The relationship of the size of the footprint of the fibular graft to the surface area of the vertebral endplate in the reconstruction of the anterior column of the spine

Abstract

INTRODUCTION : The anterior column of the spine is often destroyed by trauma, infection or tumours. It is reconstructed by using an autograft, allograft or synthetic cages. The fibular autograft provides good strength, incorporates quickly and has less risk of disease transmission, which is a big advantage in communities with a high incidence of HIV. Various authors cite that its major drawback is the size of its footprint because of the possibility of subsidence. We could not, however, find any literature that measures its size. AIM : To measure the size of the footprint of the fibular graft in relation to the surface area of the vertebral endplate. The clinical relevance is that it may guide the surgeon in deciding how many struts of the fibular graft to use in reconstructing the anterior column, and also quantifies the statement that the fibular strut has a small footprint. MATERIAL AND METHOD : CT angiograms are done frequently for peripheral vascular diseases. These angiograms show CT scan images of the lumbar and thoracic vertebrae, and fibulae of the same patient. We retrospectively examined 60 scans done during the years 2012 and 2013. From the CT scans, we measured the surface area of the endplates of the vertebral bodies of T6, 8, 12, L2, and the surface area of the cut surface of the proximal 10 cm, 20 cm and 30 cm of the fibular graft, all in square millimetres (mm2). We then compared the areas of the vertebral measurements to the area of the fibular graft measurements. RESULTS : The middle third of the fibular graft had the biggest axial surface area. The ratio of the fibular graft surface area to that of the thoracic vertebral endplate is 1:3–6. These ratios suggest that more than one fibular strut graft is required to reconstruct the anterior column in the thoracic spine. CONCLUSION : The results show that the fibular graft is better suited for reconstruction in the upper thoracic spine. Below that more than two struts are required.