You-Li Chou

Gait analysis after ankle arthrodesis.

The purpose of this study was to employ a computerized motion analysis system to identify the effect of ankle arthrodesis on the three-dimensional kinematic behavior of the rear and fore foot during level walking. A three-segment rigid body model was used to describe the motion of the foot and ankle. The results demonstrated that sagittal plane motion of the hindfoot was significantly decreased in the foot of patients having had ankle arthrodesis compared to normal subjects. The kinematic data indicated a generalized stiffness of the hindfoot on the involved foot in the sagittal plane. Sagittal plane movement in the forefoot and transverse plane movements in the hindfoot and forefoot increased in patients compared to controls.

RETRACTED: Gait analysis and energy consumption of below-knee amputees wearing three different prosthetic feet

This study scientifically measures the dynamic gait characteristics and energy consumption of 16 male below-knee amputees, eight vascular and eight traumatic, while wearing solid ankle cushion heel (SACH), single axis and multiple axis prosthetic feet via six-camera motion analysis, metabolic measurement cart and heavy-duty treadmill. Subjective results are additionally determined via questionnaire after testing. Motion analysis showed statistically significant differences at P<0.05 between the SACH, single axis and multiple axis foot in the velocity, cadence, stride length and single limb stance. Significant differences were found in energy consumption between the traumatic and vascular groups, and significant changes in walking under different speeds and different inclines. Results provide quantitative and qualitative information about the dynamic performance of the various feet, which can be helpful in prescribing the optimal prosthetic foot for individual amputees.

Fuzzy clustering of gait patterns of patients after ankle arthrodesis based on kinematic parameters

Kinematic parameters for 10 normal subjects and 10 patients with ankle arthrodesis are grouped using the fuzzy cluster paradigm. The features chosen for clustering are Euler angles of the sagittal plane in the hindfoot, the forefoot and combined hindfoot and forefoot joints. Gait patterns are identified using information provided by cluster validity techniques, giving three, three and two clusters for the hindfoot, forefoot and combined hindfoot and forefoot joints, respectively. The cluster centers represent distinct walking strategies adopted by normal subjects and patients after ankle arthrodesis. Utilizing angle values normalized by gait cycle, it is possible to classify any subject and to generate an individuals membership value for each of the clusters. The clinical utility of the fuzzy clustering approach is demonstrated with data for subjects with ankle arthrodesis, where changes in membership of the clusters provide an objective technique for measuring changes of gait pattern after ankle arthrodesis. This approach can be adopted to study other clinical entities where different cluster centers would be established using the algorithm provided in this study.

THE GAIT ANALYSIS OF PREGNANT WOMEN

During pregnancy, a woman changes obviously in body weight, body shape, and endocrine system. Those changes make the posture and gait pattern of the pregnant women different from those of the non-pregnant women. At the same time, activities of daily living become more difficult. But there was still no published paper discussing the posture and gait changes of the pregnant women in details and in a whole. In this study, we used the optimization method to define the hip joint center of the pregnant women. The optimization method could compensate the lack of the anthropometric data of the pregnant women. Due to the variations of physiological changes in the pregnant women, it was difficulty to standardize the gait analysis of pregnant women, even in the same gestational age. The results revealed that there really was some correlation between the significant finding of gait analysis and sacroiliac pain of the pregnant women. The sacroiliac pain often occurred in the following conditions of gait analysis: (1) when the hip extension moment increased; (2) when the knee extension moment decreased; (3) when the angle of ankle plantar-flexion decreased; and (4) when the sacroiliac ajoint torsion increased. The gait analysis of the pregnant is a feasible, but complicated method for study. The data of gait analysis were also compare with questionnaires for further analysis.

KINEMATICS PROPERTIES AND ENERGY COST OF BELOW-KNEE AMPUTEES

This study scientifically measures the dynamic gait characteristics and energy cost of six male below-knee amputees, three vascular and three traumatic, while wearing SACH, single axis and multiple axis prosthetic feet via six-camera motion analysis, metabolic measurement cart and heavy-duty treadmill. Subjective results are additionally determined via questionnaire after testing. Motion analysis showed statistically significant differences at p < 0.05 between the solid ankle cushion heel (SACH), single axis and multiple axis foot in the velocity, cadence, stride length end gait cycle. Significant differences were found in energy cost among the prosthetic feet tested, and significant changes in walking under different speeds and different inclines. Results provide quantitative and qualitative information about the dynamic performance of the various feet which can be helpful in prescribing the optimal prosthetic foot for individual amputees.

ELBOW LOAD DURING DIFFERENT TYPES OF BENCH-PRESS EXERCISE

The bench press is one of the most popular weight training open-kinetic chain exercise (OKCE) for the upper extremity. Reviewing the literature, there is a very little research regarding the biomechanical analysis of the OKCE of the upper extremity. The purpose of this study is to develop an OKCE testing model of the upper extremity by using the 3D Motion Analysis System. Furthermore, elbow joint loading of two different hand grip position during the bench-press exercise will be investigated. Thirteen male students volunteered for the study. Their average age was 26.1 years, with an average height of 170.6 cm, and an average weight of 70.3 kg. With both hands in neutral position, each subject was asked to perform bench-press type 1 (normal shoulder width), and bench-press type 2 (150% shoulder width). During the type 2 bench-press exercise, there is a significant increase in anterior–posterior and medial–lateral force on the elbow joint loading than the type 1 bench-press exercise. The valgus–varus, flexion–extension moment, and supination–pronation moment of the type 2 bench-press exercise are also greater than the type 1 bench-press exercise. As shown in this study, keeping the distance of both hand grips as shoulder width may reduce the elbow joint loading during bench-press exercise. These data will provide helpful information in clinical rehabilitation and treatment of the upper-extremity injures.

