Radionuclide bone imaging in patients with low back pain presenting to the orthopaedic surgeon.

This study looks retrospectively at 113 patients with low back pain referred by orthopaedic surgeons for bone scanning. 79 scans (70%) were reported normal and 34 scans (30%) abnormal. 61 out of the 79 patients with normal scans were diagnosed and managed as "chronic back strain". Negative bone scans were also encountered in 3 patients with degenerative disease, 3 with prolapsed intervertebral disc and one with spondylolysis. In those patients with positive scans, a varied range of diagnoses was encountered, the main ones being bone metastases, previous trauma, osteomyelitis and degenerative disease. The scan was shown to be helpful in deciding on the presence or absence of pathology, and in identifying the sites of involvement, but not the nature of the disease. A higher likelihood of positivity is seen in the more elderly patients as well as those below 20 years of age. In interpreting the scan, the clinical context is important e.g. a history of trauma, previous surgery or of malignant disease. The bone scan may be normal in disc prolapse and in degenerative disease of the spine.