Distal Pedicle Subtraction Osteotomy for Ankylosing Spondylitis With the Dual Complications of Andersson Lesions and Idiopathic Spinal Cord Hernia: A Rare Case Report

Background and importance: Ankylosing spondylitis (AS) is a systemic chronic inflammatory disease. Andersson lesion (AL) is a late complication of advanced AS. Idiopathic spinal cord hernia (ISCH) is a rare disorder of the spinal cord. However, according to our literature review, the simultaneous occurrence of AL together with ISCH in a single AS patient had never been reported.

Clinical presentation: A 49-year-old male reported a 30-year history of thoracolumbar pain and limited mobility and was diagnosed with AS with dual complications of AL and ICSH. Before correction surgery, physical examination, x-ray, CT,MRI and Blood HLA-B27 examination were performed and a series of radiological parameters, including the degree of kyphosis and the T1-pelvic angle (TPA), were measured. Several days after surgery (Distal PSO was used), we performed examinations to check the patient's physical condition which showed the patient recovered remarkably. CTA was done, indicating that the patient's aorta moved anteriorly with the osteotomy side undamaged. A series of morphological parameters were measured again, including TPA, LL, and TK. CT and MRI were performed again, reflecting significant bone-to-bone fusion and successful recovery. The patient relieved the symptoms and regained his daily activities.

Conclusions: We deepen the understanding of the diagnosis and treatment of AS with rare complications of AL and ISCH. Distal PSO could be an effective option for severe AS patient.