Recent Advances in Managing Ankylosing Spondylitis with Andersson Lesion: A Clinical Overview and Case Report

Ankylosing spondylitis (AS) is a chronic inflammatory disorder that primarily affects the spine and sacroiliac joints, leading to pain, stiffness, and progressive thoracolumbar kyphotic deformity. A key complication in advanced AS is the development of Andersson lesions (AL), degenerative vertebral lesions resulting from the disease's progression. These lesions can cause significant mechanical pain, often mistaken for the chronic discomfort associated with AS. The exact cause of AL remains unclear, with hypotheses ranging from spinal stress fractures to delays in the ankylosing process. Understanding AL's pathophysiology is essential for timely diagnosis and effective management.

A 52-year-old male presented with a 20-year history of diffuse abdominal pain, later developing insidious lower back pain over the past 2 months. The pain was aggravated by walking and prolonged standing. Physical examination revealed tenderness in the D11 region of the spine, with limited chest expansion and positive findings on the modified Schober's test. Radiographic studies showed irregularities and erosions at the D11-D12 vertebral levels, and magnetic resonance imaging confirmed the presence of an AL associated with asymmetrical bilateral sacroiliitis. The patient tested positive for human leukocyte antigen-B27, supporting a diagnosis of AS with an AL. Medical management, including methotrexate, sulfasalazine, non-steroidal anti-inflammatory drugs, and corticosteroids, led to significant pain reduction and improved mobility. The patient's condition remained stable with continued treatment over a 2-year follow-up period.

AL s are chronic, often overlooked complications of AS that can lead to spinal instability and neurological deficits if untreated. Early recognition and management are critical to preventing progressive kyphotic deformities and associated complications. While conservative treatment remains the cornerstone for managing AL, surgical intervention may be required in cases of severe pain, deformity, or neurological involvement. Understanding AL's presentation and treatment options is vital for improving patient outcomes in AS.