Abstract
Nine patients (5 male and 4 female) are described with mild pain in the lumbar and thoracolumbar spine, early morning pain, morning stiffness, and moderately reduced mobility of the spine. Initial x-ray examination of the spine revealed sclerosis of one or several vertebral bodies and erosions in various parts of the vertebral bodies. In the further course of the disease squaring, sacroiliitis, and arthritis of the apophyseal joints was found. Seven of the 9 patients had the histocompatability antigen HLA B27. On the basis of these observations it is considered that 7 of these 9 patients had ankylosing spondylitis, the erosive lesions of the vertebral bodies being the first visible signs of the disease.