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Purpose: The purpose of the present study was to examine the degree of stretching (%) that is applied to each of the tendon fiber bundles that compose the Achilles tendon (AT) by twist type when the calcaneus is pronated or supinated. Methods: Three AT twist types (least, moderate, extreme twists), one for each type were investigated. Using the MicroScribe system, the AT and the calcaneal tuberosity were digitized to reconstruct three-dimensional models. Using this system, the calcaneus rotations in the pronation (20°) and supination (20°) directions were simulated, and the degrees of stretching (%) of each tendon were calculated. Results: For all twist types, when the calcaneus was pronated, the medial head of the gastrocnemius (MG) and lateral head of the gastrocnemius (LG) shortened and the soleus muscle (Sol) stretched, and when supinated, MG and LG stretched and Sol shortened. In particular, severe twist type had the largest degree of stretching of Sol when the calcaneus was pronated (Type I: 1.7% ± 3.4%, Type II: 2.4% ± 1.4%, Type III: 3.7% ± 6.0%), and furthermore, each tendon fiber composing Sol had different degrees of stretching. Conclusions: The study results suggest that the degree of stretching applied within the AT with calcaneus pronation is not constant, and that, especially in Type III twists, the risk of developing AT disorders may increase. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a numerical simulation procedure of moored ship motions due to initial attack of large-scaled tsunamis and investigate the effects on the motions and mooring loads. The effect of methodology on selection of tsunami wave components and of the drag forces are then considered by using the numerical simulation method, applying to several case studies for LNG-carrier. Large ship motions and excessive mooring loads beyond the safe working loads are induced by the resonant tsunami wave components in the sway and surge motions and drag forces. [Copyright &y& Elsevier]

Purpose: Patellofemoral pain syndrome is a common orthopedic trauma among runners. It is unclear whether patellofemoral joint stress (PFJS) is the highest (or lowest) when the knee joint flexion angle and extension moment are in combination under the condition that vastus medialis (VM) activation decreases. This study aimed to investigate the effects of changes in the PFJ contact area by decreasing the activation of the VM muscle on PFJS. Methods: A PFJ sagittal model was used to quantify PFJ reaction force and PFJS. The PFJ model and mathematical modelling procedure were used to quantify PFJS based on previous studies. The simulation ranges were set to knee joint flexion angles of 10-45° and extension moments of 0-240 Nm. PFJS was calculated for the normal condition (NC) and decrease condition (DC) in VM activation. Results: When the knee joint angle and knee joint moment were at the maximum, the PFJS showed the maximum value under both conditions (NC; 14.9 N/cm², DC; 16.4 N/cm²). PFJS was found to be higher in DC than that in NC for all simulation ranges. Conclusion: Decreased VM activation may be involved in the mechanism of patellofemoral pain syndrome. In addition, the results of this study provide evidence that clinicians can enhance VM to relieve pain in patients with patellofemoral pain syndrome. [ABSTRACT FROM AUTHOR]

Purpose: Females are two times as likely to experience patellofemoral pain syndrome (PFPS) than males, however, the reason for this difference between sexes remains unclear. Patellofemoral joint (PFJ) stress is believed to contribute to PFPS alterations through knee joint rotation alignment, but the influence of knee joint rotation conditions on PFJ stress is unclear. We aimed to investigate the influence of sex and knee joint rotation alignment on PFJ stress. Methods: Simulation ranges were set to knee joint flexion angles of 10--45° (common to both sexes) and extension moments of 0--240 Nm (males) and 0--220 Nm (females). The quadriceps force and effective lever arm length at the quadriceps muscle were determined as a function of the knee joint flexion angle and extension moment. The PFJ contact area, which is specific to sex, and knee joint rotation were calculated from cadaver data, and PFJ stress was estimated. Results: In all knee joint rotation conditions, PFJ stress was higher in females than in males. Additionally, PFJ stress in males and females was the largest under neutral conditions compared with other rotation conditions. Conclusion: The results of the present study may be useful for understanding the underlying mechanisms contributing to the differences in PFPS in males and females. [ABSTRACT FROM AUTHOR]

Background: Examining coordination between segments is essential for prevention and treatment of injuries. However, traditional methods such as ratio, cross-correlation technique, and angle-time plot may not provide a complete understanding of intersegmental coordination. The present study aimed to quantify the coordination among the rearfoot, midfoot, and forefoot segments during walking. Methods: Twenty healthy young men walked barefoot on a treadmill. Reflective markers were fixed to their right shank and foot based on the Leardini foot model. Three-dimensional joint angles were calculated at the distal segment, and were expressed relative to the adjacent proximal segment. The coupling angle representing intersegmental coordination was calculated by using the modified vector coding technique, and categorized into the following four coordination patterns: in-phase with proximal dominancy, in-phase with distal dominancy, tanti-phase with proximal dominancy, and anti-phase with distal dominancy. Results: The results showed that the midfoot was dominantly everted compared with the rearfoot and forefoot during the early stance (i.e., the rearfoot-midfoot coordination and midfoot-forefoot coordination were mainly in-phase with distal and proximal dominancy, respectively). Conclusion: This result may suggest that the midfoot plays a more significant role than the rearfoot and forefoot during early stance. The results of the present study can help in understanding the interaction of the intersegmental foot kinematic time series during walking. The results could be used as data to distinguish the presence of injuries or abnormal inter-segmental foot motions such as pes planus. Additionally, these data might be used in the future in a comparison with data on foot deformities. [ABSTRACT FROM AUTHOR]