The examination should include evaluation for nonorganic signs of low back pain. When the patient straightens the knee for the examiner to test quadriceps strength, he is also doing a sitting straight leg raising test. The presence of three or more of these signs correlates well with the absence of anatomic disorder. The history and physical examination usually will lead the clinician to a diagnosis or will indicate further studies to obtain. Complete blood count, sedimentation rate, rheumatologic studies, and chemistry measurements can be helpful when inflammatory or metabolic conditions are suspected.
Bone scans are often helpful when tumor or infection is possible.
Radiographs should be obtained in patients who have not responded to nonoperative treatments or when infection, deformity, or tumor is considered. Axial imaging modalities such as computed tomography or magnetic resonance imaging should be used primarily in patients for whom surgical intervention is likely. Imaging studies should be considered as an anatomic road map in patients with symptoms and signs that would lead to surgical intervention. In general, this means that nonoperative treatments should be tried for an adequate time before considering surgery. Specific indications can be based on the diagnosis encountered.