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The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments

Background Normative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects. Methods A total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW). Results Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW. Discussion Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.

Physico-mechanical and erosive wear analysis of polyester fibre-based nonwoven fabric-reinforced polymer composites

The research work aims to study the physico-mechanical and erosive wear behaviour of polyester fibre-based needle-punched nonwoven fabric mat reinforced epoxy composites. Therefore, the epoxy composites with varying proportion of polyester fibre-based needle-punched nonwoven fabric mat were fabricated and characterized for their physical, mechanical and erosive wear properties. The experimental results indicated that the increase of fibre content enhanced the physical and mechanical properties of the composites. To optimize and improve the erosive wear performance of fabricated composites, the Taguchi method was implemented. For this, L27 orthogonal array was constructed to examine the influence of the five control factors including impingement angle, impact velocity, stand-off distance, fibre content and erodent size. The experimental schedule was carried out in an air jet erosion test rig. The results indicate that the impact velocity emerges as the most significant control factor affecting the erosive wear of fabricated composites. Finally, the possible erosive wear mechanisms were studied by examining the composites eroded surfaces with scanning electron microscopy.

Biomechanical Performance of Habitually Barefoot and Shod Runners during Barefoot Jogging and Running

The purpose of this study was to evaluate the biomechanical performances, running stability of habitually barefoot (BR) and shod runners (SR) during barefoot jogging and running. Ten healthy male subjects, 5 habitually shod runners and 5 habitually barefoot runners, from two different ethnics participated in this study. Subjects performed jogging (2m/s) and running (4m/s) along a 10-m runway. Three-dimensional lower-limb kinematics, ground reaction force, center of pressure (COP) and contact time (CT), were collected during testing. During jogging and running, all participants adopted rear-foot strike pattern, SR had larger VALR. SR showed significantly larger lower-limb range of motion (ROM) in sagittal plane, significantly larger hip abduction and opposite knee ROM in frontal plane, as well as significantly larger ankle internal rotation in horizontal plane. All participants’ CT showed decreased trend with running speed up; and SR was significantly longer than BR; BR and SR in COP showed different trajectories, especially forefoot and rearfoot areas. Habitually barefoot and shod runner from different ethnics still exist significant differences in lower-extremity ROM; and different foot morphological of participants is an important influential factor for these variations.

The Variation of Plantar Temperature and Plantar Pressure during Shod Running with Socks or not

Foot temperature can be affected by friction and contact pressure, in this study, we explored the specific changes of foot temperature under different friction conditions, running with socks versus no socks. The relationship between vertical loading force and foot temperature will also be investigated at the same time. Ten male recreational runners wore the same shoes and socks and were tested running 8km/h on a treadmill. The plantar temperature during running was recorded every 3 minutes for a total of 45 minutes. Post-run temperature change was recorded every 3 minutes for 12 minutes. The plantar pressure was recorded before running and at the first 15 minutes during running. The subjects with socks and no socks were tested on separate occasions. There were no significant differences found between the socks and no socks conditions. However, central metatarsal head, lateral metatarsal head, medial rearfoot and lateral rearfoot regions exist differences were reflected at the first 6minutes-12minutes of running. The foot temperature became more stable after 15minutes of running. Also, plantar pressure increased significantly in the hallux, other toes, first metatarsal head and central metatarsal regions. It also could conclude that lower initial temperature had a greater increase trend during the running start stage. When the ankle in plantarflexion stage, toe and forefoot regions showed a higher rise in temperature and also presented higher plantar pressure correspondingly.

Biomechanical Analysis of Augments in Revision Total Knee Arthroplasty

Augments are a common solution for treating bone loss in revision total knee arthroplasty and industry is providing to surgeons several options, in terms of material, thickness and shapes. Actually, while the choice of the shape and the thickness is mainly dictated by the bone defect, no proper guidelines are currently available to select the optimal material for a specific clinical situation. Nevertheless, different materials could induce different bone responses and, later, potentially compromise implant stability and performances. Therefore, in this study, a biomechanical analysis is performed by means of finite element modelling about existing features for augment designs. Based upon a review of available products at present, the following augments features were analyzed: position (distal/proximal and posterior), thickness (5, 10 and 15 mm) and material (bone cement, porous and solid metal). For all analyzed configurations, bone stresses were investigated in different regions and compared among all configurations and the control model for which no augments were used. Results show that the use of any kind of augment usually induces a change in bone stresses, especially in the region close to the bone cut. The porous metal presents result very close to cement ones; thus it could be considered as a good alternative for defects of any size. Solid metal has the least satisfying results inducing the highest changes in bone stress. The results of this study demonstrate that material stiffness of the augment should be as close as possible to bone properties for allowing the best implant performances.

Using Gold-standard Gait Analysis Methods to Assess Experience Effects on Lower-limb Mechanics During Moderate High-heeled Jogging and Running

A limited number of studies have explored lower-limb biomechanics during high-heeled jogging and running, and most studies have failed to clarify the wearing experience of subjects. This protocol describes the differences in lower-limb kinematics and ground reaction force (GRF) between experienced wearers (EW) and inexperienced wearers (IEW) during moderate high-heeled jogging and running. A three-dimensional (3D) motion analysis system with a configured force platform was used to synchronously capture lower-limb joint movements and GRF. 36 young females volunteered to participate in this study and were asked about high-heeled shoe-wearing experience, including frequency, duration, heel types, and heel heights. Eleven who had the experience of 3 to 6 cm heels for a minimum of three days per week (6 h per day) for at least two years and eleven who wore high heels less than twice per month participated. Subjects performed jogging and running at comfortable low and high speeds, respectively, with the right foot completely stepping onto a force platform when passing by along a 10 m walkway. EW and IEW adopted different biomechanical adaptations while jogging and running. IEW exhibited a generally larger range of joint movement, while EW showed a dramatically larger loading rate of GRF during running. Hence, further studies on the lower-limb biomechanics of high-heeled gait should strictly control the wearing experience of the subjects.

Analysis of Foot Kinematics with Unstable Sole Structure Using Oxford Foot Model

To determine the influence of the unstable sole structure on foot kinematics and provide theoretical basis for further application.12 healthy female subjects walked through a 10-meter experimental channel with normal speed wearing experimental shoes and control shoes respectively at the gait laboratory. Differences between the groups in triplanar motion of the forefoot, rearfoot and hallux during walking were evaluated using a three-dimensional motion analysis system incorporating with Oxford Foot Model (OFM). Compare to contrast group, participants wearing experimental shoes demonstrated greater peak forefoot dorsiflexion, forefoot supination and longer halluces plantar flexion time in support phase. Additionally, participants with unstable sole structure also demonstrated smaller peak forefoot plantarflexion, rearfoot dorsiflexion and range of joint motion in sagittal plane and frontal plane.. The difference mainly appeared in sagittal and frontal plane. With a stimulation of unstable, it may lead to the reinforcement of different flexion between middle and two ends of the foot model. The greater forefoot supination is infered that the unstable element structure may affect the forefoot motion on the frontal plane and has a control effect to strephexopodia people. The stimulation also will reflexes reduce the range of rearfoot motion in sagittal and frontal planes to control the gravity center of the body and keep a steady state in the process of walking.