- Spinal involvement starts at the thoracolumbar spine and finally involves whole spine
- Leads to progressive kyphosis of thoracic spine and loss of lordosis of cervical and lumbar spines and compensatory flexion deformity of hips and knees
- Costovertebral joints affected which leads to restrictive lung capacities
- Sacroiliitis occurs early in the course of ankylosing spondylitis and is regarded as a hallmark of the disease
- Complete fusion of the vertebral bodies by syndesmophytes and other related ossified areas produces bamboo spine
- Fractures in ankylosed spine are transverse, extending anterior to posterior; called as chalk stick fractures
- 80-90% are positive for HLA-B27
- Early disease is treated with anti inflammatory with DMARDS/biologicals
- Operative treatment is indicated for fully ankylosed and deformed spine
