Journal of Hand Therapy xxx (2014) 1e6
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Scientific/Clinical Article
The push-off test: Development of a simple, reliable test of upper extremity weight-bearing capability Joshua I. Vincent PT, MPT a, c, *, Joy C. MacDermid PT, PhD b, c, Susan L. Michlovitz PT, PhD b, d, Richard Rafuse PT, MPT e, Christina Wells-Rowsell PT, MPT e, Owen Wong PT, MPT e, Leslie Bisbee MCISc, BScPT e a
University of Western Ontario, Health and Rehabilitation Sciences, London, Ontario, Canada School of Rehabilitation Science, McMaster University, Hamilton, Ontario, Canada c Roth-McFarlane Hand and Upper Limb Center, St. Joseph’s Hospital, London, Ontario, Canada d Cayuga Hand Therapy PT, Ithaca, NY, USA e School of Physiotherapy, University of Western Ontario, London, Ontario, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 April 2013 Received in revised form 18 February 2014 Accepted 1 March 2014 Available online xxx
Study design: Longitudinal clinical measurement study. Introduction: The push-off test (POT) is a novel and simple measure of upper extremity weight-bearing that can be measured with a grip dynamometer. There are no published studies on the validity and reliability of the POT. The relationship between upper extremity self-report activity/participation and impairment measures remain an unexplored realm. Purpose: The primary purpose of this study is to estimate the intra and inter-rater reliability and construct validity of the POT. The secondary purpose is to estimate the relationship between upper extremity self-report activity/participation questionnaires and impairment measures. Methods: A convenience sample of 22 patients with wrist or elbow injuries were tested for POT, wrist/ elbow range of motion (ROM), isometric wrist extension strength (WES) and grip strength; and completed two self-report activity/participation questionnaires: Disability of the Arm, Shoulder and the Hand (DASH) and Work Limitations Questionnaire (WLQ-26). POT’s inter and intra-rater reliability and construct validity was tested. Pearson’s correlations were run between the impairment measures and self-report questionnaires to look into the relationship amongst them. Results: The POT demonstrated high inter-rater reliability (ICC affected ¼ 0.97; 95% C.I. 0.93e0.99; ICC unaffected ¼ 0.85; 95% C.I. 0.68e0.94) and intra-rater reliability (ICC affected ¼ 0.96; 95% C.I. 0.92e0.97; ICC unaffected ¼ 0.92; 95% C.I. 0.85e0.97). The POT was correlated moderately with the DASH (r ¼ 0.47; p ¼ 0.03). While examining the relationship between upper extremity self-reported activity/participation questionnaires and impairment measures the strongest correlation was between the DASH and the POT (r ¼ 0.47; p ¼ 0.03) and none of the correlations with the other physical impairment measures reached significance. At-work disability demonstrated insignificant correlations with physical impairments. Conclusion: The POT test provides a reliable and easily administered quantitative measure of ability to bear the load through an injured arm. Preliminary evidence supports a moderate relationship between loading bearing measured by the POT and upper extremity function measured by the DASH. Level of evidence: 1b Ó 2014 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.
Keywords: Upper limb Weight-bearing Push-off test Reliability Construct validity Impairment measures Self-report measures
Introduction
This study was approved by the Health Sciences Research Ethics Board (HSREB) of the University of Western Ontario in London, Ontario, Canada. No funds were received in support of this study. * Corresponding author. Health and Rehabilitation Sciences, Faculty of Health Sciences, Elborn College, Room 1424, 1201 Western Road, London, ON N6G 1H1, Canada. Tel.: þ1 519 694 6222; fax: þ1 519 646 6049. E-mail addresses: [email protected], [email protected] (J.I. Vincent).
Unlike the lower limb where weight-bearing is a predominant physical requirement for mobility, the need for weight-bearing through the upper limb is intermittent and is more related to stability. However, the importance of weight-bearing in the upper limb is often under-estimated. There are functional tasks such as pushing opening a heavy door, pushing up from a sitting position or moving a heavy object that require upper extremity
0894-1130/$ e see front matter Ó 2014 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jht.2014.03.002
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weight-bearing. In conditions like stroke, spinal cord injury, or lower extremity musculoskeletal disorders the upper limb can assume a greater role in weight-bearing when performing day to day activities.1e3 For instance, nearly half of the body weight is transferred through the upper limb during the use of walker in patients with lower extremity disorders.4 Weight-bearing capacity can also reflect the stability of upper extremity joints since an unstable joint is not suitable for load-bearing. For these reasons, it might be clinically relevant to determine the amount of load that can be tolerated through the upper limb during rehabilitation of upper extremity injuries. The distal radio-ulnar joint (DRUJ) plays a very important role as a weight-bearing mechanism.5 There are various biomechanical studies that have explored the effect of the position of forearm that influences the contact area inside the DRUJ and the amount of force that passes through it. Shabaan and colleagues6 have found that the contact area within the DRUJ was reduced in full pronation and was significantly decreased in extreme supination during axial loading. The same authors have determined that the pattern of loading of the forearm during weight-bearing increases with the loading of the hand; the axial loading was minimum at full pronation and maximum at full supination.7 Also, grip strength was found to be maximum in neutral forearm for men and; supination and neutral forearm for women.8 All the above mentioned factors play an important role in determining the amount of force that goes through the arm and in turn the weight bearing capability of the arm. Ability to tolerate load through the upper extremity may also reflect the joint irritability or pain tolerance in much the same way that the pain free grip test assesses pain in response to loading of muscle.9 The “Press-test” which is used as quick test for the diagnosis of triangular fibrocartilage complex (TFCC) injury has shown to have high sensitivity and specificity.10 However, this test is used only for diagnosis and the results of this test cannot be quantified. Thus, potentially a quantifiable joint loading test might be a useful indicator of weight-bearing ability in bone and joint disorders like wrist and elbow arthritis, TFCC injury, ulnar sided wrist pain, fractures around wrist, elbow and forearm (post-union) and also help in tracking progress during the sub-sequent visits serving as a prognostic tool. Assessment tools for the wrist and elbow have, in the past, focused on obtaining measures of impairment with the assumption that these reflect activity limitations.11 Self-report measures are taking center stage in reporting activity limitations currently. The International Classification of Functioning, Disability and Health (ICF),12 a biopsycho-social model which provides a coherent view of social, individual and biological perspectives of health calls for the examination of the relationships between physical impairments and activity limitations or participation restrictions. It is vital to explore these associations as this information would be of significance when assessing new methods of treatment and validating current and future clinical outcome scoring systems13 and also to enable a better understanding of how one might focus rehabilitation interventions to maximize health. However, these relationships cannot be anticipated, because complex processes that involve personal and environmental factors can interact to determine the overall health impact. This becomes particularly relevant as health care focus shifts toward a broader; more holistic view of optimal functioning that includes body functions, activities and societal participation. When considering the use of a new impairment measure to measure the load bearing capability of the upper limb, the value of such a measure is based on established key measurement principles. Fundamental is the reliability of the test. However, it is equally important to establish the relationship between any new measure
and other health indicators that are used to reflect the upper extremity impairment or activity/participation like self-report questionnaires, so that it is clear to what extent the new measure provides unique information. The push-off test (POT) was developed by one of the authors (SM) to measure the weight bearing through the upper limb using methods and tools feasible for clinical practice. It is a simple and easy test that does not require any extra equipment other than the grip dynamometer which is routinely used in hand clinics. A grip dynamometer was adapted by reversing the handle to perform this test (the details of the test are described later in this paper). There are no published studies on the validity and reliability of the POT. There is also an ongoing debate on the relationship between selfreport activity/participation measures and impairment measures e whether they complement each other and provide similar information or do they tap into different constructs of the same problem. Purpose The primary purpose of this study was to analyze the inter-rater reliability, intra-rater reliability and construct validity of the pushoff test (POT). The secondary purpose is to estimate the relationship between upper extremity self-report activity limitation/participation restriction questionnaires and impairment measures. Methods Subjects Twenty-six subjects were identified by convenience sampling from the Roth-McFarlane Hand and Upper Limb Center, London ON, Canada. Potential subjects who were undergoing treatment at the center were initially identified through a search of medical records. Patients were included as study participants if they satisfied the following criteria: 1) Attending the center with wrist or elbow problems 2) Between the ages of 18 and 65 years (adult working population) The exclusion criteria included: 1) Pathologies affecting both arms 2) Shoulder pathologies affecting upper extremity function 3) Contraindicated for medical reasons including co-morbidity or status of presenting condition 4) Unable to comprehend/read questionnaires. Two of the 26 participants were excluded following discovery of a concurrent shoulder injury. One other participant was found to have a fracture of the wrist that had not healed and another participant was unable to complete the testing due to alternate time commitments. Finally, twenty-two participants (male:female e 15:7; age range 22e61) with wrist or elbow injuries (wrist:elbow e 12:10) such as fractures and soft tissue injuries (mean post-injury period 32 weeks) were included in the study (see Table 1). Informed consent was obtained prior to inclusion in the study and their rights were protected. Of the 22 patients who participated in the study, four did not complete the WLQ-26 due to unemployment, and one participant failed to properly complete the questionnaire. Procedure Study design: Longitudinal clinical measurement study.
