BackgroundPatients undergoing total knee arthroplasty (TKA) often experience strength deficits both pre- and post-operatively. As these deficits may have a direct impact on functional recovery, strength assessment should be performed in this patient population. For these assessments, reliable measurements should be used. This study aimed to determine the inter- and intrarater reliability of hand-held dynamometry (HHD) in measuring isometric knee strength in patients awaiting TKA.MethodsTo determine interrater reliability, 32 patients (81.3% female) were assessed by two examiners. Patients were assessed consecutively by both examiners on the same individual test dates. To determine intrarater reliability, a subgroup (n = 13) was again assessed by the examiners within four weeks of the initial testing procedure. Maximal isometric knee flexor and extensor strength were tested using a modified Citec hand-held dynamometer. Both the affected and unaffected knee were tested. Reliability was assessed using the Intraclass Correlation Coefficient (ICC). In addition, the Standard Error of Measurement (SEM) and the Smallest Detectable Difference (SDD) were used to determine reliability.ResultsIn both the affected and unaffected knee, the inter- and intrarater reliability were good for knee flexors (ICC range 0.76-0.94) and excellent for knee extensors (ICC range 0.92-0.97). However, measurement error was high, displaying SDD ranges between 21.7% and 36.2% for interrater reliability and between 19.0% and 57.5% for intrarater reliability. Overall, measurement error was higher for the knee flexors than for the knee extensors.ConclusionsModified HHD appears to be a reliable strength measure, producing good to excellent ICC values for both inter- and intrarater reliability in a group of TKA patients. High SEM and SDD values, however, indicate high measurement error for individual measures. This study demonstrates that a modified HHD is appropriate to evaluate knee strength changes in TKA patient groups. However, it also demonstrates that modified HHD is not suitable to measure individual strength changes. The use of modified HHD is, therefore, not advised for use in a clinical setting.
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Objectives: To develop an instrument to measure adherence to frequency, intensity, and quality of performance of home-based exercise (HBE) programs recommended by a physical therapist and to evaluate its construct validity and reliability in patients with low back pain. Methods: The Exercise Adherence Scale (EXAS) was developed following a literature search, an expert panel review, and a pilot test. The construct validity of the EXAS was determined based on data from 27 participants through an investigation of the convergent validity between adherence, lack of time to exercise, and lack of motivation to exercise. Associations between adherence, pain, and disability were determined to test divergent validity. The reliability of the EXAS quality of performance score was assessed using video recordings from 50 participants performing four exercises. Results: Correlations between the EXAS and lack of time to exercise, lack of motivation to exercise, pain, and disability were rho = 0.47, rho = 0.48, rho = 0.005, and rho = 0.24, respectively. The intrarater reliability of the quality of performance score was Kappa quadratic weights (Kqw) = 0.87 (95%-CI 0.83–0.92). The interrater reliability was Kqw = 0.36 (95%-CI 0.27–0.45). Conclusions: The EXAS demonstrates acceptable construct validity for the measurement of adherence to HBE programs. Additionally, the EXAS shows excellent intrarater reliability and poor interrater reliability for the quality of performance score and is the first instrument to measure adherence to frequency, intensity, and quality of performance of HBE programs. The EXAS allows researchers and clinicians to better investigate the effects of adherence to HBE programs on the outcomes of interventions and treatments.
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Caregivers of persons with profound intellectual and multiple disabilities (PIMD) often describe the quality of the daily movements of these persons in terms of flexibility or stiffness. Objective outcome measures for flexibility and stiffness are muscle tone or level of spasticity. Two instruments used to grade muscle tone and spasticity are the Modified Ashworth Scale (MAS) and the Modified Tardieu Scale (MTS). To date, however, no research has been performed to determine the psychometric properties of the MAS and MTS in persons with PIMD. Therefore, the purpose of this study was to determine the feasibility, test-retest reliability, and interrater reliability of the MAS and MTS in persons with PIMD. We assessed 35 participants on the MAS and MTS twice, first for the test and second a week later for the retest. Two observers performed the measurements. Feasibility was assessed based on the percentage of successful measurements. Test-retest and interrater reliability were determined by using the Wilcoxon signed rank test, intraclass correlation coefficients (ICC), Spearman's correlation, and either limits of agreement (LOA) or quadratically weighted kappa. The feasibility of the measurements was good, because an acceptable percentage of successful measurements were performed. MAS measurements had substantial to almost perfect quadratically weighted kappa (>0.8) and an acceptable ICC (>0.8) for both inter- and intrarater reliability. However, MTS measurements had insufficient ICCs, Spearman's correlations, and LOAs for both inter- and interrater reliability. Our data indicated that the feasibility of the MAS and MTS for measuring muscle tone in persons with PIMD was good. The MAS had sufficient test-retest and interrater reliability; however, the MTS had an insufficient test-retest and interrater reliability in persons with PIMD. Thus, the MAS may be a good method for evaluating the quality of daily movements in persons with PIMD. Providing test administrators with training and clear instructions will improve test reliability.
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