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Glossary of Terms


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Glossary Items in Alphabetical Order

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Glossary items beginning with A (26)

Adolescent Scoliosis - lateral spinal curvature that appears before the onset of puberty and before skeletal maturity.

Adult Scoliosis - scoliosis of any cause which is present after skeletal maturity.

Ankylosing Spondylitis - An inflammatory disease of the spine which gradually restricts spinal movement. Primarily occurs in young adults; they commonly have morning pain. Often called "bamboo spine disease".

Anterior - The front portion of the vertebral body. It may also indicate the position of one structure relative to another.

Anterior Longitudinal Ligament - A ligament which attaches to the anterior aspect of every vertebra, from the base of the skull to the sacrum.

Anterior Sacroiliac Ligaments - Ligaments which span the anterior aspect of the sacroiliac joints, spanning from the sacrum to the iliac bones. They are not as strong as the posterior sacroiliac ligaments.

Anterior Spinal Fusion - A surgical technique which involves the removal of the intervertebral disc, and replacement with bone graft. Additional structural supports may be placed in the disc space, such as hard (cortical) bone grafts, metal or synthetic spacers, to maintain good spinal alignment.

Anterior Superior Iliac Spine - The palpable bony prominence at the front of the iliac bone on each side of the pelvis. This is used as a landmark for physical examination.

Anteroposterior View (AP View) - An x-ray in which the patient faces toward the x-ray beam, which passes from anterior to posterior through the patient, and away from the x-ray film.

Apex of Scoliosis - The area of greatest curvature or displacement from the midline of the body.

Apical Vertebra - When referring to a scoliosis, it is the vertebra with the greatest distance from the midline and has the most rotation.

Apophysis - A growth plate which is not apparent on x-rays until the bone is maturing, when it the begins to ossify (change to bone). The iliac apophysis is often used to estimate a child's skeletal maturity.

Arachnoid - A thin layer of connective tissue which is part of the dura which surrounds the brain, and contains the spinal fluid around the spinal cord.

Artery of Adamkiewicz - An artery which primarily supplies blood to the anterior spinal artery to the thoracic and lumbar spinal cord. The level at which it enters the spinal canal varies widely, commonly from T8 to L3. Ischemia from impaired blood flow in this artery may result in spinal cord ischemia.

Ataxic Gait - Uncoordinated, unsteady walking with the feet spread apart (wide-based) which may be caused by either spinal stenosis or a brain (central nervous system) disease.

Atlanto-axial Instability - Abnormal, excessive motion between the first and second cervical vertebrae (C1 & C2). This may be due to disease or injury.

Atlanto-axial Joint - This joint between C1& C2, allows approximately 50% of the cervical spine side-to-side rotation.

Atlanto-axial Rotatory Subluxation - A rotational subluxation of the C1-C2 joints. The patients often appear with the head tilted and cocked to one side and are unable to turn their heads to the other side. Often secondary to injury or retropharyngeal inflammation seen after tonsillectomy. The diagnosis is often delayed, and may require CT scan for a definitive answer.

Atlanto-dens Interval - A measurement on lateral x-rays of the cervical spine of the space between the anterior ring of C1 and the anterior aspect of the dens (odontoid). This space may increase with injury to the supporting ligaments, or damage to the ligaments from disease.

Atlanto-occipital Dislocation - A separation of the upper cervical spine from the skull, secondary to trauma. This is often a fatal injury.

Atlanto-occipital Joint - The joint between the skull and the first cervical vertebra (C1).

Atlas - The first cervical vertebra (C1) to which the skull attaches above and the axis (C2) attaches below.

Autologous Blood - blood collected from a person for later transfusion to that same person. This technique is often used prior to elective surgery if blood loss is expected to occur. This may avoid the use of bank blood from unknown donors.

