Clinimetrics of the Upright Motor Control Test in chronic stroke

Abstract Introduction Insufficient literature exists regarding the clinimetric properties of the Upright Motor Control Test Knee Extension and Flexion subtests (UMCT‐KE and UMCT‐KF, respectively). This study examined the interrater and test‐retest reliability of these subtests, and determined the relationship between the UMCT‐KE and a clinical measure of muscle function in a sample of adults with chronic stroke. Methods Three raters independently administered the UMCT‐KE and UMCT‐KF on adults with chronic stroke with spasticity/abnormal movement patterns. Testing of each participant occurred on two occasions (T1 and T2) separated by a two‐week interval. A fourth rater independently administered the Five Times Sit to Stand Test (FTSST), a measure of lower extremity muscle function (power), on T2. Results Twenty‐nine adults aged 55 ± 8 years, comprising 21 men (72%), and who were 9 ± 5 years poststroke, completed the study. Most of the participants (66%, 19/29) did not require an assistive device during walking. The UMCT‐KE and UMCT‐KF demonstrated substantial interrater reliability (W = 0.63–0.67 and 0.72–0.75, respectively) and substantial to almost perfect test‐retest reliability across the raters (W = 0.75–0.82 and 0.85–0.87, respectively). The UMCT‐KE showed positive inverse correlation with the FTSST (ρ = −0.52, p = .003). Conclusions Scores on both subtests are reproducible within raters and across different raters. The relationship of UMCT‐KE scores with FTSST scores implies that the UMCT‐KE can provide information that relates with the construct of muscle function in a weight‐bearing position.


| INTRODUCTION
Voluntary control of the lower limbs is an important factor for controlling the upright position (Arya, Pandian, Abhilasha, & Verma, 2014). Impairment in voluntary control of movement exists among individuals with stroke and persists well beyond the inpatient rehabilitation period (Neckel, Pelliccio, Nichols, & Hidler, 2006). The Upright Motor Control Test (UMCT) (Hislop & Montgomery, 2007) or Upright Control Test (Keenan, Perry, & Jordan, 1984) was originally developed at the Rancho Los Amigos Hospital in Downey, California to assess voluntary control of the paretic lower limb. The test was first described in 1983 in an unpublished manuscript by Toman (Toman, unpublished thesis).
It has been used to determine the influence of muscle tone on lower extremity control in an upright position in individuals with neurologic injury (Barto, Gronley, Perry, & Yoshida, 1985;Keenan et al., 1984;Perry et al., 1995;Sweeney & Smutok, 1983). It has also been used as an outcome measure in stroke clinical trials as a measure of functional muscle strength (Almarez, Macatangay, Santos, & Flores, 2010;Ambrosini, Ferrante, Pedrocchi, Ferrigno, & Molteni, 2011;Ferrante, Pedrocchi, Ferrigno, & Molteni, 2008). A recent systematic review has reported the practical advantages of using the UMCT, such as short administration time, simple instrumentation, and uncomplicated testing procedures (Gorgon & Lazaro, 2016). Therefore, the UMCT can be used in a range of practice settings especially those with limited resources (Gorgon & Lazaro, 2016).
Among the subtests of the UMCT, the Knee Extension (UMCT-KE), and Flexion (UMCT-KF) subtests have been suggested to be reflective of total voluntary lower extremity control and not just voluntary control of the knee joint muscles (Perry et al., 1995).
The UMCT-KE provides information regarding supportive functions of the leg during the stance phase of walking (Ade, Smith, & Spigel, 2012). The UMCT-KF provides information regarding control of leg advancement during the swing phase of walking (Ade et al., 2012).
However, no reliability studies have been published to support the reproducibility of test results (Gorgon & Lazaro, 2016 (Mercer et al., 2009). However, how it relates with other categories within the same ICF domain, such as muscle functions, has not been studied. According to the ICF, muscle functions include force generated by contraction of a muscle/muscle group (World Health Organization, 2001) and impaired muscle function has been linked to difficulty in movement control in people with stroke (Neckel et al., 2006). Knowledge of such relationships can guide clinicians in using information from the UMCT in determining outcomes and designing interventions.
Thus, this study aimed to: (1) determine the interrater and test-retest reliability of the UMCT-KE and UMCT-KF, and (2) determine the relationship of the UMCT-KE with a clinical measure of muscle function.

