Uneven hips, often called pelvic asymmetry or leg length discrepancy (LLD), can directly cause back pain. This misalignment occurs when one side of the pelvis is higher than the other, creating an uneven foundation for the spine. Since the body relies on the pelvis for balanced weight distribution, this imbalance introduces mechanical stress to the entire musculoskeletal structure. A measurable asymmetry frequently contributes to chronic lower back discomfort that requires addressing the underlying pelvic tilt.
Structural Versus Functional Unevenness
The causes of uneven hips fall into two distinct categories, which determines the appropriate intervention. Structural unevenness is a fixed difference in the actual bone length of the lower extremities, often called a true leg length discrepancy. This type can result from congenital conditions, a past fracture that healed improperly, or an injury to a growth plate during childhood.
Functional unevenness, in contrast, occurs when the legs are the same length, but soft tissue imbalances make one appear shorter or longer. This apparent discrepancy is typically caused by muscular tension or tightness in the hip flexors, hamstrings, or the quadratus lumborum. Poor posture, scoliosis, or a misalignment of the sacroiliac joint can also cause this acquired asymmetry. Functional unevenness is more responsive to rehabilitation therapies aimed at restoring muscle balance and flexibility.
Biomechanical Link to Spinal Stress
The primary mechanism by which an uneven pelvis leads to back pain is through compensatory realignment of the spine. When the pelvis is tilted, the body naturally attempts to keep the eyes and head level, which forces the spinal column to develop unnatural curves. This compensation often manifests as a mild, acquired form of scoliosis, where the lower and mid-spine curve laterally to offset the pelvic tilt. This lateral curvature creates an asymmetrical distribution of load across the vertebral discs and facet joints.
This constant uneven weight bearing causes chronic muscle strain, particularly in the deep paraspinal muscles and the quadratus lumborum on one side of the lower back. The asymmetrical forces also alter the rotational axis of the sacrum, increasing mechanical stress on the sacroiliac (SI) joint, which connects the spine to the pelvis. Over time, this sustained, uneven loading can lead to inflammation, joint irritation, and the development of chronic low back pain. The imbalance can also affect gait, causing an unequal stride length or weight shift during walking that exacerbates the stress on the kinetic chain.
Diagnostic Methods
A healthcare professional begins the diagnostic process with a physical examination to assess posture and range of motion. They visually inspect the patient’s stance and palpate bony landmarks, such as the iliac crests, to determine if one side is higher than the other. Tests like the Allis test, which compares the relative height of the knees, may also be used to quickly assess potential leg length differences.
To quantify the difference, the clinician may use a tape measure to compare the length from the anterior superior iliac spine to the medial malleolus of the ankle. Another common technique is the “standing on blocks” method, where blocks of known height are placed under the shorter limb to visually level the pelvis. The most definitive way to differentiate between structural and functional causes is through imaging, typically a standing full-length X-ray of the lower extremities and spine, which allows for precise measurement of bone length.
Corrective and Pain Management Strategies
The strategy for managing pain and correcting the unevenness depends on whether the cause is structural or functional. For a confirmed structural leg length discrepancy, the primary conservative treatment is to equalize the length using a shoe insert, orthotic, or heel lift. This external correction aims to restore a level pelvic base, reducing the need for spinal compensation and relieving associated muscle tension. For a significant difference (generally 2 to 5 centimeters), surgical intervention to lengthen the shorter limb or shorten the longer limb may be considered.
Functional unevenness is primarily addressed through targeted physical therapy and exercises aimed at correcting muscle imbalances. This approach focuses on stretching chronically tight muscles, such as the hip flexors and the quadratus lumborum, to restore normal resting length. Simultaneously, strengthening exercises are prescribed to activate weak muscles, particularly the core stabilizers and gluteal muscles. These routines improve pelvic stability, which helps maintain the corrected alignment over time. Other interventions may include chiropractic adjustments or massage therapy to relax tense soft tissues and improve joint mobility. Ergonomic changes, such as avoiding prolonged sitting or carrying uneven loads, are also recommended to prevent the functional asymmetry from recurring.