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Glossary of orthopedic terms

This reference guide provides definitions for common orthopedic health terms that you may hear when your child is being treated for an orthopedic related condition. Many terms also have links to additional information on this website. Feel free to ask your child’s doctor, nurse, or any of our staff members for further information regarding any term you may still be unfamiliar with.

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Movement of a limb or body part away from the midline of your body

The cup-shaped socket of the hip joint

Adaptive equipment
Equipment that supports a child's positioning needs, such as seating, standing, positioning, and mobility, or assists with function

Adolescent scoliosis
Lateral spinal curvature that appears before skeletal maturity

The inward movement of an arm or leg toward the body

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

Ankle foot orthosis (AFO)
A short leg brace. Usually made of lightweight plastic that is worn inside the shoe. An AFO helps with better positioning of the feet and ankles

Anterior cruciate ligament (ACL)
The ligament, located in the center of the knee, that controls rotation and forward movement of the tibia (shin bone)

Anterior spinal fusion
A fusion performed on the front of the spine; usually involves replacing inter-vertebral discs with bone

Arthritis (osteoarthritis)
Joint inflammation, resulting in pain, swelling, stiffness, and limited movement.

Term used to describe a number of rare, non-progressive conditions characterized by stiff joints and abnormal muscle development

A thin, fiberoptic scope introduced into a joint for diagnostic and treatment procedures inside the joint; can be used for diagnosis or repair

A surgical procedure to open and explore a joint

Articular cartilage
Connective tissue that reduces friction between bony surfaces; found on the surfaces of bones within joints

Weakening of muscle tissue from lack of use

Avascular necrosis (AVN)
A disease caused by the temporary or permanent loss of blood supply to bones; bones lacking blood can collapse and die

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Relating to both sides of the body

Bone age
An x-ray of the hand and wrist is compared to the average appearance of the bones at different ages. An estimate of remaining growth is obtained.

Bone graft
Pieces of bone used to create fusion. Bone graft may be obtained from the patient's iliac crest, rib, wrist, or from the bone bank.

Bone remodeling
The absorption of bone tissue and the simultaneous depositing of new bone; a bone’s continuous self-renewal, self-healing, and self-realignment, partially through reorientation of the growth plate.

Brace, spinal
A semi-rigid plastic device, which pushes on muscles and ribs near the spinal column. The brace is designed to decrease the abnormal spinal curvature while worn.

Brachial plexus
A complex network of nerves between the neck and shoulders. These nerves control muscle function in the chest, shoulder, arms, and hands, as well as sensibility (feeling) in the upper limbs.

Brachial plexus birth palsy (BPBP)
An injury (stretch, compression, or tear) to all or part of the brachial plexus nerve complex; occurs during childbirth; can result in loss of muscle function or paralysis of upper arm.

Fluid-filled sacs located between the bones, ligaments, or other adjacent structures that help cushion the friction in a joint

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A surgical procedure to tighten loose tissue around the shoulder joint

A smooth, rubbery tissue that cushions the bones at the joint, and allows the joint to move easily without pain

External devices used to hold a bones of the hip joint in place while they develop in proper position

Cervical spine
That portion of the vertebral column contained in the neck, consisting of seven cervical vertebrae between the skull and the rib cage

A bending or curvature deformity of the finger which occurs in the plane of the hand

A congenital deformity of the foot usually marked by a curled shape or twisted position of the ankle and heel and toes.

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

Computed tomography (CT, CAT) scan
A non-invasive procedure that uses x-ray equipment and powerful computers to create detailed, cross-sectional images of your child’s body. The CT scanner is a large machine that looks like a big doughnut.

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

The tightening or shortening of a muscle during a short period of time.

Permanent contraction of a muscle.

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Diagnosis, diagnostics
Identifying disease or injury through examination, testing, and observation.

Developmental dysplasia of the hip
A condition in which the head of the femur is not stable within the hip socket. If this condition goes untreated, it can lead to pain and osteoarthritis.

The inter-vertebral disc is a strong, rubbery, and gelatin-like structure which normally separates the individual vertebral bodies and allows movement between them. Discs are usually removed from the portion of the spine undergoing anterior fusion and replaces with bone chips to create a fusion.

The removal of all or part of an intervertebral disc (the soft tissue that acts as a shock absorber between the vertebral bodies).