J.I. Vincent et al. / Journal of Hand Therapy xxx (2014) 1e6 Table 1 Patient characteristics
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Table 2 Inter-rater reliability of the push-off test
Characteristic
Values
POT-1 vs POT-2
ICC
95% confidence interval
Subjects (n) Male/female (n) Average age in years Age range Average post-injury period
22 15:7 42 22e61 years 32 weeks
Affected extremity Unaffected extremity
0.97 0.85
0.93e0.99 0.68e0.94
n (%) Dominant hand affected Yes No Injured joint Wrist Elbow Received PT treatment Yes No Currently working Yes No
10 12 12 10 17 5 16 6
Upon obtaining patient consent to proceed, subjects were invited to the clinical outcomes research laboratory at the center, where they underwent an initial assessment. A self-report comorbidity questionnaire14 and a comprehensive baseline information form were also completed to ensure no serious medical complications or co-morbidities were present prior to testing. Physical impairment tests namely POT, wrist/elbow active range of motion (AROM), isometric wrist extension strength (WES) and grip strength were performed bilaterally, with the unaffected arm serving as a normative comparison. Prior to subject testing, the order of all physical tests was randomized to reduce potential sources of bias. One of three evaluators was randomly assigned the role of primary tester of all physical impairments. Another evaluator was randomly assigned the role of secondary tester for the POT to maintain blinding of impairment scores. For all physical tests, a standardized protocol was used and recordings made in triplicate. The average of three trials was used as the criterion measure for all the impairment tests. Subjects were given instruction and demonstration of the test, as well as an initial submaximal trial in order to familiarize the subject with the test. Subjects also performed the POT a second time with a randomly assigned second evaluator; this was to provide data to determine the inter-rater reliability of this new load-bearing test. Patients were also asked to complete two self-report activity limitation/participation restriction questionnaires, the Disability of the Arm, Shoulder and the Hand (DASH)15 and Work Limitations Questionnaire (WLQ-26).16 The data from these questionnaires would aid in examining the construct validity of the POT and also the relationship between the upper extremity self-report activity limitation/participation restriction questionnaires and impairment measures.
The test arm is positioned approximately in 10 e40 shoulder extension and 10 e40 elbow flexion. Hand/wrist and forearm are placed in comfortable patient self-determined position. Dynamometer set-up: Handle set in the second position (3.8 cm), and reversed so that the convex side of the handle faces upwards. Stabilization: Dynamometer placed on a stable, non-slip surface. The assessor provides additional stabilizing support of the dynamometer against the table to prevent slipping during test performance. Test procedure: Test instructions are similar as those suggested by the American Society of Hand Therapists17 and Mathiowetz18 for grip strength protocols, except substituting “push” for “grip”. A 30second rest period was incorporated between trials and the average of three trials was taken.19 The test involves having subject’s weight-bear through a grip dynamometer until they have applied their maximum tolerable loading (Fig. 1). Wrist AROM: A composite score was taken to determine the arc of movement within the planes of wrist movement. Therefore, maximal sagittal AROM for the wrist was calculated in degrees as maximum flexion from neutral combined with maximum wrist extension from neutral. The two arcs of movement for the wrist were flexion/extension (sagittal) and radial/ulnar deviation (frontal). For both measurements, the participant was seated in a straight-back chair with a table set in front. Goniometer placement for measurement of both arcs of movements was consistent with published standards.20 Elbow AROM: A composite score was also derived for elbow arcs of movements similar to the method as described for wrist AROM. The arcs of movement consisted of flexion/extension (sagittal) and pronation/supination (transverse). Elbow flexion/extension AROM was measured in the seated position in accordance with clinical practice.20 Elbow pronation/supination AROM was measured using the distal forearm method, which has been shown to provide reliable scores using either a traditional goniometer or the NK device used in this study.21 Isometric wrist extension strength: Patients were placed in the seated position as described previously. The J-Tech handheld
Outcome measures Physical impairment measures “Push Off” test (POT): This new functional test determines the amount of pressure that an individual can place through an injured upper extremity. A grip dynamometer is adapted by reversing the handle so that the convex side points upward allowing for upper extremity loading to be applied with the palm cupped on the bar. The protocol for the “push-off” test (Table 2) was developed by one of the paper authors (SM). Testing position: Subject positioned at a 74e76 cm high table, buttocks leaning against the table but not sitting upon the table.
Fig. 1. The Push-off test.
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dynamometer was used.1 The hand/wrist was placed over the edge of the table, where it was free from AROM restrictions. A “break test” protocol with the instruction, “Hold, don’t let me move you,” was used while the evaluator matched the force of the patient until a movement was created. The evaluator released the held position within 7 s to avoid fatigue of the muscles. Static grip strength: This was measured according to a standardized methodology as described by the American Society of Hand Therapists (ASHT).17,22 The J-Tech grip dynamometer handle was set to the second position (3.8 cm) and patients were instructed to exert maximal effort. A standardized rest period of 30seconds was incorporated to discourage fatigue between trials.19 This protocol has been shown to provide high reliability with the NK device.22
reliability; 0.26e0.49 ¼ low reliability and 0.00e0.25 ¼ little, if any, reliability.33 Construct validity: Construct validity was assessed by using Pearson’s correlation coefficient (r) to examine correlations between the POT and self-report activity/participation questionnaires. Pearson’s correlation coefficients were interpreted as follows: 0.90e1 ¼ very strong correlation; 0.70e0.89 ¼ strong correlation; 0.40e0.69 ¼ moderate correlation; 0.20e0.39 ¼ weak correlation; and 0.00e0.19 ¼ very weak correlation.34 The relationship between upper-extremity self-report activity limitation/participation restriction questionnaires and impairment measures was also examined using the Pearson’s correlations obtained and were interpreted in a manner similar to construct validity.
Self-report activity/participation measures DASH: The DASH is a 30-item self-report measure designed to measure upper extremity disability.15,23 Twenty-one items address function, while the remaining nine items examine symptoms and social participation related to upper extremity pathology.23 This questionnaire has been demonstrated to be valid and responsive in patients with proximal and distal disorders, and is therefore useful for the entire upper extremity.23e26 The English version of the DASH questionnaire was used for this study. WLQ-26: The WLQ-26 is a self-report scale that measures the degree to which chronic health problems interfere with the ability to perform job roles and affect worker-productivity.16,27,28 The content and format of the WLQ-26 originated from focus groups, cognitive interviews, and alternate forms comparison.16 It has four sub-scales, time or scheduling demands, physical work demands, mental work demands, and interpersonal demands. It has been found to be valid, reliable and responsive for use among several different job tasks, both service and manual, and chronic condition groups.16,27,29,30 The WLQ-26 responses are interpreted as the approximate percentage of time in the previous 4 weeks that a person was limited in performing a specific class of job demands.16
Results
Data analysis The original formula [(sum of items 30)/1.2] of the DASH was used to score the questionnaire (no missing items). Four different subscales of the WLQ-26 were calculated by summing relevant items and deriving a percentage score. For both questionnaires, a higher score denoted greater dysfunction whereas a lower score represented less dysfunction. Physical differences between patients were controlled for by representing the physical impairment as a percentage of the patient’s unaffected side (deficit score).31 Statistical analysis Data entry, quality checking and analysis (reliability and construct validity) were performed using the SPSS software. The level of statistical significance was set at p < 0.05. Reliability: Inter-rater reliability and intra-rater reliability of the POT were determined by using a two-way mixed effect model that calculated a single intra-class correlation coefficient (ICC type 2, 1) and their associated 95% confidence intervals (95%CI).32 The ICC values ranges from 0 to 1; 1 ¼ perfect reliability, 0.90e0.99 ¼ very high reliability; 0.70e0.89 ¼ high reliability; 0.50e0.69 ¼ moderate
