David A. Boone

Prosthesis evaluation questionnaire for persons with lower limb amputations: Assessing prosthesis-related quality of life

OBJECTIVE To develop a self-report questionnaire for persons with lower limb amputations who use a prosthesis. The resulting scales were intended to be suitable to evaluate the prosthesis and life with the prosthesis. The conceptual framework was health-related quality of life. DESIGN Multiple steps of scale development, terminating with test-retest of the Prosthesis Evaluation Questionnaire (PEQ) by mail. SOURCE OF SAMPLE: Records from two Seattle hospitals. PATIENTS Ninety-two patients with lower limb amputations who varied by age, reason for amputation, years since amputation, and amputation level. MAIN OUTCOME MEASURES The 10 scales used were 4 prosthesis function scales (Usefulness, Residual Limb Health, Appearance, and Sounds), 2 mobility scales (Ambulation and Transfers), 3 psychosocial scales (Perceived Responses, Frustration, and Social Burden), and 1 Well-being scale. Validation measures were the Medical Outcomes Study Short Form-36, the Social Interaction subscale from the Sickness Impact Profile, and the Profile of Mood States-short form. RESULTS Nine PEQ scales demonstrated high internal consistency. All met test-retest criteria for comparing group results. Validity was described based on methods used to gather original items, distribution of scores, and comparison of scores with criterion variables. CONCLUSIONS The PEQ scales displayed good psychometric properties. Future work will assess responsiveness of PEQ scales to changes in prosthetic components. We conclude that they will be useful in evaluation of prosthetic care.

Microprocessor-based ambulatory activity monitoring in stroke patients

PURPOSE Recovery of ambulatory function after stroke is routinely assessed using standardized subject- or observer-rated instruments that do not directly measure ambulatory activities in the home-community setting. Accuracy of conventional pedometers in stroke patients is not established, limiting their application in mobility outcomes monitoring. This study investigates the accuracy and reliability of a mechanical pedometer versus microprocessor-based step activity monitoring (SAM) in gait-impaired hemiparetic stroke patients. METHODS Accuracy and test-retest reliability of ankle-worn SAM and belt-worn pedometer were tested directly against hand tallied stride counts and cadence during a battery of timed walks in 16 chronic hemiparetic stroke patients. Patients performed replicate 1-min floor walks at self-selected and fastest comfortable paces, and two 6-min walks on separate days. RESULTS SAM cadence and total stride counts are more accurate than pedometers during 1-min walks at self-selected (99 +/- 1 vs 87 +/- 11.3%, mean +/- SD, P < 0.01); fast pace (98 +/- 2.3% vs 85 +/- 15%, P < 0.01); and repeated 6-min walks performed on separate days (99 +/- 1% vs 89 +/- 12%, P < 0.01). Although SAM is highly reliable (r = 0.97, P < 0.0001) and accurate in all patients under every walking condition tested, the mechanical pedometer demonstrates this high level of accuracy in only half of stroke patients and has poor test-retest reliability (r = 0.64, P < 0.05). CONCLUSION SAM, but not the conventional pedometer, provides accurate and reliable measures of cadence and total stride counts in hemiparetic stroke patients. Portable microprocessor-based gait monitoring offers potential to quantitatively measure home-community-based ambulatory activity levels in this population.

Quantitative comparison of plantar foot shapes under different weight-bearing conditions.

Knowledge of the plantar foot shape alteration under weight bearing can offer implications for the design and construction of a comfortable and functional foot support. The purpose of this study was to quantify the change in three-dimensional foot shape under different weight-bearing conditions. The plantar foot shapes of 16 normal feet were collected by an impression casting method under three weight-bearing conditions: non-weight bearing, semi-weight bearing, and full-weight bearing. An optical digitizing system was used to capture the three-dimensional plantar surface shape of the foot cast. Measurements and comparisons from the digitized shapes were conducted for the whole foot and regions of the foot. The data showed that increased weight bearing significantly increased the contact area, foot length, foot width, and rearfoot width, while it decreased average height, arch height, and arch angle. Compared with the non-weight-bearing foot shape, the semi-weight-bearing condition would produce increases in the contact area of 35.1% +/- 21.6 %, foot length of 2.7% +/- 1.2%, foot width of 2.9% +/- 2.4%, and rearfoot width of 5.9% +/- 4.8%, and decreases in the arch height of 15.4% +/- 7.8% and arch angle of 21.7% +/- 17.2%. The full-weight-bearing condition would produce increases in the contact area of 60.4% +/- 33.2%, foot length of 3.4% +/- 1.3%, foot width of 6.0% +/- 2.1%, and rearfoot width of 8.7% +/- 4.9%, and decreases in the arch height of 20.0% +/- 9.2% and arch angle of 41.2% +/- 16.2%. The findings may be useful for considering the change of foot shape in the selection of shoe size and shoe or insole design.

Quantification of prosthetic outcomes: elastomeric gel liner with locking pin suspension versus polyethylene foam liner with neoprene sleeve suspension.

For this randomized crossover trial, we compared two common transtibial socket suspension systems: the Alpha liner with distal locking pin and the Pe-Lite liner with neoprene suspension sleeve. Our original hypotheses asserted that increased ambulatory activity, wear time, comfort, and satisfaction would be found with the elastomeric suspension system. Thirteen subjects completed the study. Following 2.5-month accommodation to each condition, ambulatory activity was recorded (steps/minute for 2 weeks), and subjects completed three questionnaires specific to prosthesis use and pain: the Prosthesis Evaluation Questionnaire (PEQ), a Brief Pain Inventory (BPI) excerpt, and the Socket Comfort Score (SCS). Upon completion, subjects selected their favored system for continued use. Ten subjects preferred the Pe-Lite and three the Alpha. Subjects spent 82% more time wearing the Pe-Lite and took 83% more steps per day. Ambulatory intensity distribution did not differ between systems. No statistically significant differences were found in questionnaire results. Subject feedback for each system was both positive and negative.

