New England Spine Care

DEFINITION

Sacroiliacs (SI) are a pair of joints which are part of the pelvis. Sacroiliac joint is the connection between the sacrum and ilium. Sacrum is part of the spine and ilium creates the socket for the hip joint. This joint is smooth at birth and its anatomy changes with age, the surfaces of the joint becomes rough which gives more stability to the joint. There are number of ligaments that stabilizes this joint. It has a minor degree of motion when transitioning from sitting to standing, walking, running and climbing stairs. When sitting, body weight is transferred to the front of the pelvis through the sacroiliac joints. When standing, body weight is transferred through the sacroiliac joints to the hips and the legs. So, throughout life, whether standing or sitting, or at any point when you are weight bearing, this joint is working hard.

 

A portion of the sacroiliac joint is a synovial type. In general, synovial type joints do degenerate with age, could be subjected to trauma or be part of rheumatological disorders. As a result, sacroiliac joints can be a source of pain. Approximately 1 out of every 4 cases of back pain is emanating from the sacroiliac joints. Sacroiliac pain and dysfunction is more common in females which seems to be related to hormonal changes throughout life. Sacroiliac joint is a common source of back, buttock and leg pain in mid to late pregnancy, commonly known as “sciatica of pregnancy”. Sacroiliitis is a sacroiliac disorder in rheumatological disorder (ankylosing spondylitis) which is more common in male. In patients with scoliosis, pelvic obliquity, and in individuals with leg length discrepancy, the prevalence of sacroiliac related back pain is higher.

 

Also, prevalence of sacroiliac pain is higher in individuals who have knee, ankle or foot pain (or had surgery) and are limping or are using crutches or walking boots. Pain associated with the sacroiliac joint is often in the lower back, and the buttock, and the groin and can refer down to the leg. Often pain radiates behind the thigh. Some patients describe lower leg pain as well. It is not associated with numbness or tingling. Intensity and characteristics of the pain could vary from patient to patient. It could be anywhere between mild to severe pain, infrequent to steady and constant. Patients report pain in sitting position, transitioning from sitting to standing and vice versa, and getting in and out of cars. Often pain improves with lying down. Bending, twisting, standing, stairs, carrying items all could exacerbate pain related to sacroiliac joint. Patients often complain about stiffness in the lower back especially after getting up and trying to walk around. Groin pain is a common characteristic of sacroiliac joint but this symptom is also shared with other conditions including hip arthritis.

DIAGNOSIS

It is rather difficult to accurately diagnose sacroiliac pain. A comprehensive physical exam combined with basic x-rays and targeted sacroiliac injections can help diagnose sacroiliac dysfunction. In case of sacroiliitis, laboratory tests can accurately identify ankylosing spondylitis. In general, MRI is not as helpful to diagnose sacroiliac dysfunction by exception of sacroiliitis in ankylosing spondylitis or in rare cases of infection. Often, when the cause of back pain is not clear, patient's do end up having an MRI primarily to identify herniated discs or spinal stenosis that can cause back pain as well.