Understanding spine care terminology helps patients evaluate their treatment options more effectively. This glossary defines key terms in spinal anatomy, common disc conditions, and non-surgical treatments — including intra-annular fibrin injection and biologic disc repair. Candidate eligibility and outcomes vary individually; this resource supports informed conversations with your clinical team.

Annulus Fibrosus

The annulus fibrosus is the tough, outer ring of an intervertebral disc, made up of strong layers of collagen fibers. Its primary role is to contain the gel-like nucleus pulposus within the disc and provide structural integrity, allowing the spine to withstand bending and twisting movements. Damage to this structure — often in the form of tears — is a frequent contributor to chronic back pain. Annular tears can compromise the disc’s ability to hold its contents, leading to degeneration and pain as inflammatory chemicals leak out and irritate nearby nerves.

Nucleus Pulposus

The nucleus pulposus is the soft, gel-like center of a spinal disc, primarily composed of water. It acts as the spine’s main shock absorber, cushioning the vertebrae during movement and daily activities. When the surrounding annulus fibrosus is damaged, the nucleus pulposus may bulge or leak out, contributing to a herniated disc. This protrusion can compress nearby nerves, potentially causing pain, numbness, or weakness in areas supplied by those nerves — though presentations vary by individual.

Intervertebral Disc

An intervertebral disc is a cushion-like structure located between each vertebra in your spine, acting as both a shock absorber and a spacer that allows for spinal flexibility. Each disc consists of two main parts: the tough outer annulus fibrosus and the soft, gel-like nucleus pulposus. Discs are susceptible to degeneration, injury, and tears over time, which may contribute to chronic back pain, nerve compression, and mobility issues. Addressing disc health is central to many non-surgical spine treatment strategies.

Vertebra

A vertebra is one of the 33 individual bones that make up your spinal column, stacked to form a protective column around the spinal cord. These bones provide structural support for your body and enable movement. Your spine is divided into regions: 7 cervical (neck), 12 thoracic (mid-back), 5 lumbar (lower back), and fused sacral and coccygeal bones. Each vertebra interacts with discs and facet joints, and proper alignment supports nerve health and spinal stability.

Annular Tear

An annular tear is a rip or fissure in the annulus fibrosus, the tough outer layer of a spinal disc. These tears are a common and often overlooked contributor to chronic back pain. They can allow inflammatory chemicals from the disc’s nucleus to leak out and irritate nearby spinal nerves, causing persistent pain — even without disc herniation. Because discs have a limited blood supply, annular tears often struggle to heal on their own, making them a target for advanced regenerative treatments designed to seal and repair the damage. See also: Annular Tears: A Root Cause of Back Pain and the Role of Repair.

Degenerative Disc Disease (DDD)

Degenerative Disc Disease (DDD) refers to the natural breakdown of spinal discs over time, a process that can occur with aging or injury. Despite its name, DDD is a condition, not a disease, and it involves changes such as loss of disc height, reduced hydration, and the development of annular tears. While many people experience disc degeneration without symptoms, others develop chronic back pain, stiffness, and nerve compression. Our clinical team focuses on treatments that address underlying disc health to help alleviate DDD symptoms in appropriate candidates.

Herniated Disc

A herniated disc occurs when the nucleus pulposus — the disc’s gel-like center — pushes through a tear in the annulus fibrosus and extends outside the normal disc space. This is often called a “ruptured disc” or “slipped disc.” A herniated disc may press on nearby spinal nerves, potentially causing sharp pain, numbness, tingling, or weakness that radiates into the arms or legs (sciatica or radiculopathy). Evaluation is individualized; treatment approaches focus on relieving nerve compression and, in some candidates, repairing the underlying disc damage.

Sciatica

Sciatica describes pain that radiates along the path of the sciatic nerve, which branches from your lower back through your hips and buttocks and down each leg. It is a symptom, not a standalone condition, and typically affects one side of the body. Sciatica is most commonly associated with a herniated disc or bone spur in the lower spine that compresses part of the sciatic nerve. Patients may experience shooting pain, numbness, tingling, or weakness that impacts daily activities like sitting or walking. See also: 10 Myths About Sciatica and Non-Surgical Relief.

