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.
Later, sclerosis of the involved area may be seen on one or both sides. Oblique radiographs may show a well-marginated defect in the pars as a break in the neck of the Scotty dog. If increased uptake can be seen on bone scan, healing of the stress fracture is possible with conservative treatment. In patients with radiographically confirmed spondylolysis but no focal accumulation on scintigraphy, the nonunion of the stress fracture is established, and it is unlikely to heal with immobilization. A complete history, a detailed physical examination and appropriate laboratory and imaging modalities can usually pinpoint the problem.