Objective To explore the threshold and latency of patients receiving cochlear implantation using electrically evoked auditory brainstem responses (EABR), and to evaluate the significance of EABR applied to those patients.Methods The EABR and ECAP were recorded in 14 subjects who were operated for Nucleus24 cochlear implant.They were assigned to Group A and Group B according to the results of ECAP. The threshholds of EABR, the wave latency of III and V and inter-wave latency of III-V of EABR were compared and analyzed between Group A and Group B.Results The threshholds of EABR were higher in Group B than in Group A on electrode No 22 when the pulse width was 25,50,75,100,125 ?s,respectively. There were significant differences between Group A and Group B(P0.05).Conclusion The threshholds of EABR were lower in patients whose ECAP findings were positive. The latencies of III and V,and inter-wave latency of III–V of EABR had no significant difference according to the positive findings of ECAP.

OBJECTIVE: To report intraoperative round window cochlear microphonic potential test (CM) in patients with profound sensorineural deafness. METHOD: Intraoperative round window CM test were performed on 40 cases with profound sensorineural deafness during cochlear implantation surgery under general anesthesia in the standard operating room. CM were compared with their reliable preoperation distortion product otoacoustic emission (DPOAE). RESULT: The CM were found in 40 patients. The rate at 0.5, 1.0, 2.0, 4.0. kHz was respectively 90%, 97.5%, 100%, 92.5%. The preoperation DPOAE were found in some frequency in 9 cases. The rate at 0.5, 1.0, 2.0, 4.0 kHz was respectively was 2.5%, 2.5%, 17.5%, 2.5%. CONCLUSION The elicited rate of CM was obviously higher than the one of DPOAE in the same patient with profound sensorineural deafness. The intraoperative round window CM may objectively and accurately estimate the part of cochlear function in patients with profound sensorineural deafness.
Adolescent ; Adult ; Child ; Child, Preschool ; Cochlear Implantation ; methods ; Cochlear Microphonic Potentials ; Female ; Hearing Loss, Sensorineural ; physiopathology ; Humans ; Infant ; Male ; Young Adult

Objective To analyze characteristics of muscle activity and changes of corresponding kinematic parameters of the lower limbs for the elderly carrying heavy objects under synchronous stop modes, and explore the effects of hand weight-bearing and stop modes on gait stability and body balance of the elderly. Methods The ankle, knee, hip joint angles and surface electromyography (EMG) signals of bilateral lower limbs were collected under the condition of emergency stop and planned stop by loading 0 kg, 2.5 kg on both hands and 5 kg on right hand. Results Under different weight-bearing modes, the ankle and hip angles of bilateral lower limbs were significantly different (P<0.05), while the knee angles did not change significantly, and different stop modes significantly affected the angle changes in each joint (P <0.001); the average EMG of tibia anterior muscle, lateral femoral muscle, and biceps femoris in braking leg showed higher muscle activity during emergency stop. Conclusions In order to cope with the instability caused by weight-bearing and emergency stop, the elderly will have a corresponding balance mechanism in the lower limbs. During an emergency stop, braking the tibialis anterior muscle of the leg requires a higher muscle activity level to control flexion angle of the ankle joint, thereby reducing amplitude of the ankle joint fluctuation. The single-handed load increases the muscle performance differences between the braking leg and trailing leg, resulting in the lateral instability.

Objective To study the changes of plantar pressure during backward walking, so as to explore its effects on balance ability of human gait. Methods Plantar pressure measurement system (Pedar-X pressure insoles) was used to collect the plantar pressure data from 10 subjects during forward walking and backward walking, respectively. The experiment was conducted on the treadmill, and the forward walking was set as the control group. According to the test conditions and intuitive feeling of test participants, 4 speed values (2.0, 2.5, 3.0, 3.5 km/h) were selected to carry out the experiment under two walking modes, respectively. The changes in parameters such as plantar pressure center trajectory, plantar pressure and foot-ground contact time under different speed were analyzed. Results Under two walking modes at different walking speed, subjects showed different plantar pressure during walking. During backward walking, the plantar pressure center transferred from the front foot to the heel and from inside to outside. Compared with forward walking, the plantar pressure during backward walking decreased significantly while the foot-ground contact time increased. Conclusions The study on pressure distribution during backward walking contributes to comprehensively understanding the mechanism of dynamic balance and provides a new perspective for related study on walking stability.

Objective To study the factors leading to the increased risk of falls when the elderly cross obstacles with different load distributions in their hands, and to explore the gait strategies to prevent falls for elderly people with different load distributions during obstacle crossing. Methods Twelve young healthy (control group) and 12 elderly healthy participants performed walking tasks with or without obstacle crossing at their daily speed under different load distributions. Surface electromyography (sEMG) signals were collected from both sides of the lateral femoris, rectus femoris and medial femoris. Then the average sEMG was analyzed and compared. The numbers of contact incident during obstacle touching were also recorded. Results Age, weight carrying and obstacle all had significant influences on the activity level of lower limb muscles in elderly people. A total of 9 contact incidents occurred in 1 152 obstacle crossing tests. In addition, the contribution of right vastus medialis muscle was the greatest in the elderly and young adults when they completed the weight carrying and obstacle crossing tasks. Conclusions The elderly people had the lowest risk of falling down by taking advantage of the dominant side of the leg to take the lead in obstacle crossing under the uniform distributions of load. The research findings provide references for systematic assessment of fall risk in the elderly and have certain guiding significance for lower limb exercise or rehabilitation training in the elderly.

