Lumbar spinal stenosis is one of the most diagnosed and treated spinal pathologies. LSS (sagittal diameter <10mm) is reported to be associated with a threefold higher risk of developing LBP. In absolute LSS (10 mm limit), the US prevalence is 2.6% in congenital LSS and 7,3% for acquired LSS. The prevalence in the US population increases with age and is sex independent, the prevalence in the general population remaining unknown (Cole et al. 2009).
Stenosis comes from stenoses, ancient Greek for “narrowing”. Lumbar spinal stenosis (LSS) is defined as spinal canal narrowing with possible subsequent neural compression (Hsiang 2012). Bierma-Zeinstra et al. (2006) defines LSS as any narrowing of the lumbar spinal canal, which leads to compression of its content. Lumbar spinal stenosis is a painful and potentially disabling condition often encountered in older adults (Delitto et al. 1998). Symptoms are diverse, but most common are pain in the legs and neurogenic claudication symptoms (pain during walking, numbness, tingling, weakness and radiating pain down to the ankles) (Bierma-Zeinstra et al. 2006). Central canal stenosis commonly occurs at an intervertebral disc level, and defines midline sagittal spinal canal diameter narrowing (Hsiang 2012). Lateral recess stenosis is defined as narrowing (less than 3-4 mm) between the facet superior articulating process and the posterior vertebral margin (Hsiang 2012).
Bierma-Zeinstra et al. (2006) classify LSS in three types: degenerative, developmental and congenital. The degenerative type is often due to arthrotic changes, the congenital type a result of anatomical variations or malformations (e.g. scoliosis) Bierma-Zeinstra et al. (2006). The developmental type is caused by growth disturbances of the posterior elements of the spine (Amundsen et al. 1995). The most common cause of LSS is arthritis, causing disc degeneration which in turn can decrease the disc height, settle the spine and reduce the canal through which the nerves passes (American Academy of Orthopaedic Surgeons, 2009). Degenerative changes of the facet joints may result in ossification aimed support (eg spurs), which in turn narrows the canal over time as well (American Academy of Orthopaedic Surgeons, 2009).
The natural course of LSS can be benign, but typically the syndrome becomes worse over time, with accumulation of symptoms and decreased walking ability (Albert et White 2009).