This syndrome is characterized by the acute onset of pain during torsional strain, tenderness over the affected joint, and relief of symptoms by infiltration of the joint with a local anesthetic.
The most frequent causes of low back pain are muscle and ligament strains, disk disease and arthritis. One relatively uncommon disorder sometimes overlooked in the differential diagnosis of low back pain is sacroiliac sprain syndrome.
The sacroiliac joints are among the strongest in the human body. These joints possess a synovial membrane, and they are joined by strong anterior and posterior ligaments. Furthermore, these joints are extremely stable and have very little motion. The joints are, however, susceptible to injuries similar to those incurred in other joints.
Although there is some controversy about whether the sacroiliac sprain syndrome really exists, most clinicians are convinced that it is a true disorder.
Certain situations increase the risk of straining the sacroiliac joints. During pregnancy, the ligaments in the sacroiliac area soften and lengthen. Softening and lengthening of these ligaments may also occur with prolonged bending or lifting and with degenerative arthritis.
In most cases, the mechanism of injury involves the act of straightening up from a stooped position. A postural defect, such as pelvic inclination and/or excessive lumbar lordosis is an associated finding.
Patients with sacroiliac sprain syndrome may or may not have a history of trauma or torsional strain. Frequently, they complain that their symptoms have been present for a relatively long period of time. Pain may be located over the sacroiliac joint, or it may be referred, usually to the groin and the posterior thigh, and less often to the leg.
The pain often intensifies when the patient lies on the affected side. Leg pain may radiate over the lateral aspect of the greater trochanter and down the front of the thigh.
The distribution of pain is not consistent with a nerve root compression syndrome or radiculopathy. Sacroiliac pain is experienced as a dull ache in the bones above the buttock on one side. But because the nerves in that region are not very specific, pain caused by the sacroiliac joint can also be experienced in the groin, back thigh, and lower abdomen.
On physical examination, forward bending is limited and painful when the patient is standing, but improves when the patient is seated. The patient is most comfortable while sitting on the affected buttock. Tenderness is present over the involved sacroiliac joint and may also be found over the buttock or the posterior superior iliac spine. Muscle spasm is a prominent feature. Unlike sciatica, patients with sacroiliac sprain syndrome do not have tenderness in the sciatic notch.
In the acute phase of sacroiliac sprain syndrome, pain may be relieved by bed rest and the application of heat. Nonsteroidal anti-inflammatory drugs are helpful in reducing inflammation. Associated muscle spasm, if present, may be treated with muscle relaxants.
Physical therapy, such as mobilization exercises or manipulation of the sacroiliac joint may be useful. However, manipulation of the sacroiliac joint should be performed only by a physician or physical therapist who is skilled in this technique.
In recalcitrant cases, the affected joint may be injected with a corticosteroid combined with a local anesthetic. Injection of the joint should be performed only by a physician with experience of this technique. As with any ligamentous injury, four to six weeks may be required for healing.
The duration of bed rest is best determined by the patient. Patients are nearly always able to return to work, school or their usual daily routine after a few days or, at most, a few weeks of therapy.