Autonomic Dysreflexia - This involves over stimulation of the autonomic nervous system in paraplegic patients with spinal cord injury at or above T6, which may manifest itself with excessive sweating, goose flesh, headaches, high blood pressure, slow heart rate, and unusual flushing of the skin. It can be caused by infection, over-distention of the urinary bladder, constipation, or a skin wound. If it remains untreated, it can become a medical emergency or cause death.

Autotransfusion - The practice and technique of transfusing previously drawn autologous blood back to the same patient.

Axis - The second cervical vertebra consisting of a ring of bone and the odontoid as a cephalad projection. As it articulates with the Atlas (C1), it provides 50% of the cervical spine rotation.

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Glossary items beginning with B (8)

Basilar Impression/ Invagination - The upper cervical spine presses into the base of the skull (foramen magnum). Spinal cord or brainstem compression may occur. Diseases which cause softening of the bone may cause this.

Bilateral Facet Dislocation - Usually a bilateral cervical spine injury involving a severe ligamentous / soft tissue injury, allowing the cephalad vertebra to move forward on the inferior vertebra. This usually requires surgical intervenation.

Biomechanical Back Pain - Induced by muscular strain/ ligamentous injury, causing other muscles or structures to become stressed, becoming painful also.

Block Vertebrae - The congenital fusion of two or more vertebrae. These vertebrae do not have normal growth potential.

BMP - Bone morphogenetic protein. A genetically engineered protein which stimulates bone production, to help your bone heal and/or fuse. These proteins are made by our bodies, but in much smaller quantities. These are added to your bone. BMP is not yet FDA-approved for all types of surgery, but surgeons may use the medicine for whatever application they feel is appropriate for the patient.

Body Cast - A cast which surrounds the chest, abdomen and pelvis. It may also include the shoulders. This may be used to correct scoliosis in very young patients or for postoperative spinal immobilization.

Bone Graft - Human bone, which is harvested from one location in an individual and placed in another individual (allograft bone) or in a different location in the same individual (autogenous bone). A common place to take autogenous bone graft from is the anterior and posterior iliac crests (the hip bones).

Bone Spur - An overgrowth of bone in response to stress or injury.

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Glossary items beginning with C (6)

Cervical Spine - Seven spinal segments (C1-C7) between the base of the skull (occiput) and the thoracic spine. The normal cervical spine alignment is lordosis.

Cervicothoracolumbosacral orthosis (CTLSO) - A type of brace which immobilizes the cervical, thoracic and lumbar spine. This may be used to help stabilize/ prevent progression of scoliosis curve(s) while a child is growing, or to immobilize the spine after surgery.

Coccyx - The last segment of the spine, below the sacrum, also called the tailbone.

Compensatory Curve - In spinal deformity, a secondary curve located above or below the structural curvature, which develops in order to maintain normal body alignment.

Congenital scoliosis - Scoliosis due to bony abnormalities of the spine present at birth. These anomalies are classified as failure of vertebral formation and/or failure of segmentation.

Corpectomy - The surgical removal of all or part of the vertebral body.

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Glossary items beginning with D (10)

Decompensation - In scoliosis, this refers to loss of spinal balance when the thoracic cage is not centered over the pelvis.

Decompression - To relieve pressure on the spinal cord or nerve roots. The pressure may result from bone (the lamina, pedicles, vertebral body), fractured bone fragments, disc herniation, ligaments, bone spurs, tumor, infection, or abnormal curvature of the spine (scoliosis or kyphosis).

Disc Degeneration - The loss of the fluid content, structure and functional integrity of the disc.

Disc Herniation - The tear of the firm, fibrous tissue called the annulus with rupture of the soft, gelatinous inter-vertebral disc through the outer aspect of the disk. Extrusion, implies that the fragment of disc material that is not attached to the annulus and may move up or down from the site of herniation; sometimes it has passed through a hole in the posterior longitudinal ligament. The term herniated nucleus pulposus (HNP) is a catchall phrase for all of these conditions.

