Combined Ponte and Pedicle Subtraction Osteotomies for Severe Thoracolumbar Kyphotic Deformity in Ankylosing Spondylitis: A Case Report

Abstract

Introduction and Importance: Ankylosing spondylitis (AS) is an immune-mediated inflammatory disease of the axial skeleton that may progress to spinal rigidity and fixed kyphotic deformity with marked sagittal imbalance, in selected cases requiring corrective osteotomy. Case Presentation: A 25-year-old male with a three-year history of inflammatory back pain was diagnosed with AS based on HLA-B27 positivity, elevated inflammatory markers, and characteristic imaging findings. Although inflammatory symptoms improved after subcutaneous etanercept, the patient developed progressive rigid thoracolumbar kyphosis with clinically significant sagittal imbalance. Considering the rigidity of deformity and the magnitude of sagittal malalignment, we performed posterior instrumented fusion with combined Ponte osteotomy (PO) and pedicle subtraction osteotomy (PSO) to achieve adequate correction and restoration of sagittal alignment. Estimated blood loss was 3000 mL, and the patient received 2 units of packed red blood cells (PRBCs) perioperatively/intraoperatively. Deformity correction was conducted under intraoperative neurophysiological monitoring (IONM) using somatosensory-evoked potentials (SSEPs) and motor-evoked potentials (MEPs), with no significant signal changes. Postoperative radiographic assessment demonstrated substantial improvement in sagittal alignment. Clinical Discussion: AS management requires a multidisciplinary approach integrating medical therapy and orthopedic correction when deformity causes functional limitation. Despite controlled inflammatory activity on biologic therapy, surgery was required to address fixed kyphosis and restore global sagittal balance. The patient showed meaningful improvements in pain, posture, and functional capacity, supported by improved BASDAI and ASDAS-CRP scores and radiographic alignment. Conclusion: Combined Ponte osteotomy and pedicle subtraction osteotomy can effectively correct severe rigid thoracolumbar kyphotic deformity with sagittal imbalance in AS, improving sagittal alignment and quality of life.