Bony Fusion

Fusion of the lumbar spine with bone grafts is useful in patients with slip progression or persistent pain despite conservative measures. This can be achieved by a variety of methods including anterior interbody, posterior interbody, posterior, or intertransverse fusion. No prospective randomized study has compared these different methods. In an extensive literature review, however, Turner et al. assessed patients who underwent spinal fusion, usually for a herniated disc or spondylolisthesis, and found no statistically significant difference in the clinical outcome attained by each of these methods. Although Turner et al. did find anterior interbody fusions to have a significantly higher rate of pseudoarthrosis, this probably represents a patient selection bias because many surgeons use this approach for more difficult cases. Still, many spinal surgeons may be unfamiliar with the approach required for anterior interbody fusion. In addition, such an approach does not permit simultaneous decompression, and, therefore, anterior interbody fusions are generally avoided. Similarly, posterior fusions make subsequent decompression difficult and need to be extended above the loose L5 posterior element in isthmic spondylolisthesis. Therefore, posterior fusions are also used infrequently. Finally, although excellent results have been reported by some authors using posterior interbody fusion, experience with this technique is limited, and it necessitates removal of the posterior elements and retraction of the cauda equina. Consequently intertransverse fusion, also known as ala-transverse and posterolateral fusion, had gained the widest clinical acceptance in the past.