A Modified Microsurgical Endoscopic-Assisted Transpedicular Corpectomy of the Thoracic Spine Based on Virtual 3-Dimensional Planning

Background and Objective

The main difficulties of transpedicular corpectomies are lack of space for vertebral body replacement in the neighborhood of critical structures, the necessity for sacrifice of nerve roots in the thoracic spine. and the extent of hemorrhage due to venous epidural bleeding. We present a modified technique of transpedicular corpectomy by using an endoscopic-assisted microsurgical technique performed through a single posterior approach. A 3-dimensional (3D) preoperative reconstruction could be helpful in the planning for this complex anatomic region.

Methods

Surface and volume 3D reconstruction were performed by Amira or the Dextroscope. The clinical experience of this study includes 7 cases, 2 with an unstable burst fracture and 5 with metastatic destructive vertebral body disease, all with significant retropulsion and obstruction of the spinal canal. We performed a comparison with a conventional cohort of transpedicular thoracic corpectomies.

Results

Qualitative parameters of the 3D virtual reality planning included degree of bone removal and distance from critical structures such as myelon and implant diameter. Parameters were met in each case, with demonstration of optimal positioning of the implant without neurological complications. In all patients, the endoscope was a significant help in identifying the origins of active bleeding, residual tumor, extent of bone removal, facilitating cage insertion in a minimally invasive way, and helping to avoid root sacrifice on both sides.

Conclusions

Microsurgical endoscopic-assisted transpedicular corpectomy may prove valuable in enhancing the safety of corpectomy in destructive vertebral body disease. The 3D virtual anatomic model greatly facilitated the preoperative planning.

Introduction

The destructive metastatic thoracolumbar spine disease can be treated in different ways. During the past decades, many surgical techniques of reconstruction and stabilization have been described involving anterior,1, 2, 3, 4 posterior, or both approaches.5, 6, 7 The combined posterior-anterior approach for thoracolumbar corpectomy and stabilization is an established procedure for surgical treatment of destructive metastatic thoracolumbar spine disease.6, 7 The main disadvantage of these procedures is directly related to the morbidity of the approach. Transpedicular corpectomy is an alternative to dorsoventral combined surgery for vertebral body replacement as a result of destructive thoracolumbar vertebral body disease.8, 9, 10, 11 The transpedicular approach provides a wider exposure of the posterior and lateral portion of the dura than strictly anterior approaches, but the outcome of this treatment is greatly affected by tumor extent, with long-term follow-up results remaining unknown. Various complications were reported including intraoperative complications, immediate postoperative complications, and neurological deterioration. The overall complication rate in the literature is from 9.5%–21.,4%,¹² including postoperative morbidity and mortality rates due to the primary tumor disease.¹³

Although efforts were devoted to ensure safety and efficacy, the possibility of damage to important vessels, such the great radicular artery of Adamkiewicz, remains. An endoscopic-assisted approach may allow access to deep structures through a less invasive approach, thereby decreasing morbidity and making difficult pathology surgically more accessible. Although endoscopic techniques have been used as an adjunct to conventional approaches for procedures, such as thoracic discectomy, transthroracic transpleural vertebrectomies, and intradural tumor resection, this is the first report of an endoscopic-assisted approach for a dorsolateral, transpedicular route. In this article, we report a modified technique of transpedicular corpectomy by using an endoscopic-assisted biportal approach to ensure a safe corpectomy, better management of hemorrhage from the epidural space. and better visualization of deep and midline structures. This strategy also avoids sacrificing both nerve roots for vertebral and tumor resection and subsequent vertebral body replacement. In addition, the incorporation of 3-dimensional (3D) preoperative planning enabled safe corpectomy and facilitated cage insertion.