Testing for low back flexion

Schober test to measure the forward flexion of the lumbar spine in a patient with suspected or proven ankylosing spondylitis. With the patient standing erect, make a mark over the spinous process of the fifth lumbar vertebra or on the imaginary line joining the posterior superior iliac spine. Make another mark 10 cm above it in the midline. When the patient bends maximally forward, the distance between the two points normally exceeds 15 cm.