Discectomy - Removal of all or part of an intervertebral disc (the soft tissue that acts as a shock absorber between the vertebral bodies). This may be done for fusion or because of herniation.

Distal - Situated away from or farther from a point of reference; opposite of proximal

Double curve - Two lateral curvatures (scoliosis) in the same spine.

Double major curve - Describes a scoliosis in which there are two structural curves which are usually of equal size.

Double thoracic curve - A scoliosis with a structural upper thoracic curve, as well as a larger, more deforming lower thoracic curve and a relatively non-structural lumbar curve.

Dura - The 3 layer membrane which contains the spinal cord and spinal fluid. It can be torn or stretched during spinal surgery. It can often be repaired nor patched with fascia or allograft dura.

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Glossary items beginning with E (0)

There are no terms that start with "E".

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Glossary items beginning with F (5)

Facet - A posterior structure of a vertebra which articulates with a facet of an adjacent vertebra to form a facet joint that allows motion in the spinal column. Each vertebra has two superior and two inferior facets. This is frequently where arthritic spurs can cause compression of nerve roots or canal stenosis.

Flatback Syndrome/Fixed Sagittal Imbalance Syndrome - Forward posture usually due to a flattened lumbar spine from postoperative or degenerative changes. When viewed from the side, the patient's head may be several centimeters in front of their hips.

Foramen - An opening allowing for the emerging of spinal nerve roots between two vertebrae.

Foraminotomy - A procedure carried out in conjunction with disc surgery. The foramen (openings for the individual nerve roots to pass from the spine) may become narrowed because of disc impingement, intervertebral collapse, and spondylolisthesis. The surgical widening of the foramen is an attempt to relieve the pressure on the nerve roots.

Fusion - The uniting of two or more bony segments.

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Glossary items beginning with G (1)

Gardner-Wells tongs - A device used to position the head or apply traction to the neck during surgery. The tongs are attached to your skull with a screw above each ear after you are asleep in surgery.

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Glossary items beginning with H (3)

Hemivertebra - A congenital abnormality of a vertebral body caused by incomplete development of one side of a vertebra. Usually a wedge shape which causes scoliosis or kyphosis.

Hyperkyphosis - "Kyphosis" refers to an abnormal increase in this forward curvature.

Hysterical scoliosis - A non-structural deformity of the spine that develops as a manifestation of a psychological disorder.

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Glossary items beginning with I (6)

Idiopathic scoliosis - A structural spinal curvature for which the cause has not been established. There is no evidence of underlying physical or radiographic pathology. The most common type of scoliosis.

Iliac Bone - A part of the pelvic bone that is above the hip joint and from which autogenous bone grafts are frequently obtained.

Inclinometer - An instrument used to measure the angle of thoracic (rib) or lumbar (flank) prominence, referred to as the angle of trunk rotation (ATR).

Infantile scoliosis - A curvature of the spine that develops before three years of age.

Internal Fixation - The immobilization of bone fragments or joints with implants (metal screws, rods, etc.) in order to promote healing or fusion.

Interspinal or intervertebral disc - The structure that normally occupies the space between two moving vertebrae. It is more prominent in the cervical and lumbar spines. It is much like a radial tire. The centermost portion of the disc (nucleus pulposus) is normally composed of a clear gelatinous material that varies in consistency from a firm jelly material to a very thick and less pliable substance. This core is then surrounded by numerous layers of fibrous (fibrocartilaginous) material called the annulus fibrosus. That structure goes to the normal margins of the vertebral body. There is a thick ligament (approximately 2mm) that covers the anterior part of the vertebral body called the anterior longitudinal ligament, and on the spinal canal side posteriorly is the posterior longitudinal ligament.

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Glossary items beginning with J (1)

Juvenile scoliosis - Scoliosis developing between the ages of three and ten years.

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Glossary items beginning with K (2)

Kyphoscoliosis - A structural scoliosis associated with increased kyphosis (roundback).