1 J-Tech Medical Industries, 4314 Zevex Park Lane, Salt Lake City, UT, USA, 84123, www.jtechmed.com.
Reliability of the POT The POT showed high inter-rater reliability (see Table 2) (ICC affected ¼ 0.97; 95% C.I. 0.93e0.99; ICC unaffected ¼ 0.85; 95% C.I. 0.68e0.94) and intra-rater reliability (see Table 3) (ICC affected ¼ 0.96; 95% C.I. 0.92e0.97; ICC unaffected ¼ 0.92; 95% C.I. 0.85e0.97). Construct validity of the POT The POT had a significant moderate correlation with the DASH (r ¼ 0.47; p ¼ 0.03) (see Table 4). It exhibited correlations that were not significant with the four subscales of the WLQ-26 (r ¼ 0.32 to 0.41; NS). Relationship amongst self-report activity limitation/participation restriction questionnaires and physical impairment measures The WLQ-26 sub-scales demonstrated very low to moderate correlations with physical impairments with only 4 out of the 24 correlations being significant (see Table 4). The subscales of WLQ did not exhibit any significant correlations with the DASH (r ¼ 0.17e0.33; NS) (see Table 5). The only physical impairment measure with which the DASH had a significant correlation was the POT (r ¼ 0.47; p ¼ 0.03). Discussion This study provided preliminary support for the newly described “POT” impairment test that assess upper extremity loading, establishing appropriate levels of inter-rater reliability, intra-rater reliability and construct validity. The POT demonstrated a moderate relationship to upper extremity disability indicating that the test is relevant to measure disability but that it also provides information that is different than provided by self-report. The POT is a novel impairment measure reflecting the loadbearing capacity through the upper extremity. Grip dynamometers are typically available in hand clinics to test grip strength, the use of the same instrument to conduct additional testing presents a
Table 3 Intra-rater reliability of the Push-off test Measure Rater Rater Rater Rater
e e e e
1 1 2 2
Affected Unaffected Affected Unaffected
ICC
95% confidence interval
0.95 0.92 0.97 0.93
0.90e0.98 0.84e0.96 0.94e0.99 0.86e0.97
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Table 4 Correlation between self-report questionnaires and physical impairment measures
WES deficit Grip strength deficit Total ROM deficit Composite wrist ROM deficit Composite elbow ROM deficit “Push-off” deficit
DASH
Time demands
Mental demands
Interpersonal demands
Physical demands
0.41 0.22 0.30 0.13 0.37 0.47*
0.25 0.27 0.50* 0.32 0.53* 0.41
0.22 0.27 0.44 0.26 0.47 0.32
0.14 0.29 0.38 0.26 0.38 0.32
0.37 0.52* 0.46 0.27 0.49* 0.38
*Significant at the 0.05 level.
viable approach to measurement of load bearing capacity in clinical practice. The POT is easy to administer with consistent instructions as it uses a protocol that is similar to the American Society of Hand Therapists17 and Mathiowetz grip strength protocols18 which are commonly used in routine clinical practice. Hence, we expect that this test to be accessible and quickly adaptable with minimal training required for implementation. Unlike the “Press test”10 which is used as a simple diagnostic test for TFCC, the POT has the potential of serving not only as a diagnostic test and but also as an outcome assessment tool for use during follow-up sessions to chart improvement from treatment. POT has the markings of a diagnostic and prognostic tool to assess the load bearing capability of the upper limb in musculoskeletal disorders around the wrist and elbow which need to be explored further. Outcome measures should be tested for stability and reproducibility of outcomes between raters and within raters before being used in clinical practice.35 One of the most fundamental measurement properties is reliability, since providing consistent stable measurements in the absence of change is a prerequisite to other measurement properties. Despite, the small sample the reliability coefficients were high for both intra-and inter-rater reliability and the confidence intervals indicated good precision on these estimates (except for inter-tester reliability on the unaffected side). The POT is an impairment measure that may be affected by multiple physical variables such as pain or pain tolerance, joint stability or control. This may explain why it was more strongly correlated with the upper extremity function (DASH) while not demonstrating significant correlations with physical impairment indicators. The observation that physical impairments did not significantly correlate to at work disability (WL-26) was not unexpected since multiple work, worker and workplace factors contribute to at-work disability. Further, the DASH measures function on a scale where everyone responds to the same items; and has been correlating to impairment in previous studies.36,37 Conversely, the WLQ-26, measures difficulty at-work; difficulty in tasks that would vary across individuals and as such not all people are measuring on the same metric across comparisons. Our findings were affected by our small sample. Some of the correlations that were in the moderate range were not statistically significant, which is unlikely to occur in larger samples. Further, a smaller sample provides less precise estimates of effects. This study
Table 5 Correlation between DASH and subscales of the WLQ-26 WLQ-26 subscales
Pearson correlation
Physical demands Mental demands Time demands Interpersonal demands
0.33 0.32 0.31 0.17
describes a new test and measurement properties estimates, and although promising, the findings should be considered as preliminary. We advise that multiple independent studies are needed to verify the reliability and validity of this test in other samples. It is important to see whether the test can be applied to a range of patients. Since we expect the POT to provide information about joint status that is related to function, exploration of how it relates to different functional tests and to imaging of joint damage is needed to indicate test validity. Since it can be readily performed in clinic with commonly available grip devices, clinician-scientists are encouraged to test its usefulness in larger sample sizes and to report additional data on aspects of validity like the convergent validity, divergent validity, and responsiveness. Unlike the POT, other impairment measures did not relate to function. The lack of correlation between the DASH and grip strength deficit obtained in this study does not correspond with results from previous studies. Roumen et al38 found a significant correlation between grip strength and hand function in elderly patients with Colle’s fracture. Tremayne et al11 also found strong and significant correlations between grip strength and the tasks of the Jebsen Test of Hand Function (JTHF) in patients with fracture of the distal radius. This may indicate differences in the measures used in these studies or differences in the populations tested. Similarly, wrist extension strength deficit again did not correlate significantly with the DASH. Since this impairment is rarely reported in the literature, we found little comparative data. Since this study included different upper extremity disorders, variations in individual patients’ conditions may have attenuated the observed relationships between specific impairments and self-reported disability. The physical demands subscale of the WLQ-26 correlated moderately with grip strength deficit and composite elbow ROM deficit. This corresponds with previous studies suggesting that grip strength and function are related11,38 and affirms the common clinical usage of grip strength as an important outcome measurement tool, particularly in work related assessments. Grip strength deficit, however, did not significantly correlate with any of the other WLQ-26 subscales. Composite elbow ROM deficit’s significant moderate correlation to the physical demands subscale illustrates the elbow’s important role in helping position the hand in space while performing functional activities at work. For example, tasks such as answering a phone, reaching to the ground, or placing files or objects on a shelf, all require a substantial arc of elbow flexion and extension. The mental demands or interpersonal demands subscales of the WLQ-26 did not achieve significant correlation with any of the impairment measures. While this might appear intuitive, it has been shown that physical and mental burdens share co-variation.39 Patients whose physical capacity did not allow them to complete work activities in a timely fashion might experience mental demands or interpersonal demands as a result. While the time demands subscale’s significant moderate correlations with the composite elbow ROM deficit and total ROM deficit underscores the
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importance of upper extremity joint ROM especially the elbow in performing functional tasks in a timely manner. The strengths of the current study are, the broad spectrum of wrist and elbow disorder participants that were included in the study which increases generalizability and that reliability of our measures was supported. Our study also had limitations including the small sample size. Post-hoc power analyses indicated that 40 patients would be appropriate to provide precise estimates. Although 22 subjects completed all physical tests and the DASH, only 17 subjects fully completed the WLQ-26. Thus, correlations between the WLQ-26 and the physical tests or the DASH may be less stable. Use of a table with a standardized height is a limitation of the test which could affect the outcome in people of varying heights. We recommend the use of a height adjustable table to solve this issue in future studies. Finally, since this study was of shorter follow-up, we did not examine responsiveness. Future clinical and research recommendations Further research is required to define the “push-off” test as a useful diagnostic and assessment tool. The next wave of validation research should include studies on specific health conditions that might exhibit joint loading derangements such as arthritis or contexts where “loading” might be particularly relevant. Studies of POT as a prognostic measure and comparative responsiveness require longitudinal studies. Conclusion This developmental study determined that a load-bearing test (POT) could be performed reliably by a variety of patients with elbow and wrist disorders. Preliminary evidence suggests that the POT is moderately related to self-reported function; but, also provided unique information suggesting a useful role in the assessment “toolbox” of hand therapists. Caution should be exercised while interpreting these results keeping in mind the low sample size. The study provides further indication that impairments cannot accurately predict patient function and should be considered as moderately associated, but distinct, health constructs. References 1. Harvey LA, Crosbie J. Weight bearing through flexed upper limbs in quadriplegics with paralyzed triceps brachii muscles. Spinal Cord. 1999;37(11): 780e785. 2. Opila KA, Nicol AC, Paul JP. Upper limb loadings of gait with crutches. J Biomech Eng. 1987;109(4):285e290. 3. Reistetter T, Abreu B, Bear-Lehman J, Ottenbacher K. Unilateral and bilateral upper extremity weight-bearing effect on upper extremity impairment and functional performance after brain injury. Occup Ther Int. 2009;16(3e4): 218e231. 4. McQuade KJ, Finley M, Oliveira AS. Upper extremity joint stresses during walker assisted ambulation in post-surgical patients. Rev Bras Fisioter. 2011;15(4):332e337. 5. Shaaban H, Giakas G, Bolton M, Williams R, Scheker LR, Lees VC. The distal radioulnar joint as a load-bearing mechanismea biomechanical study. J Hand Surg Am. 2004;29(1):85e95. 6. Shaaban H, Giakas G, Bolton M, et al. Contact area inside the distal radioulnar joint: effect of axial loading and position of the forearm. Clin Biomech (Bristol, Avon). 2007;22(3):313e318. http://dx.doi.org/10.1016/j.clinbiomech.2006.05.010. 7. Shaaban H, Giakas G, Bolton M, et al. The load-bearing characteristics of the forearm: pattern of axial and bending force transmitted through ulna and radius. J Hand Surg Br. 2006;31(3):274e279. http://dx.doi.org/10.1016/ j.jhsb.2005.12.009. 8. De Smet L, Tirez B, Stappaerts K. Effect of forearm rotation on grip strength. Acta Orthop Belg. 1998;64(4):360e362. 9. Tarhan S, Ünlü Z, Ovalı GY, Pabus¸çu Y. Value of ultrasonography on diagnosis and assessment of pain and grip strength in patients with lateral epicondylitis. Turk J Rheumatol. 2009;24(3):123e130.
