A patient's posterior superior iliac spines are at the same height as the anterior superior iliac spines. Which of the following tests would be MOST appropriate for further investigation of this finding?

• A. Measurement of leg length
• B. Muscle length testing of the hip flexors
• C. Muscle length testing of the hamstring muscles
• D. Measurement of lumbar flexion range of motion

Answer: (B)

Understanding pelvic alignment and how hip muscle length influences it is key here. The hip flexors, especially the iliopsoas, cross the hip joint and attach toward the lower spine. If these muscles are tight, they tend to pull the pelvis into anterior tilt, which can increase lumbar lordosis and alter how the pelvis sits, even if the pelvis appears level when the person is standing. Testing the length of the hip flexors directly assesses this potential limitation and helps determine whether tight hip flexors are contributing to functional pelvic changes.

This makes hip flexor length testing the most informative next step. Other tests—like measuring leg length, checking hamstring length, or assessing lumbar flexion ROM—don’t target the specific issue of whether shortened hip flexors are influencing pelvic position as directly or as meaningfully.