Etiology and pathogenesis of spondylolisthetic spondylolisthesis.

The commonly accepted hypothesis set up by Brocher in 1950 that the dysplasia of the pars interarticularis vertebrae is an essential requirement for the occurrence of spondylolysis should be thought over in light of recent findings. Newly published investigations show that disturbed spinal growth leads to dysplasia of the vertebral arch and to spondylolysis. Disturbances that play an important role are biomechanical stress factors that result from the evolution from a quadripedal to a bipedal human locomotion as well as stress fractures of the vertebral pars interarticularis and defects in vertebral maturation in small infants.