Usually is caused by repetitive stress to the back → commonly seen in gymnastics, basketball, football, rowing, diving, downhill skiing, or weightlifting
Spondylolysis → stress fracture through the pars interarticularis (pars fracture)
Pars: small portion of the vertebra that connects the upper and lower facet joints
Weakest portion of the vertebra → susceptible to injury
Most commonly occurs in the 5th vertebra of the spine
Spondylolisthesis → Anterior portion of the vertebra slips out of alignment due to prior stress fracture (spondylolysis)
The slippage most often occurs during periods of rapid growth
Can also be congenital
Both spondylolysis and spondylolisthesis are more likely to occur in the younger population that participate in sports that require overstretching (hyperextension)
Repetitive hyperextension can weaken the pars interarticularis leading to fracture and/or slippage