Vertebral forward slippage in immature lumbar spine occurs following epiphyseal separation and its occurrence is unrelated to disc degeneration: is the pediatric spondylolisthesis a physis stress fracture of vertebral body?
METHODS
Radiographic and histologic evaluation of a rat model of lumbar spine slippage.


OBJECTIVE
To clarify the pathomechanism of slippage in the immature spine.


BACKGROUND
There are controversial hypotheses regarding the pathogenesis of slippage of the pediatric spine with pars defects. Some studies supported that disc degeneration was its cause, while others indicated the growth plate injury was the cause.


METHODS
An immature lumbar spine slippage model in 4-week-old rats was used. Following posterior destabilizing surgery, the lumbar spine was radiographically and histologically examined at 1, 3, 5, and 7 days after surgery.


RESULTS
Radiographically, slippage occurred about 7% in the % slip on day 7, and no slippage was observed before day 5. Histologically, epiphyseal separation also appeared on day 7; before day 5, the growth plate showed no abnormalities. Within 7 days after the operation, the anulus fibrosus did not show any sign indicating degeneration. The nucleus pulposus was also normal up to day 7.


CONCLUSIONS
The findings of this study support the hypothesis that vertebral forward slippage of the immature spine occurs following epiphyseal separation and its occurrence is unrelated to disc degeneration.
Sairyo
Koichi
K
Department of Orthopedics, University of Tokushima School of Medicine, Tokushima, Japan.
Katoh
Shinsuke
S
Sakamaki
Tadanori
T
Inoue
Megumi
M
Komatsubara
Shinji
S
Ogawa
Takayuki
T
Sano
Toshiaki
T
Goel
Vijay K
VK
Yasui
Natsuo
N
D000818:Animals; D001696:Biomechanical Phenomena; D002648:Child; D004195:Disease Models, Animal; D004838:Epiphyses / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology; D005260:Female; D015775:Fractures, Stress / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D006132:Growth Plate / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000254:growth & development / Q000293:injuries* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D011859:Radiography; D051381:Rats; D017208:Rats, Wistar; D000072042:Salter-Harris Fractures; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D016103:Spinal Fractures / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology