"grade 0: normal pars interarticularis; MRI: no signal abnormality, pars interarticularis intact"
"grade I: stress reaction; MRI: marrow oedema; intact cortical margins"
"grade II: incomplete stress fracture; MRI: marrow oedema; incomplete cortical fracture or fissure"
"grade III: acute complete stress fracture; MRI: marrow oedema; complete cortical fracture extending through pars interarticularis"
"grade IV: chronic stress fracture; MRI: no marrow oedema; fractures completely extending through pars interarticularis"
"Scottie dog sign: on oblique radiographs, a break in the pars interarticularis can have the appearance of a collar around the dog's neck"
"Oppenheimer ossicle"
Expected headings
"Associations"
"Classification"
"repeated microtrauma, resulting in a stress injury and eventual fracture of the pars interarticularis; a dysplastic pars is usually present"
"~55% (range 25-80%) of patients with spondylolysis will progress to spondylolisthesis 2,13, which is seen radiographically in ~25% 4; in most patients, this occurs before the age of 16 years"
"grade 0: normal pars interarticularis; MRI: no signal abnormality, pars interarticularis intact"
"grade I: stress reaction; MRI: marrow oedema; intact cortical margins"
"grade I: stress reaction; MRI: marrow oedema; intact cortical margins"
"grade II: incomplete stress fracture; MRI: marrow oedema; incomplete cortical fracture or fissure"
"grade II: incomplete stress fracture; MRI: marrow oedema; incomplete cortical fracture or fissure"
"grade III: acute complete stress fracture; MRI: marrow oedema; complete cortical fracture extending through pars interarticularis"
"grade III: acute complete stress fracture; MRI: marrow oedema; complete cortical fracture extending through pars interarticularis"
"grade IV: chronic stress fracture; MRI: no marrow oedema; fractures completely extending through pars interarticularis"
"grade IV: chronic stress fracture; MRI: no marrow oedema; fractures completely extending through pars interarticularis"