Activity and participation levels after discharge from rehabilitation self reported by people with lower limb
7.1. Balance and Locomotor function in known groups with lower limb amputation at high risk of prosthetic with lower limb amputation at high risk of prosthetic
non-use.
Synopsis
This chapter reports findings of a known groups analysis for performance measures including the 10MWT, TUGT, 6MWT and FSST that may be used during rehabilitation of people with lower limb amputation. The chapter forms a manuscript being prepared for peer review submission.
This chapter was presented at the following conferences:
15thWorld Congress of the International Society for Prosthetics and Orthotics (ISPO), 22nd to 25th June 2015, Lyon, France.
Australian New Zealand Society for Vascular Surgery (ANZSVS), 13th to 16th October 2017, Perth, Western Australia
Momentum 2017 Physiotherapy Conference, Australian Physiotherapy Association, 19th to 21st October 2017, Sydney, Australia.
123
Abstract
Background: There is limited data for balance and locomotor performance of people with lower limb amputation who are undergoing rehabilitation to inform clinical decision making.
Objectives: To gain knowledge on the balance and locomotor skills of known groups at high risk of discontinuing prosthetic use and test the construct validity of the 10MWT, TUGT, 6MWT and FSST in these groups.
Design: Retrospective cohort study
Methods: Descriptive variables and 10m walk (10MWT), timed up and go (TUGT), 6 minute walk (6MWT) and four square step (FSST) tests were abstracted from the medical records for 201 consecutive participants with lower limb amputation.
Participants were classified as in known high or low risk groups and the Mann Whitney U Test was used to analyse if there were differences in locomotor test performance.
Results: Performance on locomotor tests were significantly impaired for people in known groups at high risk of prosthetic non-use including those with above transtibial amputation level, older age, bilateral amputation and high comorbidities (p < .025).
However, performance on locomotor tests, were not significantly different (p > .449) for Aboriginal people and on the 10MWT and TUGT for the diabetes and atraumatic sub-groups (p > .075).
Limitations: Missing data, low numbers of participants in some known groups and assessment times varied.
Conclusions: The 10MWT, TUGT, 6MWT and FSST have construct validity as they significantly differentiated between the locomotor performance of known groups at high risk of prosthetic non-use including above transtibial amputation level, older age,
bilateral amputation and high comorbidities. However, it appears that the 6MWT was the best marker of locomotor performance during rehabilitation as it distinguished between all the groups at high and low risk of prosthetic non-use.
Key words: Performance measures, lower extremity, amputation, leg prosthesis, rehabilitation outcome
124
Balance and Locomotor function in known groups with lower limb amputation at high risk of prosthetic non-use.
7.1.1. Introduction
Locomotor tests may be used during prosthetic rehabilitation of people with lower limb amputation as they provide health professionals with objective information on a client’s potential to walk indoors, outdoors and to negotiate obstacles in complex walking environments (Dite et al., 2007; Franchignoni et al., 2004; Gailey et al., 2002; Schoppen et al., 1999). Although locomotor tests measure rehabilitation outcome and enhance communication between clients, clinicians, administrators and funding organisations less than 50% of health professionals routinely use locomotor tests during rehabilitation (Gaunaurd et al., 2015; Jette et al., 2009; Wong et al., 2016a). Some commonly perceived barriers to the implementation of locomotor tests in clinical practice include lack of time, space, equipment, knowledge, training and confidence with test
administration and difficulty with interpretation (Gaunaurd et al., 2015; Jette et al., 2009).
To assist with interpretation of locomotor tests in lower limb amputation cohorts Roffman et al. (2016b) developed performance criteria for the 10 metre walk test (10MWT), Timed up and go test (TUGT), 6 minute walk test (6MWT) and Four square step test (FSST) that were moderately predictive of prosthetic non-use after discharge (see Table 7.1A). This study established predictive validity and clinical utility for the 10MWT, TUGT, 6MWT and FSST during amputee rehabilitation as clients’ locomotor skills progressed (Roffman et al., 2016b).
One of the gaps identified in the literature was the need for a known groups analysis to improve understanding of balance and locomotor skills in sub-groups at high risk of abandoning prosthetic use after rehabilitation discharge (Heinemann et al., 2014;
Roffman et al., 2016b; Rogers & Stevens, 2015a, 2015b; Stevens, 2010; Wong et al., 2016a). Known groups analyses have been used to determine construct validity for tests
125 Table 7.1A: Performance measure thresholds from ROC curve analysis and associated accuracy statistics (95% CI) for people who become prosthetic non-users at 12 months after discharge
(Roffman et al., 2016b).
Performance
Sensitivity (%) Specificity (%) Area Under the
Curve Youden Index
126 by demonstrating ability to significantly distinguish between groups that are known to differ in the literature based on the presence or absence of a characteristic (Gailey et al., 2002; Gaunaurd, 2012; Hattie & Cooksey, 1984; Megens et al., 2007). Another form of construct validity is convergent validity which is demonstrated when a high level of correlation exists between tests that measure similar functional domains (Gailey et al., 2013; Gaunaurd, 2012). An example of convergent validity is increased 6MWT distance as time decreases for TUGT (Bhangu et al., 2009).