Kyphosis - The normal forward curvature of the thoracic spine. A posterior convex angulation of the spine as evaluated from the side (roundback). Contrast to lordosis.

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Glossary items beginning with L (9)

Lamina - An anatomical portion of a vertebra. For each vertebra, two lamina connect the pedicles to the spinous process as part of the neural arch.

Laminectomy - An operation for removal of part or all of the lamina of a vertebra commonly performed in order to be able to remove an intervertebral disc protrusion or to decompress a nerve root.

Lateral - Situated away from the midline of the body.

Lordoscoliosis - A lateral curvature of the spine associated with increased lordosis (swayback).

Lordosis - The normal mild anterior angulation (swayback) of the lumbar spine as evaluated from the side. Contrast to kyphosis.

Lumbar Curve - A spinal curvature whose apex is between the first and fourth lumbar vertebrae (also known as lumbar scoliosis).

Lumbar Spine - Five mobile segments of the lower back (L1 to L5). These are the largest of the vertebral segments and provide most of the bending and turning ability of the back, in addition to bearing most of the weight of the body.

Lumbosacral - Pertaining to the lumbar and sacral regions of the back.

Lumbosacral Curve - A lateral curvature with its apex at the fifth lumbar vertebra or below (also known as lumbosacral scoliosis).

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Glossary items beginning with M (1)

Medial - Situated closer to the midline of the body.

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Glossary items beginning with N (1)

Nerve Root - The portion of a spinal nerve in close proximity to its origin from the spinal cord.

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Glossary items beginning with O (1)

Osteotomy - the surgical removal of a wedge or piece of vertebral bone to alter the alignment of the spine; may also be used in previously fused vertebrae to enable the surgeon to move them.

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Glossary items beginning with P (8)

Pedicle - The part of each side of the neural arch of a vertebra which projects backward from the vertebral body. It connects the lamina with the vertebral body.

PLIF - Posterior Lumbar Interbody Fusion - A technique for performing an anterior fusion (front of the spine) of 2 vertebrae from a posterior approach.

Posterior - Located behind a structure, such as relating to the back side of the body.

Posterior Longitudinal Ligament - A ligament which attaches to the posterior aspect of every vertebra, from the base of the skull to the sacrum.

Posterior Spinal Fusion - A surgical technique which involves roughening or removing the hard bony surfaces (decortication) of the lamina(e), spinous processes, and facet joints, to stimulate two or more spinal bones (vertebrae) to heal together (fusion). Bone grafting with autogenous and/ or allograft bone is used to enhance the fusion process. Instrumentation (implants) may also be used.

Primary Curve - The first, or earliest, curve to appear.

Proximal - Nearer or closer to a point of reference; opposite of distal.

Pseudarthrosis - An area of the spinal fusion where the bone did not heal (fuse). Often found with broken instrumentation and, in some instances increased pain, although not always.

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Glossary items beginning with Q (0)

There are no terms that start with "Q".

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Glossary items beginning with R (1)

Risser Sign - Used to evaluate skeletal and spinal maturity, this refers to the appearance of a crescent-shaped line of bone formation which appears across the top of each side of the pelvis on plain x-ray.

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Glossary items beginning with S (15)

Sacral Spine - (Sacrum) - The curved triangular bone at the base of the spine, consisting of five fused segments of the lower spine that have four foramen on each side. The sacrum articulates (connects) with the last lumbar vertebra and laterally with the pelvic bones.

Sacroiliac Joint - The joint between the ilium and sacrum one each side of the pelvis which has a small amount of motion. It may be a source of low back pain. The ligamentous attachments may become injured as well.

Sacroilitis - Inflammation within the sacroiliac joint. This may be an associated symptom of ankylosing spondylitis.

Sciatica - A lay term indicating pain along the course of a sciatic nerve, especially noted in the back of the thigh and below the knee.

Scoliometer - A proprietary name for an inclinometer used in measuring trunk rotation.

