Buttock Pain May Start in the Sacroiliac Joint

An ache in the lower back or one buttock may come from the sacroiliac joint, the connection between the pelvis and the bottom of the spine. It often feels deep, though motion can make it sharper. Discomfort may also reach the hip, upper leg, or groin. Possible sources include age-related cartilage damage, injury, low-bone-density stress fractures, pregnancy-related ligament changes, and joint inflammation. In some cases, doctors cannot identify a reason.

Twisting, pressure, jumping, and sustained hard running can aggravate the area. Symptoms vary with the cause: movement may provoke a mechanical problem, while inflammation may bring extended stiffness after waking or pain later at night. A clinician usually reviews the symptom pattern and performs several examination maneuvers. Scans or a targeted injection may help locate the painful area.

Physical therapy is commonly the starting treatment. It aims to ease tightness, improve pelvic stability, and strengthen supporting muscles. When tolerable, walking, incline walking, and swimming can build core strength without high impact. Heat or ice for 15–20 minutes and pain medicines such as acetaminophen or nonsteroidal anti-inflammatory drugs may offer relief. More severe or persistent cases may be treated with joint injections or radiofrequency ablation; fusion surgery is rarely used. Medication may be prescribed when an inflammatory disease is responsible.