Thoracic Disc Injuries

Updated: May 30, 2017
  • Author: Kambiz Hannani, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Overview

Background

Thoracic disc injury, first described in 1838, is an uncommon site of injury owing to the stabilizing effect of the rib cage. [1] The similarity of symptoms to lumbar disc herniation makes the diagnosis of a thoracic disc injury difficult, [2, 3, 4, 5, 6] but the process tends to be self-limiting and rarely requires surgical intervention. [4]

(See also the articles Disk Herniation and Thoracic Spine, Trauma [in the Radiology section], Thoracic Discogenic Pain Syndrome [in the Sports Medicine section], Lumbar Disc Disease [in the Neurosurgery section], and Herniated Nucleus Pulposus [in the Orthopedic Surgery section], as well as Return to Contact Sports After Spinal Surgery and Thoracoscopic Spine Surgery for Decompression and Stabilization of the Anterolateral Thoracic and Lumbar Spine on Medscape.)

For patient education resources, see the Bone Health Center, Back, Ribs, Neck, and Head Center, Back, Neck, and Head Injury Center, and Muscle Disorders Center, as well as Back Pain and Chronic Pain.

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Epidemiology

Frequency

United States

The incidence of thoracic disc injuries is 1 in 1 million persons per year, and these injuries account for 0.25-0.75% of all disc herniations. [7]

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Functional Anatomy

The thoracic discs are unusually stable compared with the cervical and lumbar discs. The stability of the thoracic discs is secondary to the surrounding rib cage, with the stabilizing effect of the rib articulations. However, the blood supply of the thoracic spine is more tenuous than the cervical and lumbar spine, especially at the T4-T9 watershed area, which is more prone to ischemic injury.

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Sport-Specific Biomechanics

The facet orientation in the thoracic spine is vertical, with a slight medial angulation. This orientation allows for easier lateral bending and rotation versus pure bending. Biomechanical studies have shown that intervertebral discs are at the highest risk of injury when combined with bending and torsional forces. Therefore, the thoracic spine discs are at a decreased risk of injury because of the decreased bending potential in this segment of the spine.

The spinal cord-to-canal ratio (the ratio of the cross-sectional area of the cord to the cross-sectional area of the spinal canal) is 40% in the thoracic spine versus 25% in the cervical spine. The thoracic spine is also naturally kyphotic. These 2 facts make the thoracic spine more sensitive to cord compression from disc herniation.

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