What is the importance of the spinal canal encroachment in the management of thoracolumbar burst fracture without neurological deficit?

The relevant features in the treatment of thoracolumbar fractures vary in the literature. The classical surgical indications of burst fractures are loss of vertebral body height, kyphosis, neurological deficit and canal encroachment. Recent papers have attributed less importance to canal impingement as a surgical indicator in intact patients, irrespectively of the degree of encroachment. The several thoracolumbar fracture classifications have prompted efforts to guide the surgical indications. We analyzed the relevance attributed to the canal encroachment by thoracolumbar fracture classifications in the management of burst fractures without neurological deficit. Objective: To evaluate the relevance attributed by the thoracolumbar fractures classifications to the canal encroachment in the management of burst fractures without posterior ligamentous complex disruptions or neurological deficits. Methods: A literature search was performed by tracking the related articles of thoracolumbar fractures classifications from Vaccaro’s to Holdsworth’s study. We analyzed the role of canal impingement in the management of burst fractures without posterior ligament complex injury or neurological deficits in each classification. Results: Seven classifications were included. Holdsworth considered the burst fractures as stable, irrespectively of the amount of canal impingement or neurological deficit. Denis considered that the burst fracture carried a neurological instability criterion, therefore, in these cases he suggested surgical treatment because of the risk of new neurological damage. McAffee postulated that there is no reliable predictor to correlate the severity of canal encroachment with the risk of neurological damage. Ferguson and Allen discussed the possibility of anterior decompression, stabilization and anterior fusion of the spine in certain cases of burst fractures. The classifications of McCormack, Karaikovic and Gaines, Magerl and Vaccaro did not include canal encroachment in their considerations. Conclusion: The thoracolumbar fractures classifications did not directly consider the severity of canal encroachment in the treatment decision making of burst fractures without neurological damage. It is not possible to predict which patients will deteriorate if not operated. It remains unclear what is the risk of neurological deterioration in a SCE greater than 50%.