RT Journal
A1 Hu, Serena S.
A1 Tribus, Clifford B.
A1 Diab, Mohammad
A1 Ghanayem, Alexander J.
T1 Spondylolisthesis and Spondylolysis
JF The Journal of Bone & Joint Surgery
JO The Journal of Bone & Joint Surgery
YR 2008
FD March 1
VO 90
IS 3
SP 656
OP 671
DO 
UL http://dx.doi.org/
AB 
There are five types of spondylolisthesis: dysplastic, isthmic, degenerative, traumatic, and pathologic1. In the dysplastic type, facet joints allow anterior translation of one vertebra on another. Because the neural arch of the olisthetic vertebra is intact, it can compress the cauda equina as it translates. This type accounts for the only reported case of spondylolisthesis at birth2. "Isthmic" is from the Greek, meaning narrow. The isthmic type involves a lesion of the pars interarticularis (the narrow part of bone between the superior and inferior articular processes) (Fig. 1). There are three subclasses: A, which is due to a stress fracture of the pars interarticularis; B, an elongation of the pars interarticularis; and C, which is due to an acute fracture of the pars interarticularis. Dysplastic and isthmic are the two subtypes found in children, with the latter accounting for approximately 85% of cases.