Achieving 360° fusion in high-grade spondylolisthesis using HMA screws.

Circumferential (360°) fusion yields better long-term outcome in patients with high-grade spondylolisthesis. This result may be achieved by combined anterior and posterior techniques or by an all-posterior approach. As the anterior approach is fraught with numerous complications, many surgeons prefer the all-posterior approach to achieve circumferential fusion. We have described in this chapter the technique of using HMA screws to achieve posterior interbody fusion in situ, to be combined with posterolateral fusion and pedicle screw instrumentation to provide the 360° fusion in high-grade spondylolisthesis. This technique not only provides an increased chance of interbody fusion because of cancellous bone but also avoids the donor site morbidity associated with cortical fibular strut graft.