Ambulatory activity in men with diabetes : relationship between self-reported and real-world performance-based measures

The measurement of physical activity, especially walking activity, is important for many outcome studies. In many investigations, the Physical Activity scale of the short-form-36 (SF-36) health assessment questionnaire is used in lieu of an actual physical measurement of walking. This study determined the relationship between the SF-36 questionnaire and the Step Activity Monitor (SAM), a real-world performance-based tool that counts the actual number of steps taken during daily activities. We studied the physical activity of 57 men with diabetes using step count monitoring and the SF-36 questionnaire. The subjects averaged 3,293 steps/day, but had a very wide range (111-11,654) and a large standard deviation (SD = 2,037). The correlations between total daily steps and the SF-36 Physical Component Summary score, and the Physical Function, Bodily Pain, and Vitality scales of the SF-36 were only fair (Pearsons r = 0.376, 0.488, 0.332, 0.380, respectively). The corresponding coefficients of determination range from only 7.7% to 23.8%. Physical activity is a complex concept not completely represented by either the SF-36 or the step counts. The correlation between actual walking activity and the SF-36 is not as strong as many researchers believe. Caution should be exercised with the use of the SF-36 to specifically measure walking activity.This study assessed the reliability of gait performance with concurrent measures of oxygen consumption (VO2) in stroke survivors (SS). Nine male SS (60.00 +/- 15.08 yr) had a recent history of stroke (44.56 +/- 51.35 days since the stroke) and were receiving rehabilitation. Four had a right cerebrovascular accident (CVA), and five had a left CVA. Subjects walked without assistance, although three used a single cane to complete the test. Within 30 minutes, subjects completed two trials of a 5 min walk while walking back and forth on a 5 m walkway wearing a portable gas analyzer to collect samples of gases. The intraclass correlation coefficient (ICC) was used to assess reliability. The ICC for gait energy expenditure, walk distance, gait speed, and gait energy cost were 0.64, 0.97, 0.95, and 0.97, respectively. Assessment of gait performance with concurrent measures of VO2 is a reliable procedure with SS.

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 Centers and the University of British Columbia-Medical Engineering Resource Units 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.

Use of the Prosthesis Evaluation Questionnaire (peq)

The Prosthesis Evaluation Questionnaire (PEQ) was developed specifically to provide functional outcome measures in prosthetics that are more tuned to prosthesis-related changes in quality of life. It is a self-report questionnaire containing 54 questions organized into nine functional domain scales. Each of the scales may be used individually to measure only a specific domain of interest. The PEQ has been used in a wide variety of studies and a summary of results across studies is presented.

Finite-Element Analysis to Determine Effect of Monolimb Flexibility on Structural Strength and Interaction Between Residual Limb and Prosthetic Socket

Monolimb refers to a kind of transtibial prostheses having the socket and shank molded into one piece of thermoplastic material. One of its characteristics is that the shank is made of a material that can deform during walking, which can simulate ankle joint motion to some extent. Changes in shank geometry can alter the stress distribution within the monolimb and at the residual limb-socket interface and, respectively, affect the deformability and structural integrity of the prosthesis and comfort perceived by amputees. This paper describes the development of a finite-element model for the study of the structural behavior of monolimbs with different shank designs and the interaction between the limb and socket during walking. The von Mises stress distributions in monolimbs with different shank designs at different walking phases are reported. With the use of distortion energy theory, possible failure was predicted. The effect of the stiffness of the monolimb shanks on the stress distribution at the limb-socket interface was studied. The results show a trend--the peak stress applied to the limb was lowered as the shank stiffness decreased. This information is useful for future monolimb optimization.

Use of a Step Activity Monitor in Determining Outcomes

Step activity is a natural measure of mobility function that is well suited to questions of prosthetic and orthotic outcomes. Step count data are relatively easily comprehended and interpreted. The StepWatch ™ Activity Monitor (SAM) is an instrument that was developed to accurately measure the impact of various interventions on the real-world activity level of individuals. It counts and records the number of steps taken in short time intervals (typically 1 minute) for up to 2 months continuously. The patient or subject is not required to do anything but wear the monitor on the leg. Many independent studies have validated the high accuracy of the SAM in populations with greatly varying gait styles and abilities.

Perception of socket alignment perturbations in amputees with transtibial prostheses

A person with amputations subjective perception is the only tool available to describe fit and comfort to a prosthetist. However, few studies have investigated the effect of alignment on this perception. The aim of this article is to determine whether people with amputation could perceive the alignment perturbations of their prostheses and effectively communicate them. A randomized controlled perturbation of angular (3 and 6 degrees) and translational (5 and 10 mm) alignments in the sagittal (flexion, extension, and anterior and posterior translations) and coronal (abduction, adduction, and medial and lateral translations) planes were induced from an aligned condition in 11 subjects with transtibial prostheses. The perception was evaluated when standing (static) and immediately after walking (dynamic) using software that used a visual analog scale under each alignment condition. In the coronal plane, Friedman test demonstrated general statistical differences in static (p < 0.001) and dynamic (p < 0.001) measures of perceptions with angular perturbations. In the sagittal plane, it also demonstrated general statistical differences in late-stance dynamic measures of perceptions (p < 0.001) with angular perturbations, as well as in early-stance dynamic measures of perceptions (p < 0.05) with translational perturbations. Fisher exact test suggested that people with amputations perceptions were good indicators for coronal angle malalignments but less reliable when defining other alignment conditions.