Comparison of osteitis condensans ilii and ankylosing spondylitis in female patients: clinical, radiological and HLA typing characteristics.

A study comparing 12 patients with ankylosing spondylitis (AS) to 25 with osteitis condensans ilii (OCI), referred to a rheumatic disease center, was carried out to determine whether OCI represents a varient of AS in women. In the group with OCI, chronic lumbodorsal pain was present in 9, 36%, a 'fibrositis' syndrome in 6, 24%, and 16, 64% had recurrent episodes of polyarthralgia. A definite arthritis with effusion developed in 10 patients, 40%. No patient with OCI had iritis or colitis, whereas 4 patients with AS had iritis and four had colitis. Radiographs of the spine showed no evidence of spondylitis in the OCI group. Of the 25 patients with OCI, only 2, 8% were HLA B27 positive compared with 11 of 12 patients with AS, 92%. These results suggest that OCI is not a variant of AS in women.