The intervertebral disc is a building block of the spine, or spine.

Position. The intervertebral disc belongs to the spine, a bone structure located between the head and the pelvis. Starting under the skull and extending into the pelvic region, the spine is made up of 33 bones, the vertebrae (1). The intervertebral discs are arranged between the neighboring vertebrae but are only 23 in number because they are not present between the first two cervical vertebrae, as well as at the level of the sacrum and the coccyx.

Structure. The intervertebral disc is a fibrocartilage structure that sits between the articular surfaces of two neighboring vertebral bodies. It is made up of two parts (1):

• The fibrous ring is the peripheral structure made up of fibro-cartilaginous lamellae inserting into the vertebral bodies.
• The nucleus pulposus is the central structure forming a gelatinous mass, transparent, of great elasticity, and attached to the fibrous ring. It is positioned towards the rear of the disc.

The thickness of the intervertebral discs vary according to their locations. The thoracic area has the thinnest discs, 3 to 4 mm thick. The discs between the cervical vertebrae have a thickness ranging from 5 to 6 mm. The lumbar region has the thickest intervertebral discs measuring 10 to 12 mm (1).

Shock absorber role. Intervertebral discs are used to absorb shocks and pressure from the spine (1).

Role in mobility. Intervertebral discs help create mobility and flexibility between the vertebrae (2).

Role in cohesion. The role of the intervertebral discs is to consolidate the spine and the vertebrae between them (2).

Dos disease. It is defined as a localized pain originating most often in the spine, in particular in the intervertebral discs. Depending on their origin, three main forms are distinguished: neck pain, back pain and back pain. Sciatica, characterized by pain starting in the lower back and extending into the leg, is also common and is caused by compression of the sciatic nerve. Different pathologies can be at the origin of this pain. (3)

Osteoarthritis. This pathology, characterized by wear of the cartilage protecting the bones of the joints, can notably affect the intervertebral disc (4).

Herniated disc. This pathology corresponds to the expulsion behind the nucleus pulposus of the intervertebral disc, by wear of the latter. This can result in compression of the spinal cord or sciatic nerve.

Drug treatments. Depending on the pathology diagnosed, certain drugs may be prescribed as painkillers.

Physiotherapy. Back rehabilitation can be carried out through physiotherapy or osteopathy sessions.

Surgical treatment. Depending on the pathology diagnosed, a surgical intervention may be performed on the back.

Physical examination. The observation of the back posture by the doctor is the first step in identifying an abnormality in the intervertebral discs.

Radiological examinations. Depending on the suspected or proven pathology, additional examinations may be performed such as an X-ray, an ultrasound, a CT scan, an MRI or a scintigraphy.

Published in the scientific journal Stem Cell, an article reveals that researchers from an Inserm unit have succeeded in transforming adipose stem cells into cells that can replace intervertebral discs. This would make it possible to renew the worn intervertebral discs, which are the cause of certain lumbar pain. (6)