Pain Generators And Mechanisms Of Low Back Pain

Pain generators are the various anatomical structures and pathophysiological functions that are responsible for low back pain and produce a distinctive clinical profile. Any anatomical structure that constitutes the spine or contributes to its stability has the potential to cause pain.

In evolutionary terms, our unique posture with an upright spine set the stage for us to become human. There is a growing body of evidence that suggests that our upright bipedal posture puts more stress on various structures of the lower spine and may contribute to development of back pain.

Consult pain management doctors in Hyderabad at chronic back pain hospitals.

An understanding of the anatomy and biomechanics of the spine is fundamental to identifying these pain generators and can assist the clinician in selecting appropriate management strategies.

Structure of spine

The vertebral column also known as spinal column originally develops as a series of 33 vertebrae, one on top of the other. It consists of 5 regions

Cervical (neck region) consisting of 7 vertebrae
Thoracic (upper and mid back) consisting of 12 vertebrae
Lumbar (lower back) consisting of 5 vertebrae
Sacral consisting of 5 fused vertebrae and is wedged between hip bones
Coccyx (tail bone) consisting of 4 fused vertebrae

Curvatures of spine

The adult vertebral column has four curvatures along its length.
The function of the curves is to increase strength as well as flexibility.
There are 2 primary curvatures and 2 secondary curvatures.
Primary curves (thoracic and sacro-coccygeal) are concave anteriorly and are retained from the original fetal curvature.
The secondary curvatures (cervical and lumbar) develop gradually after birth as the child starts to hold his head and begins to walk.

Structural abnormalities such as kyphosis, scoliosis, excess lordosis and straightening of spine are important sources of low back pain.

Joints of the spine

Facet joints

The vertebrae are joined together by 2 pairs of facet joints. These joints provide stability to the spine.
Facet joint is a very common cause of low back pain.

Sacroiliac joint

The SI joint connects the spine with the pelvis. There are 2 sacroiliac joints one on each side and they function to transfer weight and energy between the legs and upper body. The joint is supported by many strong ligaments and there is minimal movement in the joint.
Sacroiliac joint dysfunction may account for 30 percent of all cases of low back pain.

Intervertebral discs

Between 2 vertebrae there are intervertebral discs which act like shock absorbers.
Each disc is made up of two parts: a hard, tough outer layer, called the annulus, surrounds a gelatinous, moist center, called the nucleus. The nucleus of the disc can herniate through small tears in the annulus due to excessive axial loading.
Annular tear is one of the more common pain generators. It may be associated with low back pain. However, disc material leaks through the tear and irritates the nerve root causing radiating leg pain.

Ligaments of spine

The ligaments are strong bands of connective tissue that hold the vertebrae together. Their function is to stabilize the spine, and protect the intervertebral discs.

The 3 principle ligaments are

Anterior longitudinal ligament (ALL): The ALL prevents hyperextension (excess backward bending) of the spine.
Posterior longitudinal ligament (PLL): The PLL prevents hyperflexion (excess forward bending).
Ligamantum Flavum: The ligamentum flavum maintains the curvatures of the spine.

Ligament sprain is one of the common causes of low back pain,

Muscles of the Spine

Two main muscle groups contribute to the stability of the spine.

The extensor muscles are attached to the back of the spine and enable us to stand up and lift objects.
The flexor muscle group include the abdominal muscles and enable forward bending.

Muscle spasm or trigger points are important causes of acute low back pain.

Mechanisms of low back pain

Structural abnormalities of spine causing mis-alignment and suboptimal biomechanics

Scoliosis: lateral (sideways) curve of the spine
Lordosis: Exaggerated inward arch in the lower back
Kyphosis: Exaggerated outward arch of the spine

Overuse / Injury

Sprains due to torn or overstretched ligaments
Strains due to torn muscles or tendons
Spasm due to contraction of muscles
Trauma due to road traffic accidents, sports injuries and falls (vertebral fractures, muscle, tendon, and ligament disruption etc)

Degenerative changes

Spondylosis: Generalised degeneration of spine due to normal wear and tear of joints, discs and bones of spine
Spinal canal stenosis due to degenerated discs, hypertrophic (enlarged) facet joints and thickened ligamentum flavum causing compression of spinal nerves and neurogenic claudication
Spondylolisthesis: happens when one vertebra slips over the other causing back as well as leg pain due to facet disruption and nerve entrapment
Sacro-iliac joint dysfunction due degenerative changes in supporting ligaments

Inflammatory causes

Osteoarthritis
Rheumatoid arthritis
Spondylitis
Sacroiliitis
Ankylosing spondylitis

Nerve entrapment (maybe due to degenerative changes, overuse or injury)

Herniated intervertebral disc causing inflammation or compression of nerve root (sciatica)

Weakness of muscles of spine

Weakness of muscles of back as well as abdominal muscles can alter the curvature of the spine and put more stress on it, leading to back pain

Reduced bone density (osteoporosis) and strength can lead to pain and vertebral fractures in severe cases.

Make an appointment with pain management doctors at cervical spine surgery specialist in Hyderabad

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