Thesis (MHSc--Health Science) -- Auckland University of Technology, 2005. / Also held in print (xix, 96 leaves, col. ill., 30 cm.) in Akoranga Theses Collection. (T 613.71 DEN)

Identifying potential risk factors that affect slip-induced falls is key to developing effective interventions for reduction of injuries caused by these accidents. Existing epidemiological evidence suggests that localized muscle fatigue might be considered as an intrinsic risk factor that causes lack of balance control leading to falls. The literature on the relationship between localized muscular fatigue of the lower extremity and the gait parameters affecting slip severity is scarce. The purpose of the present study was to examine how lower extremity fatigue (quadriceps) alters gait parameters and increases slip severity. Sixteen healthy young participants were recruited to walk across an unexpected slippery floor in two different sessions (Fatigue and No fatigue). Kinematic and kinetic data were collected using a three-dimensional video analysis system and force plates during both sessions. The gait parameters important in assessing slip severity were compared for the two different sessions to evaluate the effects of fatigue. A repeated measure one-way analysis of variance (ANOVA) and multivariate analysis was employed to predict statistical significance. The results indicated a substantial increase in the heel contact velocity (HCV), required coefficient of friction (RCOF), slip distance II (SDII), peak average knee joint moment during slip recovery (kneemompeak), fall frequency and, a decrease in the transitional acceleration of the whole body COM (TA) in the fatigue session further indicating higher slip severity due to fatigue. In addition, a strong positive correlation was observed between RCOF and HCV, HCV and SDII, and, SDII and kneemompeak. These findings provide new insights into the relationship between localized muscular fatigue and slip initiation/recovery process. The present study concluded that localized muscular fatigue affects the gait parameters and increases slip severity and hence can be considered as a potential risk factor for slip-induced falls. / Master of Science

While amputee gait has been studied in great detail, the influence of prosthetic foot sagittal and coronal plane stiffness on amputee walking biomechanics is not well understood. In order to investigate the effects of sagittal and coronal plane foot stiffness on amputee walking, a framework for manipulating the stiffness of a prosthetic foot needs to be developed. The sagittal and coronal plane stiffness of a low profile carbon fiber prosthetic foot was manipulated through coupling with selective-laser-sintered prosthetic ankles. The carbon fiber foot provided an underlying non-linear stiffness profile while the ankle modified the overall stiffness of the ankle-foot combination. A design of experiments was performed to determine the effect of four prosthetic ankle dimensions (keel thickness, keel width, space between the ankle top and bottom faces, and the location of the pyramid connection) on ankle-foot sagittal and coronal plane stiffness. Ankles were manufactured using selective laser sintering and statically tested to determine stiffness. Two of the dimensions, space between the ankle top and bottom faces and the location of the pyramid connection, were found to have the largest influence on both sagittal and coronal plane stiffness. A third dimension, keel thickness, influenced only coronal plane stiffness. A number of prosthetic ankle-foot combinations were created that encompassed a range of sagittal and coronal plane stiffness levels that were lower than that of the low profile carbon fiber foot alone. To further test the effectiveness of the framework to manipulate sagittal and coronal plane stiffness, two ankle-foot combinations, one stiffer than the other in the sagittal and coronal planes, were used in a case study analyzing amputee walking biomechanics. Differences in stiffness were large enough to cause noticeable changes in amputee kinematics and kinetics during turning and straight-line walking. Future work will expand the range of ankle-foot stiffness levels that can be created using this framework. The framework will then be used to create ankle-foot combinations to investigate the effect of sagittal and coronal plane stiffness on gait mechanics in a large sample of unilateral transtibial amputees. / text

Idiopathic congenital clubfoot can be treated either operatively (comprehensive surgical release (CSR)) or conservatively (ponseti technique (PCT)). This thesis compared the mid-term outcomes after CSR and PCT treatments to a typically developing sample. A Dynamical Systems Analysis (DSA) approach and a multi-segment foot model were used to examine group differences in multi-segment foot and lower extremity kinematics, kinetics, coordination and coordination variability during walking. Ten children with clubfoot treated with PCT and seven children with clubfoot treated with CSR were evaluated retrospectively and compared to ten typically developing children. Multi-segment foot and lower extremity kinematic (240 Hz) and kinetic (1080 Hz) data were collected while participants walked barefoot at a fixed walking velocity (1.0 m/s-1 ±5%). Sagittal plane metatarsophalangeal (MTP) and three-dimensional (3D) forefoot-rearfoot, ankle, knee and hip joint range of motion (ROM) during stance and 3D ankle, knee and hip peak joint moments during push-off were calculated. A modified vector coding technique was used to quantify the multi-segment foot and lower extremity coordination and coordination variability throughout stance for forefoot-rearfoot inversion/eversion (Ff-Rf), rearfoot inversion/eversion–tibial internal/external rotation (Rf-Tib) and femur-tibia internal/external rotation (Fem-Tib) couples. Reduced MTP and forefoot-rearfoot ROM was observed in the CSR group while the PCT group demonstrated values comparable to CTR. Sagittal plane ankle ROM was similar between groups however, the CSR group demonstrated reduced frontal plane ROM compared to PCT. Peak ankle plantar flexion moment was reduced in the last 50% of stance in the clubfoot groups. The CSR group demonstrated greater knee and hip moments compared to CTR and PCT. The PCT group demonstrated lessor peak ankle eversion, knee external rotation and knee valgus moments compared to CTR. No significant differences were observed in Ff-Rf, Rf-Tib and Fem-Tib coordination and coordination variability throughout stance between the groups. PCT and CSR gait was characterized by restricted multi-segment foot motion and abnormal lower extremity joint moments; suggesting mild residual deformity. Despite residual deformity, the coordination and coordination variability results indicate that the PCT and CSR groups are not functionally limited and demonstrate similar multi-segment foot and lower extremity movement patterns as CTR.