Osteoporosis: Glossary of Terms

Bone
Organs composed of hard living tissue providing structural support to the body and made mostly of collagen and calcium.

Bone density
The amount of calcium and minerals in the bone tissue.

Bone mass
The total amount of bone tissue in the skeleton.

Bone mineral density (BMD) test
A test used to diagnose osteoporosis. It detects bone loss even in its early stages. The test can also be used to determine if a person is at risk for fractures and can be used to monitor increases in bone density as a result of treatment.

Calcitonin
A naturally occurring hormone secreted by the thyroid gland known to increase bone density. It can also help relieve pain associated with fractures. It is available in two forms: injection or nasal spray.

Calcium
A mineral found in many foods and used by the body to help strengthen bones and teeth.

Cancellous bone
Also called trabecular bone; an inner spongy structure that resembles a honeycomb. The inner bone cavities contain bone marrow where red blood cells are produced.

Cartilage
Stretchy tissue that, as the body grows, develops into bone. Remaining cartilage helps keep bones flexible.

Compression fracture
An injury to the spine in which one or more vertebrae collapse. If the collapse is only in the front part of the spine, it becomes wedge shaped and is called a compression fracture or wedge fracture. However, if the vertebral body is crushed in all directions it is called a burst fracture.

Cortical bone
The outer layer of bone. Hard bone - the dense outer covering of bone; also known as compact cortical bone.

Hormone replacement therapy (HRT)
Also called estrogen replacement therapy (ERT). This treatment is often given to women to replenish estrogen levels lost during menopause thereby slowing down the rate of bone loss and reducing the risk of fractures. However, experts do not know all the risks of long-term use of this therapy.

Kyphotic curve
Commonly called "humpback." A telltale sign of advanced osteoporosis and the result of the collapse of vertebrae in the thoracic spine. A severe kyphotic curve can cause pain, tingling, numbness, and weakness.

Kyphoplasty
A relatively new treatment for compression fractures that involves the use of a catheter and "balloon" which are injected into the space between the vertebrae. The balloon is inflated and filled with an orthopedic cement that hardens and helps return the vertebral space to its original height.

Ossification
The process of cartilage changing into hard bone.

Osteoblast
A type of cell that form bone.

Osteoclast
A type of cell that break down bone.

Osteocyte
A cell within regions of adult bone involved in the maintenance of bone.

Osteomalacia
Also known as "adult rickets." A condition in which bones become soft as a result of a Vitamin D deficiency.

Osteopenia
A condition in which there is a decrease in bone density but not necessarily an increase in the risk or incidence of fracture.

Osteoporosis
A condition in which there is a decrease in bone mass and bone density and an increased risk and/or incidence of fracture. Peak bone mass - the maximum amount of bone a person can achieve during skeletal growth.

Periosteum
A fibrous membrane that covers the outside of bone.

Raloxifene (brand name Evista®)
A drug recently approved for the prevention of osteoporosis that prevents bone loss. It is from a new class of drugs called Selective Estrogen Receptor Modulators (SERMs).

Skeletal system
The rigid framework of bones in the body that supports soft tissues and protects internal organs.

Spinal column
Also called the vertebral column; extends from the skull to the pelvis and is made up of 33 individual bones called vertebrae. The spinal column is divided into four regions: cervical, thoracic, lumbar, and sacral.

Vertebrae
Any one of the 33 bony segments of the spinal column.

Vertebroplasty
A new procedure used to treat compression fractures that utilizes orthopedic cement, which is injected into the space between the vertebrae. The cement hardens and returns the vertebral space to its original height.