Temporary external transpedicular fixation of the lumbosacral spine: a prospective, longitudinal study in 330 patients.

STUDY DESIGN: In this study, 330 patients with incapacitating low back pain underwent temporary external transpedicular fixation (TETF) of the lumbosacral spine in a prospective trial.

OBJECTIVE: To evaluate TETF as a test for selecting suitable candidates for segmental spinal fusion.

SUMMARY OF BACKGROUND DATA: Few studies regarding TETF have been published, and contradictory results concerning predictive value and morbidity were reported.

METHODS: All patients were tested with the external fixator in two different positions: fixation and nonfixation. Before and during the test and at follow-up examination, pain was assessed on a Visual Analogue Scale (VAS). The TETF test was considered to be positive if the VAS score in the fixation state was 30 or more points lower than in the nonfixation state. Hence, a positive test would imply the decision to perform segmental lumbosacral fusion. When the reduction was less than 30 points, the test was negative. Individual pain reduction and working capacity were taken as measure of outcome.

RESULTS: Most of the patients in this study (62%) underwent spinal surgery previously. The positive and negative TETF groups were quite similar, but a large within-group variation was found. Within the fusion group of 123 patients, improvement in VAS scores and improvement in working capacity were not significantly better for the positive TETF group in comparison with the negative TETF group.

CONCLUSION: In this heterogeneous group of chronic patients with low back pain, TETF of the spine (including a placebo trial) does not appear to be of value in selecting suitable candidates for spinal fusion.