Masataka Hosoda’s research while affiliated with Ryotokuji University and other places

Electromyography (EMG) is useful in investigating muscle activation; however, noninvasive evaluation of surface EMG is limited due to its complicated waveform. This study investigated muscle structure and activation using an analysis technique for surface EMG. Surface array electrodes were used in 17 healthy male subjects to record eight-channel EMGs from each biceps brachii muscle during voluntary isometric contraction with a 1-kg weight band with the subjects seated. The peaks detected by referenced EMGs were normalized and averaged as averaged pulses (APs) and the innervation zone (IZ) was estimated from the APs. Muscle fiber conduction velocities (MFCVs), estimated by the time difference of the peaks (method P) and by cross-correlation (method CC) by APs, were compared. Time periods with positive values around the central peak in AP (PP) were measured and the contribution of MFCVs by motor unit action potentials (MUAPs) was estimated. IZs were estimated in 12 subjects. Near the IZ, correlation between MFCVs by methods P and CC was lower than in other locations; MFCV was significantly larger by method P than by method CC in the vicinity of the IZ. PP of the comparison AP was significantly larger than that of the reference AP. The distribution of the MFCVs by different MUAPs was verified by computer simulation. Surface EMG was used to demonstrate the diversity of MFCVs, with some increased MFCVs, for several MUAPs in the vicinity of the IZ. This method could be applied to the evaluation of neuromuscular disorders.

The purpose of this study was to analyze age-related movement smoothness changes in the lower extremity joints during load lifting. A total of 10 young and 13 elderly subjects participated in the study. Infrared reflective markers were attached to body landmarks in each subject. While the subjects stood on force plates and lifted a box, the marker displacements and ground reaction forces were measured using a 3D motion analysis system. The jerk square mean value (JSM) was defined as the lower extremity joint movement smoothness index during lifting. JSM represented the average of the square of the joint angle third derivative value, according to the jerk third derivative of the position data. Each subject's JSM values were calculated for the hip, knee and ankle joints. Movement smoothness appeared to decrease as JSM increased. Multiple regression analyses were performed for dependent variables (hip, knee and ankle joint JSM values) and independent variables (age, hand grip strength, sex difference and lifting duration). The level of significance was set at p<0.05. For the hip joint JSM, the regression coefficient for age was significantly positive and that for lifting duration was significantly negative. For the knee joint JSM, the regression coefficient for lifting duration was significantly negative. For the ankle joint JSM, the regression coefficients for age and hand grip strength were significantly positive and that for lifting duration was significantly negative. These results suggest that movement smoothness in the hip and ankle joints during lifting decreases with advancing age.

Experimental, controlled trial, animal study.Objective:To assess morphologic changes in different cartilage plates after spinal cord injury and identify the localization of these alterations. Saitama, Japan. A total of 16 Wistar rats were used. Eight rats underwent a spinal cord injury and eight rats had no intervention as control. The cartilage alterations of the knee joint were evaluated with radiography and histomorphometric analysis. To quantify cartilage alterations, we selected the histologic characteristics: thickness of the articular cartilage, number of chondrocytes, matrix staining to toluidine blue as a reflection of proteoglycan content and surface irregularity. No differences in knee joints were found between the groups by radiography. In the medial knee joint, cartilage thickness of spinal-cord-injured knees increased at the anterior femoral region and decreased at the tibial and posterior femoral regions; however, in the lateral knee, that of spinal cord injuries did not change compared with control knees. Spinal cord injuries decreased the number of chondrocytes, especially at the anterior femoral regions. Matrix staining increased partially at the tibial regions. Surface irregularity of spinal-cord-injured knees was comparable to that of control knees in all cartilage plates. The present findings exhibit characteristics of the cartilage after spinal cord injury. These alterations were different in nature between the medial and lateral regions. Future studies should assess separately different cartilage plates, to overestimate these severities when the changes at the medial knee were examined and to underestimate when the changes at the lateral knee were examined.

Mechanical forces are crucial for the maintenance of the morphologic and functional integrity of articular cartilage. The alteration of the articular cartilage after spinal cord injury (SCI) has been described in relation to a suppression of mechanical forces, since the joint is unloaded and restricted in movement. However, the morphological and biochemical characteristics of the cartilage after SCI are still poorly understood. We identified the localization of cartilage alterations after SCI and verified the influence of mechanical forces on the articular cartilage. A total of 32 Wistar rats were used. Sixteen animals underwent an SCI and 16 animals served as control. The articular cartilage of the knee joint was assessed, respectively, at 4, 8, 10, and 12 weeks after intervention by histochemical, histomorphometric, immunohistochemical, and biochemical analyses. Cartilage thickness of spinal cord-injured knees decreased at the tibial and posterior femoral (FP) regions and increased at the anterior femoral (FA) region. Spinal cord injuries decreased the number of chondrocytes at the anterior regions and decreased the cartilage matrix staining only at the tibial regions. Immunolabeling to collagen type II was noted comparably in the superficial layer but noted weakly from the middle to deep layer. Collagen type I existed excessively at the cartilage surface and the pericellular regions. Cartilage alterations after SCI would not be explained by only a suppression of mechanical forces by unloading and immobilization, but there may be influences on the cartilage in addition to the change in mechanical forces.

