Anterior lumbar interbody fusion with threaded fusion cages and autologous bone grafts

The goal of this study was to evaluate the ability of Ray threaded fusion cages, when used in an anterior approach, to restore intervertebral height and to improve the functional and occupational performance of the patients. The present study was initiated because insertion of fusion cages through a posterior approach causes destruction of facet joints and violation of the spinal canal. The anterior approach for insertion of threaded fusion cages to accomplish lumbar interbody fusion was evaluated in a series of 13 patients suffering monosegmental disc disease. The patients' functional and occupational performance was evaluated using the Prolo score. Radiological measurements were used to evaluate disc height and degree of penetration into the endplates, and to confirm fusion. Seven of the 13 patients were short-term failures and had to be revised within 2 years. The study found that revised patients had poorer Prolo scores than non-revised patients. Although for the non-revised patients, the mean Prolo scores remained relatively stable during the 1st year, they dropped after 3 years. We were not able to identify any further clinical or radiological differences between the groups. These results indicate that although the anterior approach seems technically suitable for insertion of threaded fusion cages, destruction of the anterior longitudinal ligament and the anterior part of the annulus fibrosis appears to result in destabilisation of the motion segment.