A dislocation occurs when extreme force is put on a joint, allowing the ends of two connected bones to separate.

Double curve
Two lateral curvatures (scoliosis) in the same spine. Double major curve is two lateral curves of equal magnitude, and double thoracic curve is two thoracic curves.

An abnormal development of tissue; an alteration in the size, shape, and/or organization of cells or tissues.

Impaired or disordered muscle tone.

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The complex joint between the upper arm bone (humerus) and the forearm bones (radius and ulna).

Benign (non-cancerous) cartilage tumors seen frequently in arms and legs.

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Femoral head
Round-headed top of the thigh bone (femur)

The thigh bone, the longest and strongest of your child’s bones. The rounded top of the femur (femoral head) joins the hip socket (acetabulum) to form the hip joint

Flexion deformity
Abnormal positioning of a bone or joint in a bent, or flexed position

Fluctuating tone
Combination of low and high muscle tone

A partial or complete break in the bone

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Growth disturbance
A fracture that extends into the bone’s growth plates in still-growing children can disturb or stop the normal growth of the bone (growth arrest). This can lead to limb length discrepancies or angular deformities. Surgery on broken limbs in children must account for these growth plates

Growth plate (physis)
Areas of cartilage at either end of a bone from which growth occurs. As key components of a child's developing skeletal system, growth plates largely turns to bone (ossify) as a child grows

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A congenital anomaly of the spine caused by incomplete development of one side of a vertebra resulting in a wedge shape

High tone
Term used to describe tight or spastic muscles

Hip impingement
A condition in which the femoral head doesn't have a full range of motion within the acetabulum; caused by too much bone around the head and/or the socket turned backwards; causes pain and can result in damage to the cartilage and labrum

The bone of the upper arm

Increased tension in the muscles

Decreased tension in the muscles

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Idiopathic scoliosis
A structural spinal curvature for which cause has not been established

Iliac crest
The large flat portion of the pelvis bone from which bone graft may be taken

Infantile scoliosis
Lateral curvature of the spine that begins before age 3

Internal fixation
Metal screws and pins surgically inserted inside the bone to hold bone fragments in place to allow alignment and healing

The intravenous line that delivers fluid and medicines through a hollow tube inserted in a vein

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The largest and most complex joint in your child’s body, joining the thigh bone and shin bone and covered by the patella. It depends on four ligaments, as well as other muscles and tendons, to function properly.

Curvature of the spine with the curve pointing toward the front of the body

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Looseness, instability

Elastic band of tissue connecting bone to bone

An anterior angulation of the spine in the sagittal plane. Contrast to kyphosis

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

Pertaining to the lumbar and sacral regions of the back

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Abnormal enlargement of one or more fingers or toes

Maldevelopment (dysplasticity)
Condition in which a bone or joint is not properly developed/developing

Mal-union (mal-alignment)
A condition in which a broken bone heals in a poor alignment or a deformed state (such as an angular deformity); rare in children


A curved part of cartilage in the knees and other joints

Long bones in the palm, between the wrist and fingers

A small injury to the body, such as microtears to muscle fibers, stress to the tendon, bruising of the bone; can occur to bone, muscle, tendon or ligament. If not allowed rest in order to heal, accumulated microtraumas can lead to overuse injuries, such as stress fractures.

MRI (magnetic resonance imaging)
Produces detailed images of organs and structures within the body; best for looking at soft/non-bone tissues such as ligaments, tendons, muscle, and cartilage

Muscle tone
The amount of tension or resistance to movement in a muscle

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Neuromuscular scoliosis
A form of scoliosis caused by a neurological disorder of the central nervous system or muscle

Non-surgical (non-operative) treatments
Alternatives to surgery

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Orthopedic surgeon, orthopedist
A doctor who specializes in surgical and non-surgical treatment of the skeletal system, spine and associated muscles, joints and ligaments

The medical specialty concerned with diagnosing, treating, rehabilitating and preventing disorders and injuries to the spine, skeletal system and associated muscles, joints and ligaments

A type of arthritis caused by the inflammation, breakdown, and eventual loss of articular cartilage in the joints

A benign tumor that contains both bone and cartilage and usually occurs near the end of a long bone

