Which vertebral levels are most commonly involved in disc herniation?

The most commonly involved vertebral levels in disc herniation are L5 and S1. This is primarily due to the biomechanical stresses that the lumbar spine experiences. The lumbar region bears the majority of the body's weight and is subject to significant motion and load during activities such as lifting, bending, and twisting. The intervertebral discs in this area, particularly between the L5 and S1 vertebrae, are more prone to degeneration and injury due to the high levels of stress they face.

In addition, as individuals age, the discs can lose hydration and elasticity, leading to a greater likelihood of herniation. The L5-S1 disc is particularly vulnerable because it is located at the transition zone between the mobile lumbar spine and the sacrum, where significant forces are concentrated. This is why L5 and S1 are frequent sites for disc herniations, making them the levels most commonly discussed in relation to this condition.

Other levels, such as C5 or C6, T10 or T12, and L1 or L2, are less frequently involved in herniation due to various factors, such as the different mechanical loads they experience compared to the L5-S1 region.