10. Lester B, Halbrecht J, Levy IM, Gaudinez R. “Press test” for office diagnosis of triangular fibrocartilage complex tears of the wrist. Ann Plast Surg. 1995;35(1): 41e45. 11. Tremayne A, Taylor N, Mcburney H, Baskus K. Correlation of impairment and activity limitation after wrist fracture. Physiother Res Int. 2002;7(2):90e99. 12. World Health Organization. Towards a common language for functioning, disability and health ICF. http://www.who.int/classifications/icf/training/icf beginnersguide.pdf; Updated 2002 Accessed 09.10.11. 13. Karnezis IA, Fragkiadakis EG. Association between objective clinical variables and patient-rated disability of the wrist. J Bone Joint Surg Br. 2002;84(7): 967e970. 14. Sangha O, Stucki G, Liang MH, Fossel AH, Katz JN. The self-administered comorbidity questionnaire: a new method to assess comorbidity for clinical and health services research. Arthritis Rheum. 2003;49(2):156e163. 15. Solway S, Beaton DE, McConnell S, Bombardier C. The DASH Outcome Measure User’s Manual. 2nd ed. Toronto: Institute for Work & Health; 2002. 16. Lerner D, Amick 3rd BC, Rogers WH, Malspeis S, Bungay K, Cynn D. The work limitations questionnaire. Med Care. 2001;39(1):72e85. 17. Fess EE, Moran CA. Grip strength. In: Casonova JS, ed. Clinical Assessment Recommendations. vol. 2. Chicago: American Society of Hand Therapists; 1992. 18. Mathiowetz V. Grip and Pinch Strength Measurements. In: Amundsen LR, ed. Muscle Strength Testing: Instrumented and Non-instrumented Systems. NewYork: Churchill Livingstone; 1990. 19. Mathiowetz V. Effects of three trials on grip and pinch strength measurements. J Hand Ther. 1990;3(4):195e198. 20. Hazel MC. Musculoskeletal Assessment: Joint Range of Motion and Manual Muscle Strength. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2000:432. 21. Armstrong AD, MacDermid JC, Chinchalkar S, Stevens RS, King GJ. Reliability of range-of-motion measurement in the elbow and forearm. J Shoulder Elbow Surg. 1998;7(6):573e580. 22. MacDermid JC, Alyafi T, Richards RS. Test-retest reliability of static and endurance grip strength tests performed on the jamar and NK. Physiother Can. 2001;53:48e54. 23. Beaton DE, Katz JN, Fossel AH, Wright JG, Tarasuk V, Bombardier C. Measuring the whole or the parts? Validity, reliability, and responsiveness of the disabilities of the arm, shoulder and hand outcome measure in different regions of the upper extremity. J Hand Ther. 2001;14(2):128e146. 24. MacDermid JC. Outcome evaluation in patients with elbow pathology: Issues in instrument development and evaluation. J Hand Ther. 2001;14(2):105e114. 25. Vincent JI, Macdermid JC, King GJ, Grewal R. Validity and sensitivity to change of patient-reported pain and disability measures for elbow pathologies. J Orthop Sports Phys Ther. 2013;43(4):263e274. http://dx.doi.org/10.2519/jospt.2013.4029. 26. Turchin DC, Beaton DE, Richards RR. Validity of observer-based aggregate scoring systems as descriptors of elbow pain, function, and disability. J Bone Joint Surg Am. 1998;80(2):154e162. 27. Lerner D, Amick 3rd BC, Lee JC, et al. Relationship of employee-reported work limitations to work productivity. Med Care. 2003;41(5):649e659. http:// dx.doi.org/10.1097/01.MLR.0000062551.76504.A9. 28. Roy JS, MacDermid JC, Amick 3rd BC, et al. Validity and responsiveness of presenteeism scales in chronic work-related upper-extremity disorders. Phys Ther. 2011;91(2):254e266. http://dx.doi.org/10.2522/ptj.20090274. 29. Roy JS, Desmeules F, MacDermid JC. Psychometric properties of presenteeism scales for musculoskeletal disorders: a systematic review. J Rehabil Med. 2011;43(1):23e31. http://dx.doi.org/10.2340/16501977-0643. 30. Beaton DE, Tang K, Gignac MA, et al. Reliability, validity, and responsiveness of five at-work productivity measures in patients with rheumatoid arthritis or osteoarthritis. Arthritis Care Res (Hoboken). 2010;62(1):28e37. http:// dx.doi.org/10.1002/acr.20011. 31. Petersen P, Petrick M, Connor H, Conklin D. Grip strength and hand dominance: challenging the 10% rule. Am J Occup Ther. 1989;43(7):444e447. http:// dx.doi.org/10.5014/ajot.43.7.444. 32. Deyo RA, Diehr P, Patrick DL. Reproducibility and responsiveness of health status measures. statistics and strategies for evaluation. Control Clin Trials. 1991;12(4 suppl):142Se158S. 33. Portney L, Watkins M. Foundation of Clinical Research: Applications to Practice. Upper Saddle River, NJ: Prentice-Hall; 2000. 34. Fowler J, Chevannes M, Jarvis P. Practical Statistics for Nursing and Health Care. New York; Chichester: Wiley; 2002:213. 35. Fess EE. The need for reliability and validity in hand assessment instruments. J Hand Surg. 1986;11(5):621e623. 36. Adams J, Burridge J, Mullee M, Hammond A, Cooper C. Correlation between upper limb functional ability and structural hand impairment in an early rheumatoid population. Clin Rehabil. 2004;18(4):405e413. 37. Mink van der Molen AB, Ettema AM, Hovius SE. Outcome of hand trauma: the hand injury severity scoring system (HISS) and subsequent impairment and disability. J Hand Surg Br. 2003;28(4):295e299. 38. Roumen RM, Hesp WL, Bruggink ED. Unstable colles’ fractures in elderly patients. A randomised trial of external fixation for redisplacement. J Bone Joint Surg Br. 1991;73(2):307e311. 39. MacDonald LA, Karasek RA, Punnett L, Scharf T. Covariation between workplace physical and psychosocial stressors: evidence and implications for occupational health research and prevention. Ergonomics. 2001;44(7):696e718. http://dx.doi.org/10.1080/00140130119943.
