What is leg length discrepancy (functional vs anatomical)?

During posture assessment, chiropractors distinguish between two distinct types of leg length differences that affect spinal alignment and pelvic balance.

Anatomical leg length discrepancy occurs when there is an actual structural difference in bone length between the left and right leg. This true length difference is present regardless of posture and typically results from past injury, surgical procedures, or developmental variation. The difference is measurable from fixed bony landmarks and does not change when a patient's position shifts.

Functional leg length discrepancy appears as a leg length difference caused by postural misalignment, muscle tightness, or pelvic tilt rather than by actual bone length variation. When a patient stands or lies in a neutral position, their legs may appear unequal due to hip rotation, sacroiliac joint dysfunction, or muscle imbalance. Unlike anatomical discrepancy, functional differences can shift or resolve with postural correction and soft tissue treatment.

Both types matter during chiropractic assessment because they affect how the spine and pelvis load weight. An anatomical difference may require ongoing compensatory care, while a functional discrepancy often responds to spinal adjustments, muscle work, and postural correction. Identifying which type is present helps chiropractors in the Klang Valley determine the most appropriate treatment approach and whether orthotics or other supports may benefit long-term spinal alignment.