Which landmarks are used to measure leg lengths?

• A. ASIS to medial malleolus
• B. Umbilicus to pubic symphysis
• C. Greater trochanter to lateral malleolus
• D. Medial malleolus to lateral malleolus

Answer: (A)

Measuring leg length discrepancy relies on a fixed pelvic anchor and a distal ankle landmark to capture the entire length of the lower limb. The best choice uses the anterior superior iliac spine as the proximal point and the medial malleolus as the distal point. This pairing follows the entire path of the leg—from hip through knee to ankle—so the measurement reflects true limb length rather than trunk dimensions or regional distances.

Using the ASIS as the proximal landmark provides a stable, bony starting point on the pelvis, while the medial malleolus marks the end of the tibia at the inner ankle. When the patient is lying supine with the leg extended and the pelvis level, a flexible tape measure drawn in a straight line from ASIS to the medial malleolus gives a reproducible estimate of the leg’s functional length.

By contrast, a measurement from the umbilicus to the pubic symphysis is a trunk/torso height measure and doesn’t reflect limb length. A measurement from the greater trochanter to the lateral malleolus could be affected by hip rotation or knee position and doesn’t consistently track true limb length. A measurement from one malleolus to the other assesses ankle width, not overall leg length.