Destruction of bone caused by disease, infection or loss of blood supply

Less bone mineral density than normal, a precursor to osteoporosis

An outgrowth of bone which forms around joints, deforming the joints and limiting their movements; commonly found in joints with osteoarthritis

Loss of bone density

A surgical procedure in which bones are cut and re-orientated, with the goal of improving upper extremity function

Overuse injuries
Sports-related microtraumas that result from repetitively using the same parts of the body, usually by overtraining; can occur to muscle, tendon, ligament or bone

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The mechanical forces of a disease that adversely change the body's structure and function

Pavlik harness
A type of brace used on infants to improve the position of the femoral head in the acetabulum

Periacetabular osteotomy (PAO)
A type of surgery in which the bones surrounding the acetabulum are cut and repositioned in order to better align the femoral head within the acetabulum

The thin layer of tissue that covers a bone

Perthes disease
A condition in which the femoral head dies because of a temporary loss of blood supply to it

Any of the bones (or phalanges) of the fingers or toes

Physeal fracture
A break that occurs at, into or across a growth plate; must be treated promptly to avoid growth disturbance or deformity

Physical therapy
A rehabilitative health specialty that uses therapeutic exercises and equipment to help patients improve or regain muscle strength, mobility, and other physical capabilities

Physis, physes
A growth plate(s) at both ends of a bone; the source of bone growth

The presence of more than the normal number of fingers or toes

Post-operative (post-op)
After surgery

Posterior fusion
A technique of stabilizing two or more vertebra by bone grafting

Pre-operative (pre-op)
Before surgery

An artificial body part replacement

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Radioulnar synostosis
An abnormal bony or soft tissue connection between the radius and ulna, the two bones of the forearm

The long bone of forearm that rotates around the fixed ulna allowing for palm-down and palm-up positions of wrist

Range of motion (ROM)
The amount of movement present at a person's joint

Rib hump
The bump formed by ribs on the curve, caused by rotation of the spine and attached ribs

Risser sign
The top of the pelvis bone grows in predictable stages referred to as Risser stages. These give some indication of growth remaining in the spine and rest of the skeleton

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Curved triangular bone at the base of the spine, consisting of five fused vertebrae known as sacral vertebrae

A hardening of tissue; often occurs in advanced stages of arthritis

Sideways curvature of the spine greater than 15 degrees

Shin splints
Pain and inflammation to muscles, tendons and tissue in the area of the shin bone (tibia)

Skeletal maturity
When the bones, including the spine, are finished growing, skeletal maturity has been reached

Slipped capital femoral epiphysis (SCFE)
A condition in which the growing end of the femur slips off from the rest of the femur

Spinal column
The spinal column is made up of individual vertebral bones, ligaments and discs. It surrounds the spinal cord

Spinal cord
The spinal cord goes through the spinal column and consists of nerves, which carry and receive signals to and from the brain, arms, legs and many internal organs

An inflammatory disease of the spine

An anterior displacement of a vertebra on the adjacent lower vertebra

A partial or complete tear of a ligament

A partial or complete tear of a muscle or tendon

Stress fracture
Tiny overuse fractures, usually to a bone in the foot or the shin bone (tibia), causing pain and inflammation

Term used to describe webbed or conjoined fingers

Synovial membrane
A tissue which lines the joints and seals it into a joint capsule. The synovial membrane secretes synovial fluid (a clear, sticky fluid) around the joint to lubricate it

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A band of tough, inelastic fibrous tissue that connects a muscle with its bony attachment

Tendon transfer
Surgical procedure in which the tendon is separated from its normal attachment and is reattached in a different place. The goal of this procedure is to improve range of motion in the shoulder, wrist, elbow, and hand

The shin bone; the larger bone of the lower leg

A sustained mechanical pull to a limb to correct a dislocation or broken bone

Trigger thumb
A thumb that clicks, catches, or locks as the tip of the thumb moves from a flexed (bent) to extended (straight) position

Total joint replacement
A surgery done to replace a worn out joint

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Forearm bone that runs from the tip of the elbow to the little finger side of the wrist

A non-invasive diagnostic imaging tool

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Individual bones which make up the spinal column

Vertebral body
The front portion of the individual vertebra

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X-ray (radiograph)
Diagnostic radiology that shows the dense structures, including bones, inside your child's body

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