• Francis H Shen and Dino Samartzis.
• Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908-0159, USA. fhs2g@virginia.edu
• Spine. 2007 Jul 1; 32 (15): E423-7.

Study DesignA case report.ObjectiveTo report the successful nonoperative management of a patient with progressive ankylosing spondylitis who sustained a three-column flexion-distraction injury of the upper thoracic spine with an intact sternal-rib complex, thereby emphasizing the existence and clinical relevance of the fourth-column concept in such patients.Summary Of Background DataThree-column injuries of the cervical and lumbar spine are typically unstable and require surgical stabilization. Patients with ankylosing spondylitis are at an increase risk to sustain three-column injuries of the spine due to their progressive inflammatory disease, a state that renders the spine brittle and alters its biomechanical function. A fourth-column model of the thoracic spine has been proposed and incorporates the sternal-rib complex; however, such a model has rarely been addressed in the literature and its role regarding three-column upper thoracic spine injury with an intact sternal-rib complex in patients with ankylosing spondylitis is unknown. METHODS.: A 68-year-old white man with ankylosing spondylitis and Pickwickian body habitus sustained a three-column flexion-distraction injury at T5 following a ground-level fall. The patient complained of midthoracic back pain; however, he was neurologically intact and ambulated without aids.ResultsBecause of the patient's numerous active medical issues that substantially increased his perioperative risks combined with symptomatic improvement of his pain, the patient refused surgical stabilization. In addition, because of the patient's body habitus and pulmonary issues, external brace immobilization was not tolerated. At 17 months of follow-up, the patient remained neurologically intact, ambulated well, his midthoracic back pain had subsided, and no progressive kyphosis was noted.ConclusionsThis case confirms the existence and clinical relevance of the fourth column of the thoracic spine and its role in providing added spinal stability in the patient with ankylosing spondylitis. As such, it is still possible to achieve a favorable clinical outcome in a select subpopulation of patients with ankylosing spondylitis that sustain three-column flexion-distraction injuries who are neurologically intact and are not candidates for surgical stabilization.

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