Fuk-Tan Tang

The sit-to-stand movement in stroke patients and its correlation with falling

OBJECTIVE To use kinetic assessment of the sit-to-stand movement as a means of sorting out those stroke patients at risk for falling. DESIGN A retrospective study, using a force platform to assess sit-to-stand performance and to determine its correlation with falls in stroke patients. SETTING Hospital-based rehabilitation units. METHODS Thirty-three stroke patients (18 fallers, 15 nonfallers) and 25 age-matched healthy subjects were included in this study. Subjects sat in an adjustable chair with their feet on two force plates and performed the standing up/sitting down movement at a self-paced, comfortable speed. RESULTS The rate of rise in force (dF/dT) was significantly lower in stroke fallers than in stroke nonfallers and healthy subjects (23.78+/-17.38, 55.23+/-31.24, and 85.96+/-42.4 percent body weight per second, respectively [p < .005]). The center of pressure sway in mediolateral direction during rising/ sitting down was much greater in stroke fallers than in stroke nonfallers or healthy subjects (p < .05). Body weight distribution was asymmetric on the feet of stroke patients, with much more body weight on their sound side. CONCLUSIONS The significantly lower rate of rise in force and greater postural sway while rising/sitting down may be useful in identifying stroke patients who are at risk for falling.

Effects of total contact insoles on the plantar stress redistribution: a finite element analysis

OBJECTIVE To investigate the effects of total contact insoles on the plantar stress redistribution using three-dimensional finite element analysis. DESIGN The efficacies of stress reduction and redistribution of two total contact insoles with different material combinations were compared with those of a regular flat insole used as a baseline condition. BACKGROUND Many specially designed total contact insoles are currently used to reduce the high plantar pressure in diabetic patients. However, the design of total contact insoles is mostly empirical and little scientific evidence is available to provide a guideline for persons who prescribe such insoles. METHODS To use three-dimensional finite element models of the foot together with insoles to investigate the effects of total contact insoles on the foot plantar pressure redistributions. Nonlinear foam material properties for the different insole materials and the contact behavior in the foot-insole interface were considered in the finite element analysis. RESULTS Results showed that the peak and the average normal stresses were reduced in most of the plantar regions except the midfoot and the hallux region when total contact insoles were worn compared with that of the flat insole condition. The reduction ratios of the peak normal stress ranged from 19.8% to 56.8%. CONCLUSIONS Finite element analysis results showed that the two sets of total contact insoles used in the current study can both reduce high pressures at regions such as heel and metatarsal heads and can redistribute the pressure to the midfoot region when compared with the flat insole condition. RELEVANCE It is possible to simulate foot deformities, change in material properties, different ambulatory loading conditions, and different orthotic conditions by altering the finite element model in a relatively easy manner and these may be of interests to the medical professionals who treat foot-related problems.

Stress distribution of the foot during mid-stance to push-off in barefoot gait: a 3-D finite element analysis.

OBJECTIVE To quantify stress distribution of the foot during mid-stance to push-off in barefoot gait using 3-D finite element analysis. DESIGN To simulate the foot structure and facilitate later consideration of footwear. Finite element model was generated and loading condition simulating barefoot gait during mid-stance to push-off was used to quantify the stress distributions. BACKGROUND A computational model can provide overall stress distributions of the foot subject to various loading conditions. METHODS A preliminary 3-D finite element foot model was generated based on the computed tomography data of a male subject and the bone and soft tissue structures were modeled. Analysis was performed for loading condition simulating barefoot gait during mid-stance to push-off. RESULTS The peak plantar pressure ranged from 374 to 1003 kPa and the peak von Mises stress in the bone ranged from 2.12 to 6.91 MPa at different instants. The plantar pressure patterns were similar to measurement result from previous literature. CONCLUSIONS The present study provides a preliminary computational model that is capable of estimating the overall plantar pressure and bone stress distributions. It can also provide quantitative analysis for normal and pathological foot motion. RELEVANCE This model can identify areas of increased pressure and correlate the pressure with foot pathology. Potential applications can be found in the study of foot deformities, footwear, surgical interventions. It may assist pre-treatment planning, design of pedorthotic appliances, and predict the treatment effect of foot orthosis.

