The sacroiliac joint (Figure1) is the joint that connects the spine to the pelvis. It can be found between the sacrum, (the triangular-shaped bone in the lower portion of the spine) and the ilium of the pelvis. Joining these bones together are strong ligaments.
Unlike other joints in the body, the sacroiliac joint does not have much movement. However, it is essential in transferring the load of your upper body to your lower body. In other words, weight bearing forces go through the sacroiliac joint and acetabulum. Injury to this area affects the weight bearing ability of the joints. Its motion is a combination of rotation, tilting and sliding.
However, the sacroiliac joint may only slide a couple of millimeters and may tilt and rotate only three or four degrees.
Sacroiliac joint pain is a very common problem and one of the more common causes of low back pain. This type of pain is focused in the lower portion of the back and hip and may radiate out to the buttocks and lower back. In addition, it may radiate down the legs or around to the front, in the groin area. Pain is often worse withstanding and walking and improves with lying down.
When depending on the history and the clinical examination alone, it may be difficult to differentiate between sacroiliac joint pain and other sources of low back pain.
Examination of the sacroiliac joint usually begins with a physician conducting a Faber test. During this test, a physician forces external rotation of the affected hip in the supine position which causes pain in the sacroiliac joint. In addition, there would be tenderness over the sacroiliac joint.
According to Dreyfuss et al, however, sacroiliac joint pain was resistant to identification by 12 clinical examination tests that were standardized against a confirmatory test of intra articular injection.
There are many causes of sacroiliac joint pain including dislocation, sacroiliitis, sacroiliac joint dysfunction, and conditions that alter normal walking patterns. First, sacroiliac pain may be caused by subluxation of the joint. A slightly causes displaced sacroiliac joint places excess stress on the ligaments that hold it together.
Second, sacroiliac joint pain may be caused by sacroiliitis. This is an inflammation of one or both of the sacroiliac joints. It is characterized by pain or stiffness in the lower back, pain that radiates down the leg, decreased range of motion, or pain that worsens when walking or standing.
Another cause of sacroiliac joint pain may be sacroiliac joint dysfunction. This type of sacroiliac joint pain differs from sacroiliitis because its origin is a disruption in the normal movement of the joint. This could either be the result of either too much or too little movement in the joint. When the cartilage is damaged or worn away, bones begin to rub on each other and degenerative arthritis occurs. This is typically the most common cause of sacroiliac joint dysfunction. However, pregnancy may be a cause of sacroiliac joint dysfunction in women. During pregnancy, hormones are released that allow the ligaments to relax. This relaxation of the ligaments holding the SI joints together allows for increased motion of the joints and can lead to increased and abnormal wear on the sacroiliac joint.
Lastly, sacroiliac joint pain may be caused by conditions that alter your normal walking pattern. These conditions include: leg length discrepancy; pain in the hip, knee, ankle or foot; and pregnancy.
While there are a number of ways to determine SI joint pain, the most accurate way is to perform a diagnostic injection of the joint. This type of injection may be done in the office or more accurately using x-ray guidance with a fluoroscope. Once the doctor places a needle in the joint, an anesthetic is injected into the joint to numb the joint. If your pain goes away with the anesthetic, it can be gathered the pain you are experiencing is coming from the SI joint. In a study conducted here, 90 percent of patients that had a CT guided sacroiliac joint injection had sacroiliac joint pain confirmed by the injection.
Treatment for SI joint pain can range from conservative to surgical. First, doctors may suggest conservative measures such as rest, anti-inflammatory medication, phy
sical therapy, and a sacroiliac belt to hold the SI joint together to ease the pain. If these conservative measures are unsuccessful, a series of cortisone injections may be used to reduce the inflammation in and around the joint. If these tactics are unsuccessful, doctors may use one of two surgical approaches: radiofrequency ablation or fusion. Sacroiliac joint pain does remain a diagnostic and therapeutic challenge. In a study conducted here, CT scans were negative in 42 percent of symptomatic sacroiliac joints with a positive sacroiliac joint injection test (Figure2).
Once it has been determined the pain is originating from the SI joint, doctors may perform a procedure called radiofrequency ablation. During this procedure, the nerves that provide sensation to the joint are burned with a needle called a radiofrequency probe. This eliminates sensation from the joint, making it essentially numb. This procedure is a temporary solution, although it can be repeated. The other surgical option available for sacroiliac joint pain is fusion (Figure3).
During this procedure, the articular cartilage from both ends of the Sacroiliac’s bone is removed. The two bones are held together with plates and screws until they fuse into one bone. This will stop the motion between the bones, thus eliminating pain from the joint.