#393 Percutaneous Transiliac Approach into L5-S1 for Discectomy and Fusion
MIS Techniques and Outcomes
Poster Presented by: W. Smith
W.D. Smith (1), (2)
G.M. Christian (1)
(1) Western Regional Center for Brain & Spine Surgery, Neurosurgery, Las Vegas, NV, USA
(2) University Medical Center of Southern Nevada, Neurosurgery, Las Vegas, NV, USA
Introduction: Lumbar interbody fusion at any level requires removal of nucleus material and fusion bed preparation with resultant bleeding bone and limited structural damage to the endplate. This is best accomplished with an access that is parallel to the disc space. The minimally invasive far lateral access to the ventral spine utilizing neuromonitoring affords the benefits of an ALIF approach while avoiding catastrophic vascular and visceral complications, as well as eliminating the need for assistance to gain retroperitoneal access. However, the far lateral approach is limited to L4-5 and the levels above due to obstruction by the ilium of a parallel access into L5-¬S1 space. The transiliac approach yields a parallel access into LS-S1 and allows a thorough discectomy and better preparation of the fusion site, while avoiding injury to the exiting nerves of the lumbar plexus and the retroperitoneal vessels.
Methods/technique: Knowledge of the peridiscal vascular and neural anatomy is a prerequisite, along with preoperative planning with a CT scan and intraoperative free run and evoked EMG neuromonitoring. The L5-S1 intervertebral level is targeted 90° off-midline using standard fluoroscopy and skin markings. An incision is made over the iliac bone and a small transiliac dilator is introduced. Over this dilator, a 7mm working portal is delivered to access the lateral aspect of the L5-S1 disc space. A discectomy and fusion preparation is performed using standard minimally invasive instrumentation and practices. An empty expandable device is delivered through the portal into the enucleated disc space and it is subsequently filled with allograft bone, completing the fusion procedure. Supplemental posterior fixation is then applied.
Experience: Of the 118 cases completed by one surgeon from July 2009 to November 2011, there have been 2 incidences of transient nerve palsies. One patient developed a postoperative hematoma that resulted in an L5 motor paresis, which improved by the 3 month postoperative visit. Another patient developed a foot drop that has been slowly improving with therapy and splinting, but permanent weakness is still present after the 12-month post-operative visit. There have been no vascular injuries and no fractures to the ilium as a result of the transiliac approach.
Conclusion: Although knowledge of peridiscal vascular and neural anatomy is a prerequisite, along with preoperative planning and intraoperative neuromonitoring, the transiliac approach into L5-S1 for discectomy and fusion is not a technically demanding procedure that demands a long learning curve.