Radiculopathy

Radiculopathy is a condition caused by the compression or irritation of a spinal nerve root, leading to symptoms that radiate along the path of that nerve. Depending on where the nerve compression occurs, symptoms may include pain, numbness, tingling, or weakness. Cervical radiculopathy affects the neck and arms, while lumbar radiculopathy affects the lower back and legs. Common causes include herniated discs, degenerative disc disease, or spinal stenosis. Identifying the specific nerve root involved is key to developing an effective, individualized treatment plan.

Failed Back Surgery Syndrome (FBSS)

Failed Back Surgery Syndrome (FBSS) is a term used to describe chronic pain that persists or returns after one or more spine surgeries. Patients with FBSS continue to experience significant back or leg pain despite having undergone surgical procedures. This syndrome highlights the challenges of traditional surgical interventions and the importance of exploring all available pathways. Our clinical team evaluates non-surgical and regenerative options for patients who have not found adequate relief through conventional surgeries or who wish to explore non-surgical alternatives. See also: 5 Things to Know Before Choosing Spine Surgery.

Fibrin

Fibrin is a naturally occurring protein in your blood that plays a role in wound healing and tissue repair. When an injury occurs, fibrin molecules link together to form a mesh-like scaffold that helps stop bleeding and provides a framework for new tissue to grow. In regenerative disc treatment — such as intra-annular fibrin injection — fibrin is precisely delivered into the damaged intervertebral disc. It may act as a biologic seal for annular tears and support the body’s natural healing processes to restore disc integrity in appropriate candidates; individual responses vary.

Annulargram

An annulargram, also known as a discogram with CT, is a specialized diagnostic procedure used to identify tears within the annulus fibrosus, the outer layer of a spinal disc. During the procedure, a contrast dye is injected directly into the suspected disc under fluoroscopic (live X-ray) guidance. This allows the physician to visualize tears or dye leakage that may not be clearly apparent on standard MRI scans. An annulargram also helps determine whether a specific disc is contributing to a patient’s pain, making it a valuable tool for evaluating candidacy for biologic disc repair.

Intradiscal Injection

An intradiscal injection refers to any medical procedure in which substances are delivered directly into the intervertebral disc space. Unlike injections that target the area around the disc or the epidural space, intradiscal injections reach the disc itself. This precise delivery method is important for regenerative treatments like intra-annular fibrin injection, where the goal is to repair damaged disc tissue from within. By delivering therapeutic agents directly to the site of injury, intradiscal injections aim to promote healing, reduce inflammation, and support disc function in eligible candidates.

Biologic Disc Repair

Biologic disc repair is a non-surgical approach focused on promoting the body’s natural ability to heal damaged intervertebral discs. This treatment specifically targets annular tears — rips in the outer layer of the disc that allow the inner nucleus to leak, contributing to pain and degeneration. Using techniques such as intra-annular fibrin injection, biologic disc repair aims to seal these tears, prevent further leakage, and create a scaffold that may encourage the disc’s own cells to regenerate and strengthen damaged tissue. Candidate eligibility is assessed individually; outcomes vary by case. See also: Biologic Disc Repair: Conditions It May Help.

Epidural Steroid Injection

An epidural steroid injection is a common treatment for nerve pain caused by spinal conditions. During the procedure, a corticosteroid medication — often combined with an anesthetic — is injected into the epidural space surrounding the spinal cord and nerve roots. The steroid may help reduce inflammation and swelling around irritated nerves, providing temporary relief from pain, numbness, or tingling in some patients. Epidural steroid injections do not address underlying disc damage or annular tears and are typically limited in frequency due to potential side effects. See also: Epidural Steroid Injections vs. Annular Tear Repair: A Long-Term Perspective.