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A Preliminary Comparison of Function and Outcome in Patients with Diabetic Dysvascular Disease

Trantowski-Farrell, Rebecca PT, DPT; Pinzur, Michael S. MD

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JPO Journal of Prosthetics and Orthotics: October 2003 - Volume 15 - Issue 4 - p 127-132
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The number of nontraumatic lower extremity amputations (LEA) in the United States increased from 36,000 in 1980 to 86,000 in 1996. 1 Approximately half are performed at the transtibial (below-knee) level; 80% are performed as a consequence of peripheral vascular disease and diabetes. Most patients are over 60 years old. 2–4 LEA drastically alters the quality of life for both patients and their families in numerous ways, despite advances in prosthetic technology and rehabilitation methods. 5–7 Persons with co-morbid conditions accompanying the LEA are often overwhelmed by the mental and physical demands associated with gaining proficiency with a prosthesis. 3,5,6

Successful resumption of daily activities with a prosthesis is accomplished by only 56% to 87% of potential prosthetic candidates, depending on the method of patient selection. 3,8–10 Many patients are capable of learning to use the prosthesis in a structured setting but discard it within the first year. Gautheir-Gagnon et al. 2 described a patient profile that was significantly correlated with prosthetic wear and active use both indoors and outdoors. This profile was based on: physical health status, demographic profile (age, educational level, employment, and domestic arrangement), time frames of rehabilitation factors, and adaptation to amputation.

Although many patients may ambulate at a functional level that approaches their premorbid capacity, their ability to perform tasks of normal daily living demonstrates greater impairment in community mobility and recreational activity compared with household activities. 5,9,11,12 The energy cost of mobility is greater in persons with prostheses, ranging between 10% and 40% in unilateral transtibial amputees. 13–16 This functional and task performance deficit is even greater after transfemoral amputation. 13–16 Persons with associated co-morbidities, especially cardiopulmonary co-morbidity, often have difficulty meeting the energy and metabolic demands for ambulation with a prosthesis. Larson et al. 17 reported that 88% of patients with above-ankle amputations as a result of diabetes walked less than 1 km daily at 1 year after transtibial amputation.

Jette 18 has defined physical impairment and disability as directly influencing functional mobility. “Disability” conveys restrictions or inabilities to perform socially defined roles and individual tasks demanded by physical and sociocultural environments. These roles and activities encompass the basic activities of daily living, including mobility and personal care; instrumental mental activities of daily living (i.e., meal preparation, chores, and financial management); social activities (i.e., church attendance or socializing with family and friends); and recreation or leisure activities (i.e., reading, shopping, sports and physical recreation). Disabilities may affect the quality of life, depending on numerous environmental and internal factors, including personality, coping skills, and emotional conditions.

Clinical reports of functional outcome after LEA have generally been based on either patient self-reporting via questionnaires or objective aerobic laboratory testing. The Prosthetic Evaluation Questionnaire (PEQ) was specifically designed to measure health-related quality of life (HRQL) in patients with LEA. 19–21 Few studies have attempted to correlate HRQL measures with objective testing of physical capacities. The timed “Up and Go” test has been used for testing the mobility of elderly patients with LEA. 22 This testing method revealed that mobility scores showed the strongest correlation with the physical subscales of the Groningen Activity Restriction Scale. 22 O’Keefe et al. 23 found strong correlation between scoring on the Six-Minute Walk Test (SMWT) and total score on a chronic heart failure questionnaire in patients with chronic heart failure. Juenger et al. 24 also used the SMWT in patients with cardiac disease to correlate impairment with SF-36 subscale scores 25 of social function, general health, and physical function. Miller et al. 26 were able to correlate performance on a modified Two-Minute Walk Test and a Timed Up and Go Test.

None of these investigations fully explored the relationship between functional limitation and perceived impact on HRQL. Understanding this dynamic relationship would be extremely beneficial in developing rehabilitation programs that could address the special needs of this patient population. The goal of this investigation was to determine whether physical capacity after transtibial amputation was correlated with patient perceived HRQL. Diabetic/dysvascular transtibial amputees were selected as the focus population because they are currently the largest group of new amputees who have the potential to return to their premorbid lifestyles.


After approval from the Loyola University Medical Center Institutional Review Board, six subjects with unilateral transtibial amputations agreed to participate in a preliminary study. Subjects were recruited during follow-up visits to an amputee clinic or during hospitalization for medical issues unrelated to their residual limb or cardiopulmonary conditions. Inclusion criteria were: 1) ambulatory transtibial amputee, 2) amputation performed as an adult as a result of diabetes, vascular disease, or a combination, 3) use of current prosthesis for at least 6 months, and 4) age greater than 50 years. Exclusion criteria were: 1) amputation performed as a child or as a result of trauma, 2) type I diabetic, 3) under age 50, 4) inability to walk with the prosthesis, 5) uncontrolled angina or hypertension, 6) recent history of cardiac dysrhythmia or myocardial infarction, or 7) active cardiac or pulmonary insufficiency.

All subjects were examined in the Physical Therapy Inpatient Unit by the same licensed Physical Therapist (R.T-F.). All subjects underwent the SMWT (Table 1) and completed the PEQ.

