Study design: In this study, 133 patients with incapacitating low back pain underwent temporary external transpedicular fixation of the lumbosacral spine in a prospective trial. Of these patients, 67% had undergone one or more spinal procedures in the past. On the basis of temporary external transpedicular fixation, 55 of 133 patients were treated conservatively. With an average follow-up period of 37 months, the clinical results were analyzed.
Objective: To evaluate temporary external transpedicular fixation as a test for selecting suitable candidates for fusion of the lumbosacral spine.
Summary of background data: The few reports regarding this test are contradictory in terms of predictive value and morbidity. Only three reports include a placebo trial.
Methods: All patients were tested with the external fixator in three different positions: neutral fixation, slight distraction, and nonfixation (bars disconnected). The patient was unaware of the exact position of the external fixator and thus served as his or her own control. Before and during the test and at follow-up examination, pain was assessed on a visual analog scale.
Results: In the group that eventually underwent spinal fusion, the average preoperation visual analog scale score was 77. During test fixation, the average score was 26, in nonfixation 69, and at follow-up after surgery 40. In the control group, these figures were 75, 53, 44, and 71, respectively. As statistical analysis showed, the only factors that could be associated with the improved pain score was the performance of the spinal fusion (P = 0.0001) and the duration of low back pain before the test (P = 0.04).
Conclusion: In selecting suitable candidates for spinal fusion, temporary external transpedicular fixation (including a placebo trial) can be a valuable test.