

The Kendall Test aka modified Thomas Test is a common orthopedic test to assess the length of the rectus femoris muscle of the quadriceps.
To perform the test, have your patient in a supine position with both legs off the table. Then ask your patient to bring one knee to the chest and hold it.
The test is positive if the hanging leg does come up and does not remain at 90° flexion. To make sure this happens due to tightness of the rectus femoris, you can palpate additionally.
Of course, both sides need to be tested.
Other common orthopedic tests to assess muscle length around the hip:
Magee, D. J. (2014). Orthopedic physical assessment-E-Book. Elsevier Health Sciences.