Combined anterior-posterior osteotomy technique for correction of chin-on-chest deformity in ankylosing spondylitis: illustrative case.

BACKGROUND: Patients with ankylosing spondylitis (AS) often develop rigid chin-on-chest deformities that severely impair horizontal gaze and quality of life. Corrective strategies typically rely on high-morbidity posterior three-column osteotomies (3COs) or complex multistage "sandwich" procedures. This report describes a simplified combined approach utilizing targeted anterior osteotomies. OBSERVATIONS: A 50-year-old male with AS presented with severe chin-on-chest deformity, dysphagia, and inability to maintain horizontal gaze. The patient underwent a C3-7 anterior cervical discectomy and fusion where anterior osteotomies were achieved via bilateral uncinectomies and manual distraction with oversized interbody spacers. This was followed by a C2-T2 posterior fusion with a C6-7 posterior column osteotomy. Postoperatively, the cervical sagittal vertical axis significantly improved, and horizontal gaze was fully restored. The patient was discharged on postoperative day 4 without neurological complications. LESSONS: Strategic anterior osteotomies (uncinectomies and distraction) combined with a lower-grade posterior osteotomy can provide sufficient sagittal correction for chin-on-chest deformity in AS. This technique offers a potentially less morbid alternative to traditional 3COs in selected patients with AS. https://thejns.org/doi/10.3171/CASE26137.