The alignment is normal, with normal lumbar lordosis. The bone scans show intense activity focally over the pedicles of L-4 vertebra. As with other stress fractures, it is more common among young athletes, especially gymnasts and football lineman. Activity-related pain is the common symptom. Although spondylolysis means lysis of a vertebral structure, the term is used almost exclusively to refer to the interruption of the pars interarticularis, which may be either unilateral or bilateral.
Spondylolisthesis refers to slippage or displacement, without regard for direction.
A second peak occurs in the adolescent population. It is also associated with Scheuermann disease. Plain anteroposterior, lateral and oblique radiographs of the lumbar spine should be obtained with the patient standing. The radiographic changes are variable. Initial radiographs are often negative.