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.

Centroid position estimating method for observational analysis.

[Purpose] This study aimed to develop a clinical observation method to evaluate the position of the mass center. From the human visual capability, we considered it would be practical to divide the body into two parts: the upper and the lower body mass. If we could identify their optimal position, we could observe the middle point in between as the center of mass. [Participants and Methods] Twenty healthy males performed forward bending, backward bending, squatting, and walking. The three-dimensional coordinates were analyzed using a conventional model. In addition, five "virtual" markers were assigned as upper and lower mass, respectively. The midpoints of each five virtual marker combinations defined the mass centers, providing 25 coordinates. We calculated the difference in the coordinates between mass centers from virtual markers and mass centers using a conventional model. The combination with the slightest error was evaluated to determine the 95% confidence interval of the observed points and whether the value was clinically beneficial. [Results] The optimal combination of the upper and lower mass was Th8 and in the middle of both hip and knee centers. [Conclusion] The overall magnitude of error was about 30 mm and enough to evaluate the center of mass with macroscopy.

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.

The interrelationship between three-dimensional foot mobility and bodyweight bearing.

[Purpose] To clarify the three-dimensional nature of foot mobility and its interrelationships within the foot due to bodyweight bearing. [Participants and Methods] Data regarding left foot mobility due to body weight bearing were collected from 31 healthy adults. Foot shape differences while sitting and standing, and their interrelationship were examined. The same examiner reapplied the landmark stickers when misaligned during measurement position changes. [Results] The foot length, heel width, forefoot width, hallux valgus angle, and calcaneus eversion angle were significantly larger in the standing than in sitting position. The digitus minimus varus angle was significantly smaller in the standing than in sitting position. The medial and lateral malleoli, navicular, and dorsum of the foot were displaced medially and inferiorly; the other indices, except for the midfoot, were displaced anteriorly. The interrelationships within the foot showed a positive correlation between the calcaneus eversion angle and the medial displacement of the medial and lateral malleoli, navicular, and dorsum of the foot points. There was a negative correlation between the calcaneus eversion angle and inferior displacement of the medial malleolus, navicular, and dorsum of the foot. [Conclusion] The intra-foot coordination relationship in response to bodyweight bearing was clarified.

Characteristics of the scapula movement during shoulder elevation depend on posture.

[Purpose] This study aimed to clarify the differences in scapular movement during flexion and abduction of the shoulder joint with different postures. [Participants and Methods] This study included 15 male participants. Their shoulder flexion and abduction and angles of the scapular upward rotation, scapular anterior tilt, scapular external rotation, and thoracic spine flexion were measured. Measurements were taken in three positions: the control, thoracic spine flexion, and thoracic spine extension positions using a three-dimensional motion capture system. [Results] In the shoulder flexion, the amount of change in the scapular external rotation was significantly greater in the thoracic flexion than in the thoracic extension. In shoulder abduction, the amount of change in the scapular anterior tilt and external rotation was significantly greater in the thoracic flexion than in the thoracic extension. A comparison of the scapular angles in shoulder flexion and abduction showed that the upward rotation, posterior tilt, and external rotation were significantly greater in abduction than flexion. [Conclusion] To avoid posture-induced incoordination of the scapula and thorax movement during shoulder elevation, postural adjustment of the thoracic spine based on the movements is necessary for the shoulder joint exercises.

Evaluation of the relationship between the static measurement of transverse arch flexibility of the forefoot and gait parameters in healthy subjects.

[Purpose] To investigate the relationship between the static measurement of the transverse arch of the forefoot, using a 3-dimensional (3D) foot scanner, and kinetics and kinematics of gait parameters in the sagittal plane. [Subjects and Methods] Twenty healthy subjects participated in this study. The transverse arch of the forefoot was measured under three conditions as follows: condition 1, sitting; condition 2, standing; and condition 3, foot forward and lower leg tilting anteriorly to the maximum position with heel contact. Gait parameters were recorded using a 3D motion analysis system and force plate. Correlation coefficients between TAF for each comparison of conditions and gait parameters were calculated using the Spearman correlation analysis. [Results] Rates of the transverse arch of the forefoot width and height between condition 2 and condition 3 were significantly correlated with the anterior and posterior component of ground reaction forces, the hip joint extension angle, and the ankle plantar flexion moment. [Conclusion] Our study's findings indicated that increased stiffness of the transverse arch of the forefoot was related to the increase in ankle plantar moment, and decreased stiffness of the transverse arch of the forefoot was related to the increase in hip joint extension angle during gait.

The effects of new taping methods designed to increase muscle strength.

[Purpose] Although there are several studies on the use of elastic tape to influence muscle strength, results are contradictory and controversial. Our previous studies based on the sliding mechanism between superficial fascia and subcutaneous tissue may help the muscle strength. The purpose of this study was to confirm the effects of new taping methods on muscle strength. [Subjects and Methods] Sixteen healthy male participants took part in this study. Tape was applied on the right gluteus maximus and hip extension strength was determined by an isokinetic evaluation (30°/sec, concentric mode, four conditions). Condition 1: Tape was applied from the muscle insertion to origin; Condition 2: Tape was applied from the origin to insertion; Condition 3: Dummy tape with no direction; Condition 4: No tape was applied. [Results] The mean value of conditions 1-4 were 398.2 ± 24.3 Newton (N), 343.7 ± 25.9 N, 363.7 ± 26.4 N, and 371.3 ± 26.3 N, respectively (mean ± SE). The result of condition 1 was significantly greater compared with the other conditions. [Conclusion] This new method corresponded to a tape direction of insertion-rigin may help to increase the muscle strength.

Ankle, knee, and hip joint contribution to body support during gait.

[Purpose] Support moment was defined as the sum of ankle plantar flexion, knee and hip extension moments. There are some mechanical relationships among the 3 joints. If these relationships were understood, it might be possible to determine which joint should be strengthened to improve gait. The aims of this study were to examine the mutual relationship among kinetic variables of the 3 joints during different phases. [Subjects and Methods] Twenty-five healthy subjects volunteered for this study. They were asked to walk on a platform at a self-selected speed. Correlation coefficients between support moment and vertical ground reaction force were calculated for each subject. Pearson correlation analysis was performed among the 3 joint moments and between each joint moment and vertical ground reaction force. [Results] Knee and hip extension moments showed negative correlation throughout the stance. Ankle moment had a positive with hip but a negative correlation with knee moment except in the initial contact and pre-swing. Hip moment in the initial contact, knee moment in the loading response, and ankle moment from the terminal stance to pre-swing had a high correlation with vertical ground reaction force. [Conclusion] The results may indicate which joint should be strengthened to improve gait pattern.