Low Back Pain Definitions

The definition of low back pain should not be ignored, and a topographical description is preferred. Starting with the wrong topographical area can lead to the wrong diagnosis. A topographical definition makes no assumption as to cause of the pain, only its location.

The importance of having clear definition has been demonstrated in a 1989 study. They found the interobserver reliability of defining a patients pain pattern as being in the "back" to be very poor (Kappa 0.16). Defining the pain pattern as "buttock pain" had moderate agreement (Kappa 0.44); foot pain, leg pain, and thigh pain all had good agreement (Kappa 0.73, Kappa 0.96, and Kappa 0.78 respectively)

It is important to get the patient to show you exactly where they feel the pain rather than simply take what they say for granted. Anecdotally, there are a wide array of terms that are used by patients to describe what taxonomically is lumbar spine pain. For example I have commonly heard patients call the lumbar spinal area the hip. I'm not sure if this is a New Zealand specific language pattern.

Low Back Pain

The IASP taxonomy does not recognise the term "back pain," rather it categorises it into lumbar spinal pain and sacral spinal pain. There is also an overlapping definition called lumbosacral pain. These three categories constitute the colloquial term "low back pain." Another overlapping definition is thoraco-lumbar pain, but this is not low back pain. The IASP taxonomy are periodically updated, so to get the latest definition go to IASP and in part I (topics and codes) click on "spinal pain, section1: spinal and radicular pain syndromes." The definitions here are up to date as of August 2021.

Lumbar Spinal pain

"Pain perceived as arising from anywhere within a region bounded superiorly by an imaginary transverse line through the tip of the last thoracic spinous process, inferiorly by an imaginary transverse line through the tip of the first sacral spinous process, and laterally by vertical lines tangential to the lateral borders of the lumbar erectores spinae...If required, lumbar spinal pain can be divided into upper lumbar spinal pain and lower lumbar spinal pain by subdividing the above region into equal halves by an imaginary transverse line."

Sacral Spinal Pain

"Pain perceived as arising from anywhere within a region bounded superiorly by an imaginary transverse line through the tip of the first sacral spinous process, inferiorly by an imaginary transverse line through the posterior sacrococcygeal joints, and laterally by imaginary lines passing through the posterior superior and posterior inferior iliac spines."

Lumbosacral Pain:

"Pain perceived as arising from a region encompassing or centred over the lower third of the lumbar region as described above and the upper third of the sacral region as described above."

Not Low Back Pain

Pain in regions adjacent to the above topographical areas are not low back pain. There are a variety of other taxonomical definitions to describe pain in other areas.

Gluteal Pain:

"Referred pain over the lower limb girdle posteriorly may be described as gluteal pain. For this purpose the gluteal region may be defined as a sector central on the greater trochanter and spanning from the posterior inferior iliac spine to the anterior superior iliac spine. "

This is very commonly mistaken for back pain. Local causes of gluteal pain should be considered first before lumbar referred conditions.

Posterior Hip Pain

"Referred pain immediately below [the gluteal pain region[ posteriorly should be qualified as posterior hip pain"

Anterior Hip Pain

"Pain immediately below [the gluteal pain region anteriorly[ should be qualified as anterior hip pain."

Groin Pain

"Pain focused over the inguinal ligament may be qualified as groin pain."

Loin Pain:

"Pain located over the posterior region of the trunk but lateral to the erectores spinae is best described as loin pain to distinguish it from lumbar spinal pain."

The identification of loin pain is important because it is more likely to be due to a visceral disorder, for example it could lead to missing a diagnosis of pyelonephritis or renal colic.

Thoracic Spinal Pain:

"Pain perceived as arising from anywhere within the region bounded superiorly by an imaginary transverse line through the tip of first thoracic spinous process, inferiorly by an imaginary transverse line through the tip of the last thoracic spinous process, and laterally by vertical lines tangential to the most lateral margins of the erectores spinae muscles. Pain located over the posterior chest wall but lateral to the above region is best described as posterior chest wall pain to distinguish it from thoracic spinal pain. If required, thoracic spinal pain can be further qualified by dividing the above region into thirds from the top down, to establish regions of upper thoracic, mid thoracic, and lower thoracic spinal pain"

Thoraco-Lumbar Pain:

"Pain perceived as arising from a region encompassing or centred over the lower quarter of the thoracic region as described above and the upper third of the lumbar region as described above."

Sciatica:

"This term is an anachronism and should be abandoned. It stems from an era when the mechanisms of referred pain and radicular pain were poorly understood. It was used to describe pain that appeared to travel along the course of the sciatic nerve. The unfortunate legacy of this term is that it has been applied erroneously to any or all pain of spinal origin perceived in the lower limb. Furthermore, because nerve root compression has been believed to be the cause of sciatica, many forms of referred pain in the lower limb have been erroneously ascribed to this cause. Clinical experiments have shown that the only type of pain that is evoked by stimulating nerve roots is radicular pain as described above (Norlen 1944; Smyth and Wright 1959; McCulloch and Waddell 1980). Consequently, at the most, sciatica and radicular pain can be considered as synonymous. However, there is no justification on physiological grounds for equating sciatica and referred pain. The two are distinct in mechanism and quality. Pain in the lower limb should be described specifically as either referred pain or radicular pain. In cases of doubt no implication should be made and the pain should be described as pain in the lower limb."