BIOMECHANICAL STUDIES OF TRANSTHORACIC VERTEBRAL BODY REPLACEMENT WITH AUTOLOGOUS BONE-GRAFTS (FIBULA AND RIB)

Thoracic processes which destroy vertebral bodies leave gaps which usu ally have to be bridged. The aim of our experiments was to find out wh ether rib and fibula grafts are suitable vertebral body substitutes fr om the biomechanical point of view. Therefore, we examined characteris tics of vertebral body/bone graft/vertebral body arrangements under th e influence of pulsating compression forces in a testing machine. The deformation of the rib graft alone was 0.78 mm under a preselected pea k load of 1010 Newton. When the rib graft was placed between two verte bral bodies, the deformation (creeping) was 6 mm under a peak load of 1010 Newton. The deformation of the fibula graft alone was 0.41 mm, an d when placed between vertebral bodies maximally 3 mm. The results of our experiments lead to the conclusion that ribs modified according to our design are prinzipally suitable for vertebral body replacement in the thoracic region as far as primary stress resistance is concerned. Characteristics of these bone grafts in the human body are being foll owed-up.