Nobuharu Suzuki

Age-related changes in the interactive mobility of the hip and knee joints: a geometrical analysis

This study examined any systematic age-related change in the passive range of motion (PROM) of the hip and knee joints. Seventy-seven healthy male volunteers ranging in age from 15 to 73 years were assessed. A geometrical range of motion (ROM) analysis was applied, which could evaluate the effects of both monoarticular and biarticular muscles. The PROM of the hip joint decreased progressively with advancing age, whereas that of the knee joint remained unchanged. In addition, the interactive PROM of the hip and knee joint associated with biarticular rectus femoris and hamstring muscles also showed an age-related reduction. The progressive reduction of the ROM is probably caused by shortening of muscles or connective tissues due to reduced compliance of joint structures and degenerative changes in spinal alignment, as well as by diminished muscle stretching resulting from a decrease in daily physical activities with advancing age.

Geometrical analysis of hip and knee joint mobility in cerebral palsied children

The present investigation attempted to define a geometrical hexagon model for representing the sagittal range of motion (ROM) of hip and knee joint. The effect of both monoarticular and biarticular muscles on joint mobility in children with spastic cerebral palsy (SCP) were analyzed by this geometrical method. Photographic analysis was used to measure hip and knee joint angle at six different boundary positions. The ROM in normal children indicated age dependent reduction of maximal hip flexion and shortening of hamstring and rectus femoris muscles. A number of SCP children showed greater reduction of both hip flexion and extension and shortening of hamstring and rectus femoris muscles, whereas the ROM of knee joint was similar to that in normal children. The deteriorated hip joint mobility seems to be associated with shortening of muscle due to their intrinsic spasticity. The impaired ROM was more noticeable in SCP non-ambulator child than in independent ambulator. Thus, more extended range and frequent opportunity of joint motion may play an important role in improving the joint mobility in this patient group. Copyright 1998 Elsevier Science B.V.

Hemodynamic and hormonal changes during lower body negative pressure in bedridden disabled patients

Hemodynamic responses and hormonal changes induced by lower body negative pressure (LBNP) were measured in bedridden patients with severe disabilities to identify their cardiovascular function. After a control period of 5 minutes supine, each subject underwent a LBNP test of ‐20 mmHg for 5 minutes. Disabled patients were classified into two groups: Group HI consisted of the members who had a blood pressure response to LBNP exposure similar to normal control subjects, and group H2 patients displayed a greater reduction in blood pressure than the normal response. Both disabled groups demonstrated a significantly higher level of resting heart rate as well as a smaller stroke volume and cardiac output than normal subjects. Exposure to LBNP in disabled patients produced a smaller decrement in stroke volume and cardiac output than in normal subjects. The expected increase in heart rate for the compensatory effect was not observed in the HI group, and a decreased heart rate lower than resting values was measured...

Change in heart rate variability in bedridden patients with severe physical disability

The change in power spectral density of heart rate variability (HRV) during sitting and to an exposure to lower body negative pressure of ‐20 mmHg was estimated in 21 bedridden patients with severe...

A Simulation Study on Walking Disabilities Associated with Restriction of Joint Range of Motion.

The restriction of the range of motion (ROM) of joints is one of the major causes contributing to walking disabilities as well as neural dysfunction and decreased muscle force. This study was designed to develop a biomechanical model of walking consisting of both the neural and muscunloskeletal systems, and to simulate the characteristics of walking disability due to restriction of the ROM of hip and knee joints. The neural and muscunloskeletal functions in the present model were represented by neural oscillators and a two-dimensional five-link model, respectively. The walking patterns produced under the non restricted ROM of the joints were similar to those obtained from normal individuals. The simulation with the restricted ROM of joints demonstrated more unstable walking with increasing severity of the joint impairments as well as with increasing walking velocity. Even if the ROM of hip and/or knee joints of this model was restricted, both stride length and cadence during stable walking were within the range determined from normal individuals. However, the vertical acceleration of the body center of gravity was considerably greater during walking with the restricted joints compared with free joint movement. These characteristics obtained from the simulation were very similar to those of disabled walking produced experimentally by healthy subjects whose lower limb joints were restricted by orthotic devices. It is considered that the present biomechanical model/simulation is a useful way to identify a single cause such as joint contracture from the multiple and complex impairments associated with walking disabilities and to assess the degree of the disabilities due to the specified impairment.

Biomechanical Analysis of Alignment in Standing Posture in Children with Cerebral Palsy.

The purpose of this study is to determine the quantitative relationship between the restriction of the ROM (range of motion) of joints and alignment in standing posture in children with cerebral palsy (CP). The measurement of alignment was carried out on three planes : horizontal, backward-inclined and forward-inclined planes. Alignment in CP children without a restricted ankle joint (NR-CP) was similar to that in normal subjects who can maintain an upright posture on any plane merely by adjusting the ankle joint alone. CP children with a restricted ankle joint (R-CP) demonstrated a severe crouching posture characterized by a forwardly inclined trunk, backwardly inclined thigh and forwardly inclined leg. This pathological posture may result not only from the contracture of the ankle joint but also from muscle shortening over the two joints. A biomechanical model of the restriction of the ROM was developed and used to simulate the alignment in a standing posture. The simulation results for normal and NR-CP subjects were consistent with the experimental measure. ments. However there was some difference between the simulation and the measurements for R-CP children, particularly for the forward-inclined plane. If the mathematical model used in this study accurately reflects the effect of the restriction of the ROM on the alignment, other factors such as impaired neuromuscular function might contribute to the difference. The present biomechanical approach is useful to develop effective measures for improving posture in CP children.

Assessment of Cardiovascular Regulation to Lower Body Negative Pressure in Bedridden Disabled Patients

Disabled patients who are bedridden over a long period of time may be considered to be exposed to a continued weightlessness, similar to subjects in space flight. Cyanosis, edema, and cerebral anemia appear frequently in these patients simply because of passive orthostatic posture. These symptoms imply a deterioration in cardiovascular function which has occurred during the years of enforced bed rest in these patients. The purpose of the present study was to identify the cardiovascular response to lower body negative pressure (LBNP) in severely disabled patients during prolonged recumbency.