Bone and Joint EXAM 3

stem

marrow

osteoblasts

Key points about osteoprogenitor cells

- From ____ cells

- Reside in the _____

- Give rise to the _____

Produce and mineralize bone

what is the function of osteoblasts

osteoblast; lacuna

mechanical

Osteocyte

- An ______ that is completely embedded in the bone matrix in a _____

- Is responsible for detecting and responding to ______ forces

resorption

mineralized

Osteoclasts

- Bone _____

- Only reabsorb _____ bone

macrophages

what type of cell are osteoclasts similar to

- epiphysis

- metaphysis

- diaphysis

what are the 3 compartments of long bone

Epiphysis

- From subarticular bone plate to the growth plate

- Source of red marrow, site of erythropoiesis

- Location of articulation at the tip of long bone

Metaphysis

- From the growth plate to the area where the bone develops its fluted shape

- Responsible for linear growth

- After ossification important for mechanical load

Diaphysis

- Shaft or "body" of the bone between the 2 metaphyses

- hollow; contains the bone medulla, which houses yellow marrow

periosteum and endosteum

what are the two layers of bone

periosteum of bone

- Fibrous capsule covering the bone

- Provides innervation, circulation and nutrition (esp. to outer 1/3)

endosteum of bone

- Inner surface of bone

- Typically in contact with bone marrow

osteoprogenitor cells

what can be found in both the periosteum and endosteum

Involved in fracture healing and bone growth

what is role of osteoprogenitor cells found the in periosteum and endosteum

- compact bone

- cancellous bone (spongy bone)

what are the 2 Structural Types of Bone

compact bone

- Dense (AKA "cortical"); the outer shell that defines the shape of the bone

- 80% of the adult skeleton

- Shafts and around cancellous bone at the end of joints

cancellous bone

- "trabecular," "spongy" bone

- At ends of long bones within the medullary canal, in vertebrae, and in flat bones

- MANY more bone cells than compact bone

cancellous bone

- Reduces impact of strong external forces

- Leaves space for hematopoeisis

the trabecula

what is the basic unit of cancellous bone

Femoral head and condyles

what are examples of trabecula

lamellar bone

- Parallel alternating arrangement of Type I collagen fibers that are highly organized to provide strength to bone

- Normal adult skeleton will ONLY have this

- Cortical and trabecular bone have this pattern

- Manufactured slowly

woven bone

- Irregular arrangement of Type I collagen

- Numerous osteocytes in the matrix

- Haphazardly arranged collagen causing low tensile strength

- acts as a scaffolding

- Rapidly produced

- Found in the fetus, areas surrounding tumors and infections and healing fractures

- Always "pathologic" in the adult skeleton

osteon

functional unit of compact (cortical) bone

osteons

- Run parallel to the bone shaft

- Made up of the Haversian canal and the osseous lamellar bone around it

- Cylinder composed of 4 to 20 concentric lamellae arranged around a central opening

- Haversian canals

- Volkmann's canals

- Lacunae

- Canaliculi

what are the components of an osteon

Haversian canals

- Central canal of osteon containing blood vessels, lymphatics, nerves

- Run parallel to the long axis in the cortex

Volkmann's canals

- Carry blood vessels for nutrient exchange between osteons

- Connect the Haversian canals to one another and to the periosteum

- Run perpendicular to the long axis

Lacunae

small, microscopic cavities, pits, or spaces that house osteocytes

canaliculi

microscopic canals or tunnels that facilitate nutrient transport and communication between osteocytes

- Nutrient arteries

- Perforating arteries

what are the 2 types of arteries that supply blood to bone

nutrient arteries

Supply the marrow and internal 1/3 - 2/3 of the cortex

perforating arteries

- From the periosteal arteries

- They anastomose in the cortex with branches from the nutrient arteries

- Organic matrix

- Inorganic matrix

what is the Bone matrix comprised of:

organic matrix of bone

_____ matrix of bone: type I collagen secreted by osteoblasts and non-collagenous proteins

inorganic matrix of bone

______ matrix of bone

- composed primarily of a form of calcium phosphate called hydroxyapatite 

- Mineral component that provides bone with its strength

hyaline

epiphyseal plate

chondrocytes

osteoblasts

Bone Growth for Length

- Main cartilage mass at end of bone is typical _____ cartilage which gets replaces with bony tissue

- The cartilage in the region of the ________ next to the epiphysis continues to grow by mitosis. The ________, in the region next to the diaphysis, age and degenerate. ________ move in and ossify the matrix to form bone.

