comparison between TKAs and asymptomatic knees revealed several significant differences in all three planes. Clinical scores of both TKAs did not have significant difference. In our cohort of patients, TKA implant design had few measurable influences on kinematics during gait and on clinical results. TKA with these implants did not reproduce natural knee kinematics during gait. Significant research and development in new TKA designs are needed to improve clinical scores and reproduce natural knee kinematics.

Turning while walking is a crucial component of locomotion; yet, little is known about how the biomechanics of turning gait differ from those of straight walking. Moreover, it is unclear how populations with restricted gait ability, such as children with cerebral palsy (CP) adapt to turning, compared to their typically developing (TD) peers. Thus, the aims of this thesis were to quantify the biomechanical differences between turning gait and straight walking in TD children and to explore if further, pathology specific, changes present during turning in children with CP. Biomechanical data, including three-dimensional body motion, ground reaction forces, and muscle activity from both groups were collected during straight walking and 90 degree turning gait using motion capture technology. Experimental data were used to compute joint kinematics (angles) and joint kinetics (moments and power) as well as more novel measures to quantify turning fluency and dynamic stability. These data were also used to derive walking simulations using a musculo-skeletal model of the human body in order to quantify muscle contributions to medio-lateral center of mass (COM) acceleration. The results show that both groups preferred to redirect their body during turning about the inside, rather than the outside, limb (with respect to the turn center). For TD children, substantial biomechanical adaptations occurred during turning, compared to straight walking. Furthermore, turning gait simulations reveal that proximal (hip abductors) and distal (ankle plantarflexors) leg muscles were mainly responsible for the redirection of the COM towards the new walking direction during turning. For children with CP, the results suggest that turning gait may be better able to reveal gait abnormalities than straight walking for a number of kinematic and kinetic gait variables. Potentially, analysis of turning gait could improve the identification and management of gait abnormalities in children with CP.