Isthmic vs Degenerative Spondylolisthesis
For posterior spinal decompression surgery to aggravate Spondylolysis or Spondylolisthesis, signs/symptoms of Spondylolysis or Spondylolisthesis should occur within 10 years of the surgery.
Spondylolysis and spondylolisthesis - Mayfield Clinic
Dysplastic Spondylolisthesis results from congenital abnormalities of the upper sacral facets or inferior facets of the fifth lumbar vertebra that allow slipping of L5 on S1.
Type II. Isthmic: This type results from a defect in the pars interarticularis that allows forward slipping of L5 on S1. Three types of isthmic spondylolistheses are recognized: