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Biomedical subjects

D A Winter

Publications and source records attributed to D A Winter.

At least 91 records · Page 5Linked to original sources
PubMed1979

A new definition of mechanical work done in human movement.

The definition of efficiency of human movement has often been unable to cope with activities such as level gait because the numerator of the efficiency equation includes only external work done by the body on an external load. The major purpose of this paper is to propose a definition that not only accounts for any external work but also the internal work done by the limbs themselves. The internal work involves a new biomechanical analysis that takes into account all potential and kinetic energy components, all exchanges of energy within and between segments, and both positive and negative work done by the muscles. This analysis was applied to a study of over-ground level gait on eight subjects walking at different walking speeds. The internal work/stride as calculated from the sum of segment energies was compared with the same calculation on the body's center of mass energy. The latter was found to be in error (low) by 16.2% and could be low by as much as 40%. The average internal work per body mass per distance walked was 1.09 J/kg.m.

Adult↗
PubMed1976

Clinical telemetry of EMG and temporal information during gait.

Multichannel telemetry has formed an integral part of the clinical assessment of children's walking problems. EMG signals and temporal information from foot switches are transmitted from a small belt-pack unit which provides almost complete freedom of movement for the child. Although patients with various crippling diseases have been studied, the investigation of problems resulting from cerebral palsy has been most valuable clinically. The effects of orthopaedic surgery to release or transfer muscles can be asssessed more positively and the causes of some unexplained gait patterns can be investigated more thoroughly.

Cerebral Palsy↗
PubMed1976

The locomotion laboratory as a clinical assessment system.

As a routine clinical tool the locomotion laboratory has been a long time evolving. This paper reviews the development, successes and failures of locomotion assessment systems. A detailed picture of the state of knowledge of normal gait is presented along with some suggested directions regarding needed technological development as well as some criticism of the lack of biomechanical modelling. As examples of clinical applications, four major gait pathologies are reviewed: amputees, hemiplegia, cerebral palsy and joint replacement. The state of knowledge of each of these patient populations is presented along with a critique of the assessment methods and conclusions. It is hoped that this paper will provoke discussion regarding the real purpose of a clinical locomotion laboratory, and put some perspective on the cost in terms of equipment, space, newly trained or retrained personnnel and computer systems.

Amputees↗
PubMed1976

Electromyographic temporal analysis of gait: normal human locomotion.

The telemetered electromyographic (EMG) activity of pretibial muscles (tibialis anterior), triceps surae (lateral gastrocnemius), medial hamstring group and quadriceps (vastus lateralis) of 20 normal subjects was examined during locomotion. The ages of the subjects ranged from 8 to 72 years (mean, 37 years). A microswitch shoe was used to correlate the EMG activity with eight specific components of the gait cycle. Tibialis anterior showed two peaks of activity, the first at the swing-stance transition, the second at the stance-swing transition. Gastrocnemius showed a single peak of activity recorded during push-off. The medial hamstring showed its greatest activity during deceleration in the swing phase. Vastus lateralis demonstrated peak activity at the transition from swing to stance. The mean cadence was 106 steps per minute. Swing phase occupied 39.6% and stance phase 60.4% of the gait cycle.

Adolescent↗
PubMed1976

Electromyographic temporal analysis of gait: hemiplegic locomotion.

The telemetered electromyographic (EMG) activity of quadriceps, hamstrings, triceps surae and pretibial muscles on the affected side of 20 adult hemiplegic subjects was examined during locomotion. The subjects ranged in age from 29 to 68 years (mean, 52.1). Duration of the lesions ranged from 1 month to 8 years: in 11 subjects the duration of the lesions ranged from 1 to 9 months (mean, 4.9 months), and in the remaining 9 subjects from 1 to 8 years (mean, 4 years 2 months). Shoes with five microswitches, two in the heel and three in the sole, were used to correlate the EMG activity with eight specific components of the gait cycle. The results of the study showed a loss of the phasic pattern associated with normal locomotion. The hemiplegic subjects showed the greatest activity in the period of midstance. Expressed as a percentage of the total cycle, the mean stance time of the paretic lower limb was 67% and the mean swing time was 33%. The unaffected lower limb showed a stance phase of 80% and a swing phase of 20%.

Adult↗
PubMed1975

Locomotion studies as an aid in clinical assessment of childhood gait.

A clinical locomotion laboratory has been developed to provide quantitative information in the management of gait disorders. The biomedical engineering development of this system identified two major clinical constraints: (a) the need for instrumentation that would not alter the natural gait of the patient and (b) the need for data-processing techniques that would permit analysis and correlation of the large volume of electromyographic (EMg) and kinematic information. The net result has been a unit that incorporates a multichannel telemetry system to capture the EMG and foot-switch information and a television computer system to handle the kinematic information. Gait studies on children with hemiparesis, muscular dystrophy and cerebral palsy have yielded quantitative EMG and kinematic information on the pathomechanics of ambulation in these disorders. Because the information obtained is quantitative, an accurate measure of improvement (or lack of it) after treatment can be documented. Therefore, the locomotion laboratory may have an important role in the preoperative and postoperative evaluation of children whose abnormal gait may require surgical corrective procedures or rehabilitative treatment including the use of prostheses or orthoses.

Adolescent↗
PubMed1975

Some characteristics of schizophrenics and their parents.

This study was designed to test four hypotheses: (a) parents of schizophrenics constitute a discrete group amongst the parents of psychiatric patients with regard to aspects of their construing; (b) schizophrenics can be differentiated from other psychiatric patients by aspects of their construing; (c) the construing of parents of psychiatric patients is related to that of their disturbed children; and (d) parents of schizophrenics differ from parents of other psychiatric patients in their personality and attitudes. An experimental group of parents of acute schizophrenics and a control group of parents of acute non-schizophrenic psychiatric patients were given a battery of psychological tests, and their hospitalized children completed a shortened battery. There was some confirmation of each hypothesis. Both experimental groups structured supplied, but not their own personal, constructs more abnormally than the corresponding control groups, and showed more deviant sexual identification, though this latter was a function of social class. The parents' structuring of supplied constructs was related to that of their children. There were also some differences in personality between the groups of parents.

Adolescent↗
PubMed1975

Multichannel biotelemetry systems for use in EMG studies, particularly in locomotion.

The authors describe their experience with the different types of telemetry systems, applicable for locomotion studies and other similar areas of research. They describe the differences between frequency modulation (FM) systems and time-domain multiplexing (PAM) systems. They discuss the advantages and the disadvantages of each of these systems, particularly as applied to the transmission of EMG signals.

Electromyography↗
PubMed1975

A voluntarily controlled electrohydraulic above-knee prosthesis.

Most above-knee amputees to date are using prostheses employing either constant friction or some type of programed hydraulic damping which the wearer has no control over and which limits his gait speeds. A new system was designed and tested in which voluntary control of a lower-limb prosthesis is derived from the EMG signals of residual thigh muscles in the stump. These signals, after suitable conditioning, open or close solenoid valves, which form a closed hydraulic loop around the damping cylinder in the knee joint. Thus, the amputee is able to voluntarily vary the resistance to knee flexion, from free swing to full lock, by operating valves controlling the resistance to flow around a hydraulic cylinder. The main advantages of this system are a variable and more aesthetic gait, stability over uneven terrain, and because the lock prevents only knee flexion, the amputee can rise on his prosthesis and so use a passive appendage as an active element of his skeleton. The results of this project demonstrate that the concept of an EMG voluntarily controlled hydraulic prosthesis is viable; however, continuing effort is required to make this system lighter, more compact, and cosmetically acceptable.

Biomechanical Phenomena↗