Graft integration in the lumbar spine of bovine cancellous bone compared to autologous iliac crest in a sheep model

Background: Spinal injuries are common and a standard procedure for the stabilisation of spinal injuries is ventral spondylodesis with an autograft from the iliac crest. Because of the high incidence of harvesting complications there is a need to search for alternative materials. The aim of our study was to evaluate graft integration in the lumbar spine of bovine cancellous bone compared to autologous iliac crest material.

Methods: Two groups of eight female adult sheep (median age 3 years, range 2.4-3.8 years) received surgical treatment in the form of anterior monosegmental spondylodesis. The spondylodesis was performed in all animals in the motion segment L3/4 through a lateral approach with the animals lying on their right sides. To produce serial sections, the explanted vertebral segments were implanted in methyl methacrylate. On one side the histological preparation was examined qualitatively and in addition we analysed the quantity of the bone structure with special software.

Results: The bone structure in both groups did not differ significantly and demonstrated integration of the grafts in the adjacent vertebral bodies. Fractures and lysis occurred in the region of the intervertebral disc and were more frequent in the group with the bovine graft.

Conclusions: The bony integration of the grafts of both groups was not significantly different and showed good results. Almost all of the bovine grafts fractured or presented regions of lysis. In our opinion bovine cancellous bone graft is not a good alternative to autologous iliac crest.