Patients with low back pain (LBP) have one thing in common: they'd like to know what's causing the pain. Yet doctors are often at a loss to give answers to patients. We do know that two-thirds of all patients have chronic LBP caused by lumbar discs, the small joints on the back of the spinal column (the facet joints), or the sacroiliac (SI) joint.

In this study, physiotherapists and radiologists teamed up to test patients for signs of these three problem areas. The therapists measured pain levels and carried out certain tests known to identify the three areas under study. Patients were given injections based on the therapists' findings.

The placement of the needle helped confirm the diagnosis. Once the needle was in place, a numbing agent was injected. If the patient's pain went away, the test was positive. That means the injected site was considered to be the problem.

The radiologist told the therapist where the pain was coming from. The therapist then reviewed the results of tests given before the injection. They found all patients with SI problems had pain when moving from a sitting to standing position. SI patients rarely had pain above a certain level of the spine. Usually, their pain was only on one side.

Patients with problem discs also had pain when rising from sitting. In addition, they felt pain in the center of the low back after repeated test movements. Patients with facet joint problems never had pain centered in their back. They also never had pain when rising from a seated position.

The authors conclude it is possible to narrow down the diagnosis in LBP. Better classification of LBP can be done by looking at the pain location and pain patterns. The patient's history and the examination offer good clues to point doctors and therapists in the right direction.

Sharon Young, PT, Cert, MDT, et al. Correlation of Clinical Examination Characteristics with Three Sources of Chronic Low Back Pain. In The Spine Journal. November/December 2003. Vol. 3. No. 6. Pp. 460-465.