PURPOSE OF THE STUDY: To evaluate a group of 11 patients with L5 burst fractures treated by L4-S1 posterior instrumented spinal fusion without reconstruction of the anterior column. MATERIAL: The group included seven men and four women aged between 14 and 66 years (average, 37.5 years), followed for 12 to 36 months (average, 18 months). Ten patients were treated by posterior instrumented spinal fusion at the L4-S1 level, and one with an associated injury to L3 underwent L2-L4-S1 posterior instrumented spinal fusion. The spinal column was inspected in eight patients in whom neurological symptoms or significant stenosis were present. METHODS: On admission, the evaluation of post-traumatic radiographs included measurements of the angle between the L4 lower and the S1 upper end-plates, the angle between the upper and lower end-plates of L5 and height of the anterior and posterior rims of the L5 vertebral body. CT scans were assessed for a relative narrowing of the spinal canal. The patient's neurological status was also evaluated. At 3, 6, 12, 24 and 36 months of follow-up, radiographs, neurological findings and subjective complaints were assessed. RESULTS: On comparison of pre-operative values with those 3 months after surgery, the differences were on average 3.6 degrees for L4-S1 lordosis, 2.5 degrees for the angle between the upper and lower end-plates of L5, and 1 mm for the height of the anterior rim; there was no difference in posterior rim height. Eight patients had the same values at the latest as at 3- month follow-up. Three patients with broken screws showed the loss of L4-S1 lordosis by 4 to 13 degrees (average, 9 degrees). Neither the angle between the upper and lower end-plates of L5, nor vertebral body height were changed. The narrowing of the spinal canal by vertebral body fragments ranged from 0 to 60 % (average, 35 %) of canal space. On admission, neurological findings were normal in two patients and involved nerve root syndrome in five patients. In four patients it was not possible to assess their neurological status. At he latest follow-up, ten patients were free from peripheral neurological lesions, one still had lumbar radicular syndrome, two patients reported mild or moderate lumbosacral pain and seven patients were without complaints. Subjective complaints could not be assessed in two patients because of their mental state. An early post-operative complication included wound dehiscence in one patient (9 %) and, in three patients, broken screws in S1 were recorded as late complications. DISCUSSION: Only a few references referring to a relatively low number of patients with L burst fractures treated by surgery were found in the literature. Most of the authors report limitations of reduction and good clinical outcomes. CONCLUSIONS The posterior instrumented spinal fusion of L5 alone is sufficient for the treatment of most L5 burst fractures. Early removal of the fixator is indicated in active patients. Often good clinical outcomes are in contradiction with radiological findings. The possibilities of spinal canal decompression by ligamentotaxis at this level of injury are limited. When significant spinal stenosis is present, laminectomy or hemilaminectomy is necessary to achieve decompression of the spinal canal.