A lateral pelvic tilt (LPT) is a common postural condition defined by an imbalance where one side of the pelvis is positioned higher or lower than the other side when standing or moving. This misalignment creates an uneven foundation for the spine and the lower limbs, affecting how the body manages weight and movement. The underlying causes of this unevenness are diverse, ranging from fixed anatomical differences to dynamic muscular imbalances and daily habits.
Understanding the Mechanics of the Tilt
The most visible manifestation of LPT is often described as a “hip hike” on one side or a “hip drop” on the opposite side. When standing on one leg, the pelvis should remain level, but LPT occurs when the hip of the unsupported leg drops downward, or the hip of the supported leg elevates.
This lateral shift forces the body to make compensations both above and below the pelvis. The spine typically develops a compensatory lateral curve, sometimes called a functional scoliosis, to keep the head level with the horizon line. Below the pelvis, the leg on the high side may appear shorter, and the leg on the low side may appear longer, leading to uneven pressure distribution through the knees, ankles, and feet.
Anatomical and Skeletal Drivers
Some causes of lateral pelvic tilt are structural, meaning they are fixed differences in the body’s bone structure that are not easily changed by exercise or posture correction. The most distinct of these is a true leg length discrepancy (LLD), where there is an actual, measurable difference in the length of the bones between one leg and the other. This structural difference can result from childhood injuries to the growth plate, congenital conditions, or complications from a severe fracture or bone infection.
A true LLD physically forces the pelvis to tilt, with the hip on the side of the longer leg sitting higher to accommodate the length difference. Fixed spinal deformities, particularly structural scoliosis, can also physically drive a lateral pelvic tilt. Since scoliosis involves a fixed, unnatural lateral curvature of the spine, the pelvis often rotates and tilts to counterbalance the forces generated by the spinal curve.
Functional Causes and Muscular Imbalances
The most frequent drivers of lateral pelvic tilt are functional, stemming from muscle imbalances and habitual asymmetrical postures. Unlike structural causes, these are dynamic and often correctable issues involving how the muscles hold and move the pelvis. A primary functional cause is weakness in the gluteus medius and gluteus minimus muscles, which are the main stabilizers of the pelvis during single-leg activities like walking or running.
If the gluteus medius on the stance leg is weak, it fails to stabilize the pelvis, causing the opposite hip to drop—a movement pattern known as a Trendelenburg gait. The body then recruits other muscles to compensate for this instability.
The quadratus lumborum (QL), a deep muscle in the lower back, often becomes hyperactive or tight on the side where the hip is hiking up. The QL’s function includes side-bending the trunk and elevating the hip, so a tight QL on one side pulls that side of the pelvis upward in an attempt to stabilize the unstable area.
Tightness in the hip flexors, particularly the iliopsoas, can also contribute to the tilt by pulling the pelvis into an imbalanced position. This shortening is often compounded by habitual asymmetrical behaviors that reinforce one-sided muscle tension and weakness. Constantly standing with body weight shifted onto one leg, carrying a heavy bag consistently on one shoulder, or sitting cross-legged with the same leg on top all promote these imbalances. These repetitive postures teach the muscles to function asymmetrically, resulting in a chronic lateral pelvic tilt where some muscles become habitually shortened and others become lengthened and weak.