Sandwich strategy for the treatment of kyphosis with scoliosis and bilateral hip ankylosis in ankylosing spondylitis: a case report.

Ankylosing spondylitis can present with severe kyphosis, scoliosis, and bilateral hip ankylosis, posing significant therapeutic challenges. Conventional "hip-first" or "spine-first" strategies are often limited by interdependent biomechanical constraints. This case report describes a successful staged "sandwich" protocol in a 48-year-old male with ankylosing spondylitis, thoracolumbar kyphosis, scoliosis, and bilateral hip ankylosis. The treatment involved three sequential stages: first, right total hip arthroplasty; second, pedicle subtraction osteotomy from T10 to L4; and third, contralateral total hip arthroplasty. This approach addressed critical issues including intraoperative positioning, global spinopelvic realignment, and individualized acetabular component orientation. Postoperative radiographs demonstrated marked improvement in spinal sagittal and coronal alignment, with well-positioned hip prostheses. The "sandwich" strategy adheres to a coherent biomechanical principle of "unlock-rebalance-match," systematically restoring mobility, correcting alignment, and ensuring long-term prosthetic stability. This approach offers a promising alternative for managing complex hip-spine syndrome in advanced ankylosing spondylitis.