MedGen

Spondylolisthesis is defined as forward slipping of a vertebral body on the one below it. Spondylolysis is defined as a defect in the pars interarticularis without vertebral slipping (summary by Wiltse et al., 1975). [from OMIM]

Spondyloepiphyseal dysplasia, Reardon type is an extremely rare type of spondyloepiphyseal dysplasia (see this term) described in several members of a single family to date and characterized by short stature, vertebral and femoral abnormalities, cervical instability and neurologic manifestations secondary to anomalies of the odontoid process. [from ORDO]

Complete bilateral fractures of the pars interarticularis resulting in the anterior slippage of the fifth lumbar vertebral body (L5) onto the sacrum (level S1). [from HPO]