Temporary external transpedicular fixation of the lumbosacral spine

Study Design. In this study, 133 patients with incapacitating low back pain underwent temporary external transpedicular fixation of the lumbosacral sp ine in a prospective trial. Of these patients, 67% had undergone one or mor e spinal procedures in the past. On the basis of temporary external transpe dicular fixation, 55 of 133 patients were selected for spinal fusion and th e other 78 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 contrad ictory in terms of predictive value and morbidity. Only three reports inclu de a placebo trial. Methods. All patients were tested with the external fixator in three differ ent positions: neutral fixation, slight distraction, and nonfixation (bars disconnected). The patient was unaware of the exact position of the externa l 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 sca le. Results. In the group that eventually underwent spinal fusion, the average preoperation visual analog scale score was 77. During test fixation, the av erage score was 26, in nonfixation 69, and at follow-up after surgery 40. I n the control group, these figures were 75, 53, 44, and 71, respectively. A s statistical analysis showed, the only factors that could be associated wi th 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 e xternal transpedicular fixation (including a placebo trial) can be a valuab le test.