Medical Term Glossary

Plain-language explanations of the medical terms that appear on CT, MRI and X-ray reports — what each one means, when it matters, and what to ask your doctor.

All Brain Spine Chest Abdomen Msk Pelvis General

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

B

Bone marrow edema

An area inside a bone where extra fluid has built up among the soft tissue that fills its core. It usually signals that the bone is reacting to something — a recent injury, repeated stress, inflammation, or a nearby joint problem — and shows up as a bright patch on MRI sequences sensitive to water.

Also: bone bruise, bone marrow edema syndrome, bone marrow lesion

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Bursitis

Inflammation of a bursa — one of the small fluid-filled cushions that sit between bone and the soft tissues around joints. When a bursa becomes irritated, it fills with extra fluid and shows up on imaging as a fluid pocket. Most cases settle with rest and time; a smaller number are infected and need treatment.

Also: bursa inflammation, bursal distension, bursal inflammation

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C

Cortical bone

The hard, dense outer layer of bone — the part you would feel if you tapped a bone with your knuckle. It surrounds and protects the softer, spongy inner bone (called trabecular or medullary bone). Most of the strength of a bone comes from this outer shell, and radiologists pay close attention to it for fractures.

Also: bone cortex, compact bone, cortex

D

Dislocation

A joint where the bones are no longer lined up the way they should be. In the full form the bone surfaces have lost contact completely; in a partial form (subluxation) they are misaligned but still touch. Most need to be put back into place promptly, although the urgency varies by joint and whether nearby structures are injured.

Also: dislocated joint, displaced joint, joint displacement

urgent

I

Impingement

A radiology word for pinching — when two structures inside a joint rub or compress each other during normal movement instead of gliding cleanly past each other. Most often described in the shoulder (between the bones at the top) and the hip (between the ball and the rim of the socket), and not always painful.

Also: FAI, femoroacetabular impingement, hip impingement

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J

Joint effusion

Extra fluid inside the capsule that wraps around a joint. A small amount of fluid is normal and keeps the joint lubricated; a larger amount usually signals that something has stirred up the lining — an injury, arthritis, infection, gout, or inflammation — and is making more fluid than the joint can absorb.

Also: fluid in the joint, fluid on the knee, intra-articular effusion

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L

M

Meniscal tear

A split in one of the two C-shaped pads of cartilage that sit between the thigh bone and the shin bone inside the knee. These pads cushion and stabilise the joint. Tears can follow a sudden twist or develop gradually with age, and not every tear seen on a scan causes pain.

Also: bucket-handle tear, lateral meniscus tear, medial meniscus tear

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O

Osteoarthritis

The most common form of joint wear. The smooth cartilage that lines the ends of the bones inside a joint gradually thins, the joint space narrows, and small bony ridges form along the edges. Extremely common with age — most adults over 60 show some of it on imaging, and many feel nothing from it.

Also: DJD, OA, degenerative arthritis

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R

Rotator cuff tear

Damage to one of the four small muscle-tendons that wrap around the top of the shoulder and keep the arm bone seated in its socket. The tear can be a thin partial fray on the surface or a full break through the tendon. Many are gradual age-related wear; others follow a sudden injury.

Also: cuff tear, partial-thickness cuff tear, rotator cuff injury

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T

Tendinopathy

A catch-all term for a tendon that's been irritated, overloaded, or worn down over time. The tissue thickens, loses some of its tidy fibre pattern, and may show small areas of damage inside it. Common in shoulders, elbows, knees, and ankles, and often linked to repeated load rather than a single injury.

Also: tendinitis, tendinosis, tendon degeneration

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Medical Term Glossary

B

Bone marrow edema

Bursitis

C

Cortical bone

D

Dislocation

I

Impingement

J

Joint effusion

L

Labral tear

Ligament tear

M

Meniscal tear

O

Osteoarthritis

R

Rotator cuff tear

T

Tendinopathy

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