- Cartilage proliferation

- Calcification of cartilage and then degeneration

- Bone formation on the cartilage remnants

- Resorption of bony trabecular tips

what is the order of events for the growth of bone in terms of length

periosteal; osteogenic

Bone growth for width

- Bone laid down in regular fashion at _____ surface of diaphysis by _____ cells

- Appositional growth

- Concurrent resorption of bone on inner, endosteal surface

fracture

Any deficit in the continuity of bone

fractures

what is the most common type of bone lesion

stress fractures

Fracture in normal bone that is unable to withstand repeated abnormal stress

insufficiency fracture

A Fracture as a result of normal stress applied to bone with deficient elastic resistance or has been weakened by decreased mineralization is classified as what type of fracture

pathologic fracture

A Fracture in diseased, weakened bone due to focal pathology is classified as what type of fracture

incomplete

full

Key points about stress fractures

- Stress reaction in small fracture usually _____

- Stress fracture is ___ thickness

open fracture

- AKA: Compound

- Communicate with "outside world"- dirt!

- If it breaks through the skin

closed fracture

Skin remains intact, fracture remains enclosed

open fracture

closed fracture

simple fracture

One fracture line

simple fracture

segmented fracture

Two fracture lines, resulting in "floating" piece of bone

segmented fracture

comminuted fracture

Multiple fragments at fracture site, associated with multiple fracture lines

Comminuted fracture

displaced fracture

Fracture associated with fragments moving out of alignment, necessitating medical realignment (reduction)

angulation fracture

distal segment tilts away from normal axis

by the position of the distal segment in relation to the proximal

how are displaced fractures named

medial displaced fracted

lateral displaced fracture

distracted displaced fracture

overriding with posterior and superior displacement fracture

distracted and rotated laterally displacement fracture

transverse fracture line

fracture is perpendicular to bone axis

transverse fracture line

oblique fracture line

fracture occurs diagonal across bone axis

oblique fracture line

spiral fracture line

torsional fracture that spirals around bone, often due to twisting

spiral fracture line

linear/longitudinal fracture line

fracture is parallel with axis of bone

linear/longitudinal fracture line

greenstick fracture

Incomplete break, causing bending of bone

greenstick fracture

torus fracture

- AKA: impacted, buckle

- Broken bone ends driven into one another

torus fracture

compression fracture

Crushed bone, causing wider/flatter appearance

vertebral fractures

where are compression fractures commonly seen

compression fracture

avulsion fracture

Fracture due to tendon/ligament pulling off small piece of bone

avulsion fracture

- Greenstick Fracture

- Epiphyseal (growth plate) fractures

- Plastic deformation

what types of fractures are more likely to be seen in children (3 types)

- Can cause growth to be arrested or altered

- Immediate intervention required

what are the clinical implications of Epiphyseal (growth plate) fractures

plastic deformation of bone

No fracture but the bone permanently bends

Salter Harris grading scale

a system used to grade pediatric fractures that involve the growth plate (physis), categorized into Types I–V based on the injury's impact on the growth plate, metaphysis, and epiphysis

Salter Harris grade 1 growth plate fracture

Salter Harris grade?

Salter Harris grade 2 growth plate fracture

Salter Harris grade?

Salter Harris grade 3 growth plate fracture

Salter Harris grade?

Salter Harris grade 4 growth plate fracture

Salter Harris grade?

Salter Harris grade 5 growth plate fracture

Salter Harris grade?

Plastic deformation of bone

when reach 30 y/o

when does bone mass reach its peak

- Women experience loss beginning in late 30s, accelerated during and after menopause

- Men experience bone loss in mid-late 60s

what happens once Bone mass reaches it peak at 30 y/o

- Low bone mineral density (BMD)

- Age

what are the 2 most important risk factors for fractures

- hematoma formation

- cellular proliferation

- callus formation and ossification

- consolidation and remodeling

what are the phases of healing for fractures (4 steps)

clotting

fibrin

leukocytes, macrophages

Neo

Hematoma formation phase of bone healing

- Within 48-72 hours _____ factors initiate the formation of hematoma

- Creates ____ meshwork

- Extensive necrosis requiring _____ and ____ to clean up debris

- ___-vascularization

the hematoma formation phase

what phase of bone healing is characterized by the creation of a fibrin meshwork, the presence of leukocytes and macrophages, as well as neovascularization

48-72 hours

how long does it take for Clotting factors initiate the formation of hematoma during bone healing from a fracture

Fibroblasts and osteoblasts

Cellular proliferation phase of bone healing

• ______ and ______ proliferate and form fibrocartilage collar around fracture site

cellular proliferation phase of bone healing

what stage of bone healing is characterized by Fibroblasts and osteoblasts proliferate and form fibrocartilage collar around fracture site

fracture

osteoblasts

woven

Callus formation and Ossification phase of bone healing

- Callus bridges gap between ends of _____

- Cartilage collar is replaced by bone by _____

- Early _____ bone formed within 7 days

Callus formation and Ossification phase of bone healing

what phase of bone healing is characterized by the formation of Callus bridges that gap between ends of fracture and osteoblasts replacing cartilage with bone