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Glossary of Orthopaedic Terms


Arthritis—inflammation of a joint or joints resulting in pain or swelling

ACL—anterior cruciate ligament; attaches to the front of the knee and passes through the middle of the knee; functions to prevent hyperextension of the joint and to prevent the femur from sliding backward in relation to the tibia.  The ACL is particularly prone to sports injuries due to stretching and tearing of the ligament

Arthroscopy—the surgical examination of a joint using an endoscope (a long, slender instrument) that is inserted into the joint through a small incision

Avascular Necrosis (AVN)—a bone tissue disease that results from impaired or disrupted blood supply (as caused by injury or disease); results in severe pain in the affected region and weakened bone that may collapse; when AVN occurs near a joint, collapse of the joint surface is possible

Bunion—an inflammation and swelling of the bursa (small sac) on the first joint of the big toe

Bursa—a small, fluid-filled sac between a tendon and a bone

Bursitis—inflammation of a bursa, especially of the shoulder, elbow, or knee joint; symptoms can include pain, tenderness, and decreased mobility of the joint

Carpal Tunnel Syndrome—a condition caused by pressure on the median nerve in the carpal tunnel of the wrist; symptoms can include weakness, pain, numbness, and tingling in the hands and fingers

Cartilage—a tough, elastic tissue that lines the joints in the body to cushion against shock

Contusion—an injury in which the skin is not broken; a bruise

Cortisone—a steroid preparation that can be injected into various areas of the body to provide pain relief from conditions such as an arthritic joint; in some cases, cortisone may alleviate problems like bursitis and tendonitis

DeQuervain’s Syndrome—a painful condition at the wrist on the side closer to the thumb, resulting from tendons getting trapped beneath a ligament as they travel to the thumb; can be treated with a brace, a cortisone injection, or surgery to relieve the pressure on the tendon(s)

Dupuytren’s Contracture—a thickening and shrinking of the fascia, the layer of deep tissue just under the skin of the palm; as the tissue shrinks, the fingers may be drawn into a bent position

EMG (Electromyogram)—a test that records the electrical activity of a nerve or muscle

Fracture—a break, rupture, or crack of the bone or cartilage

Ganglion Cyst—a fluid-filled cyst that forms on the top of a joint or tendon in the hand or wrist

Hammertoe—a toe, usually the second toe, that is permanently flexed downward resulting in a claw-like shape

Herniated Disc—a painful rupture of the outer cartilage of a disc that results when the cushion that lies between vertebrae in the spine is pushed outside its normal position; symptoms can include pain, weakness, and/or numbness in the legs (lumbar disc) or arms (cervical disc)

Inflammation—the normal reaction of body tissue to injury or infection; symptoms can include pain, heat, redness, and swelling

Joint—a point of contact between two or more bones; usually allows for movement

Ligament—a band or sheet of tough tissue that connects bones or binds cartilage to provide stability

Meniscus—a soft cartilage that exists in the knee joint and serves as a cushion; if torn, symptoms can include pain, swelling, or locking; meniscus can be either removed or repaired through an arthroscopic procedure

Morton’s Neuroma—a benign growth of nerve tissue that usually develops between the third and fourth toes; symptoms can include a sharp, burning pain in the ball of the foot, stinging toes, and/or numbness in the foot

Osteoarthritis—a type of arthritis, occurring most often in older patients, that is characterized by chronic deterioration of the cartilage of the joints; symptoms can include joint pain, stiffness, and swelling

Osteoporosis—a disease in which bone mass and density decreases over time resulting in a weakening of the bones that makes them especially subject to fracture and deformities; the disease most commonly affects older women

Plantar Fasciitis—an overuse injury characterized by inflammation of the tough, fibrous tissue that connects the heel bone to the base of the toes; initial symptoms can include mild heel pain, and if left untreated, problems with the foot, knee, hip, and back

Rotator Cuff—a group of muscles and tendons that connect the arm to the shoulder joint and enable the arm to rotate

Scoliosis—an abnormal sideways curvature of the spine

Shoulder Impingement—a condition that occurs when a rotator cuff tendon or a bursa in the shoulder is compressed as the arm is raised; symptoms can include arm and shoulder pain, especially upon lifting the arm

SLAP Lesion—a tear of a piece of cartilage that lines the socket of the shoulder joint; usually occurs after an injury to the shoulder and may require arthroscopic surgery for its repair

Soft Tissue—tissues (including muscles, tendons, ligaments, and nerves) that connect, surround, or support other organs and musculoskeletal structures of the body

Spinal Stenosis—a narrowing of the spinal canal that creates pressure on the spinal cord and nerve roots; symptoms can include low back pain and leg pain

Sprain—a stretching or tearing of the ligaments of a joint; symptoms can include swelling, inflammation, hemorrhage, and discoloration

Strain—a stretching or tearing of the muscles or tendons

Stress Fracture—a hairline fracture or small crack of a bone that has been subjected to repeated stress or excessive activity; an overuse injury

Synovium—a thin membrane (in freely moving joints) that secretes a fluid that allows for movement between the solid parts of a joint

Tendon—a tough band of fibrous tissue that connects bones to muscles and other tissues

Tendonitis—a condition marked by inflammation of a tendon

Tennis Elbow—a degenerative condition marked by painful inflammation of the tissue surrounding the outer side of the elbow; usually caused by excessive strain and twisting of the forearm.

Total Joint Replacement—surgical procedures in which parts of an arthritic or damaged joint are removed and replaced with a prosthesis (a plastic or metal device)

Trigger Finger—an abnormal condition in which inflammation and thickening of the tendons of the finger make it difficult to straighten or bend the finger; tendons may become momentarily stuck and then snap into a straightened position like a trigger being pulled and released


Definitions adapted from the following sources:

The American Heritage Science Dictionary, © 2002 Houghton Mifflin Company
The American Heritage Stedman’s Medical Dictionary, © 2002 Houghton Mifflin Company
Merriam-Webster’s Medical Dictionary, © 2002 Merriam-Webster, Inc.