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World J Orthop. Oct 18, 2018; 9(10): 185-189
Published online Oct 18, 2018. doi: 10.5312/wjo.v9.i10.185
Intra-operative computed tomography guided navigation for pediatric pelvic instrumentation: A technique guide
Jason B Anari, Patrick J Cahill, John M Flynn, David A Spiegel, Keith D Baldwin
Jason B Anari, Patrick J Cahill, John M Flynn, David A Spiegel, Keith D Baldwin, Department of Orthopaedic Surgery, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, United States
Author contributions: Anari JB contributed to primary manuscript preparation; Cahill PJ, Flynn JM and Spiegel DA contributed to manuscript review, contributed patients; Baldwin KD contributed to secondary manuscript preparation, contributed patients.
Conflict-of-interest statement: The authors have no conflicts-of-interest to disclose that are pertinent to this article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Keith D Baldwin, MD, Assistant Professor, Department of Orthopaedic Surgery, Children’s Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, United States. baldwink@email.chop.edu
Telephone: +1-856-4040635 Fax: +1-215-5907861
Received: July 2, 2018
Peer-review started: July 2, 2018
First decision: July 19, 2018
Revised: July 29, 2018
Accepted: August 4, 2018
Article in press: August 5, 2018
Published online: October 18, 2018
Abstract

Pelvic instrumentation for neuromuscular scoliosis has been part of neuromuscular scoliosis surgery since the era of the Luque Galveston construct. Unit Rod (Medtronic Sofamor-Danek, Nashville, TN) instrumentation brought with it the concept of cantilever correction by placing the implants in the pelvis and then gradually bringing the rod to the spine by sequentially tightening the sublaminar wires, with the goal of creating a level pelvis over a straight spine. More recently surgeons have utilized pedicle screw constructs in which the corrective strategies have varied. Challenges with pelvic fixation using iliac screws linked to the spinal rod have led to the development of the S2-alar-iliac technique (S2AI) in which the spinal rod connects to the pelvic screw. The screw is placed in the S2 ala, crosses the sacro-iliac joint and into the ilium through a large column of supra-acetabular bone. This column is the same area used for anterior inferior iliac spine external fixation frames used in trauma surgery. S2AI screw placement can be technically difficult and can require experienced radiology technologists to provide the appropriate views. Additionally, although the technique was originally described being placed via freehand technique with intra-operative flouroscopy, the freehand technique suffers from the anatomic anomalies present in the pelvis in neuromuscular scoliosis. As such, we prefer to place them using intra-operative navigation for all pediatric spinal deformity cases. Below in detail we report our intra-operative technique and an illustrative case example.

Keywords: Posterior instrumentation, Pediatric, Spinal deformity, Image guidance, Technique

Core tip: S2-alar-iliac technique (S2AI) screws are used commonly in 2018 in posterior spinal fusion surgery when a fusion to the pelvis is indicated. The benefits of this instrumentation choice are well known; and now with 3D technology surgeons can safely place S2AI screws reproducibly even in aberrant pediatric anatomy.