📑
Chapter Summary
• Context: The thoracic spine occupies a distinct position in spine surgery because it combines a relatively rigid skeletal segment with intimate anatomical relationships with the spinal cord, great vessels, pleura, lungs, heart, trachea, esophagus, thoracic duct, and autonomic chains. Its 12 vertebrae exhibit progressive anatomical changes from T1 to T12 in the morphology, width, and sagittal angle of the pedicles, transverse processes, lamina, and facet joints. Additionally, the rib cage restricts multiaxial mobility, provides visceral protection, and dictates surgical exposure. Pathologies affecting this region include adult and pediatric deformities, traumatic fractures, primary neoplasms, metastatic epidural spinal cord compression, spondylodiscitis, and thoracic disc herniations. Selecting between posterior, posterolateral (costotransversectomy, lateral extracavitary), anterolateral (transthoracic, video-assisted thoracoscopic surgery [VATS]), retropleural, or thoracoabdominal corridors depends on vertebral level, pathology epicenter, adjacent visceral/vascular structures, and previous surgeries. Thorough imaging, precise intraoperative level verification, and vascular planning (including the artery of Adamkiewicz) are paramount for preventing neurological and cardiopulmonary complications.
• Chapter Objective: To present the vertebral, muscular, vascular, neural, pleuropulmonary, and diaphragmatic surgical anatomy relevant to the primary approaches to the thoracic spine. By the end, the reader should be able to recognize morphological variations from T1 to T12; correlate disease pathology with the optimal surgical corridor; understand the anatomical principles of posterior, posterolateral, anterolateral, and thoracoabdominal approaches; and identify critical neurovascular hazards and prevention strategies.
• Vertebral Anatomy and Regional BiomechanicsThoracic vertebrae articulate with ribs via costovertebral and costotransverse joints. From T1 to T12, transverse processes shorten, pedicle height and width increase, and pedicle convergence changes: at T1, pedicles converge significantly toward the midline; by T12, pedicles become nearly sagittal. Thoracic pedicles are significantly narrower than lumbar pedicles and possess a thicker medial cortex, increasing the risk of lateral wall breach and thoracic wall/visceral injury. Facet joints are coronally oriented from T1 to T10, transitioning to a sagittal/oblique orientation at T11–T12. The rib cage makes this the most rigid segment of the spine, where axial rotation decreases and lateral bending/flexion increases caudally. Normal thoracic kyphosis ranges from 20° to 50° (Cobb angle). Global sagittal alignment parameters include sagittal vertical axis (SVA < 5 cm normal), T1 pelvic angle (TPA 10°–15° in adults 40–65 years, 15°–25° over 65 years), and pelvic tilt. Surgical correction of hyperkyphosis requires careful multi-level osteotomies to prevent acute cord tethering.
• Adjacent Structures and Vascular PlanningIn anterolateral and lateral exposures, the surgeon must negotiate the pleura, lungs, heart, esophagus, thoracic duct, sympathetic trunk, and splanchnic nerves. The aorta, inferior vena cava, segmental intercostal vessels, and the great radiculomedullary artery (artery of Adamkiewicz, typically arising between T9 and T12 on the left in 75% of individuals) dictate the choice of surgical side and vascular clipping. The aortic arch restricts left-sided exposure at T3–T4, whereas the thoracic duct ascends on the right and crosses to the left at T5.
• Posterior and Posterolateral ApproachesThe posterior midline approach provides access to all thoracic levels for decompression, tumor resection, fracture reduction, and posterior instrumentation. The patient is positioned prone with the abdomen free to decrease epidural venous engorgement, and the operative level is confirmed by intraoperative fluoroscopy or navigation. Subperiosteal dissection minimizes hemorrhage and preserves facet capsules. Costotransversectomy and lateral extracavitary approaches provide access to the anterior column (vertebral body and disc) and spinal canal through a single dorsal incision without deliberately entering the pleural cavity. Meticulous subperiosteal rib resection, neurovascular bundle identification, prevertebral fascial preservation, and temporary stabilizing rod placement during corpectomy ensure structural and neurological safety.
• Anterolateral and Transthoracic ApproachesT1–T3 can be accessed via an anterior low cervical approach with or without manubriotomy/sternotomy; T3–T4 via transaxillary or high thoracotomy; and T2–T11 via standard anterolateral thoracotomy or VATS. Generally, a left-sided thoracotomy is preferred to avoid the liver and inferior vena cava, though a right-sided approach is indicated at T3–T4 to avoid the aortic arch. In scoliosis, the approach is chosen on the convex side. Double-lumen endotracheal intubation allows single-lung ventilation and controlled lung deflation for visualization.
• Thoracolumbar Junction CorridorsThe thoracoabdominal approach is utilized for T9–L5 lesions, preferably on the left side. At the T11–L2 transition, the retropleural, retroperitoneal, and retrodiaphragmatic corridors provide access without traversing peritoneal contents. Detaching costal insertions and arcuate ligaments allows anterior mobilization of the diaphragm, connecting the retropleural and retroperitoneal spaces. Preserving a 1.5–2 cm peripheral diaphragmatic cuff facilitates airtight, watertight repair. T11–T12 is typically exposed retropleurally, T12–L2 retroperitoneally, and T12–L1 retrodiaphragmatically.
• Clinical Application: Surgical approach selection must match the epicenter of the pathology: dorsal lesions are addressed via posterior laminectomy, laminoplasty, or transpedicular decompression; ventral pathologies require costotransversectomy, lateral extracavitary, or anterior transthoracic corpectomy; and circumferential disease requires combined or wide posterolateral resection. Pure laminectomy is contraindicated for central ventral calcified disc herniations or anterior vertebral tumors because it necessitates excessive spinal cord traction. Preoperative CT and MRI angiography map segmental vasculature and identify the origin of the artery of Adamkiewicz. Intraoperatively, radiopaque marking and intraoperative imaging avoid wrong-level surgery. Maintaining the abdomen free reduces bleeding from Batson plexus. Pleural tears must be repaired or drained with a chest tube, and diaphragmatic tears closed hermetically to prevent post-traumatic diaphragmatic herniation. Primary risks include spinal cord ischemia/injury, intercostal neuralgia, pneumothorax, hemothorax, chylothorax, pleural effusion, and major vascular laceration.
