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Biomedical subjects

D S Childress

Publications and source records attributed to D S Childress.

14 recordsLinked to original sources
PubMed1992

Automated fabrication of mobility aids (AFMA): below-knee CASD/CAM testing and evaluation program results.

In 1988 the Department of Veterans Affairs Rehabilitation Research and Development Service, under the directorship of Margaret J. Giannini, M.D., began a nationally directed computer-aided design and computer-aided manufacturing (CAD/CAM) research program for the Automated Fabrication of Mobility Aids (AFMA). Under this program CAD/CAM research and development centers were established at the Prosthetics Research Study in Seattle, WA; at Northwestern University and the VA Lakeside Medical Center in Chicago, IL; and at the VA Medical Center and New York University Medical Center in New York, NY. These three centers conducted a collaborative program: (a) to introduce CAD/CAM technologies to prosthetists, physicians, therapists, and rehabilitation health care professionals in the United States; (b) to evaluate the feasibility of using CAD/CAM systems in clinical prosthetics settings; (c) to test and evaluate the University College London-Bioengineering Center's and the University of British Columbia-Medical Engineering Resource Unit's respective systems for the computer-aided design and computer-aided manufacture of prosthetic sockets (CASD/CAM) for below-knee amputees; and, (d) to obtain quantitative data for refinement of the CASD/CAM systems tested, and for the development of new, enhanced, more efficacious, and expedient systems.

Adult↗
PubMed1988

Pendular model of paraplegic swing-through crutch ambulation.

Kinematics of swing-through crutch ambulation for an individual with complete T11-T12 spinal cord injury was examined and quantitative aspects of the body-swing phase used to formulate and evaluate a 3-link pendular model. Model simulation parallels measured kinematics when shoulder motion is forced to follow the measured motion while hips and crutch tips are free pivots. Shoulder control contributes to increased ground clearance, influences timing and stride length, and gives flowing gait. Results indicate that mechanical work requirements during the body-swing phase are low. Metabolic energy demands exceed mechanical work requirements, due particularly to support of the body by the arms and shoulders. Exploiting low mechanical work requirements of the body-swing phase might be achieved through alternative mechanisms to assist ground clearance and to stabilize the wrists, arms, and shoulders while weight bearing.

Adult↗
PubMed1984

Design and evaluation of a prosthesis control system based on the concept of extended physiological proprioception.

This paper describes the design and evaluation of an experimental prosthesis-control system based on the concept of extended physiological proprioception (EPP). It was originally hypothesized that EPP control effected by residual shoulder motion could be effectively applied in multifunctional prostheses for shoulder disarticulation amputees. The experimental system developed for this study utilized a force-driven control scheme and a shoulder motion transduction system in which direct cable linkages to the prosthesis components were used to implement EPP position-servo relationships between shoulder elevation-depression and prosthesis elbow flexion, and between shoulder protraction-retraction and prosthesis wrist rotation. The results of experiments performed with this prosthesis (and with an experimental velocity-controlled prosthesis implemented for comparison purposes) clearly demonstrated the superior performance provided by EPP control of prosthesis function.

Arm↗
PubMed1984

An analysis of extended physiological proprioception as a prosthesis-control technique.

This research was devoted to an investigation of the practicality and potential effectiveness of applying the concept of extended physiological proprioception (EPP) to the control of upper-limb prostheses. The purpose of this study was to verify that EPP control, implemented by coupling prosthesis function to residual shoulder motion in a position-servo relationship, could be effectively applied in multifunctional prostheses for shoulder disarticulation amputees. Although Simpson has shown that the principle works, the authors wanted to quantify its effectiveness and analyze its limitations. Studies were performed analyzing the feasibility of using shoulder elevation-depression and protraction-retraction as prosthesis control inputs. The results of this study showed that a prosthesis mechanism with nonlimiting dynamic response characteristics and shoulder-activated EPP control of wrist rotation and elbow flexion/extension, exhibited functional characteristics comparable to those of the physiological elbow and wrist as defined by tracking capabilities. The results of this investigation also showed that shoulder-effected position control of prosthesis function has considerably more potential for providing effective control than similarly effected velocity control.

Arm↗
PubMed1967

Mechanics of horizontal movement of the human eye.

1. The mechanics of the muscle-eyeball system of the human has been re-investigated by careful examination of the motion of the eye after it is mechanically adducted and released by means of a suction contact lens attached to it.2. Orbital stiffness during adduction is found to be about 1.25 g/deg which is near the value of 1.2 g/deg reported by Robinson (1965) for abduction. However, the results also show that the stiffness decreases to 0.65 g/deg after approximately 5 degrees of adduction.3. It is concluded that for horizontal motion the globe may be considered as being in series with an elastic component which has a stiffness of 9.0 g/deg. This series elastance, arising from the extraocular muscles, muscle tendons, and from other orbital tissue appears to increase in stiffness as muscle innervation increases.4. The experiments show that the muscle-eyeball system of the human is heavily damped which confirms the results of Robinson (1964).5. Evidence is presented which indicates that the extraocular muscles are dominant factors in horizontal eye motion.

Eye Movements↗