Strategy for Surgical Correction of Thoracolumbar Kyphosis Caused by Ankylosing Spondylitis

Abstract

Various osteotomy techniques have been proposed to correct the kyphotic deformities caused by ankylosing spondylitis (AS). However, no technique could cater to all AS-related deformities well regarding the various mobility of calcified discs and the severity of deformities. Therefore, a thorough understanding of the strength and weaknesses of each method is essential. Then, a strategic approach could be formulated to select the most appropriate technique for a specific patient so as to have a correction operation with effectiveness, safety, and surgical simplicity. Among all preoperative examinations, the evaluation of disc mobility and the severity of kyphotic deformity is mandatory, which constitutes the base for the selection of osteotomy techniques. Since posterior column osteotomy (PCO) is the simplest technique, it should be used as much as possible. If up to three mobile discs are preserved, and the severity of the deformity is only moderate, e.g. the global thoracolumbar angle is less than 60[Formula: see text], contemporary poly-segmental PCO is selected. Staged PCO (SPCO), proposed by the authors, is the enhanced PCO with more excellent correction capability. If the disc mobility is not favorable enough, SPCO can be considered instead. PSO is the most versatile technique, capable of correcting all kinds of deformities regardless of disc mobility and severity of the kyphosis. This technique can be used in every case if surgical complexity is not a concern to the operator. Especially, PSO is the exclusive indication for those firmly ankylosed deformities without any mobile disc.