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 AND 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.