| MATERIALS AND METHODS
This study used an observational methodological design (Portney & Watkins, 2009). The University of Philippines Manila Research Ethics Board approved the study protocol. All participants provided written informed consent.
Adults with chronic stroke were conveniently sampled from a multidisciplinary outpatient therapy clinic and stroke support group in an urban area in the Philippines. The inclusion criteria were: (1) age of at least 18 years; (2) presence of chronic stroke (6 months or more had elapsed since stroke diagnosis); (3) ability to follow at least three unrelated commands; (4) ability to maintain standing with or without physical assistance; and (5) presence of lower extremity spasticity (Modified Modified Ashworth Scale score of 1 or higher (Abolhasani et al., 2012)) or abnormal movement synergy (inability to isolate lower extremity joint movements on command). Potential participants were excluded if they: (1) were medically diagnosed with severe visual, hearing, cognitive, behavioral, or receptive language impairment; (2) had major sensory deficits; (3) had a recent lower extremity musculoskeletal injury; or (4) had bilateral stroke.
The UMCT-KE and UMCT-KF were administered following the procedure described by Perry et al. (Figure 1) (Perry et al., 1995). For the UMCT-KE, the patient stood with knees in 30 degrees of flexion.
The patient then transferred full weight on the more affected lower extremity by lifting the opposite foot off the floor. Finally, the patient attempted to extend the more affected knee. The rater scored knee extensor strength using a three-point ordinal scale: 3 or "strong," (can support the body weight by fully extending the knee from flexion); 2 or "moderate," (can support the body weight on the flexed knee without collapsing into further flexion but cannot control extension); and 1 or "weak," (cannot support the body weight on the flexed knee or the test knee collapses into further flexion). For the UMCT-KF, the patient stood with knees in extension. The patient then brought the knee of the more affected lower extremity up toward the chest as high and fast as possible three times. The rater scored knee flexor strength using a two-point ordinal scale: 3 or "strong," (can flex the knee to >60 degrees, three times in 10 s); and 1 or "weak," (cannot flex the knee to >60 degrees, three times in 10 s, or cannot move the lower limb at all). If required for either procedure, assistance was given in maintaining balance by allowing the participant to place the palm or forearm on the rater's palm or forearm. However, if a participant needed to bear excessive weight on the rater to complete the task, a lower score was given. Verbal cues were provided if necessary but were generally avoided.
Scores on the UMCT-KE were related to scores on the Five Times Sit to Stand Test (FTSST), a commonly used clinical test of muscle function. The test involved recording the time it took for a participant to complete five repetitions of the sit-to-stand task, with a shorter time reflecting better performance (Mong, Teo, & Ng, 2010). Participants were encouraged to not use their hands to help push up during the test. Although it has been regarded as a reliable and valid measure of functional lower extremity strength in adults with chronic stroke (Mong et al., 2010), the FTSST involves force production of muscles used in sit-to-stand within a given time constraint and is therefore a measure of muscle power. As the sit-to-stand maneuver involves use of the lower extremity muscles, most notably the knee extensor group (Bohannon, Bubela, Magasi, Wang, & Gershon, 2010), in a weight-bearing position, FTSST scores were tested for correlation with UMCT-KE scores.
Raters obtained data on the UMCT-KE and UMCT-KF on two testing sessions (T1 and T2) that were separated by a two-week time interval. Three physical therapists of varying years of clinical experience administered the tests. Prior to testing, all raters underwent training on test administration and scoring. Testing sessions were conducted in a well-lit, cool, and quiet room in an outpatient therapy clinic. The order of raters was counterbalanced. Similar testing conditions were observed on all occasions. On T2, raters were blinded to the UMCT scores of the participants from T1. A fourth physical therapist who was blinded to the UMCT scores of the participants administered the FTSST on T2. For all tests, participants were given one practice trial, followed by two test trials. Scores were recorded and best scores were used in data analysis.

| RESULTS
Twenty-nine adults (mean age = 55 ± 8 years; men = 72%, 21/29) with chronic stroke (mean time since stroke onset = 9 ± 5 years, range = 1-21 years) participated. Fifty-five percent (16/29) had left hemisphere stroke or right-sided muscle weakness. Most of the participants (66%, 19/29) did not require an assistive device or physical assistance from another person while walking. Demographic characteristics of the participants are further detailed in Table 1 Table 2).  of the ICF (World Health Organization, 2001). The UMCT-KE may successfully capture the ability of patients to accept load on the more affected lower extremity, which is an important dimension of sit-to-stand performance (Lomaglio & Eng, 2005). The positive relationship between the UMCT-KE and FTSST builds on evidence from the study by Mercer et al. that showed direct correlations between UMCT-KE scores and force platform measurements of limb loading (Mercer et al., 2009). This finding warrants more research that will