19.1 Preprocedure Planning

Posterior osteotomies of the spine and vertebral column resection (VCR) are technically demanding surgical procedures that allow for significant correction of spinal deformity. Vertebrectomy as a surgical technique for scoliosis was originally described in the early twentieth century, ¹ though more recent techniques began to appear in the literature in the 1970s and 1980s. ^{2 ,​ 3 ,​ 4} The benefit of these techniques is that a circumferential approach to complex three-dimension deformities allows for better control and improved correction. Pedicle screw and rod constructs have provided for increased stability and the ability to manipulate these deformities, and throughout the 1990s these osteotomy techniques became more widespread in pediatric and adult patients. ^{5 ,​ 6} The Ponte-type procedure consists of posterior column disruption via segmental osteotomies, while VCR involves complete resection of the anterior vertebral body, both of which are accomplished via a posterior-only approach. ^{7 ,​ 8 ,​ 9 ,​ 10 ,​ 11} In fact, we typically perform all VCR procedures with Ponte osteotomies (POs) as the initial phase of the surgery, which has obviated the requirement for traditional anterior and posterior approaches and provides complete access to the spinal column and spinal cord during the disarticulation process of deformity correction. ¹² Most important to note, however, is that these types of severe deformity-correction procedures are technically demanding and are typically performed only by experienced surgical teams. ^{7 ,​ 13} The risk of neurologic compromise and injury is very high, related to both the types of spinal deformities undergoing correction and the complete instability of the spinal column inherent with posterior-column osteotomies and VCR. ^{3 ,​ 9} Appropriate patient selection, thorough preoperative planning, and comprehensive postoperative management protocols are of utmost importance for successful utilization of POs and VCR procedures. Every patient being considered for surgical management of severe spinal deformity must be counseled for the risk of catastrophic complications, and the operating surgeon must be vigilant in preparation for the procedure.

Unique considerations for preoperative planning in patients with neuromuscular scoliosis must also be included in the preprocedural period. ^{9 ,​ 14 ,​ 15} Proximal muscle weakness and spasticity often lead to development of progressive, severe scoliotic deformities that limit function and lead to sitting discomfort. ¹⁴ The goal of surgical intervention in this population therefore has less to do with correction of limited coronal or sagittal deformities, but rather to restore the sitting balance of the patient and minimize the risk of development of pressure sores, or for relief of positional difficulties. For particularly severe deformities in neuromuscular patients requiring restoration of sitting balance, VCR allows for the most significant correction. ¹⁴ However, it cannot be overstated that the rate of complications in these patients is also higher than other patient populations, typically due to the high rate of associated comorbidities in patients with neuromuscular scoliosis. ^{9 ,​ 14 ,​ 15} The potential for significant intraoperative blood loss is high with the highest mean percent blood loss typically occurring in patients with higher magnitude coronal and sagittal corrections required. ¹⁴ Strategies to minimize surgical time and blood loss are highly important, and it is recommended that various antifibrinolytics be utilized to aid in decreasing overall operative loss. We currently recommend tranexamic acid (TXA) as our intraoperative antifibrinolytic. We administer TXA at a 100 mg/kg loading dose, with a 10 mg/kg maintenance dose throughout the case. Anecdotally, we believe that doing so decreases blood loss 25 to 50% intraoperatively. ¹⁶

19.2 Setup

With the advent of posterior-only techniques like the PO and VCR, intraoperative repositioning is no longer required. Therefore, initial prone positioning on a standard radiolucent orthopaedic table is sufficient for the case. Fluoroscopy is utilized throughout the case. Generally, cranial tongs are placed in the operating room to provide traction if the type and nature of the deformity necessitate doing so; keeping the face and eyes free but the base of the skull anchored in place allows for control of the proximal deformity during correction and protects the face from significant pressure in the prone position. The abdomen hangs free and the arms remain abducted and externally rotated unless contractures do not permit doing so. It is not uncommon for the positioning of the patient to be time-consuming, given the severity of these spinal deformities, but proper positioning can minimize the occurrence of skin injuries or brachial plexopathies and is important for patient safety. When performing complex deformity reduction such as VCR, we employ POs at the periapical region to improve flexibility and exposure of the resection level; thus, any discussion of VCR mandates discussion of the PO technique.

19.3 Surgical Technique and Challenges

Complete subperiosteal dissection to the lateral extent of the transverse processes is performed, including all levels that will be included in the posterior instrumentation construct. Depending on the type of the deformity, often exposure of the convex transverse processes of the apical thoracic vertebrae may require medial rib thoracoplasties. We recommend intraoperative fluoroscopic imaging to properly identify the exposed vertebral levels.