Development of spondylolytic olisthesis in adolescents.
BACKGROUND
Although it has been well documented that slippage in patients with spondylolysis is most prevalent during the growth period, the exact time when slippage initiates and halts during the growth period is still unknown. Moreover, the contribution of spinal deformities, such as wedging of the vertebral body to the slippage, remains controversial.


OBJECTIVE
To clarify when slippage in pediatric spondylolysis initiates and halts.


METHODS
Retrospective study.


METHODS
We radiographically examined 46 athletes under 18 years of age with spondylolysis at the fifth lumbar vertebra (L5). The mean age at the first consultation was 13.3 years. The average follow-up period was 6.0 years.


METHODS
Longitudinal observation of slippage at L5 on radiogram in correlation with the maturity of the lumbar spine.


METHODS
From a lateral radiogram of each patient, percent slippage, lumbar index (LI), and skeletal age of the affected vertebra were measured. Changes in the percent slippage over time were investigated, and the correlation between the percent slippage and LI was analyzed.


RESULTS
From the cartilaginous stage to the apophyseal stage, the slippage increased in 80.0% of the patients (16 of 20). From the cartilaginous stage to the epiphyseal stage, slippage increased in 11.1% of the patients (3 of 27). None of the patients (0 of 22) showed an increase after the epiphyseal stage. In 20 patients in whom slippage increased during the follow-up period, the percent slippage at the final consultation and the LI at the first consultation showed no significant correlation; however, the percent slippage and the LI at the final consultation were significantly (p<.01) correlated.


CONCLUSIONS
In conclusion, slippage was more prevalent in individuals of a younger skeletal age whose lumbar spine was immature, and it halted during the epiphyseal stage when the growth period was over and the vertebra matured. Furthermore, the results suggest that wedge deformity of an affected vertebra might be the result rather than the cause of slippage.
Department of Orthopedic Surgery, The University of Tokushima, 3-8-15, Kuramoto-cho, Tokushima 770-8502, Japan.
K
K
Sairyo
S
S
Katoh
T
T
Ikata
K
K
Fujii
K
K
Kajiura
V K
VK
Goel
D000293:Adolescent; D017677:Age Distribution; D002648:Child; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D011336:Probability; D011859:Radiography; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D013169:Spondylolysis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D013997:Time Factors