BIOMECHANICAL ANALYSES FOR THE EFFECTS OF ELBOW INITIAL FLEXION ANGLES ON UPPER EXTREMITY DURING A FALL

Elbow joint loading was evaluated during a forward fall at various elbow initial flexion angles, in order to determine which is the best elbow initial flexion angles to prevent the elbow injury during a fall. Subjects were asked to perform a forward fall and followed by a push-up motion in different elbow initial flexion angles: 0°, 20°, 40° and unrestricted group. Fall on the outstretched hand is the leading cause of upper extremity injury. There are far more extension type of supra-condylar fracture of the elbow than flexion type. Flexion of the elbow may represent the effects of damper and spring. Using the motion analysis system, the kinematics and kinetics of the elbow joint were investigated under various elbow initial flexion angles. The loading biomechanics of the elbow joint differed with various elbow initial flexion angles. The ground reaction forces decrease with increase of elbow flexion upon impact. Different initial elbow flexion angles would affect the biomechanics of upper extremities during falls. Forward fall with elbow in extension is more dangerous. Knowledge of elbow kinematics and kinetics may be helpful in preventing injuries by reducing the ground reaction force with changes of the elbow initial flexion angles during a fall.

COMPARATIVE ANALYSIS OF ELBOW JOINT LOADING IN PUSH-UP AND BENCH-PRESS

Upper extremity pain and dysfunction are common orthopedic problems in individuals who practice physical activities involving the upper limbs. Push-ups (PUs) and bench-presses (BPs), representing closed kinetic chain (CKC) and open kinetic chain (OKC) exercises, respectively, are among the most popular training exercises for the upper extremity in sports training and clinical rehabilitation applications. Utilizing a self-developed exercise testing model, the present study examines the difference in elbow joint loading between OKC and CKC exercises of the upper extremity. As many as 15 physically healthy male subjects with an average age of 19.8 years (S.D. 1.4), an average height of 176.8 cm (S.D. 4.2), and an average weight of 69.27 kg (S.D. 5.0) were studied. Each subject was asked to perform two different types of exercise, namely PUs and BPs. The kinematics, kinetics, and muscle activation of the elbow joint were calculated and analyzed using laboratory-developed motion analysis procedures. The PU exercises result in a greater loading on the elbow joint than the BP exercises, but produce a lower muscle activation. OKC exercises yield a greater muscle strengthening effect than CKC exercises. The increased shear stress on the elbow joint should be carefully noted when performing PU exercises. The results presented in this study provide valuable information for treatment and rehabilitation purposes in clinical applications.

Kinematical strategy to regain balance during a forward fall on a slippery floor

Slips and falls often occur in the industrial environments. They are not only caused by environmental hazards but also by some biomechanical factors related to deficient ability of postural control to arrest impending falls. The purpose of this study is to simulate the slip condition in human walking and to find out the possible related factors of biomechanics. Eleven male and 9 female recruited were healthful without any musculoskeletal and neurological impairments. In order to provide different disturbance level, three lean angles of tilting boards were designed as 10, 20, 30 degrees with respect to horizontal plane. Subjects wore a safety harness, stood on the tilting board and were released without awareness. A forceplate applied a soap patch was in front of the tilting board to serve the slippery perturbation and to measure the fool/floor reactions. Movements of body segments were measured using the motion analysis system. The results were shown that lean angle had a significant effect to all parameters except step length, response time, maximum ankle forward velocity, hip forward velocity, and ankle flex angle. The gender significantly affected on the step length, response time, maximum ankle forward velocity, and knee forward velocity. Larger lean angle made subjects to take a more rapid step. In order to absorb the shock in foot strike, subjects flexed more their knee and increased the foot landing angle in larger lean angle. Male tended to adopt the long step-length strategy to respond to the slippery perturbation and female tended to use the short step-length strategy instead. The results of maximum ankle forward velocity suggested that short step-length strategy could be belter to reduce the foot slip than long step-length strategy.

MOTION ANALYSIS OF MOUTH MOVEMENT UTILIZING CHALLIS TECHNIQUE-EXPERIMENT MODEL AND CLINICAL STUDY USING VIDEO-BASED SYSTEM

An Expert Vision motion analysis system with five analog video cameras was used to evaluate the mouth movement during two facial animations (smile and puffy face). Sixteen skin markers were adhered to the face of subject according to the anatomic landmarks to represent the functional movement of the facial muscles. The trajectory of the four or eight peri-oral skin markers was simultaneously evaluated by Challis technique, instead of individual movement of single marker. The 4-marker method is a little less accurate than 8-marker method. But the 4-marker method can be incorporated as a part of our modality of facial motion analysis, including two/three dimensional displacement of individual marker and absolute/relative displacement of paired markers. It was much easy for data acqusition and no extra marker was needed in the whole modality of our facial motion analysis. Physicians can use this Challis technique to evaluate grouped movement of facial markers, as a whole, in different animation.