Yong Hoon Rim

A position based kinematic method for the analysis of human gait

Human joint motion can be kinematically described in three planes, typically the frontal, sagittal, and transverse, and related to experimentally measured data. The selection of reference systems is a prerequisite for accurate kinematic analysis and resulting development of the equations of motion. Moreover, the development of analysis techniques for the minimization of errors, due to skin movement or body deformation, during experiments involving human locomotion is a critically important step, without which accurate results in this type of experiment are an impossibility. The traditional kinematic analysis method is the Angular-based method (ABM), which utilizes the Euler angle or the Bryant angle. However, this analysis method tends to increase cumulative errors due to skin movement. Therefore, the objective of this study was to propose a new kinematic analysis method, Position-based method (PBM), which directly applies position displacement data to represent locomotion. The PBM presented here was designed to minimize cumulative errors via considerations of angle changes and translational motion between markers occurring due to skin movements. In order to verify the efficacy and accuracy of the developed PBM, the mean value of joint dislocation at the knee during one gait cycle and the pattern of three dimensional translation motion of the tibiofemoral joint at the knee, in both flexion and extension, were accessed via ABM and via new method, PBM, with a Local Reference system (LRS) and Segmental Reference system (SRS), and then the data were compared between the two techniques. Our results indicate that the proposed PBM resulted in improved accuracy in terms of motion analysis, as compared to ABM, with the LRS and SRS.

Development of a spine kinematic model for the clinical estimation of abnormal curvature

The objective of this study was to develop a new three-dimensional spine kinematic model for abnormal curvature estimation. The morphological diseases such as lordosis and kyphosis are occurred lumbar and thorax segment and the apex of curvature appears the specified segment such as L3 and T6/T7. Therefore, the kinematic analysis of specified segment which is subdivided with respect to the apex of curvature as well as the analysis of whole segment such as lumbar is appropriate to estimate the rehabilitation and diagnosis of back pathological patients. Six healthy male subjects exhibiting no back pathology were participated in this study. Video data was collected with a 6-camera Vicon motion analysis system (Oxford Metrics Limited, Oxford, UK). The developed kinematic model was verified based on the previously published studies. Following the results, the range of peak-to-peak motion in the thorax (approximately 2.6 degrees) was significantly less than the other segment motions and the maximum variation was approximately 6 degrees between the lower lumbar and pelvis. This study expects to be used as a normal man’s database to discriminate the diseases of patients and to predict injury in the general industrial workplaces and agricultural conditions.

Kinetic Analysis of Kneeling Combined with twisting

In contrast to most Western people, Korean has almost seated lifestyle which causes arthritis in joint of the lower-limb of human body. Especially agricultural work in Korea requires squatting, kneeling, and bending postures, each of which are known as one of the sources of musculoskeletal disorder. About 80% of Korea agricultural workers complained of musculoskeletal disorder following the rural resource development institute in 2003 and 47.9% of them suffered knee pain. However, clear understanding of the pain related on the lower-limb joint has not been known yet. The objective of this study was to provide kneeling effect combined with twisted activities increasing rotational angle of the upper-limb and distance between body and hands based on kinetic data. Five male volunteers performed bending and squatting pose with wrenching. In order to calculate knee joint moments, Kinematics data was acquisition by motion capture system and force plate. Following the results, knee joint moments at squatting posture are greater than at standing posture. The moments are increased during at squatting postures with twisting of the body behind the back than with no twisting.

Non-Invasive Kinematic Analysis of the Triceps Surae Muscle-Tendon Complex during a Gait

The purpose of this study is to calculate the length and velocity change of gastrocnemius and soleus muscle-tendon complex (MTC) for diagnosis and estimation of the rehabilitation procedure of the patient from non-invasive 3D markers. The previous method measuring the length of MTC has been dependant on the regression equation based on the rotation angle in the sagittal plane. However, in view of the fact that movement analysis is based on the human body having a variety of structure, the measurement using merely rotation angle and regression equation which not based on each subject shank and foot length might not be accurate. In order to overcome these limitations, the length change of MTC is calculated, employing 3D MTC model accompanied with the trajectory data of markers attached anatomical landmarks, each subject measurements and femur condyle radius. Basically, more accurate length change could be acquired through the 3D trajectory data of markers in comparing with 2D data based on the rotation angle. As our study, the difference of the gastrocnemius length change between 3D marker trajectory based method and the method using a 2-D angle was approximately 4% (2cm) at maximum contraction and 1% (0.5cm) at maximum relaxation. Similarly, the difference in terms of the soleus was approximately 0.7% (0.3cm) at maximum contraction and 0.5% (0.2cm) at maximum relaxation.

A New Severity Index for Nondestructive Dynamic Analyses in Equinus Gait

Equinus gait, defined as walking on one forefoot or both forefeet, has long been considered an undesirable characteristic in patients with a variety of neuromuscular disorders. In the equinus gait, the heel contact pattern is changed according to the severity, because an excessive ankle plantar flexion instigates rearfoot lifting in patients. However, no biomechanical severity index exists to evaluate the rehabilitation procedure of equinus gait. Therefore, we developed an SIEG (Severity Index of Equinus Gait) for nondestructive evaluation of the equinus gait and to validate the index with regard to 11 kinematic and kinetic factors of gait analysis. In this study, the 3-D heel contact pattern was considered for the development of a severity index. In order to verify the result, we compared the developed severity index values with ankle joint kinematic and kinetic factors in 3 test groups. As a result, the average SIEG values ranged between 10.45 (Normal group) and 26.61 (Severe group) and the highest correlation with regard to the 3 groups was shown in the developed severity index. Additionally, we also presented a fuzzy model using Takagi-Sugeno-Kang(TSK) logic with regard to the 12 factors in order to more accurately classify equinus gait.