Pelvic Girdle

Sacroiliac joint dysfunction occurs when the sacroiliac joints—where the base of the spine meets the iliac bones of the pelvis—move either too much or too little, disrupting normal load transfer between your upper body and legs. It often arises after a fall on the bottom, a sudden twist, leg-length discrepancy or during periods of hormonal change such as pregnancy, which loosen the pelvic ligaments.

It typically presents as a sharp or aching pain low in the back or buttock, often felt on one side, and may radiate into the groin or down the back of the thigh. You might notice discomfort when standing on one leg—such as climbing stairs or stepping into a car—and relief when lying down, along with a sense of stiffness when attempting to bend forward or straighten up.

Pubic symphysis dysfunction, also known as osteitis pubis, is inflammation of the fibrocartilaginous joint uniting the left and right pubic bones. It frequently follows repetitive impact—such as running or kicking sports—or can develop during pregnancy when hormonal changes loosen the ligaments allowing increased joint mobility at the front of the pelvis.

This presents as deep pain in the centre of the groin or lower pelvis, which may spread into the inner thighs and buttocks. Activities that load the pelvis unevenly—like walking, climbing stairs, getting in and out of a car or widening the legs to dress—often provoke a sharp catch, and the area can feel tender when pressing just above the genitals.

Pregnancy-related pelvic girdle pain describes discomfort arising from altered mechanics and ligamentous laxity affecting the sacroiliac joints and pubic symphysis. It typically emerges in the second or third trimester as the body adapts to weight gain, a growing abdomen and shifting centre of gravity.

You’ll notice persistent, dull or sharp pain across the front or back of your pelvis, which may worsen when turning in bed, stepping up or down, rising from a chair or walking. A sensation of catching or grinding as you move your legs apart—such as when climbing stairs or getting dressed—is common, as is difficulty maintaining a stable gait without waddling.

Sacroiliitis is inflammation of one or both sacroiliac joints, often associated with systemic inflammatory conditions such as ankylosing spondylitis or psoriatic arthritis. More often it is caused by mechanical stress, such as lifting, twisting and compensating for a lower spinal disc strain, leading to joint swelling and stiffness.

You’re likely to experience deep, aching pain in the buttock or lower back, which can extend into the groin or posterior or lateral thigh. Symptoms typically worsen after prolonged rest—such as first thing in the morning or after sitting—and improve with gentle activity; you may also notice morning stiffness lasting more than half an hour and discomfort when lying on one side.