Management of spinal fractures in ankylosing spondylitis

Abstract

Ankylosing spondylitis (AS) is a systemic inflammatory disease of unknown origin. As the spine fuses through ligamentous ossification and syndesmophytosis, rigid hyperkyphosis develops and the spinal column finally becomes severely ankylosed. In AS, spontaneous fusion of the sacroiliac joints and spine occurs due to chronic inflammation leading to initial back pain followed by generalized stiffness of the spine. Due to multilevel bony fusion, long lever arms develop in the spinal column on which forces can act during trauma. Thus, the ankylosed spine is prone to spinal fracture even after trivial trauma, or in some cases with no trauma. It has been reported that patients with AS have a fourfold increased risk of fracture during their lifetime compared with unaffected individuals. The fractures of ankylosed spine often become critical in neurology for patients. At first, the diagnosis of fracture with minimum displacement is extremely difficult, thus a considerable number of patients are misdiagnosed at the first examination. Plain radiographs are inadequate to fully evaluate shearing fractures with minimum displacement. Because of the difficulty of initial diagnosis, delay in diagnosis often occurs. A misdiagnosed fracture may lead to pseudo-arthrosis because mechanical stress is concentrated at the fractured site. Thus, a more detailed examination by CT and/or MRI is recommended at first presentation. Moreover, when spinal fracture occurs in AS patients, mechanical stress is concentrated on the fractured segment by the long lever arms of the ankylosed spinal column. Fractures in the ankylosed spine are often unstable due to the ossification of supportive and elastic soft tissues. Because of these reasons, neurological deficit after fracture is a well-known and feared complication in AS, and that leads to paraplegia or quadriplegia which concerns to the mortality. Therefore, prompt and appropriate treatment of spinal fractures in AS requires early diagnosis and correct choice of treatments. To date, there are no prospective studies comparing conservative and surgical treatments for thoracolumbar spine fracture in AS. However, high complication rates, including nonunion and redislocation, have been reported in cases treated with conservative treatment. Thus, as like our cases presented in this chapter, surgical treatment with long-segment spinal fusion at least three bilateral points of fixation above and below the injury should be considered to obtain a favorable results, though such an invasive procedure has a surgical risk. Otherwise, treatment would be failed, because of insufficient fixation with less-invasive surgery or conservative treatment such as bed rest and bracing. However, in the treatment of ankylosed spine, the more detailed evaluation is needed. © 2013 Nova Science Publishers, Inc.