Traumatic lumbosacral instability: part 1 - proposing a definition and identifying underlying injury patterns.

Traumatic lumbosacral instability (TLSI) generally refers to a traumatic disruption of the lumbopelvic junction. The ambiguous use of this term has contributed to confusion and limited understanding of injuries that can impact lumbosacral stability. As of now, TLSI lacks a clear definition, and the underlying injury patterns remain inadequately characterized. Therefore, the objectives of the first part of this two-part series are: (1) to establish a precise definition of TLSI, (2) to identify and systematically characterize the injury patterns underlying TLSI, and (3) to outline principles for diagnosing and classifying these underlying conditions.