THE RELIABILITY AND VALIDITY OF A PASSIVE KNEE EXTENSION TEST FOR ASSESSING THE LENGTH OF THE HAMSTRING MUSCLES. Joyce White; Ross M. Allumbaugh; Shawn M. Ayotte; Julie E. Macan* Physical Therapy, University of Massachusetts Lowell, Lowell, MA PURPOSE: The purpose of this study was to determine the reliability and concurrent validity of a clinically adapted passive knee extension (PKE) test using a universal goniometer and no hip-positioning apparatus. This test is designed to measure the length of the hamstring muscles. BACKGROUNDS/SIGNIFICANCE: There are several clinical tests for indirectly measuring hamstring muscle length described in the literature. Several studies reveal limitations in these common clinical tests of hamstring length, including the straight leg raise (SLR) test and active knee extension (AKE) tests. These studies identify the need for a clinically relevant, reliable and valid PKE test that can be performed without a specifically constructed hip-positioning apparatus. SUBJECTS: Thirty-one healthy subjects, 23 females and 8 males, ranging in age from 21 to 42 years (mean=25 yrs) participated in this study. METHODS AND MATERIALS: With subjects positioned in supine, the right limbs were tested for (1) passive SLR test with the opposite thigh stabilized on the examining table with a strap; (2) PKE test using a wooden apparatus with a cross-bar designed to maintain the hip in 90 degrees of flexion; (3) PKE test with the hip manually maintained in 90 degrees of flexion by an assistant. Knee flexion angles were measured in both PKE tests, while hip flexion angles were measured in the SLR test. A 12-inch, 360 degree universal goniometer was used to obtain all joint angle measurements. The body of the goniometer was covered so that the examiner was blind to the measurement values. Assistants were used to read the goniometer and support the leg as needed during the SLR and PKE tests. Each test was repeated three times by two examiners, so that six measurements were collected per test, for a total of 18 measurements per subject. Test order was randomized and standardized procedures were used throughout the measurement process. ANALYSES: Pearson produce-moment correlation coefficients, intraclass correlation coefficients [ICC (2,1)], and standard error of measurements (SEM) were calculated to quantify intratester and intertester reliability. To examine the concurrent validity of the tests Pearson produce-moment correlation coefficients and dependent t- tests were performed RESULTS: Good intratester reliability was found for each examiner between the three trials for each of the three test (r=.90 to .95; ICC=.83 to .91; SEM=2.3 to 3.2 degrees). Good intertester reliability was also noted (r=.87 to .89; SEM=3.0 to 3.7 degrees). A significant relationship existed between the PKE tests with and without the apparatus (r=.87, p≤.01), between the SLR and the PKE test with the apparatus (r=-.79, p≤.01), and between the SLR and the PKE test without the apparatus (r=-.77, p≤.01). There was no significant difference between the PKE test with the apparatus and the PKE test without the apparatus (t=.612, df=30, p=.55). CONCLUSIONS: The PKE test without a hip-positioning apparatus was found to be valid and reliable. This test could serve as a clinically efficient method for indirectly assessing hamstring length without the disadvantages of other tests. FUNDING SOURCE: No outside funding source. None of the authors have any potential for material gains as a result of the study. This material has not been or will be published or presented at another national or international meeting prior to June 8, 2005. KEYWORDS: hamstring flexibility, hamstring length, Hamstrings, assessment, measurement Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.