Spondylolysis and spondylolytic spondylolisthesis. A review of current concepts on pathogenesis, natural history, clinical symptoms, imaging, and therapeutic management.

The purpose of this paper is to review the current concepts on spondylolysis and spondylolytic spondylolisthesis. The two are very closely connected, and both result from a growth disturbance of the lumbosacral vertebrae, linked to the human biped standing position, and depending on genetic and environmental factors. Pars defect occurs usually in early childhood. The primum movens of lumbosacral deformities in spondylolisthesis is the slippage and its biomechanical consequences for the growing vertebrae. Most cases are asymptomatic but symptomatic cases can be very disabling. Major clinical symptoms are presented here, as are the roentgenographic parameters usually required for the assessment. Most cases do not require surgery. However, surgical procedures have been widely developed in the last 60 years for the cases resistant to non-operative treatments. They are presented here in a logical order, from the most physiological to the most aggressive. Isthmic repair is reliable but requires very strict local conditions. Excision of the loose arch alone should no longer be practised especially in young patients. Fusions in situ are widely used, especially by the posterior approach, but owing to unfavourable biomechanical conditions, a significant amount of pseudarthrosis is reported as well as slip progression in young patients. Additional internal fixation is recommended. Associated reduction allows placement of the spine in the best mechanical conditions for a stable fusion. Several procedures have been reported, involving either single or staged approaches. Either anterior and posterior fusion associated with reduction seems to give the best results, in spite of some few cases of transitory neurological involvement. Resection of the olisthetic vertebra associated with reduction and fusion is a therapeutic alternative in very severe cases in young people. Elective indications are given at the end of the Discussion on the basis of current procedures, according to the type of lesion and the category of patient.