Baastrup’s syndrome (aka “kissing spines”) results from osteoarthritis of spinous processes (usually lumbar). The spinous processes rub up against each other which leads to hypertrophy and sclerosis. This can cause a patient pain that is exacerbated with extension and relieved with flexion. The disease is named after Christian Ingerslev Baastrup, a Danish radiologist (1855-1950).