VA LOGO

Clinical Relevance for the Veteran
Journal of Rehabilitation Research and
Development Vol. 36 No. 2, April 1999

Clinical Relevance for the Veteran

SUMMARY OF SCIENTIFIC/TECHNICAL PAPERS IN THIS ISSUE
 

Objective assessment of limb tissue elasticity: Development of a manual indentation procedure.
Yongping Zheng, PhD; Arthur F.T. Mak, PhD; Bokong Lue, BSc.

Purpose of the Work. The goal is to develop a clinical protocol for objective assessment of residual limb tissue elasticity. Subjects Twelve subjects took part in the study: six young subjects with sound limbs and six elderly subjects with transtibial amputation. Procedures. An ultrasound tissue indentation system with a pen-sized hand-held probe was introduced. A clinical protocol was established to use this system to assess limb tissue and the method used to extract tissue elasticity from the indentation date is presented. The issues of probe misalignment, muscular activity, rate sensitivity, material nonlinearity, and repeatability are examined. Results. Results on unimpaired subjects and on persons with transtibial amputation are reported. The protocol is demonstrated to be feasible for the objective assessment of limb tissue elasticity. Relevance to the Veteran Population. The protocol introduced would help make residual limb assessment and prosthetic socket design more objective and quantitative.
Yongping Zheng, PhD

 

Test of a vertical scan mode in 3-D imaging of residual limbs using ultrasound.
Ping He, PhD, PE; Kefu Xue, PhD; Yu Fan, PhD; Yiwei Wang.

Purpose of the Work. The goal of this project is to design and develop an ultrasound-based 3-D imaging system for computer-aided prosthetic socket design. Subjects/Procedures. The design and operation of the system are described. An emphasis is laid on the principle of reconstructing the skin surface of the limb using a vertical scan mode. The measurement accuracy of the system is tested using a cylindrical phantom and a custom-made limb model. Results. The errors in measuring the diameter of the phantom and the volume of the limb model are found to be less than 1 percent. Relevance to the Veteran Population. The new system provides a safe and low-cost mean of acquiring both the external shape and internal bony structure of a residual limb. It is expected that such a system can help prosthetists to improve the quality of design-fitting of prosthetic sockets.
Ping He, PhD, PE

 

Comparison of upper limb muscle activity in four walking canes: A preliminary study.
Faye Y. Chiou-Tan, MD; Kevin N. Magee, PhD; Thomas A. Krouskop, PhD.

Purpose of the Work. The objective of this study was to determine if new canes could be created that would improve the wrist/forearm alignment. The purpose of these canes would be to decrease the impact of repetitive stresses on the arm and increase biomechanical efficiency. Subjects. Healthy adults walking with a knee immobilizer. Procedures. Subjects were wired with surface electromyography (EMG) electrodes, which recorded the electrical voltage emitted by muscles in the arm during stance and gait with different walking canes. Results. Results showed that using these alternative canes decreased the EMG voltage of the arm as compared with the standard cane. Relevance to the Veteran Population. As the veteran population lives to be older, there are more chronic cane users. We plan to design better canes that limit trauma to the arms. It is hoped that doing so will lessen the chance of carpal tunnel syndrome and osteoarthritis.
Faye Chiou-Tan, MD

 

Utilization of prostheses among US veterans with traumatic amputation: A pilot survey.
Richard A. Sherman, PhD.

Purpose of the Work. It is important to know whether veterans can make effective use of their prostheses. The area has never been studied through a survey so a pilot was conducted. Subjects. All 170 US soldiers (a) who had traumatic amputations over the last ten years whose addresses were supplied by the VA and (b) whose medical synopses showed them to be otherwise healthy when leaving the military. Procedures. A survey of prosthetic problems was sent to the above veterans. Results. Although only 45 veterans responded (26%), all had significant problems using their prostheses for work and most had other problems as well. Relevance to Veteran Population. The group surveyed were relatively young and healty so were the least likely to have problems using their prosthetics. As they had significant problems, it is highly likely that the majority of veteran amputees also have significnat problems. The situation should be investigated through a large survey.
Richard A. Sherman, PhD

 

Skin perfusion responses to surface pressure-induced ischemia: Implication for the developing pressure ulcer.
Eric C. Herrman, MS; Charles F. Knapp, PhD; James C. Donofrio, PhD; Richard Salcido, MD.

Purpose of the work. This study describes the development of a test defining the relationship between skin blood flow and increasing surface pressure to evaluate the effect of a pressure-induced lack of perfusion over a 5-hour period. Subjects/Procedures. Pressure was applied to the hips of the fuzzy rat (almost hairless), using a computer-controlled plunger that pressed on the skin while measuring blood flow with a laser light shinning through the center of the tip of the column during the application of pressure. Pressure was increased in 10-g steps (each step lasting 30 s) until average blood flow was reduced to zero, then pressure was released. This test results in a characteristic blood flow pattern for healthy skin. The complete experimental design consists of the application of the test before and after an experimental intervention (5-hours of reduced perfusion to skin). Results. The 5-hour pressure-induced cut off of blood flow resulted in major changes to the normal perfusion pattern of the skin which could adversely affect the ability of the skin to return to normal and resist infection. Relevance to the Veteran Population. This test has application for evaluating the effect of treatments or interventions affecting skin tissue breakdown and pressure-induced ulceration. Pressure ulcers are a major secondary medical condition with significant impact on important veteran populations including the spinal cord injured and the aged.
James Donofrio, PhD

 

Postural stability of wheelchair users exposed to sustained, external perturbations.
Derek Kamper, PhD; Mohamed Parnianpour, PhD; Kamran Barin, PhD; Thomas Adams, ME; Maureen Linden, MS; Hooshang Hemami, PhD.

Purpose of the Work. This study investigated the effects of spinal cord injury on the ability of an individual to withstand the braking forces experienced during normal driving. Subjects/Procedures. A manual wheelchair was secured to a platform that rotated forward to challenge the upright posture of the subject. Individuals with tertaplegia, paraplegia, or no injury participated in the study. Results. Without the use of the arms, almost all of the spinal cord-injured subjects became unstable at force levels below those seen during normal driving. Among the spinal cord-injured subjects, injury level was not always a good predictor of stability. Relevance to the Veteran Population. Trunk stability during even normal driving conditions may be compromised. Restraint of the pelvis and lower torso may improve stability without restricting movement of the upper torso and arms. Adaptive driving controls should be examined to verify that their performance is unaffected by the forces inevitably placed upon them in an effort to stabilize the upper body.
Derek Kamper, PhD

 

Mechanical characteristics of human skin subjected to static versus cyclic normal pressures.
Laura E. Edsberg, PhD; Robert E. Mates, PhD; Robert E. Baier, PhD; Mark Lauren, ME.

Purpose of the Work. This research examined the mechanical effects of static versus cyclic pressures of human skin. Procedures. Static or cyclic pressures were applied to healthy, newborn skin. The pressures used were based on interface pressure readings from human subjects resting on various support surfaces. The skin was tested in tension after being subjected to pressure. Results. Skin subjected to pressure prior to tensile testing was less stiff than control tissue. The mechanical properties of tissue subjected to static pressure were altered more than tissue subjected to dynamic pressure. Relevance to the Veteran Population. The findings of this study suggest that pressure has a direct effect on the mechanical properties of the skin. Changes in the mechanical properties of the skin may contribute to the formation of pressure ulcers.
Laura E. Edsberg, PhD

 
 

Go to TOP.