Functional vs Structural Leg Length Discrepancy: The Difference That Changes Your Plan

Step Rite Shoe Lifts

A structural difference means the bones are different lengths. A functional difference means the bones match but a tilted pelvis, a tight hip, or a fused ankle makes one leg act shorter. A clinician tells them apart with an exam and a standing X-ray, and prescribes a lift when leveling the shoe helps.

Structural

Born with it, a childhood growth plate injury, a fracture that healed short, or a joint replacement that lengthened one side. The difference is in the bone and it stays. The lift stays with it.

Functional

The bones match. Something above or below them tilts the body: a pelvis that rotated, a hip capsule that tightened, an ankle that fused in a position that shortens the leg. Some of these respond to therapy. Some get a lift anyway, because leveling the shoe is the fastest way to stop the pain while the rest is worked on.

What changes for you

The number on the order form, and whether it may change later. A structural lift is usually a fixed number for years. A functional lift may be revised as therapy progresses, and the lift height on a shoe we built can be raised or lowered when it does.