Scoliosis - Lateral deviation of the normal vertical line of the spine which, when measured by x-ray, is greater than ten degrees. Scoliosis consists of a lateral curvature of the spine with rotation of the vertebrae within the curve. Rotation of the vertebrae also occurs which produces the rib cage and flank muscle asymmetry.

Spinal Canal - The long canal between the vertebral bodies anteriorly and the lamina and spinous processes posteriorly through which the spinal cord passes. The spinal cord and nerve roots extend to the level of the second lumbar segment in adults. Below this level are numerous nerve roots from the spinal cord that resemble a horse's tail and is referred to as such (cauda equina). The thick outer covering of the spinal cord is called the dura.

Spinal Fusion - A surgical procedure of stabilizing (permanently join to prevent motion) two or more vertebra by bone grafting. Can be done from the front (anterior), back (posterior), or as a staged procedure (first anterior and then posterior), usually with instrumentation.

Spinal Instrumentation - Metal implants fixed to the spine to improve spinal deformity while the fusion solidifies (becomes solid bone). This includes a wide variety of rods, hooks, wires, and screws used in various combinations.

Spinal Stenosis - Narrowing or reduction in the diameter of the spinal canal which surrounds the spinal cord, spinal roots and spinal sac (dura). This may secondary to a disc herniation, bone fracture, arthritic overgrowth of bone and soft tissue, or occasionally may have developed before birth.

Spinous Process - The portion of the vertebrae that protrudes posteriorly from the spinal column. The spinous processes create the "bumps" felt on the midline of the back.

Spondylitis - An inflammatory disease of the spine.

Spondylolisthesis - An anterior displacement (slipping) of a vertebra on the adjacent lower vertebra. There are several causes for this. There can be varying degrees of displacement so the vertebra and the spine above that vertebra are displaced forward in relationship to the vertebrae below. It is frequently due to a developmental defect or the result of a fracture.

Spondylolysis - (also referred to as a stress fracture or a pars fracture) - Fracture of a posterior portion of the vertebra with a defect in the neural arch between the superior and inferior facets of vertebrae without separation at the defect and therefore no displacement of the vertebrae. It may be unilateral or bilateral and is sometimes due to a developmental defect but may be secondary to an traumatic fracture.

Structural Curve - A segment of the spine that has fixed (nonflexible) lateral curvature.

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Glossary items beginning with T (6)

Thoracic (Dorsal) Spine - Twelve spinal segments (T1-T12) incorporating the 12 ribs of the thorax. Other than a slight increase in size from top to bottom, they are fairly uniform in appearance.


Thoracic Curvature - Any spinal curvature in which the apex of the curve is between the second and eleventh thoracic vertebrae.

Thoracolumbar Curve - Any spinal curvature that has its apex at the twelfth thoracic or first lumbar vertebra.

Thoracolumbosacral Orthosis (TLSO) - A type of brace immobilizing the thoracic lumbar and sacral spine. This may be used to help stabilize/ prevent progression of scoliosis curve(s) while a child is growing, or to immobilize the spine after surgery.

TLIF - Transforaminal Lumbar Interbody Fusion - A minimally invasive technique for performing an anterior fusion (front of the spine) of 2 vertebrae from a posterior approach.

Transition Syndrome - A degenerative change with bony instability above or below a previous fusion.

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Glossary items beginning with U (0)

There are no terms that start with "U".

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Glossary items beginning with V (2)

Vertebra - One of the 33 bones of the spinal column. A cervical, thoracic, or lumbar vertebra has a cylindrically shaped body anteriorly and a neural arch posteriorly (composed primarily of the laminae and pedicles as well as the other structures in the posterior aspect of the vertebra) that protect the spinal cord. The plural of vertebra is vertebrae.

Vertebral Column - The flexible supporting column of vertebrae separated by discs and bound together by ligaments.

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Glossary items beginning with W (0)

There are no terms that start with "W".

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Glossary items beginning with Y (0)

There are no terms that start with "Y".

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