Spondylolisthesisis a condition of the spine with slippage of one vertebra forward over the one below it. The most common site for this problem is in the lower lumbar spine, often the last lumbar vertebra.

Until recently we haven't known if disc damage occurs allowing this slippage or not. A study from Japan using rat models suggests the slippage may occur as a result of damage to the growth plate, not the discs.

The growth plate is made up of cartilage at the end of a growing bone. The separation between the bone and cartilage closes up and the bone solidifies when the child reaches full maturity. It's possible that the stress of the bone slipping forward separates the cartilage from the bone at the growth plate. An MRI can show this, but it can be present and not appear on the MRI.