DID TIP
Dysplastic
- 20%
- abnormal L5 / S1
- around 6 years old
- tendency to worse slips
- worse symptoms as posterior elements move forwards
- may have SB occulta
- L5 kyphosis
- L5 nerve root
Isthmic
- 50%
- L5/S1
- adolescents
- L5 lordosis
- L5 nerve root
- may be acute / chronic / elongated and thinned
Degenerative
- facet joints
- L4/5
- slips limited to Grade II
Trauma
- fracture not of pars
- neural elements
Iatrogenic
- laminectomy
Pathological
- weak posterior elements
- OI, Larsen's, Marfans