This is the medical term used to describe the presence of a "defect" or fracture in the posterior arch of the vertebra. It occurs at the lumbo-sacral junction (L5/S1) in about 85% of cases. The remainder occurs at the L4/5 level or above, and in about 20% of cases, the defect is on one side.
Spondylolysis is not a congenital condition and has never been identified in a newborn infant, or a child who has not started to walk. Defects can develop as a stress fracture in individuals predisposed to the condition, due to the shape or orientation of the bones at the base of your spine.
There is an increased incidence in people who take part in certain physical, sporting activities or are post traumatic. To diagnose spodylolysis and ascertain if this is a recent injury, x-rays and a bone scan are indicated to conclusively diagnose a patient.