Sacroiliac joint pain may be a result of osteoarthritis, stress fractures, infection, trauma or inflammation, explains NYU Langone Medical Center. It can also be caused by improper twisting, bending or lifting, and weak muscles in the area can exacerbate the likeliness of the pain occurring, as can pregnancy.
When the cartilage covering the bones that makes up the sacroiliac joint becomes worn away or damaged, the result is often osteoarthritis, which is the number one cause of sacroiliac joint pain, according to MedicineNet. Other types of arthritis also cause sacroiliac joint pain, including rheumatoid arthritis and ankylosing spondylitis. In ankylosing spondylitis, inflammation causes severe pain in the sacroiliac joint until eventually, the bones fuse and lose their ability to move. Sacroiliac joint pain may manifest as pain in the lower back, buttocks, hip or thigh.
As hormones in a pregnant woman's body cause her ligaments to relax in preparation for childbirth, sacroiliac joint pain can result. Alterations in a pregnant woman's normal walking patterns can also lead to sacroiliac joint pain, as can any other disturbance to normal walking patterns. Patients who have one leg longer than the other or those who walk in a non-normal fashion due to leg, hip or foot pain are prone to develop sacroiliac joint pain, notes MedicineNet.