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Biomedical subjects

J F Lehmann

Publications and source records attributed to J F Lehmann.

At least 55 records · Page 3Linked to original sources
PubMed1978

Knee lock device for knee ankle orthoses for spinal cord injured patients: an evaluation.

The effect of a specially designed knee lock in a knee ankle orthosis was studied in 2 able-bodied volunteers and in 2 patients with spinal cord lesions. This lock allows the knee to bend during the swing phase but locks the knee securely during the stance phase. The device is intended to improve gait pattern and reduce oxygen consumption more than a standard knee lock which keeps the knee straight throughout the entire gait cycle. Energy savings with the knee locking mechanism were significant only at ambulation rates at or above 73 meters/min, a speed which could only be attained by able-bodied subjects. To achieve such high rates of ambulation a patient's hip flexors must be strong; yet a knee ankle orthosis is required only when the patient's knee extensors are weak. In patients with spinal cord injuries, this pattern of muscle strength is rarely encountered. The innervation of hip flexors or knee extensors overlaps, so voluntary control of these muscles will either be present or absent for both muscle groups. Therefore, most spinal cord injured persons who need a knee orthosis would not greatly benefit from this locking mechanism. There may be other conditions in which this device will prove valuable.

Adult↗
PubMed1978

Cancer rehabilitation: assessment of need, development, and evaluation of a model of care.

A sample of 805 cancer patients, comparable to but not identical with a national study, was screened to identify: rehabilitation problems encountered at different cancer sites; the need for rehabilitation services; and gaps in the delivery of rehabilitation care. Significant numbers of rehabilitation problems were found that could be improved by rehabilitation care. Psychologic problems were commonly encountered and seemed more severe in patients with physical disabilities; these patients have to make adjustments to both life-threatening disease and to a disabling condition. The findings suggest a need for psychosocial support services on any oncology service; where cancer is associated with significant physical disability, a comprehensive rehabilitation team with psychologic management capability is often needed. Primary barriers to optimal delivery of rehabilitation care are the lack of identification of patient problems and/or lack of appropriate referral by physicians unfamiliar with the concept of rehabilitation. Health care financial support for the patients in the sample came primarily from private insurance, Medicare and Medicaid; financial support from the patient's family held up well even in the advanced stages of the disease. A model of rehabilitation care delivery was established and implemented, with the result being that gaps and barriers to rehabilitation service delivery disappeared rapidly.

Activities of Daily Living↗
PubMed1978

Fibrous muscular contractures: treatment with a new direct contact microwave applicator operating at 915 MHz.

A patient having bilateral contractures of the rectus femoris and brachial biceps muscles due to pentazocine injection was treated with a regime of heat and stretch. Heat was provided by a new air cooled direct contact applicator operating at 915 MHz. Stretch was applied by adding weights to a cable which was attached to the arm or leg to be stretched. While the left and right elbows which were limited by the contracted biceps were not stretched sufficiently to achieve a normal range of motion, the rectus femoris muscle on both sides did achieve a normal range of motion.

Contracture↗
PubMed1977

Pneumatic and standard double upright orthoses: comparison of their biomechanical function in three patients with spinal cord injuries.

A detailed analysis of the biomechanical and physiological function of pneumatic orthoses comparing them to the standard double upright knee ankle orthoses was performed in three patients with different lesion levels. The results suggest that the main value of the long pneumatic orthosis is for early mobilization of the patient. In addition, the long pneumatic orthosis provides hip and trunk stabilization for marginal walkers who walk for exercise purposes. It is likely that most long-term functional ambulators will choose the standard knee ankle orthosis (KAO). The study dose not represent a statistical sample; therefore generalization must be limited.

Adult↗
PubMed1976

Heat and stretch procedures: an evaluation using rat tail tendon.

This study evaluated various methods of applying force to collagenous tissue at various temperatures to produce permanent elongation, using rat tail tendon as the tissue model. A materials testing machine was used to measure the forces applied and the resulting elongation produced by differing procedures. Short-term vigorous stretching and prolonged moderate stretching were compared at 37 C. The effect of heating tissue prior to applying force was evaluated, and the effect of using a prolonged application of low force was demonstrated. The data showed that the low force, long duration procedure was very effective at producing residual elongation. Elevating tissue temperature and maintaining it prior to applying force was found to cause significantly less damage; and finally, the lower loads applied at elevated temperatures for prolonged periods were found to produce significantly greater residual elongation.

Animals↗
PubMed1976

Mechanical work and fatigue: their roles in the development of muscle work capacity.

