Volumetric changes of iliac crest autografts used to reconstruct the anterior column in thoracolumbar fractures: a follow-up using CT scans.

STUDY DESIGN

Patients with a thoracolumbar injury had a reconstruction of the anterior column using an tricortical iliac crest autograft. The volume and the length of the autograft were measured after 9 and 21 months using computed tomography.

OBJECTIVE

To assess the volumetric change of an iliac crest autograft used to perform a reconstruction of the anterior column.

SUMMARY OF BACKGROUND DATA

Iliac crest autografts are commonly used to reconstruct the anterior column following spinal fractures. However, very few reports have actually looked into the changes within the autograft following surgery. To our knowledge, no study has actually measured the loss of volume and length taking place within the graft using a CT scan.

METHODS

From January 1995 through May 2000, 27 patients of the 155 operated patients treated with a posterior-anterior stabilization of a fracture within the thoracic and lumbar spine were included in this study. Selection criteria were a postoperative CT and the reconstruction of the anterior column using an iliac crest autograft. A CT scan was performed before instrumentation removal and 1 year after instrumentation removal. These scans were used to evaluate the volume and length of the graft.

RESULTS

There is a significant loss of graft volume (about 40%), half of which was not seen until after instrumentation removal. There is a correlation between the volumetric loss and the initial volume of the graft. The loss in length (24%) results in a correctional loss of the superior-inferior endplate angle totalling 12 degrees. All grafts showed good contact to the adjoining vertebrae with no case of a pseudarthrosis.

CONCLUSION

The results show that more than a third of the initial graft volume is absorbed during the consolidation process. The loss was greater, the larger the volume of the initial graft was. The efficiency, however, was not dependent on the initial graft size.