Resistive inspiratory muscle training: Its effectiveness in patients with acute complete cervical cord injury

OBJECTIVE To evaluate if resistive inspiratory muscle training (RIMT) can improve lung function in patients with complete tetraplegia within half a year after trauma. DESIGN A prospective study. The experimental patients received training with a Diemolding Healthcare Division inspiratory muscle trainer for 15 to 20 minutes per session, twice per day, 7 days a week for 6 weeks. SETTING Hospital-based rehabilitation units. PATIENTS Twenty patients who were in their first 6 months of complete cervical cord injury were randomly enrolled into RIMT (10 patients) and control (10 patients) groups. MAIN OUTCOME MEASURE Spirometry, lung volume test, maximal inspiratory pressure, maximal expiratory pressure, and modified Borg scale measurements at rest were performed before training and at the end of 6 weeks of training. RESULTS Most of the pulmonary parameters showed statistically significant improvements within the RIMT and control groups, but the improvements were greater in the RIMT group. In addition, the improvements in total lung capacity, total lung capacity predicted percentage, vital capacity, minute ventilation, forced expiratory volume in 1 second predicted percentage, and the resting Borg scale in the RIMT group showed significantly greater improvement. CONCLUSION RIMT can improve ventilatory function, respiratory endurance, and the perceived difficulty of breathing in patients with complete cervical spinal cord injury within half a year after trauma.

Comparison of the mechanical properties of the heel pad between young and elderly adults

OBJECTIVE To compare the mechanical properties of the human heel pad between young and aged adults. DESIGN A 7.5-MHz linear-array ultrasound transducer was incorporated into a specially designed device to measure the thickness of the heel pad under different loads. The heel pad was compressed with serial increments of 0.5kg to a maximum of 3kg and then relaxed sequentially. Then the load-displacement curve of the heel pad during a loading-unloading cycle was plotted. PARTICIPANTS Convenience sample of 33 volunteers without heel problems, aged 18 to 78 years, were divided into young (less than 40 years) and elderly (older than 60 years) groups. MAIN OUTCOME MEASURES Unloaded heel-pad thickness, compressibility index, stiffness, and energy dissipation ratio were calculated from the load-displacement curves. Students t-test was used to compare the mechanical properties of the heel between these two groups. RESULTS The average unloaded heel-pad thickness was 1.76+/-.20cm in the young group and 2.01+/-.24cm in the elderly group (p < .001). The average compressibility index was 53.3%+/-7.7% in the young group and 61.3%+/-5.5% in the elderly group (p < .001). Energy dissipation ratio representing shock absorbency of the heel pad, was 23.7%+/-6.9% in the young group and 35.3%+/-10% in the elderly group (p < .001). CONCLUSION Unloaded heel-pad thickness, compressibility index, and energy dissipation ratio of the heel pad were significantly increased in the elderly group, indicating loss of the elasticity of the heel pad. The loss of elasticity may be responsible for the higher incidence of heel injury in elderly individuals.

Ultrasound evaluation of plantar fasciitis

OBJECTIVE To investigate the sonographic features of plantar fasciitis (PF). METHODS High-resolution ultrasound was used to measure the thickness and echogenicity of the proximal plantar fascia and associated heel pad thickness for 102 consecutive patients with PF (unilateral: 81, bilateral: 21) and 33 control subjects. RESULTS The mean thickness of the plantar fascia was greater on the symptomatic side for patients with bilateral and unilateral PF than on the asymptomatic side for patients with unilateral PF, and also control subjects (5.47+/-1.09, 5.61+/-1.19, 3.83+/-0.72, 3.19+/-0.43 mm, respectively, p<0.001). A substantial difference in thickness between the asymptomatic side of patients with unilateral PF and control subjects was also noted (p=0.001). The heel pad thickness was not show different between control subjects and patients with PF. The incidence of hypoechoic fascia was 68.3% (84/123). Other findings among the patients from our test group included intratendinous calcification (two cases), the presence of perifascial fluid (one case), atrophic heel pads (one case), and the partial rupture of plantar fascia (one case). CONCLUSION Increased thickness and hypoechoic plantar fascia are consistent sonographic findings in patients exhibiting PF. These objective measurements can provide sufficient information for the physician to confirm an initial diagnosis of PF and assess individual treatment regimens.Objective: To investigate the sonographic features of plantar fasciitis (PF). Methods: High-resolution ultrasound was used to measure the thickness and echogenicity of the proximal plantar fascia and associated heel pad thickness for 102 consecutive patients with PF (unilateral: 81, bilateral: 21) and 33 control subjects. Results: The mean thickness of the plantar fascia was greater on the symptomatic side for patients with bilateral and unilateral PF than on the asymptomatic side for patients with unilateral PF, and also control subjects (5.47¡1.09, 5.61¡1.19, 3.83¡0.72, 3.19¡0.43 mm, respectively, pv0.001). A substantial difference in thickness between the asymptomatic side of patients with unilateral PF and control subjects was also noted (p~0.001). The heel pad thickness was not show different between control subjects and patients with PF. The incidence of hypoechoic fascia was 68.3% (84/123). Other ®ndings among the patients from our test group included intratendinous calci®cation (two cases), the presence of perifascial ̄uid (one case), atrophic heel pads (one case), and the partial rupture of plantar fascia (one case). Conclusion: Increased thickness and hypoechoic plantar fascia are consistent sonographic ®ndings in patients exhibiting PF. These objective measurements can provide suf®cient information for the physician to con®rm an initial diagnosis of PF and assess individual treatment regimens.

