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Biomedical subjects

A T Hsu

Publications and source records attributed to A T Hsu.

8 recordsLinked to original sources
PubMed2000

Efficacy of a 24-week aerobic exercise program for osteopenic postmenopausal women.

Osteoporosis is one of the most common skeletal disorders affecting postmenopausal women. The purpose of this study was to investigate whether a 24-week program of aerobic high-impact loading exercise was beneficial for enhancing physical fitness and bone mineral density (BMD) in osteopenic postmenopausal women. Forty-three postmenopausal women aged 48-65 years participated in this study. The BMD of the spine (L2-L4) and right femoral neck of each woman was below 1 SD of the mean of premenopausal women, as examined by dual X-ray absorptiometry. The assignment of subjects into exercise or control group was not randomized but based on each subject's anticipated compliance to the 6-month long exercise program. Twenty-two subjects joined the exercise group and attended the training programs and 21 served as the control group. Exercise programs included treadmill walking at an intensity above 70% of maximal oxygen consumption (VO2max) for 30 minutes, followed by 10 minutes of stepping exercise using a 20-cm-high bench. The program was conducted three times per week for 24 weeks. Physical fitness measurements included testing of flexibility, muscular strength and endurance, body composition, and cardiopulmonary fitness. The results showed that the quadriceps strength, muscular endurance, and VO2max in the exercise group had significant improvements, whereas no improvement was found in any of the physical fitness parameters in the control group. The BMD of the L2-L4 and the femoral neck in the exercise group increased 2.0% (P > 0.05) and 6.8% (P < 0.05) and those in the control group decreased 2.3% (P < 0.05) and 1.5% (P > 0.05), respectively. In conclusion, aerobics combined with high-impact exercise at a moderate intensity was effective in offsetting the decline in BMD in osteopenic postmenopausal women.

Absorptiometry, Photon↗
PubMed2000

Joint position during anterior-posterior glide mobilization: its effect on glenohumeral abduction range of motion.

OBJECTIVE: To investigate the effect of joint position during an anterior-posterior glide (APG) procedure on the range of motion (ROM) of glenohumeral abduction in cadaver specimens. DESIGN: Mechanical simulation of APG mobilization and abduction torque ROM measurement of the glenohumeral joint with a material testing system. The immediate mechanical efficacy of APG was compared in two groups of specimens at two different joint positions: midrange (n = 5) and end range (n = 6) of glenohumeral abduction. SETTING: Biomechanics laboratory. SPECIMENS: Eleven fresh cadaver shoulder specimens (mean age, 66.9+/-2.5 yrs). MAIN OUTCOME MEASURE: Improvement in glenohumeral abduction torque ROM obtained before and after APG procedure. RESULTS: Glenohumeral abduction improved significantly, as indicated by a significant increase (Kruskal-Wallis statistics, chi2 = 7.50, p = .006) in the torque ROM of the end range group (mean +/- standard error of the mean, 2.02 degrees +/- .20 degrees) over the midrange group (.64 degrees +/- .08 degrees). A significant difference in the magnitude of peak displacement of the humeral head between midrange (14.44+/-3.56 mm) and end range (3.19+/-.81 mm) groups was also found (Mann-Whitney test, p < .030). CONCLUSION: This study demonstrated that APG technique performed at close to the end of the range of abduction is more effective in improving glenohumeral abduction ROM than that performed at the middle of the range of abduction.

Aged↗
PubMed2000

Immediate response of glenohumeral abduction range of motion to a caudally directed translational mobilization: a fresh cadaver simulation.

OBJECTIVE: To investigate the immediate effect of caudal glide translational mobilization on the range of motion (ROM) of passive glenohumeral abduction with a fresh cadaver model to simulate the mobilization movement performed by a physical therapist treating patients with glenohumeral hypomobility. DESIGN: Mechanical simulation of caudal glide mobilization and abduction torque range of motion (TROM) measurement of the glenohumeral joint with 2 material testing systems. Mobilizations were conducted with the glenohumeral joint positioned at a resting position (IGR) and at the end range of abduction (IGE). SETTING: Biomechanics laboratory. CADAVERS: Twenty fresh shoulder specimens from 10 cadavers (mean age, 68 +/- 8 yr). MAIN OUTCOME MEASURE: Changes in TROM of the glenohumeral abduction in response to 5 bouts of caudal glide mobilization. RESULTS: At least 3 repetitions of TROM were required to attain consistent measurements on glenohumeral abduction ROM. Significant differences were found among changes in TROM because of rest, IGR, and IGE (Kruskal-Wallis statistics, (chi2 = 14.58, p = .001). A greater increase in glenohumeral abduction TROM was found after IGE (mean +/- standard error of the mean, 4.38 degrees +/- 0.95 degrees) compared with the rest control (0.03 degrees +/- 0.07 degrees; Mann-Whitney test, p = .001, alpha = .017) or its IGR counterpart (0.26 degrees +/- 0.46 degrees, p = .001, alpha = .017). CONCLUSION: This simulation of caudal glide translational mobilization at the end range using cadaver models improved passive glenohumeral abduction ROM but was ineffective when performed with the shoulder placed in a resting position. The mechanical responses of the glenohumeral joint to translational mobilization in a live patient may be similar, but some caution should be used in generalizing these findings.

Aged↗
PubMed2000

Physical activity, physical fitness, and osteopenia in postmenopausal Taiwanese women.

