External transpedicular fixation test of the lumbar spine correlates with the outcome of subsequent lumbar fusion.

External transpedicular fixation was applied to the lower lumbar spine in a prospective study on 42 patients with chronic low back pain combined with suspected instability of the lumbar segments; the diagnosis was failed disk surgery, spondylolisthesis, and degenerative disk disease. The aim was to realign the involved segments, to restore disk height, and to record changes in pain and performance during the external fixation test. Pain was recorded on a visual analog scale, and performance was assessed using the Oswestry disability score. As independent observer assessed the test and treatment results. Twenty-nine patients experienced relief of pain and performed better in the fixator; they were subjected to anterior interbody fusion, the external frame being kept as a stabilizing device for an additional four months. Twenty-two patients have had follow-up evaluations for two years. One and two years after successful lumbar fusion, significantly (p < 0.02) better pain and performance scores were recorded; the results of lumbar fusion corresponded to the preoperative fixation test. A temporary external fixation test may be a useful procedure in patients considered for subsequent spondylodesis.