Contents lists available at ScienceDirect
Journal of Hand Therapy journal homepage: www.jhandtherapy.org
Scientific/Clinical Article
The push-off test: Development of a simple, reliable test of upper extremity weight-bearing capability Joshua I. Vincent PT, MPT a, c, *, Joy C. MacDermid PT, PhD b, c, Susan L. Michlovitz PT, PhD b, d, Richard Rafuse PT, MPT e, Christina Wells-Rowsell PT, MPT e, Owen Wong PT, MPT e, Leslie Bisbee MCISc, BScPT e a
University of Western Ontario, Health and Rehabilitation Sciences, London, Ontario, Canada School of Rehabilitation Science, McMaster University, Hamilton, Ontario, Canada c Roth-McFarlane Hand and Upper Limb Center, St. Joseph’s Hospital, London, Ontario, Canada d Cayuga Hand Therapy PT, Ithaca, NY, USA e School of Physiotherapy, University of Western Ontario, London, Ontario, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 April 2013 Received in revised form 18 February 2014 Accepted 1 March 2014 Available online xxx
Study design: Longitudinal clinical measurement study. Introduction: The push-off test (POT) is a novel and simple measure of upper extremity weight-bearing that can be measured with a grip dynamometer. There are no published studies on the validity and reliability of the POT. The relationship between upper extremity self-report activity/participation and impairment measures remain an unexplored realm. Purpose: The primary purpose of this study is to estimate the intra and inter-rater reliability and construct validity of the POT. The secondary purpose is to estimate the relationship between upper extremity self-report activity/participation questionnaires and impairment measures. Methods: A convenience sample of 22 patients with wrist or elbow injuries were tested for POT, wrist/ elbow range of motion (ROM), isometric wrist extension strength (WES) and grip strength; and completed two self-report activity/participation questionnaires: Disability of the Arm, Shoulder and the Hand (DASH) and Work Limitations Questionnaire (WLQ-26). POT’s inter and intra-rater reliability and construct validity was tested. Pearson’s correlations were run between the impairment measures and self-report questionnaires to look into the relationship amongst them. Results: The POT demonstrated high inter-rater reliability (ICC affected ¼ 0.97; 95% C.I. 0.93e0.99; ICC unaffected ¼ 0.85; 95% C.I. 0.68e0.94) and intra-rater reliability (ICC affected ¼ 0.96; 95% C.I. 0.92e0.97; ICC unaffected ¼ 0.92; 95% C.I. 0.85e0.97). The POT was correlated moderately with the DASH (r ¼ 0.47; p ¼ 0.03). While examining the relationship between upper extremity self-reported activity/participation questionnaires and impairment measures the strongest correlation was between the DASH and the POT (r ¼ 0.47; p ¼ 0.03) and none of the correlations with the other physical impairment measures reached significance. At-work disability demonstrated insignificant correlations with physical impairments. Conclusion: The POT test provides a reliable and easily administered quantitative measure of ability to bear the load through an injured arm. Preliminary evidence supports a moderate relationship between loading bearing measured by the POT and upper extremity function measured by the DASH. Level of evidence: 1b Ó 2014 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.
Keywords: Upper limb Weight-bearing Push-off test Reliability Construct validity Impairment measures Self-report measures
Introduction
This study was approved by the Health Sciences Research Ethics Board (HSREB) of the University of Western Ontario in London, Ontario, Canada. No funds were received in support of this study. * Corresponding author. Health and Rehabilitation Sciences, Faculty of Health Sciences, Elborn College, Room 1424, 1201 Western Road, London, ON N6G 1H1, Canada. Tel.: þ1 519 694 6222; fax: þ1 519 646 6049. E-mail addresses: [email protected], [email protected] (J.I. Vincent).
Unlike the lower limb where weight-bearing is a predominant physical requirement for mobility, the need for weight-bearing through the upper limb is intermittent and is more related to stability. However, the importance of weight-bearing in the upper limb is often under-estimated. There are functional tasks such as pushing opening a heavy door, pushing up from a sitting position or moving a heavy object that require upper extremity
0894-1130/$ e see front matter Ó 2014 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jht.2014.03.002
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weight-bearing. In conditions like stroke, spinal cord injury, or lower extremity musculoskeletal disorders the upper limb can assume a greater role in weight-bearing when performing day to day activities.1e3 For instance, nearly half of the body weight is transferred through the upper limb during the use of walker in patients with lower extremity disorders.4 Weight-bearing capacity can also reflect the stability of upper extremity joints since an unstable joint is not suitable for load-bearing. For these reasons, it might be clinically relevant to determine the amount of load that can be tolerated through the upper limb during rehabilitation of upper extremity injuries. The distal radio-ulnar joint (DRUJ) plays a very important role as a weight-bearing mechanism.5 There are various biomechanical studies that have explored the effect of the position of forearm that influences the contact area inside the DRUJ and the amount of force that passes through it. Shabaan and colleagues6 have found that the contact area within the DRUJ was reduced in full pronation and was significantly decreased in extreme supination during axial loading. The same authors have determined that the pattern of loading of the forearm during weight-bearing increases with the loading of the hand; the axial loading was minimum at full pronation and maximum at full supination.7 Also, grip strength was found to be maximum in neutral forearm for men and; supination and neutral forearm for women.8 All the above mentioned factors play an important role in determining the amount of force that goes through the arm and in turn the weight bearing capability of the arm. Ability to tolerate load through the upper extremity may also reflect the joint irritability or pain tolerance in much the same way that the pain free grip test assesses pain in response to loading of muscle.9 The “Press-test” which is used as quick test for the diagnosis of triangular fibrocartilage complex (TFCC) injury has shown to have high sensitivity and specificity.10 However, this test is used only for diagnosis and the results of this test cannot be quantified. Thus, potentially a quantifiable joint loading test might be a useful indicator of weight-bearing ability in bone and joint disorders like wrist and elbow arthritis, TFCC injury, ulnar sided wrist pain, fractures around wrist, elbow and forearm (post-union) and also help in tracking progress during the sub-sequent visits serving as a prognostic tool. Assessment tools for the wrist and elbow have, in the past, focused on obtaining measures of impairment with the assumption that these reflect activity limitations.11 Self-report measures are taking center stage in reporting activity limitations currently. The International Classification of Functioning, Disability and Health (ICF),12 a biopsycho-social model which provides a coherent view of social, individual and biological perspectives of health calls for the examination of the relationships between physical impairments and activity limitations or participation restrictions. It is vital to explore these associations as this information would be of significance when assessing new methods of treatment and validating current and future clinical outcome scoring systems13 and also to enable a better understanding of how one might focus rehabilitation interventions to maximize health. However, these relationships cannot be anticipated, because complex processes that involve personal and environmental factors can interact to determine the overall health impact. This becomes particularly relevant as health care focus shifts toward a broader; more holistic view of optimal functioning that includes body functions, activities and societal participation. When considering the use of a new impairment measure to measure the load bearing capability of the upper limb, the value of such a measure is based on established key measurement principles. Fundamental is the reliability of the test. However, it is equally important to establish the relationship between any new measure
and other health indicators that are used to reflect the upper extremity impairment or activity/participation like self-report questionnaires, so that it is clear to what extent the new measure provides unique information. The push-off test (POT) was developed by one of the authors (SM) to measure the weight bearing through the upper limb using methods and tools feasible for clinical practice. It is a simple and easy test that does not require any extra equipment other than the grip dynamometer which is routinely used in hand clinics. A grip dynamometer was adapted by reversing the handle to perform this test (the details of the test are described later in this paper). There are no published studies on the validity and reliability of the POT. There is also an ongoing debate on the relationship between selfreport activity/participation measures and impairment measures e whether they complement each other and provide similar information or do they tap into different constructs of the same problem. Purpose The primary purpose of this study was to analyze the inter-rater reliability, intra-rater reliability and construct validity of the pushoff test (POT). The secondary purpose is to estimate the relationship between upper extremity self-report activity limitation/participation restriction questionnaires and impairment measures. Methods Subjects Twenty-six subjects were identified by convenience sampling from the Roth-McFarlane Hand and Upper Limb Center, London ON, Canada. Potential subjects who were undergoing treatment at the center were initially identified through a search of medical records. Patients were included as study participants if they satisfied the following criteria: 1) Attending the center with wrist or elbow problems 2) Between the ages of 18 and 65 years (adult working population) The exclusion criteria included: 1) Pathologies affecting both arms 2) Shoulder pathologies affecting upper extremity function 3) Contraindicated for medical reasons including co-morbidity or status of presenting condition 4) Unable to comprehend/read questionnaires. Two of the 26 participants were excluded following discovery of a concurrent shoulder injury. One other participant was found to have a fracture of the wrist that had not healed and another participant was unable to complete the testing due to alternate time commitments. Finally, twenty-two participants (male:female e 15:7; age range 22e61) with wrist or elbow injuries (wrist:elbow e 12:10) such as fractures and soft tissue injuries (mean post-injury period 32 weeks) were included in the study (see Table 1). Informed consent was obtained prior to inclusion in the study and their rights were protected. Of the 22 patients who participated in the study, four did not complete the WLQ-26 due to unemployment, and one participant failed to properly complete the questionnaire. Procedure Study design: Longitudinal clinical measurement study.
