ABSTRACT
Objective To investigate and analyze the risk of dislocation failure after total hip arthroplasty (THA). Methods The optical motion capture system was used to obtain the kinematic data of the lower limbs during actions of daily living (ADLs) from normal people. The visual hip prosthesis motion analysis software was designed and developed to measure the maximum safe motion space of the hip prosthesis with different design parameters and judge the safety of the hip prosthesis by analyzing the relative motion relation between the cup and prosthetic stem. Results Based on the measured kinematics data, the motion analysis software could compare the range of motion of the natural joints and that after THA. Thus, the relationship between the dislocation of hip prosthesis and ADLs was obtained and the dislocation risk after THA was investigated. Conclusions There is a high risk when activities that require a high flexion motion are performed, especially for the kneeling and squatting activity.
ABSTRACT
Objective To illustrate the influences of walking speed and road slope on lower limb motions by quantitative analysis on the changes of joint angles and muscle activation. Method Five walking speeds and three road slopes were selected from slow to fast according to the related measurement. The gaits of 15 young women were measured using the motion capture system and the EMG signals of 8 major muscles in lower limbs were collected simultaneously. The mean joint angles of hip, knee and ankle in sagittal plane at different speeds and different slopes were calculated. The subject whose data was closest to the mean value could be easily found. Results The joint angles of the subject’s hip, knee and ankle in sagittal plane at different speeds and different slopes in a gait cycle were presented and the activation curves of the 8 major muscles during lower limb movements were obtained. Conclusions In each gait cycle, the curves of joint angles and muscle activations varied little with 5 different speeds, while curves for 3 different road slopes only showed similar tendencies but with different peaks.
ABSTRACT
Objective To obtain the statistical data from the range of motion in lower limb of the Chinese people during their stair ascent so as to provide references for the design of artificial joints with large range flexion. Methods Common staircase as an experimental device was designed, and motion capture system（Optotrak Certus, NDI）and 3D force plate（AMTI, Bertec）were used to establish a systematic method to measure the lower limb motion from 40 subjects during stair ascent. Results The variation of joint angle and range of motion in hip, knee and ankle joints for the 40 subjects in different directions within one cycle were obtained and calculated. The range of motion in hip, knee and ankle joints at the sagittal plane were -1.6°~66.7°, 0°~91.4°,-20.8°~22.4°, respectively. Conclusions During the movement of stair ascent, the range of motion at the sagittal plane in hip, knee and ankle joints reached the maximum, with the most flexion in hip and knee. Compared with the movement during walking and jogging on flat road, the range of motion in joints both in hip and knee at the sagittal plane were larger during stair ascent.
ABSTRACT
Objective In order to avoid potential injuries imposed to human body, it can be feasible to use the musculoskeletal models which can be reconstructed from the cadaver color cryosection (CCC) images, computerized tomography (CT) images, magnetic resonance (MR) images or other images to analyze the dynamic properties of muscles in vivo during human movement. Methods We reconstruct the lower limb musculoskeletal model and define the uniform joint coordinate system (JCS) on the model and the subject. The coordinate transformation of the muscle attachment points both on the model and the subject is described in detail. Results The length and the moment arm of the biceps femoris (short head) during knee flexion are calculated and analyzed. Conclusion This method plays an important role in improving the kinematics and dynamic simulation and the muscle force estimation.
ABSTRACT
Objective To study the effect of reasonable jogging speed on body shape and walking gait to make people acquire graceful posture through jogging. Method Five jogging speeds were selected according to related measurements. Kinematical data of subjects (15 young women volunteers) in jogging were measured by the motion capture system, while the EMG signals of 8 major muscles in lower limb were collected simultaneously. The mean angles of hip, knee and ankle joints in sagittal plane at different speeds were calculated. The subject whose data was closest to the mean value was chosen as the research subject and analyze the kinematical data. Results The angles of the subject's hip, knee and ankle joints in sagittal plane at different speeds in a gait cycle were presented, and activation curves of her 8 major muscles were obtained during lower limb movements. Relationships between the jogging speed, jogging stage, muscle activation and joint angle were described by the scoring method. Conclusions The range of joint angle and maximum of muscle activation don't change with jogging speed monotonously. The study provides a reference for young women to choose their own jogging speed.
ABSTRACT
Objective In order to avoid potential injuries imposed to human body,it could be feasible to use the musculoskeletal models which can be reconstructed from the cadaver color cryosection(CCC)images,computerized tomography(CT)images,magnetic resonance(MR)images or other images to analyze the dynamic properties of muscles in vivo during human movement.Mothod We reconstruct the lower limb musculoskeletal model and define the uniform ioint coordinate system(JCS)on the model and the subject.The coordinate transformation of the muscle attachment points both on the model and the subject is described in detail.Results The length and the moment arm of the biceps femoris(short head)during knee flexion are calculated and analyzed.Conclusion This method plays an important role in improving the kinematics and dynamic simulation and the muscle force estimation.
ABSTRACT
Objective In order to avoid potential injuries imposed to human body,it could be feasible to use the musculoskeletal models which can be reconstructed from the cadaver color cryosection(CCC)images,computerized tomography(CT)images,magnetic resonance(MR)images or other images to analyze the dynamic properties of muscles in vivo during human movement.Mothod We reconstruct the lower limb musculoskeletal model and define the uniform ioint coordinate system(JCS)on the model and the subject.The coordinate transformation of the muscle attachment points both on the model and the subject is described in detail.Results The length and the moment arm of the biceps femoris(short head)during knee flexion are calculated and analyzed.Conclusion This method plays an important role in improving the kinematics and dynamic simulation and the muscle force estimation.
ABSTRACT
To evaluate periprosthetic von Mises stress distribution with cementless femoral stems of various contours. The study was carried out at the Department of Orthopaedics, Shanghai 6th Hospital, Shanghai, China between May 2008 and February 2009. Finite element models of proximal femoral replacement with 4 cementless stems [Alloclassic, Ribbed Anatomic, VerSys, and Securi-fit] of various contours were set up. Under the loading conditions of walking and stair climbing, 3-dimensional periprosthetic von Mises stresses were calculated, and the stress distribution patterns were compared. Periprosthetic stresses were increased in level 1, 2, and 3 under the 2 loading conditions, and more considerably in level 2 and 3. The stresses were higher on the medial side in all cases. No remarkable difference was found in the patterns between the 4 stems. The contour design of femoral stem has minor effect on initial periprosthetic von Mises stress distribution