What is Spondylolysis?
Spondylolysis is a defect or stress fracture of the pars interarticularis (the bony bridge between the superior and inferior articular processes of a vertebra), most commonly occurring at L5 and L4, resulting from repetitive mechanical stress to this weak portion of the vertebral arch. 1, 2, 3
Pathophysiology and Etiology
The lesion represents a stress fracture caused by cumulative repetitive stress imposed by physical activity, particularly in sports involving hyperextension and rotation of the spine. 2, 4
The condition is linked to human bipedal standing position and depends on both genetic and environmental factors, with the pars defect typically occurring in early childhood. 1
Spondylolysis is the most common cause of overuse-related chronic back pain in children and adolescent athletes. 5, 6
Epidemiology and Risk Factors
The condition shows particularly high prevalence among adolescent athletes involved in sports with repetitive spinal motions such as football, baseball/softball, gymnastics, and weight training. 4, 7
The most common age of injury is 15 years old, following a normal distribution pattern. 4
Many cases are asymptomatic and discovered incidentally on imaging, but symptomatic cases can be very disabling. 1, 2
Clinical Presentation
Typical presentation includes activity-related low back pain, painful spinal mobility, and hamstring tightness without radiculopathy. 3
Symptomatic patients often report constant pain or night pain as red flag features. 6
The condition can lead to spine instability and, if progressive, may result in spondylolisthesis (forward slippage of one vertebra over another). 1, 3, 7
Relationship to Spondylolisthesis
Spondylolysis and spondylolisthesis are closely connected, with the pars defect potentially leading to forward vertebral translation. 1, 3
The primum movens of lumbosacral deformities in spondylolisthesis is the slippage itself and its biomechanical consequences for the growing vertebrae. 1
Isthmic spondylolysis and isthmic spondylolisthesis are the most common forms seen in children. 3