Evaluation of disc degeneration adjacent to AOspine A fractures: pre- and post-operative MRI analysis.

Introduction: The management of type A thoracolumbar fractures varies from conservative treatment to multiple level fusion. Indeed, although Magerl defined the type A fracture as a strictly bone injury, several authors suggested associated disc lesions or degeneration after trauma. However, the preservation of mobility of the adjacent discs should be a major issue. This study was conducted to analyze the presence of immediate post-traumatic disc injuries and to know if discs degenerate after receiving treatment.

Methods: We retrospectively reviewed the files of 27 patients with an AOspine A fracture, corresponding to 34 fractures (64 discs) with pre and post-operative MRI (mean follow-up: 32.4 months). Based on Pfirrmann's and Oner's classifications of disc injuries, two observers analyzed independently the type of lesion in the discs adjacent to the fractured vertebra in immediate post-trauma and at the last follow-up.

Results: The immediate post-traumatic analysis according to Pfirrmann's classification found 97% of the cranial adjacent discs and 100% of the caudal discs classified Pfirrmann 3 or less. The analysis on the secondary MRI revealed that 78% of cranial adjacent discs and 88% of caudal adjacent discs still were classified Pfirrmann 3 or less.

Conclusions: Since, the great majority of type A fractures does not cause immediate disc injuries, these fractures are, as described by Magerl, strictly bony injuries. The quality of the body reduction seems to prevent secondary degeneration. These results may encourage surgeons not to perform arthrodesis on type A fractures even for A3 and A4.