Does it need to perform anterior column support after Smith-Petersen osteotomy for ankylosing spondylitis?

Purpose The aim of this study was to determine whether anterior column support is required in Smith-Petersen osteotomy procedure with correction angles of more than 10°, while examining the subsequent healing patterns in relation to the disrupted area. Methods An analysis was done on 26 segments of 19 patients who showed a correction angle of more than 10° in the anterior opening after SPO. There were 17 male and two female patients with a mean age of 40 years (24-56 years). The mean follow-up period was 6.5 years (2-9.1 years). The patients were classified according to the site of the anterior opening, as the disc level, the lower end-plate of the upper body (upper body), or the upper end-plate of the lower body (lower body). The healing patterns of anterior opening and the radiological correction angles were evaluated relative to the opening site. Results In all cases, bony fusion was confirmed at a mean period of 5.6 months (3-6.7 months) after surgery and the anterior opening gap was healed in 18 segments (69.2%). For patients that developed an opening in the upper body, all of the gaps were healed. The gaps in the lower body opening group were healed in 85.7% of the cases, and for the opening at the disc level, the gaps were healed only in 12.5% of the cases. The least amount of correction was obtained when anterior opening occurred in disc level. Conclusions In our study of subjects presenting with anterior opening angles from 10° to 32°, we obtained successful fusion without the need for additional anterior interbody fusion. Improved gap healing and increased correction angles were obtained when the opening was present in the upper or lower body endplates compared to those at the disc space level.