To examine whether occlusion status contributes to improvement of postural balance. Thirty healthy adolescents (15 males and 15 females; mean age, 20.3; standard deviation (SD) 1.6 years) with no equilibrium or stomatognathic function abnormalities were examined. Occlusion is a term meaning "jaw clenching." Occlusion status was evaluated by measuring masseter activity using the EMG system. Balancing ability was evaluated using the EquiTest system, which measures sway of the center of gravity produced by rapid movement of force plates as an external disturbance (three intensity levels). The time required for initiation of recovery after application of the disturbance was calculated by measuring displacement of the center of foot pressure. Data were compared according to occlusion status. Little difference in latency was observed following a small disturbances; however, the greater the disturbance the shorter the latency with occlusion, while without occlusion, latency increased with increasing disturbance. A statistically significant interaction (P<0.001) between occlusion and external disturbance was also found. This study suggested that occlusion contributes to maintenance of postural balance and improvement of stability when unexpected sway occurs in the standing position.

The purpose of this study was to objectively evaluate the fit of sockets for trans-tibial stumps in order to establish a guideline for use in the automated production of prosthetic sockets. Subjects were 24 trans-tibial amputees. Using a CAD/CAM system, 11 parameters regarding the 3D shape of the stumps and the sockets were objectively evaluated. A correlation was found between the activity level and the upper and lower volumes of the socket, and between the cause of amputation and the upper volume of the socket. It was considered desirable to make the lower part of the socket looser for patients with lower activity levels, to make the upper part tighter for patients with higher activity levels, and to make the upper part looser for amputation patients with peripheral circulatory diseases.

This study was performed to determine the current situation and future prospects regarding the information, techniques, and educational methods of Interprofessional Education (IPE) that are needed throughout the world. The authors contacted a number of schools with physical therapy faculties that have introduced IPE into their curricula as well as credits designated by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT). The IPE-related credits under the present curriculum were reviewed. In Japan, only 5 of 36 physical therapy faculties have adopted IPE into their curricula. In Japan, ninety-three credits are designated by MEXT in schools that train physical therapists. The Designated Regulation of Education of Japanese Physical Therapists was revised in 1989, and IPE-related clauses were added. This takes into account the social needs of physical therapists and recognizes the need for interprofessional knowledge. Furthermore, other clauses were added to train competent therapists: clauses regarding increased human understanding, sympathy for patients, understanding and cooperation in human relationships, understanding of patients' families, and understanding of support education methods. These are all part of the "joint education for training physical therapists," which is a small part of the curriculum.

In this study we try to clarify sequential changes in Meissner corpuscles after transection of the spinal cord. Meissner corpuscles stained with cholinesterase in the experimental group were already significantly fewer one week after spinal cord transection. The condition of rats in the first week after the operation was regarded as a spinal shock period. Denervation caused a decrease in the number of stained Meissner corpuscles in the shock period. In the experimental group at 7 weeks after the operation, atrophy of these corpuscles was statistically significant. These rats could not carry their weight on their hind limbs, and this change was regarded as the effect of disuse. The results of this study suggest the possibility of human sensory organs' atrophy after spinal cord injury.

We conducted a prospective study on the actual state of fall occurrence and the related fall factors of some dementia patients admitted to a certain geriatric hospital. Information on falls was obtained from the fall assessment recorded by staff. The number of these subjects totaled 110 (20 males and 90 females), The period of this study was 6 months. Their fall rate during that period was as high as 56%. The frequently occurring places and peak time of fall coincided with the places and times slots in which their activity was enhanced. Most of the injuries suffered due to falls were minor ones, and there were no bone fractures stemming from falls. As for the factors related to a fall, sex, age, complication, MMS score and administered internal medicine was no significant between fallers and nonfallers. Of the subjects affected with cerebrovascular diseases during or before this study period, those with vascular dementia showed the most remarkable trend to fall. It was thought that the results will be useful when applied to the carried out care of elderly persons with dementia.

The aim of this study was to assess the effects of living circumstances on the locus of control of senior citizens with hemiplegia, and to research the factors that control the locus of control from among the 10 items (activities of daily living, quality of life, degrees of paralysis, age, sex, diagnosis, type of disorder, length of living at home/institution, whether or not s/he has hobbies, whether or not s/he has friends). The subjects of this study were senior citizens with hemiplegia who were living at home (n=31) or resided in the nursing homes (n=30), and elderly able bodied people who were living at home (n=35). The results showed that there were no significant differences in the locus of control between the hemiplegia group and able bodied people group, but in the stroke patients group, patients who were living at home got a high score in the locus of control which was significantly more than that of these who resided in nursing homes. The items which controlled the locus of control were abilities of activities of daily living among the senior citizens with hemiplegia who were living at home and quality of life among these who resided in nursing homes. The results suggest that a sensitive indicator of locus of control is not physical disability but place of living. The living at home group requires the formation of an environment in which activities of daily living ability can be drawn out to the maximum, and the institution group requires the offer of a lifestyle that is high in quality and which matches the individual preferences of the people entering the institution.