Where does instability typically occur in a compression fracture?

Instability in a compression fracture predominantly occurs in the anterior vertebral bodies. In a compression fracture, the vertebral body collapses, often leading to kyphosis or sagittal imbalance. This instability arises primarily because the anterior column, comprised of the anterior part of the vertebral body and the associated anterior longitudinal ligament, is responsible for bearing weight and maintaining spinal alignment. When this structure fails, it can lead to excess motion and instability in the spinal segment.

The anterior vertebral body acts as a crucial support structure for the spinal column, and if it is compromised, this can result in altered loads and stress on adjacent structures, further contributing to instability. In contrast, the posterior vertebral bodies and the spinal canal are less directly affected in terms of weight-bearing stability in the context of a compression fracture. Therefore, understanding the role of the anterior column in stability helps clarify why instability typically arises in this region following a compression fracture.