To compare the effects of mechanical work versus fatigue on the improvement of work capacity of muscle, young, healthy men were selected to life a 45-pound weight with their quadriceps for 30 sessions, followed by 5 sessions of testing. The study consisted of two phases. Subjects in the first phase did equal amounts of mechanical work with both quadriceps, but had different amounts of fatigue from side to side because the rate of work was different. Subjects in the second phase fatigued both quadriceps, but one quadriceps was fatigued with a rest period between contraction cycles, and one was fatigued without a rest period, thus allowing the side with the rest cycle to do more mechanical work. To test the relative effects of training, a transfer-of-training design was used in both phases. The results suggest that fatigue, defined operationally as the inability or unwillingness of the subject to continue the prescribed task under given reinforcement conditions, plays a larger role in the development of work capacity of muscle than the amount of mechanical work per se.

Adolescent↗
PubMed1976

Restraining forces in various designs of knee ankle orthoses: their placement and effect on the anatomical knee joint.

A biochemical evaluation was conducted on double upright knee ankle orthoses, which were instrumented with strain gauge transducers to determine the magnitudes of the restraining forces exerted on the leg. Measurements were made on six commonly used designs of orthoses worn by spinal cord injured persons ambulating with a swing-through gait. The measurements were used to determine distribution of forces on the limb as well as their effect on anatomical knee shear. Based on the experimental data, the following basic principles of optimal orthosis design were identified: The forces required to stabilize the knee should be minimized by applying the stabilizing force as close as possible to the knee center, and by maintaining the anatomical knee as straight as possible. When the major portion of the knee stabilizing force is applied below the knee, the shear on the anatomical knee structures is markedly reduced. Further, the stabilizing forces should be well distributed over tolerant areas.

Ankle Joint↗
PubMed1976

Undergraduate education in rehabilitation medicine: trends in curriculum development and the impact on specialty manpower and delivery of service.

One hundred thirteen medical schools which offered full degree programs were identified and surveyed by questionnaires to obtain information which identified the existence, characteristics and involvement of physical medicine or rehabilitation medicine programs. The survey also attempted to identify specific changes which have occurred in undergraduate medical education in rehabilitation medicine since the Commission of Education and Rehabilitation Medicine survey of 1963-64. The results suggest that growth of the programs has not followed the expansion in the number of medical schools nor in the number of students enrolled. The programs have however, improved their administrative standing and involvement in medical schools. The impact on the undergraduate medical student is not satisfactory as judged by elective enrollment and recruiting of residents. Lack of funding was found to be one of the major obstacles to curriculum development, along with a marked shortage of academic physiatrists. The impact of the changes in undergraduate medical school curricula on rehabilitation medicine has produced considerable conjoint teaching in conjunction with a large number of basic science and clinical departments.

Curriculum↗
PubMed1976

Craig-Scott orthosis: a biochemical and functional evaluation.

The Craig-Scott double upright knee ankle orthosis was subjected to a biomechanical evaluation which included analysis of the force interaction with the supported limb and a functional evaluation. The results were compared with data previously determined from biomechanical evaluations of other common orthoses. In the Craig-Scott design, the single application of the knee stabilizing force below the knee concentrates this force in a relatively small bony area, sometimes exceeding tolerance. This might be avoided by using a tibial closure with patellar tendon bearing features. The design was found to produce relatively low anatomic knee shear. In functional aspects such as donning, doffing, transfers and ambulation, the orthosis is essentially equivalent to other double upright designs. The rigidity of the orthosis with only a tibial band closure and a bail connecting the uprights was determined to be adequate. The limited number of bands and closures provides some advantages in reduced donning and doffing time; however, in the absence of posterior closures below the knee, the orthosis had a tendency to slide forward off the leg when transferring. This disadvantage was eliminated by adding a soft posterior closure below the knee, which produced a minimal increase in donning and doffing times.

Animals↗
PubMed1975

Effect of training on the use of weight-bearing orthoses.

Weight-bearing orthoses have been disigned with the primary goal of reducing or eliminating weight bearing in skeletal structures. In evaluating various designs and adjustments of these orthoses, we found that the training of the subject in the use of his orthosis was one of the most significant factors in controlling weight bearing. Subjects fitted with instrumented ischial weight-bearing and patellar-tendon-bearing orthoses walked over a force plate which measured forces imparted to the floor. The force data from the orthoses and force plate were computer-processed with single frame, multiple exposure photographic data to provide plots of axial loading in the orthosis and total axial loading imparted to the floor during the duration of the stance phase. The difference between these two forces represents the load carried by the skeletal system. Measurements were made first with subjects who had no specific instructions about the use of their orthoses. The subjects were then instructed how to use their orthoses more efficiently. In all cases, the effect of training produced a 30 to 50 percent increase in loading borne through the orthosis.