J.I. Vincent et al. / Journal of Hand Therapy xxx (2014) 1e6 Table 1 Patient characteristics
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Table 2 Inter-rater reliability of the push-off test
Characteristic
Values
POT-1 vs POT-2
ICC
95% confidence interval
Subjects (n) Male/female (n) Average age in years Age range Average post-injury period
22 15:7 42 22e61 years 32 weeks
Affected extremity Unaffected extremity
0.97 0.85
0.93e0.99 0.68e0.94
n (%) Dominant hand affected Yes No Injured joint Wrist Elbow Received PT treatment Yes No Currently working Yes No
10 12 12 10 17 5 16 6
Upon obtaining patient consent to proceed, subjects were invited to the clinical outcomes research laboratory at the center, where they underwent an initial assessment. A self-report comorbidity questionnaire14 and a comprehensive baseline information form were also completed to ensure no serious medical complications or co-morbidities were present prior to testing. Physical impairment tests namely POT, wrist/elbow active range of motion (AROM), isometric wrist extension strength (WES) and grip strength were performed bilaterally, with the unaffected arm serving as a normative comparison. Prior to subject testing, the order of all physical tests was randomized to reduce potential sources of bias. One of three evaluators was randomly assigned the role of primary tester of all physical impairments. Another evaluator was randomly assigned the role of secondary tester for the POT to maintain blinding of impairment scores. For all physical tests, a standardized protocol was used and recordings made in triplicate. The average of three trials was used as the criterion measure for all the impairment tests. Subjects were given instruction and demonstration of the test, as well as an initial submaximal trial in order to familiarize the subject with the test. Subjects also performed the POT a second time with a randomly assigned second evaluator; this was to provide data to determine the inter-rater reliability of this new load-bearing test. Patients were also asked to complete two self-report activity limitation/participation restriction questionnaires, the Disability of the Arm, Shoulder and the Hand (DASH)15 and Work Limitations Questionnaire (WLQ-26).16 The data from these questionnaires would aid in examining the construct validity of the POT and also the relationship between the upper extremity self-report activity limitation/participation restriction questionnaires and impairment measures.
The test arm is positioned approximately in 10 e40 shoulder extension and 10 e40 elbow flexion. Hand/wrist and forearm are placed in comfortable patient self-determined position. Dynamometer set-up: Handle set in the second position (3.8 cm), and reversed so that the convex side of the handle faces upwards. Stabilization: Dynamometer placed on a stable, non-slip surface. The assessor provides additional stabilizing support of the dynamometer against the table to prevent slipping during test performance. Test procedure: Test instructions are similar as those suggested by the American Society of Hand Therapists17 and Mathiowetz18 for grip strength protocols, except substituting “push” for “grip”. A 30second rest period was incorporated between trials and the average of three trials was taken.19 The test involves having subject’s weight-bear through a grip dynamometer until they have applied their maximum tolerable loading (Fig. 1). Wrist AROM: A composite score was taken to determine the arc of movement within the planes of wrist movement. Therefore, maximal sagittal AROM for the wrist was calculated in degrees as maximum flexion from neutral combined with maximum wrist extension from neutral. The two arcs of movement for the wrist were flexion/extension (sagittal) and radial/ulnar deviation (frontal). For both measurements, the participant was seated in a straight-back chair with a table set in front. Goniometer placement for measurement of both arcs of movements was consistent with published standards.20 Elbow AROM: A composite score was also derived for elbow arcs of movements similar to the method as described for wrist AROM. The arcs of movement consisted of flexion/extension (sagittal) and pronation/supination (transverse). Elbow flexion/extension AROM was measured in the seated position in accordance with clinical practice.20 Elbow pronation/supination AROM was measured using the distal forearm method, which has been shown to provide reliable scores using either a traditional goniometer or the NK device used in this study.21 Isometric wrist extension strength: Patients were placed in the seated position as described previously. The J-Tech handheld
Outcome measures Physical impairment measures “Push Off” test (POT): This new functional test determines the amount of pressure that an individual can place through an injured upper extremity. A grip dynamometer is adapted by reversing the handle so that the convex side points upward allowing for upper extremity loading to be applied with the palm cupped on the bar. The protocol for the “push-off” test (Table 2) was developed by one of the paper authors (SM). Testing position: Subject positioned at a 74e76 cm high table, buttocks leaning against the table but not sitting upon the table.
Fig. 1. The Push-off test.
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dynamometer was used.1 The hand/wrist was placed over the edge of the table, where it was free from AROM restrictions. A “break test” protocol with the instruction, “Hold, don’t let me move you,” was used while the evaluator matched the force of the patient until a movement was created. The evaluator released the held position within 7 s to avoid fatigue of the muscles. Static grip strength: This was measured according to a standardized methodology as described by the American Society of Hand Therapists (ASHT).17,22 The J-Tech grip dynamometer handle was set to the second position (3.8 cm) and patients were instructed to exert maximal effort. A standardized rest period of 30seconds was incorporated to discourage fatigue between trials.19 This protocol has been shown to provide high reliability with the NK device.22
reliability; 0.26e0.49 ¼ low reliability and 0.00e0.25 ¼ little, if any, reliability.33 Construct validity: Construct validity was assessed by using Pearson’s correlation coefficient (r) to examine correlations between the POT and self-report activity/participation questionnaires. Pearson’s correlation coefficients were interpreted as follows: 0.90e1 ¼ very strong correlation; 0.70e0.89 ¼ strong correlation; 0.40e0.69 ¼ moderate correlation; 0.20e0.39 ¼ weak correlation; and 0.00e0.19 ¼ very weak correlation.34 The relationship between upper-extremity self-report activity limitation/participation restriction questionnaires and impairment measures was also examined using the Pearson’s correlations obtained and were interpreted in a manner similar to construct validity.
Self-report activity/participation measures DASH: The DASH is a 30-item self-report measure designed to measure upper extremity disability.15,23 Twenty-one items address function, while the remaining nine items examine symptoms and social participation related to upper extremity pathology.23 This questionnaire has been demonstrated to be valid and responsive in patients with proximal and distal disorders, and is therefore useful for the entire upper extremity.23e26 The English version of the DASH questionnaire was used for this study. WLQ-26: The WLQ-26 is a self-report scale that measures the degree to which chronic health problems interfere with the ability to perform job roles and affect worker-productivity.16,27,28 The content and format of the WLQ-26 originated from focus groups, cognitive interviews, and alternate forms comparison.16 It has four sub-scales, time or scheduling demands, physical work demands, mental work demands, and interpersonal demands. It has been found to be valid, reliable and responsive for use among several different job tasks, both service and manual, and chronic condition groups.16,27,29,30 The WLQ-26 responses are interpreted as the approximate percentage of time in the previous 4 weeks that a person was limited in performing a specific class of job demands.16
Results
Data analysis The original formula [(sum of items 30)/1.2] of the DASH was used to score the questionnaire (no missing items). Four different subscales of the WLQ-26 were calculated by summing relevant items and deriving a percentage score. For both questionnaires, a higher score denoted greater dysfunction whereas a lower score represented less dysfunction. Physical differences between patients were controlled for by representing the physical impairment as a percentage of the patient’s unaffected side (deficit score).31 Statistical analysis Data entry, quality checking and analysis (reliability and construct validity) were performed using the SPSS software. The level of statistical significance was set at p < 0.05. Reliability: Inter-rater reliability and intra-rater reliability of the POT were determined by using a two-way mixed effect model that calculated a single intra-class correlation coefficient (ICC type 2, 1) and their associated 95% confidence intervals (95%CI).32 The ICC values ranges from 0 to 1; 1 ¼ perfect reliability, 0.90e0.99 ¼ very high reliability; 0.70e0.89 ¼ high reliability; 0.50e0.69 ¼ moderate