Objective:To study the human body's sit to stand transfer trajectory and kinematics based on knee joint support to provide a basis for designing the transfer aid with knee joint support. Methods:From April to June, 2019, 20 healthy volunteers were recruited and divided into three groups according to height and gender. Under the premise of knee support, the sit to stand transfer experiments with 20 cm and 30 cm between feet were conducted respectively. All subjects were repeated twice for each experiment with an interval of one minute. High-definition camera was used to record the motion trajectories of each subject's shoulder (armpit) and knee joint during the experiment, and the kinematics rules of subjects with different heights and masses were analyzed. Results:The body forward leaning displacement was less with 20 cm between feet than with 30 cm for subjects less than 172 cm tall; and was less with 30 cm than with 20 cm for subjects more than 173 cm tall. The forward flexion displacement of trunk was less with 20 cm between feet than with 30 cm for subjects with body mass index (BMI) < 23.9 kg/m²; and was less with 30 cm than with 20 cm for subjects with BMI > 23.9 kg/m². The average time during sit to stand transfer was (1.7±0.05) s. Conclusion:In the process of sit to stand transfer, distance between feet may affect the way of joint extension, the body forward leaning distance and the forward flexion displacement of trunk. With the increase of height and mass, appropriate increase of distance between feet can reduce the difficulty of sit to stand transfer. With the increase of BMI, the time of sit to stand transfer also increases. The time spent on sit to stand transfer is more in female than in male.

Objective To investigate the influence of internal and external sphincter loss synergy on stress distributions and urine flow rates of lower urinary tract organs and tissues. Methods Based on collodion slice, the geometric model of the lower urinary tract was reconstructed, and finite element model of the lower urinary tract with muscle active force was established. Through fluid structure coupling simulation, the changes of tissue stress and urine flow rate were simulated under four conditions: normal contraction of internal and external sphincter, total loss of muscle active force and single loss of muscle active force for internal and external sphincters at the end of urination. Results The urethral stress changes in normal contraction of internal and external sphincter muscles were the same as the clinically measured urethral pressure changes. Compared with normal contraction, when the internal sphincter lost its muscle active force alone, stress of the internal sphincter and the urethra of the prostate was reduced by 33.6% and 13.8%, and flow rate of urine in this position was also reduced. When the external sphincter lost its muscle active force alone, the urethral stress of the external sphincter and external urethra was reduced by 59.5% and 24.03%, respectively. When the internal and external sphincter lost muscle active force, stress of the internal sphincter, the prostate, the external sphincter and the external urethra were reduced by 38.77%, 18.6%, 63.58%, 29.74%, respectively, and flow velocity in the corresponding position was also reduced. Conclusions Internal and external sphincter loss synergy resulted in the difference of tissue stress and urine flow rate. The results can provide the theoretical basis for surgical treatment of urinary incontinence caused by sphincter.

Three-dimensional finite element model of elbow was established to study the effect of medial collateral ligament (MCL) in maintaining the stability of elbow joint. In the present study a three-dimensional geometric model of elbow joint was established by reverse engineering method based on the computed tomography (CT) image of healthy human elbow. In the finite element pre-processing software, the ligament and articular cartilage were constructed according to the anatomical structure, and the materials and contacts properties were given to the model. In the neutral forearm rotation position and 0° flexion angle, by comparing the simulation data of the elbow joint with the experimental data, the validity of the model is verified. The stress value and stress distribution of medial collateral ligaments were calculated at the flexion angles of elbow position in 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, respectively. The result shows that when the elbow joint loaded at different flexion angles, the anterior bundle has the largest stress, followed by the posterior bundle, transverse bundle has the least, and the stress value of transverse bundle is trending to 0. Therefore, the anterior bundle plays leading role in maintaining the stability of the elbow, the posterior bundle plays supplementary role, and the transverse bundle does little. Furthermore, the present study will provide theoretical basis for clinical recognizing and therapy of elbow instability caused by medial collateral ligament injury.
Biomechanical Phenomena ; Cadaver ; Collateral Ligaments ; physiology ; Elbow Joint ; physiology ; Finite Element Analysis ; Humans ; Range of Motion, Articular ; Tomography, X-Ray Computed

Objective Aiming at the problem that mechanical properties for the continuum of muscle tissues cannot be considered in active and passive behaviors of different structurally coupled muscles, a method of passive and active coupling in the same constitutive equation was proposed to construct ahyperelastic active and passive constitutive model of skeletal muscle continuum. Methods In order to calibrate parameters of the passive constitutive model, the uniaxial tensile experiment method and conditions were given, and through theoretical derivation, the specific method of using experimental data to solve the passive model parameters was introduced. In order to verify effectiveness of the active model, the model was verified with an example. Results The curves predicted by the model were in good agreement with the experimental output stress-stretch ratio curves. At the same strain, the maximum error of passive stress and total stress were only 20 kPa and 40 kPa. Conclusions The continuum hyperelastic constitutive model can better simulate active and passive behavior of skeletal muscles, which is beneficial for modeling and simulation of human muscles in further study.

Males typically have high rates of morbidity of primary bladder neck obstruction, while the existing urodynamic examination is invasive and more likely to cause false diagnosis. To build a non-invasive biomechanical detecting system for the male lower urinary tract, a finite element model for male lower urinary tract based on the collodion slice images of normal male lower urinary tract was constructed, and the fluid-structure interaction of the lower urinary tract was simulated based on the real urination environment. The finite element model of the lower urinary tract was validated by comparing the clinical experiment data with the simulation result. The stress, flow rate and deformation of the lower urinary tract were analyzed, and the results showed that the Von Mises stress and the wall shear stress at the membrane sphincter in the normal male lower urinary tract model reached a peak, and there was nearly 1 s delay than in the bladder pressure, which helped to validate the model. This paper lays a foundation for further research on the urodynamic response mechanism of the bladder pressure and flow rate of the lower urinary tract obstruction model, which can provide a theoretical basis for the research of non-invasive biomechanical detecting system.