Relationship between ankle-foot-complex mobility during static loading and frontal moment impulses of knee and hip joints during the stance phase.

BACKGROUND: Ankle-foot-complex mobility impairments, which can be assessed by the difference between the sitting and standing positions, are related to an increase in the load on the knee and hip joints during the stance phase of the gait. RESEARCH QUESTION: What is the relationship between the ankle-foot-complex mobility during static weight bearing and the mechanical stresses on the knee and hip joints throughout the stance phase? METHODS: Ankle-foot-complex mobility and gait data were collected from 26 healthy adults. The complex mobility was established by comparing the foot indices, measured using a three-dimensional foot scanner, in sitting and standing positions. The gait data were acquired using eight cameras (recording at 100 Hz) and three force plates (recording at 1000 Hz). Stance phase data were collected via ground reaction forces. The stance phase was dissected into shock absorption and propulsion phases, during which the external knee and hip adduction moment impulses (KAMi, HAMi) were recorded. The correlation between the ankle-foot-complex mobility during static weight bearing and KAMi and HAMi during the stance phase was examined using Pearson's product-moment correlation coefficients. RESULTS: This study revealed that KAMi correlated with medial malleolus mobility (r = -0.44) throughout the stance phase. Furthermore, in the propulsive phase, KAMi correlated with calcaneus (r = 0.51) and navicular (r = -0.50) mobilities, whereas HAMi correlated with calcaneus mobility (r = -0.40). SIGNIFICANCE: The study provides insights into the relationship between the static mobility of the ankle-foot complex in healthy individuals and mechanical stress during the stance phase. Calcaneus and navicular mobilities were related to efficient push-off in the propulsive phase. Medial malleolus mobility was related to the control of the lateral tilt of the lower limb and ankle dorsiflexion motion throughout the stance phase.

Examination of body static rotation related to step length asymmetry: biomechanics of the thorax and pelvis.

[Purpose] This study determined whether the results of the mobility assessment of pelvic and thoracic rotation (static evaluation), which is often used in clinical settings, are related to step length asymmetry. Moreover, we identified the postural evaluation of rotation that may be related to gait asymmetry. [Participants and Methods] We hypothesize that a certain relationship exists between the static assessments of pelvic rotation and step length asymmetry. Fifteen healthy adult males participated in static posture and gait motion analyses using a motion-capture system. The static evaluation was analyzed using three parameters: pelvic rotation in standing, pelvic rotation with kneeling, and thorax rotation in sitting. [Results] The relationship between the asymmetric variables obtained from static evaluation and gait observations demonstrated a significant correlation. The asymmetric variables of step length and asymmetric variables of thorax rotation in sitting showed a significant relationship. Furthermore, significant correlations were found between asymmetric variables of pelvic rotation during gait and asymmetric variables of step length and between asymmetric variables of pelvic rotation during gait and asymmetric variables of thorax rotation in sitting. [Conclusion] This study revealed asymmetric relationships between thorax rotation in sitting test and step length asymmetry in the gait. Asymmetry in the thorax rotation in sitting may be caused by a gait with biased pelvic rotation.