People at high risk of discontinuing prosthetic use include those with above transtibial amputation level, bilateral lower limb amputation, diabetes, Aboriginal ethnicity, older age, atraumatic cause and high comorbidities (Roffman et al., 2014; Sansam et al., 2009;
Schoppen et al., 2003; Taylor et al., 2005; van Eijk et al., 2012; Vos et al., 2009;
Webster et al., 2012). These high risk groups have impairments that potentially reduce walking speed, distance and balance limiting their ability to perform locomotor activities with a prosthesis but in contrast to other clinical populations (Asher, Aresu, Falaschetti,
& Mindell, 2012; Dite & Temple, 2002; Forrest et al., 2014; Gardner, Katzel, Sorkin, &
Goldberg, 2002; Jenkins, 2007; Shumway-Cook, Brauer, & Woollacott, 2000; Tilson et al., 2010; van Hedel, 2009) there is a paucity of performance data to assist with
interpretation of locomotor tests in lower limb amputation cohorts (Akarsu, Tekin, Safaz, Goktepe, & Yazicioglu, 2013; Dite et al., 2007; Gailey et al., 2002; Heinemann et al., 2014; Resnik & Borgia, 2011; Stevens, 2010).
People with high level and bilateral lower limb amputation may have impaired
locomotor and balance function due to the increased energy cost of walking, decreased lever length of their residual limb and lack of proprioception from multiple prosthetic joint components (Akarsu et al., 2013; Erjavec et al., 2014; Gailey et al., 2002;
Gaunaurd, 2012; Starholm et al., 2016; Su, Gard, Lipschutz, & Kuiken, 2008).
Asymmetrical movement patterns have been identified in biomechanical studies as contributing to slower performance of locomotor activities such as sit to stand in people with unilateral lower limb amputation (Agrawal, Gailey, Gaunaurd, Gailey, & O'Toole, 2011; Burger, Kuzelicki, & Marincek, 2005). Reduced walking speed, distance and
127 balance have been reported for older participants with atraumatic causes of amputation (Erjavec et al., 2014; Schoppen et al., 1999; Su et al., 2008; van Eijk et al., 2012; Waters et al., 1976). In many of these atraumatic cases of amputation the remaining limb is in a pre-amputation state with claudication pain or diabetic peripheral neuropathy limiting locomotor performance. It is unclear which locomotor tests are most valid in the clinical setting for assessment of heterogenous rehabilitation cohorts that have high variance in physical fitness, amputation cause, age and comorbidities. To date studies have been small, focused samples of convenience (e.g. military service personnel, experienced prosthetic users), specific groups (e.g. unilateral, transtibial) or have involved
biomechanical analyses that are not easily replicated in busy clinical settings (Agrawal et al., 2011; Akarsu et al., 2013; Burger et al., 2005; Resnik & Borgia, 2011).
In Aboriginal people (who were the first inhabitants of Australia), poor health outcomes due to geographical isolation from health services, high diabetes related amputation and mortality rates have been well documented (Norman et al., 2010; Vos et al., 2009).
Language barriers, cultural and health beliefs also have the potential to impact on access to healthcare and functional outcome following lower limb amputation (Schoen et al., 2010). However, amputation has been the primary endpoint of research and performance on locomotor tests using a prosthetic limb has not been investigated for Aboriginal people (Norman et al., 2010; Schoen et al., 2010; Vos et al., 2009).
The hypotheses for this generated study were:
1. That people with lower limb amputation in known groups at high risk of abandoning prosthetic use will have slower walking speeds, reduced distance and increased time for balance tasks on locomotor tests than those in lower risk groups during rehabilitation;
and
2. That the 10MWT, TUGT, 6MWT and FSST will be highly correlated as they all test a common domain of locomotor function.
128 Therefore, the study objectives were to gain knowledge on the balance and locomotor skills of known groups at high risk of abandoning prosthetic use and test the construct validity of the 10MWT, TUGT, 6MWT and FSST.
7.1.2. Methods Participants
The Royal Perth Hospital (RPH) and Curtin University Human Research Ethics
Committees approved this study (full details in Appendix 3.1). A research assistant who was unknown to potential participants recruited and obtained informed verbal consent from participants to abstract details from the medical records.
Participants were included if: they had at least one recent major lower limb amputation (i.e. transtibial level or above) as their primary admission diagnosis, multiple limb amputation, lived in the community, were ambulant before amputation surgery, were Medicare Functional Classification Level (MFCL) K-level 1 to 4, had received
prosthetic rehabilitation and been discharged from Royal Perth Hospital (RPH), the state centre for amputee rehabilitation. Recent major lower limb amputation was defined as surgery in the weeks or months preceding rehabilitation admission. This classification enabled identification of new amputee rehabilitation cases from multi-diagnostic cases with past medical history of amputation (e.g. fractured neck of femur and past
amputation).
K-levels were assigned collaboratively in the post-operative period by the Rehabilitation Physician and Senior Physiotherapist (who had 10 years of clinical experience in
amputee rehabilitation) as part of the RPH assessment procedure for rehabilitation admission based on criteria outlined in Roffman et al. (2014). K-levels have been defined by Gailey et al. (2002).
level 0 participants and those who did not consent were excluded from this study. K-level 0 participants were monitored through the multidisciplinary amputee outpatient clinic for the duration of this study and remained K-level 0.
129 The flow chart in Chapter 6 Figure 1 details participant eligibility and recruitment into this study. A total of 307 consecutive potential participants were identified from the Amputee Physiotherapy Service Database from June 2006 to July 2011 and 264 of these participants were K-level 1 to 4 however 37 participants were deceased. A total of 201 of the 211 eligible participants (95%) were recruited for this study.