2 (Final): Bone Growth, Development and Remodeling

Flashcards covering vocabulary and processes related to bone development, ossification styles, postnatal growth, bone health conditions, and fracture types/repair.

Ossification (Osteogenesis)

The formation of bone (osseous) tissue, which begins late in the second month of life and continues into early adulthood.

Appositional growth

Growth in diameter (width) accomplished by adding new layers of matrix onto the external surface of existing cartilage or bone.

Interstitial growth

Growth in length accomplished by growth from within the cartilage or bone.

Mesenchyme

Embryonic stem cells, which are undifferentiated cells that can develop into specialized cell types.

Endochondral ossification

A complex process where mesenchyme is first transformed into a hyaline cartilage bone template, which is then gradually replaced by bone.

Intramembranous ossification

A process where mesenchyme is directly transformed into bone within fibrous connective membranes, used to create most flat bones of the skull and the clavicles.

Osteoid

The organic part of the bone matrix (ECM).

Hydroxyapatite

The inorganic bone matrix represented by the crystallized form of the mineral salt calcium phosphate.

Calcification

The deposition of calcium salts into a tissue, which causes the tissue to harden.

Bone collar

A collar of compact bone secreted by osteoblasts against the hyaline cartilage model diaphysis during endochondral ossification.

Primary ossification center

The central region of the diaphysis where bone formation begins during endochondral ossification.

Periosteal bud

A collection of blood vessels (nutrient artery and vein), nerve fibers, red marrow elements, osteoprogenitor cells, and osteoclasts that invades internal cavities during month 3.

Secondary ossification center

Ossification centers that develop in the epiphyses around birth; large long bones typically form these in both ends.

Articular cartilage

Hyaline cartilage that is 'left behind' on the epiphyseal surfaces after secondary ossification is complete.

Epiphyseal (growth) plate

The junction of the diaphysis and epiphysis where active cartilage remains and is replaced by bone for longitudinal growth until skeletal maturity.

Resting zone

The region of the epiphyseal plate facing the epiphysis where cartilage is relatively inactive.

Proliferation zone

The region of the epiphyseal plate where chondrocytes quickly divide (mitosis), pushing the epiphysis away from the diaphysis.

Hypertrophic zone

The region in the epiphyseal plate containing older, enlarged chondrocytes with lacunae that begin to erode.

Calcification zone

The region at the epiphysis-diaphysis junction where the matrix calcifies, chondrocytes die, and blood vessels invade the deteriorating matrix.

Ossification zone

The region immediately next to the diaphysis where osteoclasts and osteoblasts remodel calcified cartilaginous projections into spongy bone.

Epiphyseal plate closure

The event when chondrocytes cease dividing and the epiphysis and diaphysis fuse, typically occurring between 18 and 21 years of age.

Skeletal maturity

The point in time reaching full bone development when longitudinal bone growth concludes and only an epiphyseal line remains.

Bone Mineral Density (BMD)

The mass of bone mineral (calcium salts) per unit of volume, also known as bone mass.

Osteopenia

The first stage of bone mineral density loss that occurs when bone resorption outpaces bone deposition.

Osteoporosis

A condition where bone mineral density declines to the point that bones become porous, light, fragile, and susceptible to spontaneous fracture.

Wolff’s Law

A principle stating that the anatomy of a bone reflects the mechanical stresses (gravity, load, muscle contraction) placed upon it.

Arthritis

A group of over 100 different types of inflammatory or degenerative diseases that damage joints and peri-articular tissues.

Osteoarthritis (OA)

The most common form of arthritis where articular cartilage gradually breaks down, leading to thickened subchondral bone and osteophytes.

Osteophytes

Bony spurs that form at bone ends in advanced osteoarthritis, potentially restricting joint movement.

Fracture

A term for any break in a bone, which can result from traumatic injury or atraumatic stress.

Stress fracture

An atraumatic, incomplete 'hairline' fracture caused by repetitive submaximal loading or overuse.

Complete fracture

A fracture classification where the bone is broken into separate pieces.

Incomplete fracture

A fracture classification where the bone is not broken into separate pieces.

Displaced fracture

A fracture where the bone pieces move out of their normal alignment.

Nondisplaced fracture

A fracture where the broken bone pieces retain their normal position in alignment.

Open (compound) fracture

A fracture where the bone breaks through the skin or is visible through a large wound.

Closed (simple) fracture

A fracture where the bone is broken but the skin remains intact.

Comminuted fracture

A common type of fracture in the aged where the bone fragments into three or more pieces.

Compression fracture

A fracture common in porous bones where the bone is crushed, such as in an osteoporotic vertebra.

Spiral fracture

A ragged break occurring when excessive twisting forces are applied to a bone, common in sports.

Epiphyseal fracture

A break where the epiphysis separates from the diaphysis along the epiphyseal plate.

Depressed fracture

A typical skull fracture where the broken portion of bone is pressed inward.

Greenstick fracture

An incomplete break common in children where one side of the shaft breaks and the other side bends.

Hematoma

A mass of clotted blood that forms at a fracture site due to torn blood vessels.

Fibrocartilaginous (soft) callus

A temporary structure formed during bone repair consisting of collagen fibers and a cartilaginous matrix that connects broken bone ends.

Bony (hard) callus

A firm union of trabeculae of new spongy bone that forms within the soft callus about two months after a fracture.