PSOAS study of 354 with long-standing ankylosing spondylitis & SI radiographic changes; but 23 lacked syndesmophytes. Lack of fusion was more likely in women & w/younger age of Sx onset. All were B27+, thus B27 may be assoc w/ SI dz, not spinal dz. https://t.co/QCyTCHjK6u https://t.co/gT3tFuZCDq