The exact and underlying cause of low back or sacroiliac joint pain is one of the most difficult conditions to accurately diagnosis, as that pain can be caused by a host of different diseases and disorders. And the simple fact that lower back pain can spread to other areas of the body makes a diagnosis even more complicated.

The sacroiliac is, basically, the point where the upper and half and lower half of the body meet. And the sacroiliac joint—comprised of two bones—connects the bottom part of the spine to the pelvis, and is the location where weight from the upper to lower body is transferred.

Pain in the lower back may be caused by problems with the spine itself, such as a deterioration of discs (or a ruptured or herniated disc); sciatica in the lumbar region; stenosis (a narrowing of the spinal cavity); cauda equina syndrome (narrowing of the spinal cord); osteoporosis (a weakening of the bones); spondylitis (a “slipped disc”); inflammation of the sacroiliac joint; and simple irregularities in the bones or muscles of the back. And often it’s a combination of different conditions that leads to sacroiliac joint pain. For that reason, the exact cause of the pain can be hidden during physical examinations and image testing.

Sacroiliac joint pain is often the result of an injury, but can also result from arthritis in the joint, problems during pregnancy and difficult births for women and lingering issues from a previous surgery to the lower back. Symptoms may manifest as aching, chronic pain in the lower back, buttocks or groin, and the pain may radiate downward into the legs and feet. Standing for long periods of time or putting weight unevenly on one leg or the other may make sacroiliac joint pain worse, as can prolonged sitting, bending and running.

As with all problems with the spine and back that require a professional diagnosis for treatment, a doctor will consider a patient’s medical history—taking into account normal daily activities, occupation etc.—conduct a physical exam and employ imaging techniques (x-rays, CT scans and MRIs). Occasionally, if an infection in the area is a possibility, the physician may also test a sample of joint fluid. And to complete the diagnosis, it’s common for a doctor to anesthetize the area in order to see if the pain abates.

Once a diagnosis of sacroiliac joint pain in confirmed, the first step in treatment is to order a rest period combined with pain-relieving and anti-inflammatory medications. In order to maintain flexibility and strength in the affected and surrounding areas physical therapy may also be recommended, as may a  “sacroiliac belt” which wraps around and squeezes the hips in an effort to stability the joint. If more intensive treatment is required, the nerves causing the pain may be deadened using radiofrequency denervation or the two bones of the sacroiliac joint may be fused together in a surgical procedure.