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Biomedical subjects

F C Su

Publications and source records attributed to F C Su.

30 records · Page 2Linked to original sources
PubMed1998

The motion analysis system and goniometry of the finger joints.

The application of a video-based motion analysis system for goniometry of finger joints during measurement of the fingertip motion area has been assessed. The results indicate that the motion analysis system is reliable for angular measurements of finger joints that are comparable with those obtained by conventional goniometer. The advantages of using the motion analysis system is that it can record and show the changes in angle of all finger joints continuously during finger motion.

Adolescent↗
PubMed1998

The motion analysis system and the fingertip motion area. Normal values in young adults.

The reliability of the motion analysis system and the normal value of the fingertip motion area have been studied in young adults. The results indicate that the motion analysis system is a reliable tool for the evaluation of fingertip motion. It was found that the fingertip motion area in young adults has a linear correlation with the square of the finger length. Therefore, the normal value of the fingertip motion area can be calculated from the finger length.

Adult↗
PubMed1998

An instrumented wheel for kinetic analysis of wheelchair propulsion.

An instrumented wheel system for three-dimensional kinetic analysis of upper extremity during wheelchair propulsion has been designed and validated. This system allows the direct measurements of three-dimensional dynamic forces and moments on the handrim during wheelchair propulsion in a laboratory setting as well as in the field. Static loading tests showed a high linearity and little drift (coefficient of determination, r2 > 0.999). Under dynamic loading, the instrumented wheel provided the well-matched measurement forces and moments with the predicted values from the inverse dynamic method using video-based kinematic data (correlation coefficient, p > 0.97). The three-dimensional handrim forces and moments during wheelchair propulsion by a non-disabled subject were demonstrated.

Biomechanical Phenomena↗
PubMed1997

Gait analysis of adult patients with complete congenital dislocation of the hip.

Comprehensive gait analysis is valuable in understanding the performance of patients with lower limb disorders. The gait pattern of adult patients with untreated congenital dislocation of the hip (CDH) has not yet been reported. We studied the gait pattern in nine women (mean age 31.4 years) with Crows group IV CDH. Six had unilateral and three had bilateral involvement. They were not treated during childhood and had no pain at the time of study. A control group comprised 15 normal female subjects of the same age group. Gait was studied using a motion-analysis system, force plateforms, and computer calculation during level walking. Common abnormal gait patterns seen in patients with both unilateral and bilateral CDH were slower walking velocity, which was due to a shorter stride length, less forward tilting of the pelvis, insufficient flexion, and excessive internal rotation of the hips. The patients with unilateral CDH had a shorter step length, lower pelvis, a lateral shift of the ground reaction force, decreased maximum adduction moments of the hip and knee on the diseased side, and increased maximum adduction moments of the hip and knee on the unaffected side. This asymmetry may have been due to leg length inequality. Thus, correlation of the leg length discrepancy may be important for unilateral CDH patients in improving their gait.

Adult↗
PubMed1996

The motion analysis system and the maximal area of fingertip motion. A preliminary report.

We have used the motion analysis system to evaluate the maximal area of fingertip motion. Some modification in setting the cameras and use of a smaller marker is required. In this series, 58 examinations have been accomplished on 28 fingers with various traumatic injuries. The closed curve derived from the motion analysis system and the area calculated from it were easier to interpret and could be compared in serial examinations. A high linear correlation between the fingertip motion area and total active motion was found. The computer-aided motion analysis system complements the traditional methods of assessing an injured finger.

Fingers↗
PubMed1994

Flexion-extension rhythm in the lumbosacral spine.

STUDY DESIGN AND OBJECTIVES: This study was conducted to depict the qualitative and quantitative changes of intervertebral rotation and translation from L1-L2 to L5-S1 during flexion, standing, and extension using dynamic lumbosacral radiographs. METHODS: A radiopaque ruler was placed on the back of each subject for the normalization of translational value. Eighty-nine volunteers were examined. RESULTS: From extension to flexion, all of the intervertebral rotations approached 0 degree from the lordotic position; the translations changed from slightly retro-listhetic to zero displacement. Using L3-L4 as a baseline for calculating the intervertebral differences in flexion, all of the rotational differences were less than 1.5 degrees, except at L5-S1, which remained 5 degrees. The mean translational difference was less than 0.6 mm, except at L5-S1, where it remained 1.5 mm. CONCLUSIONS: The amount of total flexibility was level-dependent and its frequency distribution is important. Qualitative rhythmic changes from extension to flexion and quantitative values of intervertebral difference in flexion help define the normal flexibility more accurately.

Biomechanical Phenomena↗
PubMed1994

Significance of acceleration period in a dynamic strength testing study.

The acceleration period that occurs during isokinetic tests may provide valuable information regarding neuromuscular readiness to produce maximal contraction. The purpose of this study was to collect the normative data of acceleration time during isokinetic knee testing, to calculate the acceleration work (Wacc), and to determine the errors (ERexp, ERwork, ERpower) due to ignoring Wacc during explosiveness, total work, and average power measurements. Seven male and 13 female subjects attended the test by using the Cybex 325 system and electronic stroboscope machine for 10 testing speeds (30-300 degrees/sec). A three-way ANOVA was used to assess gender, direction, and speed factors on acceleration time, Wacc, and errors. The results indicated that acceleration time was significantly affected by speed and direction; Wacc and ERexp by speed, direction, and gender; and ERwork and ERpower by speed and gender. The errors appeared to increase when testing the female subjects, during the knee flexion test, or when speed increased. To increase validity in clinical testing, it is important to consider the acceleration phase effect, especially in higher velocity isokinetic testing or for weaker muscle groups.

