Surgical algorithms for ankylosing spondylitis-related pseudarthrosis : adapting to radiological and clinical variations.

Abstract

<h4>Aims</h4>To propose feasible and systematic surgical therapeutic algorithms for treatment of spinal pseudarthrosis caused by ankylosing spondylitis (AS) with diverse radiological patterns and clinical manifestations.<h4>Methods</h4>Retrospective analysis of AS patients with pre-existing pseudarthrosis was performed. All the patients were divided into six groups according to surgical procedures: anterior debridement and fixation (ADF), posterior fixation (PF), posterior laminectomy and fixation (PLF), osteotomy through pseudarthrosis (OTP), osteotomy skipping pseudarthrosis (OSP), and osteotomy skipping pseudarthrosis with laminectomy (OSPL). Sagittal parameters, pseudarthrosis characteristics, kyphosis apex location, and neurological status were assessed.<h4>Results</h4>Overall, 87 patients were evaluated (mean follow-up of 42.02 months (24 to 180)). Three cases with pseudarthrosis involving anterior-to-middle column and absence of local kyphosis underwent ADF. Conversely, PF was selected for eight cases with mild regional kyphosis and three-column involving lesions. For cases with pre-existing neurological deficit but without global kyphotic deformity, PLF was used (six cases). OTP was adopted in 16 cases with global kyphosis and identical location of apex and lesions. An additional five patients also underwent osteotomy at pseudarthrotic site with lesions located below the apex and severe spinal stenosis. Regarding 45 cases with global kyphosis, normal neurological function and absence of spinal stenosis, OSP was performed. Addtionally, if neurological deficit was complicated in the aforementioned situation, OSPL was chosen (four cases). Radiological assessment confirmed solid bony union at pseudarthrotic sites in all cases.<h4>Conclusion</h4>Developing a reliable therapeutic algorithm for AS-associated pseudarthrosis depended on its distinct radiological features and clinical manifestations. Key factors including presence of local and/or global kyphosis, extent of lesions, anatomical relationship between kyphosis apex and pseudarthrosis, and preoperative neurological status should be thoroughly evaluated to provide personalized treatment strategies.