Spinal instability is a complex problem and many factors contribute to it. It can be the result of an injury, degenerative aging, or genetics. Many factors play into spinal instability, not just "weakness of the trunk."
What is spinal stability? Spinal stability refers to the control and support between segments of the spine. When there is a problem in the stabilizing mechanisms of the spine to provide support of the segments, spinal instability may be the result.