Reliability Of Goniometric Techniques For Measuring Hip Flexor Length Using The Modified Thomas Test

The modified Thomas test (MTT) is a method of assessing flexibility of hip musculature, specifically, the iliopsoas, rectus femoris and tensor fascia latae. Current research on the MTT has shown conflicting reliability in testing. Lack of pelvic tilt control during testing could cause inaccurate measures of hip extension range of motion. PURPOSE: This study aims to determine the inter- and intra-rater reliability of the MTT using standard goniometric techniques for assessment of hip flexor length in clinical practice. METHODS: Healthy individuals (n = 65, average age 23.7 years) were recruited to participate in this study. The MTT positions a patient in supine at the edge of the mat table, then one knee is pulled toward the chest. The contralateral leg then hangs off the edge of the table while permitting the measurement of a peak hip extension angle, with a neutral pelvic tilt being maintained. For the purposes of this study, neutral pelvic tilt was enforced with therapist palpation of the lumbar spine to note the decrease of lordosis. Each participant completed the MTT while a researcher used a standard goniometer to measure hip extension range of motion. The goniometer was blinded by a piece of construction paper and read by another researcher. Every participant was measured one time on each leg by an experienced physical therapist, and then moved to another table to be measured by a student physical therapist. This process was repeated a second time, resulting in each therapist obtaining two hip extension measurements for each lower extremity of every subject. Collected data was entered into a Microsoft Excel spreadsheet and quantified using SPSS software. RESULTS: The results revealed that the MTT demonstrated high inter-rater reliability (intra-class correlation coefficient = 0.848), and high intra-rater reliability (intra-class correlation coefficient = 0.921). The average hip extension ROM for the participants was measured as 9.73 +/- 5.43 degrees. The average activity hours was calculated as 5.56 +/- 3.35 hours per week. CONCLUSIONS: The results of this study support the use of the MTT as a reliable measure of hip flexor flexibility among practitioners in clinical practice when enforcing a neutral lumbar spine.