Inhibition of tendon cell migration by dexamethasone is correlated with reduced alpha-smooth muscle actin gene expression: A potential mechanism of delayed tendon healing

Local corticosteroid injection is commonly used to treat sports‐related tendon injuries. However, isolated cases of tendon rupture following injection suggest that this treatment may impair the healing process. Tendon healing requires the migration of tendon cells to the repair site, followed by the proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of dexamethasone on the migration of tendon cells intrinsic to rat Achilles tendon at concentrations similar to those typically used for local injection treatment.

Altered heel-pad mechanical properties in patients with Type 2 diabetes mellitus

SUMMARY

Correlation of clinical and ultrasonographic features in congenital muscular torticollis

OBJECTIVE To find the relationship between the ultrasonographic pictures and the clinical features of patients with congenital muscular torticollis (CMT). DESIGN Prospective survey of patients with clinically suspected CMT by high-resolution ultrasonography. SETTING Rehabilitation department of a tertiary care center. PARTICIPANTS Two hundred fifty-six CMT patients, from the ages of 9 days to 16yrs, with a mean follow-up period of 6.7 months. MAIN OUTCOME MEASURES Correlation of the ultrasound appearance of the involved sternocleidomastoid (SCM) muscles with clinical features. The pathologic findings in diseased muscles from patients who underwent surgical intervention were also evaluated. RESULTS Muscle abnormalities were identified ultrasonographically in 218 CMT patients (85%) and were classified into four types: a fibrotic mass in the involved muscle (type I, 15%); diffuse fibrosis mixing with normal muscle (type II, 77%) and without normal muscle in the involved muscle (type III, 5%); and a fibrotic cord in the involved muscle (type IV, 3%). Compared with type I patients, type IV patients were more likely to undergo surgical treatment (odds ratio = 31.54, p = .0196). Type III patients were more likely to undergo surgical treatment, although this tendency was not statistically significant. CONCLUSION Ultrasonography can precisely identify pathologic changes in the involved SCM muscle of CMT patients. Type III and IV patients are more likely to require surgical intervention.

A comparison of automatic fall detection by the cross-product and magnitude of tri-axial acceleration

Falling is an important problem in the health maintenance of people above middle age. Portable accelerometer systems have been designed to detect falls. However, false alarms induced by some dynamic motions, such as walking and jumping, are difficult to avoid. Acceleration cross-product (AC)-related methods are proposed and examined by this study to seek solutions for detecting falls with less motion-evoked false alarms. A set of tri-axial acceleration data is collected during simulated falls, posture transfers and dynamic activities by wireless sensors for making methodological comparisons. The performance of fall detection is evaluated in aspects of parameter comparison, threshold selection, sensor placement and post-fall posture (PP) recruitment. By parameter comparison, AC leads to a larger area under the receiver operating characteristic (ROC) curve than acceleration magnitude (AM). Three strategies of threshold selection, for 100% sensitivity (Sen100), for 100% specificity (Spe100) and for the best sum (BS) of sensitivity and specificity, are evaluated. Selecting a threshold based on Sen100 and BS leads to more practicable results. Simultaneous data recording from sensors in the chest and waist is performed. Fall detection based on the data from the chest shows better global accuracy. PP recruitment leads to lower false alarm ratios (FR) for both AC- and AM-based methods.