Spinal fractures and pseudoarthrosis complicating ankylosing spondylitis: MRI manifestation and clinical significance

Purpose: To analyze magnetic resonance (MR) patterns of fractures and pseud oarthrosis of the ankylosing spondylitic spine, and related changes in the dura and adjacent soft tissue. Materials and Methods: Sixteen patients with radiographically evident fract ures or pseudoarthrosis of the spine were included. Each underwent MR studi es. Ten patients among them underwent surgical operations. Results: Both transdiscal (n = 12) and transvertebral (n = 4) fractures wer e identified. The levels were located from T9 to L3. Five of 16 patients ha d pseudoarthrosis. The fractures or pseudoarthrosis had two patterns: low s ignal on T1- and high signal on T2-weighted images, and low signal on both T1- and T2-weighted images. Disruption of anterior longitudinal ligament (A LL) was identified in 14 patients. Seven patients had vertebral translation , all had disruption of the ALL. Dural adhesions were noted in five patient s and manifested as linear epidural enhancements with triangular blunt edge s. Conclusion: MR patterns of ankylosing spondylitis are important in evaluati ng complications of fractures or pseudoarthrosis, as well as changes in dur a, soft tissue, and ligaments.