Pseudarthrosis and pseudopseudarthrosis of ankylosing spondylitis-report of 2 cases.

Pseudarthrosis is a well known, late complication of ankylosing spondylitis associated with extensive discovertebral junction destruction and fracture of the posterior elements. In contrast, the term "Pseudopseudarthrosis" is published in the recent literature to portray similar roentgenologic findings of discovertebral destruction but without bony break of the posterior arch. In this article, each complication is presented by a single case using the demonstration of plain film and computed tomography studies to compare their differences in the posterior spinal elements.