Fatores do quadril e do pé relacionados com a pronação do pé na marcha e na postura ortostática

Abstract

Changes in the magnitude of foot-ankle pronation in walking and standing posture are related to several musculoskeletal disorders of the lower limbs and trunk. Furthermore, the magnitude of pronation is influenced by several biomechanical factors of the hip (proximal) and the foot-ankle (distal). The general objective of this thesis was to investigate the interactions between proximal and distal biomechanical factors on the magnitude of pronation in walking and standing posture. The first study investigated non-linear interactions between proximal and distal factors, which predict greater and lower peak and excursion of pronation during walking. Fifty-one women were divided using the 45th and 55th percentiles and categorized with greater and lower pronation during the stance phase of walking. The pronation was measured by to variables: peak and excursion. The predictors used were eccentric strength of the hip external rotators, hip passive stiffness to internal rotation, varus foot-ankle alignment, and foot abduction angle at initial walking contact. The interactions between varus alignment, hip passive stiffness and foot abduction angle were able to predict different profiles of greater and lower pronation peak. The interactions between the strength of the hip external rotators and varus alignment were able to predict different profiles of greater and lower pronation excursion. Both peak and excursion models had a sensitivity of 61% and 78%, specificity of 96% and 83%, and total prediction of 78% and 80%, respectively. The second study investigated the influence of increasing hip passive torque to internal rotation (proximal factor), achieved through a hip and trunk muscle strengthening program, on lower limb standing posture, including foot-ankle pronation, in women with greater and lower varus alignment of the foot-ankle (distal factor). Fifty women were divided into control and intervention groups and subdivided through the 50th percentile into subgroups of greater and lower varus alignment. The intervention subgroups performed hip and trunk muscle strengthening for eight weeks and the control subgroups maintained their usual activities. The intervention group showed an increase in the hip passive torque to internal rotation movement, regardless of varus alignment (P=0.001). However, only the intervention subgroup with lower varus alignment reduced pronation in the standing posture (P=0.02). The other subgroups did not present this postural change. The studies presented in this thesis indicated that proximal and distal biomechanical factors can interact and influence the magnitude of pronation in walking and standing posture.