1 J-Tech Medical Industries, 4314 Zevex Park Lane, Salt Lake City, UT, USA, 84123, www.jtechmed.com.
Reliability of the POT The POT showed high inter-rater reliability (see Table 2) (ICC affected ¼ 0.97; 95% C.I. 0.93e0.99; ICC unaffected ¼ 0.85; 95% C.I. 0.68e0.94) and intra-rater reliability (see Table 3) (ICC affected ¼ 0.96; 95% C.I. 0.92e0.97; ICC unaffected ¼ 0.92; 95% C.I. 0.85e0.97). Construct validity of the POT The POT had a significant moderate correlation with the DASH (r ¼ 0.47; p ¼ 0.03) (see Table 4). It exhibited correlations that were not significant with the four subscales of the WLQ-26 (r ¼ 0.32 to 0.41; NS). Relationship amongst self-report activity limitation/participation restriction questionnaires and physical impairment measures The WLQ-26 sub-scales demonstrated very low to moderate correlations with physical impairments with only 4 out of the 24 correlations being significant (see Table 4). The subscales of WLQ did not exhibit any significant correlations with the DASH (r ¼ 0.17e0.33; NS) (see Table 5). The only physical impairment measure with which the DASH had a significant correlation was the POT (r ¼ 0.47; p ¼ 0.03). Discussion This study provided preliminary support for the newly described “POT” impairment test that assess upper extremity loading, establishing appropriate levels of inter-rater reliability, intra-rater reliability and construct validity. The POT demonstrated a moderate relationship to upper extremity disability indicating that the test is relevant to measure disability but that it also provides information that is different than provided by self-report. The POT is a novel impairment measure reflecting the loadbearing capacity through the upper extremity. Grip dynamometers are typically available in hand clinics to test grip strength, the use of the same instrument to conduct additional testing presents a
Table 3 Intra-rater reliability of the Push-off test Measure Rater Rater Rater Rater
e e e e
1 1 2 2
Affected Unaffected Affected Unaffected
ICC
95% confidence interval
0.95 0.92 0.97 0.93
0.90e0.98 0.84e0.96 0.94e0.99 0.86e0.97
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Table 4 Correlation between self-report questionnaires and physical impairment measures
WES deficit Grip strength deficit Total ROM deficit Composite wrist ROM deficit Composite elbow ROM deficit “Push-off” deficit
DASH
Time demands
Mental demands
Interpersonal demands
Physical demands
0.41 0.22 0.30 0.13 0.37 0.47*
0.25 0.27 0.50* 0.32 0.53* 0.41
0.22 0.27 0.44 0.26 0.47 0.32
0.14 0.29 0.38 0.26 0.38 0.32
0.37 0.52* 0.46 0.27 0.49* 0.38
*Significant at the 0.05 level.
viable approach to measurement of load bearing capacity in clinical practice. The POT is easy to administer with consistent instructions as it uses a protocol that is similar to the American Society of Hand Therapists17 and Mathiowetz grip strength protocols18 which are commonly used in routine clinical practice. Hence, we expect that this test to be accessible and quickly adaptable with minimal training required for implementation. Unlike the “Press test”10 which is used as a simple diagnostic test for TFCC, the POT has the potential of serving not only as a diagnostic test and but also as an outcome assessment tool for use during follow-up sessions to chart improvement from treatment. POT has the markings of a diagnostic and prognostic tool to assess the load bearing capability of the upper limb in musculoskeletal disorders around the wrist and elbow which need to be explored further. Outcome measures should be tested for stability and reproducibility of outcomes between raters and within raters before being used in clinical practice.35 One of the most fundamental measurement properties is reliability, since providing consistent stable measurements in the absence of change is a prerequisite to other measurement properties. Despite, the small sample the reliability coefficients were high for both intra-and inter-rater reliability and the confidence intervals indicated good precision on these estimates (except for inter-tester reliability on the unaffected side). The POT is an impairment measure that may be affected by multiple physical variables such as pain or pain tolerance, joint stability or control. This may explain why it was more strongly correlated with the upper extremity function (DASH) while not demonstrating significant correlations with physical impairment indicators. The observation that physical impairments did not significantly correlate to at work disability (WL-26) was not unexpected since multiple work, worker and workplace factors contribute to at-work disability. Further, the DASH measures function on a scale where everyone responds to the same items; and has been correlating to impairment in previous studies.36,37 Conversely, the WLQ-26, measures difficulty at-work; difficulty in tasks that would vary across individuals and as such not all people are measuring on the same metric across comparisons. Our findings were affected by our small sample. Some of the correlations that were in the moderate range were not statistically significant, which is unlikely to occur in larger samples. Further, a smaller sample provides less precise estimates of effects. This study
Table 5 Correlation between DASH and subscales of the WLQ-26 WLQ-26 subscales
Pearson correlation
Physical demands Mental demands Time demands Interpersonal demands
0.33 0.32 0.31 0.17
describes a new test and measurement properties estimates, and although promising, the findings should be considered as preliminary. We advise that multiple independent studies are needed to verify the reliability and validity of this test in other samples. It is important to see whether the test can be applied to a range of patients. Since we expect the POT to provide information about joint status that is related to function, exploration of how it relates to different functional tests and to imaging of joint damage is needed to indicate test validity. Since it can be readily performed in clinic with commonly available grip devices, clinician-scientists are encouraged to test its usefulness in larger sample sizes and to report additional data on aspects of validity like the convergent validity, divergent validity, and responsiveness. Unlike the POT, other impairment measures did not relate to function. The lack of correlation between the DASH and grip strength deficit obtained in this study does not correspond with results from previous studies. Roumen et al38 found a significant correlation between grip strength and hand function in elderly patients with Colle’s fracture. Tremayne et al11 also found strong and significant correlations between grip strength and the tasks of the Jebsen Test of Hand Function (JTHF) in patients with fracture of the distal radius. This may indicate differences in the measures used in these studies or differences in the populations tested. Similarly, wrist extension strength deficit again did not correlate significantly with the DASH. Since this impairment is rarely reported in the literature, we found little comparative data. Since this study included different upper extremity disorders, variations in individual patients’ conditions may have attenuated the observed relationships between specific impairments and self-reported disability. The physical demands subscale of the WLQ-26 correlated moderately with grip strength deficit and composite elbow ROM deficit. This corresponds with previous studies suggesting that grip strength and function are related11,38 and affirms the common clinical usage of grip strength as an important outcome measurement tool, particularly in work related assessments. Grip strength deficit, however, did not significantly correlate with any of the other WLQ-26 subscales. Composite elbow ROM deficit’s significant moderate correlation to the physical demands subscale illustrates the elbow’s important role in helping position the hand in space while performing functional activities at work. For example, tasks such as answering a phone, reaching to the ground, or placing files or objects on a shelf, all require a substantial arc of elbow flexion and extension. The mental demands or interpersonal demands subscales of the WLQ-26 did not achieve significant correlation with any of the impairment measures. While this might appear intuitive, it has been shown that physical and mental burdens share co-variation.39 Patients whose physical capacity did not allow them to complete work activities in a timely fashion might experience mental demands or interpersonal demands as a result. While the time demands subscale’s significant moderate correlations with the composite elbow ROM deficit and total ROM deficit underscores the
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importance of upper extremity joint ROM especially the elbow in performing functional tasks in a timely manner. The strengths of the current study are, the broad spectrum of wrist and elbow disorder participants that were included in the study which increases generalizability and that reliability of our measures was supported. Our study also had limitations including the small sample size. Post-hoc power analyses indicated that 40 patients would be appropriate to provide precise estimates. Although 22 subjects completed all physical tests and the DASH, only 17 subjects fully completed the WLQ-26. Thus, correlations between the WLQ-26 and the physical tests or the DASH may be less stable. Use of a table with a standardized height is a limitation of the test which could affect the outcome in people of varying heights. We recommend the use of a height adjustable table to solve this issue in future studies. Finally, since this study was of shorter follow-up, we did not examine responsiveness. Future clinical and research recommendations Further research is required to define the “push-off” test as a useful diagnostic and assessment tool. The next wave of validation research should include studies on specific health conditions that might exhibit joint loading derangements such as arthritis or contexts where “loading” might be particularly relevant. Studies of POT as a prognostic measure and comparative responsiveness require longitudinal studies. Conclusion This developmental study determined that a load-bearing test (POT) could be performed reliably by a variety of patients with elbow and wrist disorders. Preliminary evidence suggests that the POT is moderately related to self-reported function; but, also provided unique information suggesting a useful role in the assessment “toolbox” of hand therapists. Caution should be exercised while interpreting these results keeping in mind the low sample size. The study provides further indication that impairments cannot accurately predict patient function and should be considered as moderately associated, but distinct, health constructs. References 1. Harvey LA, Crosbie J. Weight bearing through flexed upper limbs in quadriplegics with paralyzed triceps brachii muscles. Spinal Cord. 1999;37(11): 780e785. 2. Opila KA, Nicol AC, Paul JP. Upper limb loadings of gait with crutches. J Biomech Eng. 1987;109(4):285e290. 3. Reistetter T, Abreu B, Bear-Lehman J, Ottenbacher K. Unilateral and bilateral upper extremity weight-bearing effect on upper extremity impairment and functional performance after brain injury. Occup Ther Int. 2009;16(3e4): 218e231. 4. McQuade KJ, Finley M, Oliveira AS. Upper extremity joint stresses during walker assisted ambulation in post-surgical patients. Rev Bras Fisioter. 2011;15(4):332e337. 5. Shaaban H, Giakas G, Bolton M, Williams R, Scheker LR, Lees VC. The distal radioulnar joint as a load-bearing mechanismea biomechanical study. J Hand Surg Am. 2004;29(1):85e95. 6. Shaaban H, Giakas G, Bolton M, et al. Contact area inside the distal radioulnar joint: effect of axial loading and position of the forearm. Clin Biomech (Bristol, Avon). 2007;22(3):313e318. http://dx.doi.org/10.1016/j.clinbiomech.2006.05.010. 7. Shaaban H, Giakas G, Bolton M, et al. The load-bearing characteristics of the forearm: pattern of axial and bending force transmitted through ulna and radius. J Hand Surg Br. 2006;31(3):274e279. http://dx.doi.org/10.1016/ j.jhsb.2005.12.009. 8. De Smet L, Tirez B, Stappaerts K. Effect of forearm rotation on grip strength. Acta Orthop Belg. 1998;64(4):360e362. 9. Tarhan S, Ünlü Z, Ovalı GY, Pabus¸çu Y. Value of ultrasonography on diagnosis and assessment of pain and grip strength in patients with lateral epicondylitis. Turk J Rheumatol. 2009;24(3):123e130.
