Objective To compare the differences in lower limb joint kinematics and muscle activation between Asian squat (AS) and Western squat (WS). Methods Eleven healthy adults were recruited to complete the biomechanical test of AS and WS. The 3D motion analysis system, force plates and surface electromyography (EMG) were used to collect kinematics, kinetics and muscle activation data of the subjects during two squats, and muscle force of the lower limb was also calculated by OpenSim. Results AS showed pelvis forward flexion, while WS showed pelvis backward extension at the time of peak knee flexion angle. Compared with the AS, a significant smaller hip flexion, larger knee flexion, larger hip abduction and hip rotation angles were found in WS at the time of peak knee flexion angle. Compared with AS, a significant greater peak force of soleus was found in WS during descent and ascent phases of squat. Additionally, a smaller peak force of anterior tibia was found in WS than that in AS during descent and ascent phases of the squat. No significant differences were found in other muscle peak force and the time of peak force between AS and WS. Conclusions The combined tibialis anterior activation and proximal joint flexion might be beneficial to stabilization during AS. The soleus muscle activation was significant in WS with heel lifting. The muscle activation pattern of proximal joint was similar between AS and WS. This study provides theoretical guidance for the design of clinical squat rehabilitation programs or the selection of squat training.

Objective To explore the joint contact force, ligament tensile force and force transmission mode of foot internal structure in Down’s syndrome child (DSC) during standing. Methods The finite element models of foot were constructed based on CT image data from one DSC and one typically developing child (TDC). The models were validated by plantar pressure measurement during static standing. To simulate foot force during standing, the ground reaction force and the triceps surae force were applied as the loading condition. Contact pressure of the tibiotalar, talonavicular and calcaneocuboid joints, tensile force of the spring and plantar calcaneocuboid ligaments, and force transmission mode in transverse tarsal joints were calculated and analyzed. Results The finite element models of foot were validated to be reliable. Compared with the TDC, the DSC showed higher contact pressure at the tibiotalar joint and lower contact pressure at the talonavicular joint. The tensile force of spring and plantar calcaneocuboid ligaments of DSC was 10 times and 58 times of TDC, respectively. The forces transmitted through both mediate and lateral columns in DSC were lower than those in TDC. Conclusions Abnormal contact pressure of the tibiotalar joint, larger tensile force of midfoot ligaments and smaller force of the transverse tarsal joint were found in DSC during standing. The abnormal alteration of stress patterns in foot internal structure of DSC should be fully considered in clinical rehabilitation, so as to provide theoretical references for screening and making intervention plans for early rehabilitation, as well as designing individualized orthopedic insoles.

Objective To explore the correlation between gait parameters at 14 days and knee function and quality of life at 3 months after total knee arthroplasty (TKA). Methods Eighteen patients who underwent TKA were analyzed by using three-dimensional gait analysis system to observe their gait parameters. Knee joint function and life quality of the patients at 3 months after TKA were evaluated with WOMAC (Western Ontario and McMaster Universities Arthritis Index) and SF-36 (short form 36-item health survey scores) assessment scale and their correlations were analyzed simultaneously. Results At 14 days after TKA, single support time (SST) and peak knee flexion at swing (PKF) of the operated side of the leg were significantly smaller than those of the healthy side of the leg. The knee flexion angle at mid-stance (MKF) and knee valgus angle at mid-stance (MKV) of the operated side of the leg were significantly larger than those of the healthy side of the leg. There was a moderate negative correlation between the spatiotemporal parameters of the operated side of the leg and the WOMAC score during gait, while a high correlation between the WOMAC score and peak knee flexion at swing (PKF), MKF and MKV. Except for the step length and forward velocity, the other gait parameters were significantly correlated with SF-36 life quality score. The single support time (SST) and PKF had a highly positive correlation, while the MKF and MKV had a moderate negative correlation with SF-36 life quality score. Conclusions The SST, MKF, MKV and PKF in postoperative early gait analysis (14 days) results can be used as the effective indicators to judge postoperative knee function and rehabilitation efficacy of life quality after TKA surgery.

The purpose of this study is to analyze the biomechanics of ankle cartilage and ligaments during a typical Tai Chi movement-Brush Knee and Twist Step (BKTS). The kinematic and kinetic data were acquired in one experienced male Tai Chi practitioner while performing BKTS and in normal walking. The measured parameters were used as loading and boundary conditions for further finite element analysis. This study showed that the contact stress of the ankle joint during BKTS was generally less than that during walking. However, the maximum tensile force of the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament during BKTS was 130 N, 169 N and 89 N, respectively, while it was only 57 N, 119 N and 48 N during walking. Therefore, patients with arthritis of the ankle can properly practice Tai Chi. Practitioners with sprained lateral ligaments of the ankle joint were suggested to properly reduce the ankle movement range during BKTS.
Ankle ; Ankle Joint ; Biomechanical Phenomena ; Humans ; Knee Joint ; Lateral Ligament, Ankle ; Male ; Tai Ji

Through providing rhythmic stimulation to movement center, rhythmic auditory stimulation (RAS) may encourage hemiplegic patients to adjust movement pattern and external rhythm in time to improve the walking function after stroke. As an emerging intervention to treat the hemiplegic patients after stroke, RAS could effectively improve temporospatial gait parameters (gait velocity, stride length, cadence, and symmetry, etc.), joint movement pattern (angle of pelvis anterior tilt, and peak angle of knee flexion in mid-swing, etc.) and balance, which may be related to rhythmic entrainment movement system and the theory of auditory-movement synchronization. Simultaneously, frequency and dosage of RAS and the patient's lesions all have effect on the outcome of intervention.