Task Specificity Of Obstacle Negotiation In Individuals With Low Bone Mineral Density

Abstract

PURPOSE: Research has previously provided conflicting evidence on the relationship between bone mineral density (BMD), and joint loading. We sought to distinguish the relationships between hip joint moments during locomotion, obstacle negotiation, and bone mineral density of the proximal femur as well as clarify the moderating role of body mass on the relationships between hip joint moments during locomotion, obstacle negotiation, and bone mineral density of the proximal femur. METHODS: Forty women (57 + 7.9 years; height of 162 + 8.62 cm; weight of 81.21 + 19.32 kg) participated in this study. A DEXA scan and a series of randomized gait trials and obstacle negotiation gait trials at two obstacle heights (10” and 20”) were completed. Full-body motion was captured using the Vicon 460 motion measurement system. Analyses were performed to determine the significance between BMD and hip joint moments across normal and osteopenic/osteoporotic groups, independently for normal and obstacle negotiation gait. Pearson correlation coefficients were calculated, with and without allometric scaling procedures to determine the extent to which hip joint moments and BMD of the proximal femur, during normal gait and two obstacle negotiation heights, were influenced by body mass. Analysis was performed to determine the significance between BMD and hip joint moments across normal and osteopenic/osteoporotic groups. RESULTS: The results suggested a significantly negative relationship between hip joint moments and obstacle height in osteopenic/osteoporotic subjects (p < .05), while no significant relationships were found in healthy subjects. Average hip joint moments (flexion/extension) of osteopenic/osteoporotic subjects were 1.32 (Nm/Kg) in flat walking, 0.97 (Nm/Kg) at the low obstacle height and, 0.71 (Nm/Kg) at the low obstacle height. Healthy subjects’ average hip joint moments(flexion/extension) were 1.46 (Nm/Kg) in flat walking, 1.38 (Nm/Kg) at the low obstacle height and, 1.34 (Nm/Kg) at the low obstacle height. CONCLUSIONS: The results support a significant relationship between BMD and joint moment loading (internal rotation) specifically during high obstacle negotiation. Further efforts are needed to help further clarify the literature.