Spinal stenosis due to posterior syndesmophytes in a patient with seronegative spondyloarthropathy.

Spinal involvement in spondyloarthropathy is characterized by inflammation concentrated at the site of bony insertion of ligaments and bones. These inflammatory sites show a peculiar tendency towards prominent fibrosis, ossification and new bone formation (syndesmophytes). The syndesmophytes arise either at the margins of intervertebral disc and these are called marginal syndesmophytes as in ankylosing spondylitis, or from the vertebral bodies beyond their corners and are called nonmarginal syndesmophytes as in psoriatic arthritis and Reiter's syndrome (1,2). In some references and in the European literature, the term 'syndesmophyte' is usually reserved for the vertical ossification that bridges two adjacent vertebrae in ankylosing spondylitis (3). Syndesmophytes predominate on the anterior and lateral aspect of the spine (1-3). We report a patient with undifferentiated spondyloarthropathy with posterior syndesmophytes resulting in symptomatic spinal stenosis.