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World J Orthop. Jun 18, 2017; 8(6): 455-460
Published online Jun 18, 2017. doi: 10.5312/wjo.v8.i6.455
Sternal metastasis - the forgotten column and its effect on thoracic spine stability
Robert Pearse Piggott, Mark Curtin, Sudarshan Munigangaiah, Mutaz Jadaan, John Patrick McCabe, Aiden Devitt
Robert Pearse Piggott, Mark Curtin, Sudarshan Munigangaiah, Mutaz Jadaan, John Patrick McCabe, Aiden Devitt, Department of Trauma and Orthopaedic Surgery, Galway University Hospitals, the West/North West Hospitals Group, HSE, Galway H91 YR71, Ireland
Author contributions: All authors equally contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Conflict-of-interest statement: Regarding the paper entitled “Sternal Metastasis - the forgotten column and its effect on thoracic spine stability”; the authors do not report any conflict of interest.
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: Robert Pearse Piggott, Orthopaedic Specialist Registrar, Department of Trauma and Orthopaedic Surgery, Galway University Hospitals, the West/North West Hospitals Group, HSE, Newcastle Road, Galway H91 YR71, Ireland. robpiggott1@gmail.com
Telephone: +353-091-544000
Received: December 13, 2016
Peer-review started: December 16, 2016
First decision: March 27, 2017
Revised: April 1, 2017
Accepted: April 23, 2017
Article in press: April 24, 2017
Published online: June 18, 2017
Abstract

Sternal metastases are not studied extensively in the literature. There is a paucity of information on their role in metastatic disease. The concept of the fourth column was described by Berg in 1993, and has been proven in case report, clinically and biomechanical studies. The role of the sternum as a support to the thoracic spine is well documented in the trauma patients, but not much is known about its role in cancer patients. This review examines what is known on the role of the fourth column. Following this we have identified two likely scenarios that sternal metastases may impact management: (1) sternal pathological fracture increases the mobility of the semi-rigid thorax with the loss of the biomechanical support of the sternum-rib-thoracic spine complex; and (2) a sternal metastasis increases the risk of fracture, and while being medical treated the thoracic spine should be monitored for acute kyphosis and neurological injury secondarily to the insufficiency of the fourth column.

Keywords: Fourth column, Sternal fracture, Sternal metastasis, Sternal-rib-thoracic spine complex, Spine stability

Core tip: The sternal-rib complex provides additional support to the thoracic spine. The role of sternal fracture affecting the stability of the thoracic spine is well established in trauma, to date however its role in metastatic disease is unclear. Biomechanical studies highlight its importance and the presence of sternal metastasis should be considered when assessing the stability of the thoracic spine in metastatic disease.