Spondylolisthesis in children

*1. What are the most common causes of spondylolisthesis in children? At what levels?
2. What is the difference between isthmic and dysplastic spondy?
3. What determines the need for treatment?

Answers:
1. Dysplastic and isthmic are most common. The most frequent level is L5-S1, then L4-5.
2. Isthmic is the result of a slip at a previoius spondy or a pars defect. Dysplastic has lenthening of the lamina and is more likely to cause cauda equina compression.
3. Over 50% slippage requires surgical fusion, less than 50% depends on severity of symptoms. Surgery rarely needed for <25% slippage.