Abstract
Ankylosing spondylitis (AS) is a chronic inflammatory disorder characterized by progressive spinal stiffness and deformity, primarily affecting the sacroiliac joints, spine, and pelvis. In advanced cases, untreated AS can lead to severe kyphosis, resulting in debilitating functional impairment and a significantly reduced quality of life. We present a case of a patient with a fixed thoracolumbar kyphotic deformity that severely affected his daily function. He underwent an L1 and L4 pedicle subtraction osteotomy (PSO) and posterior spinal instrumentation. This case highlights the challenges associated with correcting rigid spinal deformities in AS patients, where surgical intervention is often the only option to restore function and quality of life. Despite the high risk of complications, advancements in surgical techniques and implants have improved outcomes even in the most complex cases. Detailed preoperative planning, precise surgical execution, and cautious postoperative management are crucial for successful outcomes in such high-risk procedures.