Modified Closing-Opening Wedge Osteotomy to Correct Kyphosis in Ankylosing Spondylitis

BACKGROUND: The aim of this study was to analyze the clinical and radiological outcomes of modified closing-opening wedge osteotomy (mCOWO) for correcting kyphosis in ankylosing spondylitis (AS) patients. MATERIAL/METHODS: From April 2012 to April 2017, records of consecutive patients who underwent mCOWO were reviewed. The clinical and radiological outcomes were analyzed preoperatively, postoperatively, and at the most recent follow-up. RESULTS: Eleven AS patients underwent mCOWO, with a mean follow-up of 19.4 months (range, 12–45 months). The average sagittal vertical axis (SVA) was corrected from 191.9 mm preoperatively to 75.9 mm postoperatively (P<0.05) and 78.9 mm at the most recent follow-up (P<0.05). The average correction angles at the osteotomy site were 44.5° postoperatively and 45.0° at the most recent follow-up (P>0.05). Sagittal translation (ST) occurred in 2 patients, and 5 mm was the maximum. There was no neurologic damage. Solid fusion was observed at the most recent follow-up in all patients. CONCLUSIONS: Modified closing-opening wedge osteotomy (mCOWO) is an effective technique for correcting kyphosis in patients with AS.