Acceleration↗
PubMed1993

Lumbosacral kinematics in the sagittal plane: a radiographic study in vivo.

Lateral functional radiographs of flexion and extension using Putto's method were examined in 89 normal subjects. A specially-designed radiopaque ruler was placed on each film for calibration. A computer-assisted method was used for digitization and analysis. There were weak negative correlations between age and range of motion, especially at the L4-L5 level (r = 0.437). No significant correlation was noted between age and translation. For flexion-extension rotation, although large variations may limit its usefulness in judging instability in some clinical settings, the data still provide a good diagnostic basis. For translation changes, 2 mm is regarded as acceptable in most cases at levels from L1 to L5, but not at the level of L5-S1 where the average translation change was only 0.4 mm. The differences in the absolute translation value among different positions were not statistically significant (p = 0.064).

Adult↗
PubMedDate not supplied

A 2-D model of wheelchair propulsion.

PURPOSE: To illustrate the potential benefits of kinetic and kinematic models in the exploration of biomechanical studies as illustrated using a simple 2-D static optimization model of wheelchair propulsion. METHOD: A four-bar linkage analysis was used to determine sagittal plane motion through the range of wheelchair propulsion. Using anthropometric measures of wheelchair users, this analysis determined the angles of shoulder and elbow flexion/extension at a given point in the propulsion cycle. Maximal strength inputs for the model were collected from isokinetic measurements of shoulder and elbow moments. The torque inputs were given as functions of sagittal plane joint angles. Through selection of appropriate model performance criteria, optimization techniques determined shoulder and elbow torque contributions throughout the propulsion cycle. Variations in the model parameters of anterior-posterior (AP) seat position and handrim size went used to show potential of model to evaluate wheelchair configuration using the performance criteria of propulsive moment (Mo) and efficiency as defined by fractional effective force (FEF). RESULTS: The model was able to predict the magnitude and direction of force applied to the handrim from shoulder and elbow moments. These joint moments may be examined along with the generated wheelchair axle propulsion moment. While the model showed no significant changes in either Mo or FEF for AP seat changes, an increase in handrim size was shown to increase FEF. CONCLUSIONS: This model was able to simulate wheelchair propulsion and allow for performance analyses. The open nature of the model allowed for tweaking of the kinematic inputs to examine the sensitivity of such factors as seat position and handrim size in wheelchair propulsion. Strength inputs to the model may also be altered to study the potential effects of strength training or muscle weakness.

Biomechanical Phenomena↗
PubMedDate not supplied

Performance of static standing balance in children with spastic diplegic cerebral palsy under altered sensory environments.

Seven children with spastic diplegic cerebral palsy and 14 age- and gender-matched nondisabled children participated in the present study for an investigation and comparison of their static standing balance under altered sensory environments. The type of visual input (full, occluded, or sway referenced vision) and the type of somatosensory input (fixed or compliant foot support) were varied factorially to give six sensory environments. Each participant was tested barefooted for 30 s under all six conditions. A force platform collected the ground reaction force, from which standing balance was calculated as the sway area of the center of pressure. The results showed that when somatosensory information was reliable (fixed foot support), there was no significant difference in stance stability between the children with spastic diplegic cerebral palsy and their matched controls, and both types of children were equally affected by the type of visual input. However, when somatosensory information was unreliable (compliant foot support), the difference in stance stability between the children with spastic diplegic cerebral palsy and their matched controls was significantly greater when the visual input was deprived (occluded) or unreliable (sway referenced) than when it was reliable. These results suggest that the children with spastic diplegic cerebral palsy may have difficulties in resolving intersensory conflicts for maintenance of standing balance, or the demands of motor control in sensory conflict conditions outweigh the motor ability of children with spastic diplegic cerebral palsy.

Cerebral Palsy↗
PubMedDate not supplied

Prediction of muscle force involved in shoulder internal rotation.

The estimation of shoulder muscle force is important to understand the mechanism of rotator cuff injury. In general, mean parameter values are used as input for computational models. However, anatomic and biomechanical parameters vary widely among people. The purpose of this study was to evaluate shoulder muscle forces predicted by an electromyography-driven muscle model given neuromuscular parameters generated by Monte Carlo simulation. Normal distributions were used to model muscle moment arms; electromyographic and muscle physiological cross-sectional area data were modeled with log-normal distributions. Eight muscles were included in the model. Muscle force and joint moment were predicted on the basis of the simulated parameters. The results showed that the subscapularis and pectoralis major were substantial actuators for shoulder internal rotation. During maximum voluntary contraction the median of the muscle forces of the subscapularis and the pectoralis major were 1030 N and 462 N, respectively. This study demonstrated that the Monte Carlo method could be used for muscle force prediction by integrating population variability of physiological parameter into a biomechanical muscle model.

Biomechanical Phenomena↗