[The role of a systematic preoperative MRI before lumbar fusion in the prevention of transitional segment alterations].

Sacro-lumbar fusion must be carefully planned: to avoid alterations of the adjacent motion segments. This is a retrospective study to evaluate the fate of transitional segments at mid and long-term. The aim was to discuss the value of systematic preoperative MRI before spine fusion. The study group comprises 68 patients who sustained a lumbar or sacro-lumbar fusion for degenerative discopathy or spondylolysis with spondylolisthesis between January 2000 and December 2005. The preoperative evaluation included standard radiographs and MRI. Postoperative follow-up averaged 51 months and ranged from 6 to 121 months. 72% of the patients had no clinical or radiological complications, 18% developed mild lesions such as a moderate disk space narrowing or osteophyte formation and only 10% developed a significant adjacent motion segment alteration. The risk of degeneration increased with age, female sex, length of fusion and when the indication for fusion was a degenerative pathology. Compared with other studies, this work reports few true adjacent motion segment alterations because preoperative MRI allowed a better selection of the future adjacent segment.