Table 1
Table 1:
Protocol for SMWT


Currently, functional aerobic capacity and exercise tolerance are clinically evaluated with graded treadmill exercise testing. 13,14,27,28 The SMWT is an accepted clinical testing method that has been commonly used to examine ambulation tolerance and exercise capacity in patients with both cardiopulmonary and peripheral vascular disease. 23,29,30 It is an easy-to-administer, reproducible method of testing that simulates normal ambulation during activities of daily living. 31

Subjects were asked to walk continuously for 6 minutes while wearing their prosthesis. Brachial arterial blood pressure, heart rate, and respiratory rate were recorded before the test and immediately upon completion. The distance covered during the test period was recorded using a specified protocol and order (Table 1). 32 Data acquired were standardized with an accommodation for body mass, height, age, and gender, and compared with available normative data in healthy adults. 33


The PEQ is a self-reporting tool specifically used to evaluate the quality of life of patients with LEA. 19 Based on the theory that multiple life elements are affected by health, it consists of a total of 10 scales assessing prosthetic function, mobility, psychosocial response, and well-being. The PEQ is a subjective tool used to assess patients’ satisfaction with nine different scales including the following categories: 1) ambulation; 2) appearance; 3) frustration; 4) perceived response; 5) residual limb health; 6) social burden; 7) sounds; 8) utility; and 9) well-being. 20 The tenth subscale, transfers, was not used because of decreased validity and reliability. 20 Responses are made on a 10-cm visual analogue scale, with a zero score assigned to a negative attribute, and 100 assigned to favorable responses. 19

Statistical Analysis

Using Pearson correlations, three relationships were analyzed: 1) distance covered versus scores of the nine subscales, 2) subject age versus distance, and 3) years after amputation versus distance. This was computed using SPSS software. Data are reported as means ± standard deviations. Significance was set at p < .05. The actual distance in feet for the SMWT was compared with available normative data. 33


Six subjects (four men, two women) completed the study. Average age was 66 (range, 52–80) years. The results of the SMWT are detailed in Table 2. The comparison between the distance walked in the SMWT and scoring on the PEQ is detailed in Table 3. There was a strong inverse relationship between the PEQ sounds subscale and the distance walked (Figure 1). The shorter the distance walked, the more favorable the response in the PEQ. There was no statistical correlation between the distance walked in the SMWT and the PEQ subscale scores “ambulation” and “social burden”; however, regression plots did reveal a positive trend (Figures 2 and 3). One score (from the same subject) is an outlier, affecting the correlation. If this outlier subject were removed, the correlation (R) values changed, with “ambulation” versus distance changing to 0.732 (compared to 0.359), and “social burden” versus distance changing to 0.980 (compared to 0.324).

Table 2
Table 2:
Table 3
Table 3:
PEQ Subscale versus distance walked (in feet)
Figure 1
Figure 1:
Distance versus sounds subscale.
Figure 2
Figure 2:
Distance versus ambulation subscale.
Figure 3
Figure 3:
Distance versus social burden.


We initiated this investigation with the hypothesis that higher scores in the PEQ subscales, representing more positive HRQL outcomes, would be correlated with higher distances walked in the SMWT. Although there was a trend to support this hypothesis, there was certainly not a statistical correlation. This information allowed us to re-examine our original hypothesis in light of our current understanding of outcomes research. It is certainly the bias of many able-bodied examiners to perceive that simple walking ability should be correlated with perceived favorable HRQL outcomes. This may not be the case. An avid golfer might perceive a less favorable outcome after amputation if he/she is unable to return to his/her premorbid golfing proficiency, despite the fact that he/she can perform well on the SMWT. An elderly person with little walking ability may perceive a favorable outcome after LEA if he/she is able to remain sufficiently independent to avoid having to leave home and live in a skilled nursing facility.

Our results differ from those of a recently published study in which patients with decreased balance confidence reported diminished scores on the ambulation portion of the PEQ and decreased social activity on the Frenchay Activities Index. 26 However, this study used self-rated levels of confidence on the 16-item Activities Specific Balance Confidence and was not restricted to transtibial amputees. Juenger et al. 24 found positive correlations between the SMWT and quality of life subscales using the SF-36. However, this study used the non–amputee-specific generalized quality of life measure SF-36, which might not be sufficiently discriminative to the amputee population.

Our results compare favorably with an HRQL study of 60 diabetic or dysvascular transtibial amputees who completed the PEQ. In this study, the PEQ subscales associated with well-being and psychosocial responses scored highest, whereas mobility scores were the lowest. 21 Our results differed from the original publication using the PEQ; however, the original authors had a mixed patient population composed of young, traumatic amputees with various amputation levels and older dysvascular patients. 19

Admittedly, our study group was small and the walking speed was very slow. Our subjects’ current walking speed might not be sufficiently safe for outside community ambulation. 34 Despite the small size and the slow walking speed of the subjects, there are important instructive points to be learned from this preliminary study. Social issues affecting rehabilitation after illness and/or injury are multifactorial and complex. Task performance may be important to re-enter the workforce or resume certain recreational activities, but these issues may not be directly correlated with a patient’s perception of their current quality of life.

Based on this preliminary information, our next step is to determine whether the ability to walk specific distances after transtibial amputation in diabetic or dysvascular disease patients can be correlated with functional measures [i.e. functional independence measure (FIM)] and measures of HRQL. It is essential that healthcare professionals appreciate both the physical and functional task performance aspects of recovery as well as the psychosocial needs of patients with injury or disability. The plan of care and treatment need to be customized for patients’ individual goals and needs, whether it be household independence or athletic pursuits.


We gratefully acknowledge the contributions of Gail M. Huber, PT, MHPE.


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© 2003 American Academy of Orthotists & Prosthetists