Anatomical assessment of iliac crest graft size for anterior spondylodesis

Standard procedure for monosegmental anterior spondylodesis often combines anterior stabilization with autologous iliac crest graft. Recent publications defined a minimum size of the graft as a technical specification for this procedure. The cross sectional area of the graft to be transplanted should be at least 23.9% of the cross sectional area of the vertebral bodies to be fused. We investigated whether the required minimum size of autologous graft, as identified both experimentally and clinically, is compatible with the anatomical conditions in central european patients. Computed tomography scans (n = 348) of polytraumatized patients were obtained in the course of initial diagnosis. The scans were evaluated for vertebral body size and the possible size of autologous bone graft in the region of the anterior superior iliac crest. The evaluation of 348 CT scans demonstrated that 95% of the quantified iliac crest grafts would achieve the size recommended for anterior spinal fusion between T10 and T12. In 90% of all cases the planned iliac crest graft exceeded the size limit of 23,9% between concerning the endplates T10 and L2. In 85% the planned iliac crest graft exceeded the size limit of 23,9% between T10 and L3. The recommendation to take this value into account for monosegmental anterior spondylodesis should gain in importance in clinical practice.