Lumbar instability

The concept of lumbar instability was first discussed by Barr in 1951. He described instability as a side effect of disc degeneration, as loss of disc height decreased the restraint of the passive stabilizers, resulting in an increased movement in vertebral segments (Barr, 1951); the intervertebral disc being the most important structure maintaining lumbar stability (Krismer et al. 1997). It can also be described as an “increased antero-posterior translation, pathologic coupled motion, increased neutral zone, pathologic instantaneous center of rotation describe some mechanic findings occurring in the aging spine” (Krismer et al. 1997). This chronic instability can be further described as functional instability or mechanical instability. In 1982, Pope and Panjabi described instability from the biomechanical perspective, being a loss of stiffness in the spine. They defined stiffness as “the amount of motion within a system relative to a load applied to the structure” (Pope et Panjabi, 1982). Panjabi went on to further the description of instability in the 1990s, with the idea that stability of various joints in the body is maintained by a combination of the structural (passive) system, muscular (active) system, and the neural control system (Panjabi, 1992). Causes of lumbar instability may include disc degeneration, trauma, recurrent/chronic low back pain causing deconditioning or recent surgery (Alqarni et al. 2011) .

Patient History