The sacroiliac (SI) joints connect the sacrum (i.e., the triangular bone of the lower spine) to the right and left iliac bones of the pelvis. This joint features a group of very strong ligaments. There is relatively little motion in these joints; however, they support the entire weight of the upper body in the standing position, which means they must be able to sustain a great deal of stress. That stress can wear down the cartilage of the SI joints, leading to sacroiliac joint dysfunction. This condition is characterized by pain in the lower back, hips, groin, and thighs. The pain usually worsens with standing and walking and subsides when the affected person is lying down. The most common cause of sacroiliac joint dysfunction is degenerative arthritis. Other causes include pregnancy (which causes relaxation of the ligaments holding the joints together), leg length discrepancy, or underlying issues with the hips, knees, ankles, or feet. In such cases, sacroiliac joint dysfunction typically improves with treatment of the underlying condition. Other treatments of sacroiliac joint dysfunction may include pain relief injections, administration of oral anti-inflammatory medications and steroids, and participation in a physical therapy program that includes various stretching and stabilization exercises and treatments. If pain still persists following non-surgical treatment, surgery may be considered as an option.