ABSTRACT
Ankylosing spondylitis (AS) mainly affects the synovial joints and soft tissue structures of the axial skeleton. Inflammatory processes in the intervertebral joints eventually lead to ankylosits, which together with ossification of the anterior and posterior longitudinal ligaments render the spine into a rigid beam. Despite maximum conservative treatment, stiffening of the spine in an advert position can occur. In AS, this mostly is a combination of a thoracic hyperkyphosis and flattening of the lumbar lordosis: a thoracolumbar kyphotic deformity (TLKD) (1–5).