BACKGROUND AND PURPOSE: The purpose of this cross-sectional study was to investigate whether physical activity level and physical fitness parameters differ between postmenopausal Taiwanese women with normal and subnormal bone mineral density (BMD). METHODS: Seventy-six postmenopausal women aged from 42 to 65 years participated in this study. Women taking medication that might influence BMD measurements were not included. The BMDs of the lumbar spine (L2-4) and right femoral neck were measured using dual energy x-ray absorptiometry. Thirty-one women with both BMD values within the normal ranges (1.055 +/- 0.092 g/cm2 for the spine and 0.845 +/- 0.088 g/cm2 for the right femoral neck) of premenopausal Chinese women served as the normal density group. Another 43 women with both BMD values more than one standard deviation below the normal value (0.760 +/- 0.089 g/cm2 for the spine and 0.656 +/- 0.052 g/cm2 for the femoral neck) were recruited as the osteopenic group. Physical activity level was assessed with a 7-day recall questionnaire. Physical fitness assessment included tests of flexibility, muscular strength, endurance, body composition, and cardiopulmonary fitness. A multiple linear regression model adjusted for age, body weight, height, and years since menopause was used. RESULTS: The results revealed that energy expenditure and maximal oxygen consumption were significantly lower in the osteopenic group than in the non-osteopenic group (p < 0.05), while flexibility, body composition, muscle strength and muscular endurance did not differ significantly between the two groups (p > 0.05). CONCLUSIONS: These findings indicate that physical activity may play a major role in BMD levels in postmenopausal women in Taiwan. Future studies should emphasize the effect of physical exercise training on BMD in postmenopausal women.

Adult↗
PubMed1993

Quadriceps force and myoelectric activity during flexed knee stance.

The purpose of this study was to determine the quadriceps demand during single limb stance with the knee in five positions of flexion (0 degree -60 degrees). Two variables were used to estimate the quadriceps demands: the integrated electromyogram (EMG) of three vasti and the torque about the knee joint. Ten normal subjects 23-29 years of age were tested. Myoelectric activity was recorded with intramuscular electrodes and knee joint angle with an electrogoniometer. The EMG data were integrated and normalized. A visible vector system was used to determine knee flexion torque. A significant linear correlation was found between values of patellar ligament force and knee angle (R2 = 0.86). The patellar ligament force increased 4.16% of body weight per degree of knee flexion between 0 degree and 60 degrees. Both vector-estimated quadriceps force and normalized EMG showed significant correlations with knee angle (R2 = 0.91 and R2 = 0.88, respectively). Both exhibited a slower rate of rise below 30 degrees flexion and a higher rate of rise above 30 degrees. The authors' findings suggest that the stabilizing effects of plantar flexors (except gastrocnemius) on the knee joint, changing muscle moment arm length, and force ratio between the patellar ligament and quadriceps muscle with respect to knee angle are primary reasons for the quadratic normalized integrated EMG (NIEMG)-force nonlineality during flexed stance. This might indicate the existence of a critical angle of knee flexion contracture beyond which patients cope poorly with standing and functional ambulation.

Adult↗
PubMedDate not supplied

Application of an unstructured grid algorithm to artificial heart valve simulations.

The time varying flow pattern in the vicinity of mechanical heart valves (MHV) is fairly complex: it involves multiple passages and moving leaflets. The numeric simulation of unsteady flows in these multiple passages with moving boundaries presents a major challenge to computational fluid dynamics (CFD). Two major difficulties in the numeric simulation of MHV flows are 1) the generation of a body fitted grid within the multipassage device and 2) moving leaflets. The conventional finite difference and finite volume scheme obtained by using a structured grid have serious deficiencies in these applications. To fit the grid lines with the various angles of the moving MHV, the grid may often become too skewed for accurate numeric solution. To overcome these deficiencies, significant effort and attention should be placed on the grid generation and moving grid scheme. We present an unstructured moving grid finite volume method for heart valve simulations. The Navier-Stokes equations are discretized on a general tetrahedral mesh by using a finite volume scheme. With this scheme, the mesh can be automatically generated with any commercial software. The method is applied to a tilting disk (Medtronic Hall 29mm, Medtronic, Inc., Minneapolis, MN) heart valve, and results are compared with that of the steady flow solutions. Significant differences between steady and unsteady flow solutions are observed.

Algorithms↗
PubMedDate not supplied

Dimensional accuracy and retentive strength of a retrievable cement-retained implant-supported prosthesis.

The purpose of this research project was to compare the fit of a retrievable cement-retained implant-supported framework to that of a traditional wax and cast, screw-retained framework and to test the strength of the cemented restoration. Ten telescopic frameworks were luted to gold cylinders with a bis-GMA resin cement. The control group consisted of 10 frameworks fabricated with traditional wax and casting techniques directly to the gold cylinders. Frameworks were analyzed for distortion in the z-axis using scanning electron microscopy and a single screw test. Results demonstrated that the retrievable cement-retained group had a decreased gap distance and improved angular distortion (statistical significance P < .01) compared to the control group. Retentive strength measurements for the cement-retained group with a direct pull-out test revealed a mean pull-out force of 65.7 kg. Three of the 5 samples surpassed the tensile strength of the gold retaining screws (76 kg). Cement-retained restorations demonstrated superior fit in the z-axis and angular distortion compared to traditional wax and cast screw-retained frameworks. Retentive tests support a simplified technique of clinically luting telescopic implant-supported frameworks with adequate retentive strength.

Bisphenol A-Glycidyl Methacrylate↗