Biomechanical Phenomena↗
PubMed1975

Temperature distribution produced in models by three microwave applicators at 433.92 megahertz.

Temperature distributions produced in phantom models by diathermy applicators operating at a frequency of 433.92 MHz, a frequency not approved for diathermy by Federal Communication Commission regulations, and an experimental cooled contact applicator operating at an assigned frequency of 915 MHz were compared. The specially designed direct contact applicator with surface cooling elevated deep muscle temperatures as effectively as the "Rundfeldstrahler" operating at the lower frequency in spite of the better penetration of the energy at the lower frequency. The "Pyrodor" and the "Langfeldstrahler," the largest of the applicators operating at 433.92 MHz, do not appear to offer any advantage over existing diathermy equipment. The highest temperatures produced with these applicators were at the fat-muscle-interface.

Adipose Tissue↗
PubMed1975

Heating patterns produced in humans by 433.92 MHz round field applicator and 915MHz contact applicator.

Temperature distributions produced by a round field applicator operating at a frequency of 433.92 megahertz (MHz) are comparable to those produced by a 915 MHz cooled contact applicator in human volunteers with less than or equal to 1 cm or greater than or equal to 2 cm of subcutaneous fat. The major difference between the two applicators is the temperatures produced on the skin surface and in the subcutaneous fat in humans. The circulating coolant of the 915 MHz contact applicator keeps skin surface temperatures much lower than those produced by the round field applicator in thick and thin subjects. It also tends to cool the superficial subcutaneous fat layer in thin subjects but doesn't affect the deeper subcutaneous fat layer in subjects with greater than or equal to 2 cm of subcutaneous fat. The 915 MHz contact applicator gives the ability to control by cooling the temperatures produced in the superifical tissues. By regulating the temperature of coolant and time of cooling, temperature gradients can be modified so the highest temperatures may be found in the muscle. However, the superficial tissue temperature cannot be regulated with the present application of the 433.92 MHz applicator. When the two applicators were compared, it was shown that the 433.92 MHz round field applicator did not surpass the heating ability of the 915 MHz contact applicator. Therefore, at this time, there is no reason to legalize the frequency of 433.92 MHz for diathermy use in the United States.

Adipose Tissue↗
PubMed1975

Training procedures and biofeedback methods to achieve controlled partial weight bearing: an assessment.

Limiting weight bearing to a prescribed level is clinically desirable when patients use crutches or canes or wear prostheses. Several training methods currently being used in clinical settings were tested. These included the use of bathroom scales, and several more sophisticated feedback systems, to train normal subjects to limit weight bearing on a protected limb to a target load. It was found that such training was of limited value since subjects, during training and after, often exceeded target loads by 50% or more. Any retained learning was found to diminish rapidly on the first and second days after training. Even when using continuous auditory feedback, overshoot of the target load seemed inevitable due to the time lag between auditory perception and motor response, and the rapid rate of loading of the extremity.

Adolescent↗
PubMed1975

Stroke: Does rehabilitation affect outcome?

A sample of 114 consecutive stroke admissions to a rehabilitation center was studied statistically to determine functional gains achieved and retained after rehabilitation. In order to provide a measure of function, a functional profile was developed that evaluates seven activities, each according to a five-point scale. It was found that significant gains were achieved which could not be attributed merely to spontaneous recovery. An estimate of the cost benefit ratio showed that the reduced cost resulting from returning patients to the family or to independent living more than paid for the cost of providing rehabilitation services to the whole sample.

Activities of Daily Living↗
PubMed1975

Stroke rehabilitation: Outcome and prediction.

Predictors of functional outcome were developed in a group of 114 stroke patients consecutively admitted to a tertiary rehabilitation center. These predictors included a pool of medical data, the age of the patient, psychological tests and the patient's educational level. None of these predictor items showed a correlation with outcome high enough to allow precise prediction of individual outcome. They did, however, provide general indicators for those patients with severe functional impairment who are more likely to gain from a rehabilitation program. The group of medical predictors indicated that a patient with a more extensive, severe lesion, with signs of congestive heart failure, generalized arteriosclerosis, gross perceptual deficit, a lower level of education, and who is older, is less likely to improve in the rehabilitation program. Since a prediction on an individual basis was not possible, it was concluded that even the most severely involved patient should be provided with a therapeutic rehabilitation trial. There was no correlation between severity of the functional impairment at admission and the gains obtained in the rehabilitation program. The same predictors were used to predict whether the patient went home or to an institution. It was found that family income and involvement in support of the patient predicted this outcome, whereas medical data did not. Since family involvement can sometimes be changed by a therapeutic team, this predictor may also present a major target for therapeutic intervention.

Age Factors↗