Diagnosing lumbar instability depends on its origin. In mechanical instability, based on an MRI or posterior–anterior (PA) mobility assessment as discussed previously and, potentially, can be addressed via surgical stabilization (lumbar fusion) or physical therapy. Patients may have altered structural integrity, stiffness, and/or neuromuscular control during mid-range motions. These individuals may exhibit altered control or lack of stability in the neutral zone (Beazell et al. 2010, Panjabi, 1992).


The patient should be observed while entering and moving about the treatment area. Moving into the seated position may be difficult for them, as well as moving from a seated to standing position (Magee, 2006). An ‘instability jog’ or twitching also may be seen in the muscles during an active movement (Magee, 2006).


The examination should begin with active movements to identify which movements are the most painful or difficult (Beazell et al. 2010).


Test all movements.

Active ROM

Passive ROM

Special tests

Diagnostic Imaging

The use of MRI in diagnosing lumbar spine dysfunction has increased in the past two decades. The degree of disc degeneration, using standard MRI, is not thought to correlate with the amount of angulation (> 15°) or segmental instability (> 3 mm translation) (Beazell et al. 2010). An MRI can be used to measure the current status of the intervertebral discs, facet joints, and ligamentum flavum, which should be taken into consideration when evaluating stability within the lumbar spine (Kong et al. 2009). Functional instability can exist without any radiological evidence (Alqarni et al. 2011).

Differential Diagnosis

These instabilities may occur due to other problems in the spine, namely disc herniation, spondylolisthesis, spondylosis, facet joint degeneration or oedema (Beazell et al. 2010). These pathologies cause changes in the movements and placement of the spinal segments, causing instability. Several comorbidities may exist, including traction spurs, facet joint hypertrophy, and osteophytic formation (Alqarni et al. 2011).


Patient History