10. Lester B, Halbrecht J, Levy IM, Gaudinez R. “Press test” for office diagnosis of triangular fibrocartilage complex tears of the wrist. Ann Plast Surg. 1995;35(1): 41e45. 11. Tremayne A, Taylor N, Mcburney H, Baskus K. Correlation of impairment and activity limitation after wrist fracture. Physiother Res Int. 2002;7(2):90e99. 12. World Health Organization. Towards a common language for functioning, disability and health ICF. http://www.who.int/classifications/icf/training/icf beginnersguide.pdf; Updated 2002 Accessed 09.10.11. 13. Karnezis IA, Fragkiadakis EG. Association between objective clinical variables and patient-rated disability of the wrist. J Bone Joint Surg Br. 2002;84(7): 967e970. 14. Sangha O, Stucki G, Liang MH, Fossel AH, Katz JN. The self-administered comorbidity questionnaire: a new method to assess comorbidity for clinical and health services research. Arthritis Rheum. 2003;49(2):156e163. 15. Solway S, Beaton DE, McConnell S, Bombardier C. The DASH Outcome Measure User’s Manual. 2nd ed. Toronto: Institute for Work & Health; 2002. 16. Lerner D, Amick 3rd BC, Rogers WH, Malspeis S, Bungay K, Cynn D. The work limitations questionnaire. Med Care. 2001;39(1):72e85. 17. Fess EE, Moran CA. Grip strength. In: Casonova JS, ed. Clinical Assessment Recommendations. vol. 2. Chicago: American Society of Hand Therapists; 1992. 18. Mathiowetz V. Grip and Pinch Strength Measurements. In: Amundsen LR, ed. Muscle Strength Testing: Instrumented and Non-instrumented Systems. NewYork: Churchill Livingstone; 1990. 19. Mathiowetz V. Effects of three trials on grip and pinch strength measurements. J Hand Ther. 1990;3(4):195e198. 20. Hazel MC. Musculoskeletal Assessment: Joint Range of Motion and Manual Muscle Strength. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2000:432. 21. Armstrong AD, MacDermid JC, Chinchalkar S, Stevens RS, King GJ. Reliability of range-of-motion measurement in the elbow and forearm. J Shoulder Elbow Surg. 1998;7(6):573e580. 22. MacDermid JC, Alyafi T, Richards RS. Test-retest reliability of static and endurance grip strength tests performed on the jamar and NK. Physiother Can. 2001;53:48e54. 23. Beaton DE, Katz JN, Fossel AH, Wright JG, Tarasuk V, Bombardier C. Measuring the whole or the parts? Validity, reliability, and responsiveness of the disabilities of the arm, shoulder and hand outcome measure in different regions of the upper extremity. J Hand Ther. 2001;14(2):128e146. 24. MacDermid JC. Outcome evaluation in patients with elbow pathology: Issues in instrument development and evaluation. J Hand Ther. 2001;14(2):105e114. 25. Vincent JI, Macdermid JC, King GJ, Grewal R. Validity and sensitivity to change of patient-reported pain and disability measures for elbow pathologies. J Orthop Sports Phys Ther. 2013;43(4):263e274. http://dx.doi.org/10.2519/jospt.2013.4029. 26. Turchin DC, Beaton DE, Richards RR. Validity of observer-based aggregate scoring systems as descriptors of elbow pain, function, and disability. J Bone Joint Surg Am. 1998;80(2):154e162. 27. Lerner D, Amick 3rd BC, Lee JC, et al. Relationship of employee-reported work limitations to work productivity. Med Care. 2003;41(5):649e659. http:// dx.doi.org/10.1097/01.MLR.0000062551.76504.A9. 28. Roy JS, MacDermid JC, Amick 3rd BC, et al. Validity and responsiveness of presenteeism scales in chronic work-related upper-extremity disorders. Phys Ther. 2011;91(2):254e266. http://dx.doi.org/10.2522/ptj.20090274. 29. Roy JS, Desmeules F, MacDermid JC. Psychometric properties of presenteeism scales for musculoskeletal disorders: a systematic review. J Rehabil Med. 2011;43(1):23e31. http://dx.doi.org/10.2340/16501977-0643. 30. Beaton DE, Tang K, Gignac MA, et al. Reliability, validity, and responsiveness of five at-work productivity measures in patients with rheumatoid arthritis or osteoarthritis. Arthritis Care Res (Hoboken). 2010;62(1):28e37. http:// dx.doi.org/10.1002/acr.20011. 31. Petersen P, Petrick M, Connor H, Conklin D. Grip strength and hand dominance: challenging the 10% rule. Am J Occup Ther. 1989;43(7):444e447. http:// dx.doi.org/10.5014/ajot.43.7.444. 32. Deyo RA, Diehr P, Patrick DL. Reproducibility and responsiveness of health status measures. statistics and strategies for evaluation. Control Clin Trials. 1991;12(4 suppl):142Se158S. 33. Portney L, Watkins M. Foundation of Clinical Research: Applications to Practice. Upper Saddle River, NJ: Prentice-Hall; 2000. 34. Fowler J, Chevannes M, Jarvis P. Practical Statistics for Nursing and Health Care. New York; Chichester: Wiley; 2002:213. 35. Fess EE. The need for reliability and validity in hand assessment instruments. J Hand Surg. 1986;11(5):621e623. 36. Adams J, Burridge J, Mullee M, Hammond A, Cooper C. Correlation between upper limb functional ability and structural hand impairment in an early rheumatoid population. Clin Rehabil. 2004;18(4):405e413. 37. Mink van der Molen AB, Ettema AM, Hovius SE. Outcome of hand trauma: the hand injury severity scoring system (HISS) and subsequent impairment and disability. J Hand Surg Br. 2003;28(4):295e299. 38. Roumen RM, Hesp WL, Bruggink ED. Unstable colles’ fractures in elderly patients. A randomised trial of external fixation for redisplacement. J Bone Joint Surg Br. 1991;73(2):307e311. 39. MacDonald LA, Karasek RA, Punnett L, Scharf T. Covariation between workplace physical and psychosocial stressors: evidence and implications for occupational health research and prevention. Ergonomics. 2001;44(7):696e718. http://dx.doi.org/10.1080/00140130119943.
