[PATH] Bones, Joints and Soft Tissue (Part 1 BONE) [Martin] Flashcards by Cassie Dasmarinas

This image depicts what type of process?

Endochondral ossification

(in a calcaneus)

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Root word association:

Osteoporosis =

Osteomalacia =

Osteopetrosis =

Osteogenesis imperfecta =

Osteitis deformans =

Osteodystrophy =

Osteoporosis = Porous; thinned out bone

Osteomalacia = Weakened, soft bone

Osteopetrosis = Peter=rock, stone bone

Osteogenesis imperfecta = Imperfect origin of bone

Osteitis deformans = Deforming bone-itis

Osteodystrophy = Bad growing bone

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What are the (3) components of bone matrix?

Type I collagen

Osteoid

Mineral component

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Hardness of bones is due to?

Hydroxyapatite

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What are the (2) histologic forms of bone?

Woven

Lamellar

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Characteristics of woven bone?

Disorganized

Produced rapidly ; fetal development and fracture repair

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Characteristics of lamellar bone?

Slow production

Parallel collagen

Strong

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Function of osteoblasts

Synthesize, transport and assemble matrix

*Regulates mineralization

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Function of osteocytes?

Inactivate osteoblasts

Control calcium and phosphate levels

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What are osteoclasts?

Function?

Multinucleated macrophages derived from circulating monocytes

Bone resorption

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What type of bone is associated with:

Endochondral ossification?

Intramembranous ossification?

Endochondral ossification = Long bones

Intramembranous ossification = Flat bones

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When is peak bone mass achieved?

Early adulthood

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RANK

Where is it expressed?

Function?

Where is it expressed = Osteoclast precursors

Function = Breakdown

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RANK-L

Where is it expressed?

Function?

Where is it expressed = Osteoblasts and marrow stromal cells

Function = Breakdown

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OPG

Where is it expressed?

Function?

Where is it expressed = “Decoy” receptor made by osteoblasts that can bind RANKL and prevent it’s interaction with RANK

Function = Build

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A product produced by osteocyte inhibits the WNT/Beta-catenin pathway. What is it?

Sclerostin

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What are the common building circulating hormones/factors?

Estrogen

Testosterone

Vit D

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What are the common breakdown circulating hormones/factors?

PTH

IL-1

Glucocorticoids

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What is M-CSF?

Monocyte colony stimulating factor

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Function of M-CSF?

M-CSF receptor on osteoclast precursors STIMULATES tyrosine kinase cascade that is crucial for generation of osteoclasts

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What are the (3) primary developmental disorders of bone?

Osteogenesis imperfecta

Osteopetrosis

Mucopolysaccharidoses

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What is commonly associated with developmental disorders of bone?

Transcription factor defects: specifically homeobox genes

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Define:

Dysplasia

Global disorganization of bone &/or cartilage

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Define:

Syndactyly/Craniosynostosis

Abnormal fusion of bones

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What are **wormian bones?**

Extra bones within cranial sutures

What is an excellent way to determine the origin of a dwarfism pathology? Can you give examples?

Look at the chest cavity! Normal trunk length with **achondroplasia** Small chest cavity with **thanatophoric dysplasia**

**Achondroplasia** Gene mutation? Presentation? Mortality?

Gene mutation = Autosomal dominant FGFR3 gain of function Presentation = Short extremities, normal trunk length, enlarged head, bluging forehead, depression root of nose Mortality = NO change in longevity, intelligence or reproductive status

**Thanatophoric dysplasia** Gene mutation? Presentation? Mortality?

Gene mutation = FGFR3 gain of function Presentation = Small chest cavity, bell-shaped abdomen, micromelic shortening of limbs Mortality = Die at birth or soon after

Osteogenesis imperfecta: Which type has the best prognosis? Worst?

Best = Type I Worst = Type 2

Prognosis of Type II osteogenesis imperfecta?

Uniformly fatal in utero

Buzz word association for **osteogenesis imperfecta type 2?**

"Accordion-like" shortening of the limbs

What are the major clinical features of **osteogenesis imperfecta?**

Blue sclera Skeletal fragility Dentinogenesis imperfecta (small fucked teeth) Hearing impairment Joint laxity

What is the most common type of **osteogenesis imperfecta?**

Type I Also the mildest type of OI

Why is **type II** typically fatal?

Respiratory problems (They have underdeveloped lungs from small thoracic cage)

What is the difference in sclera appearance b/w **Type III** and **Type IV** OI?

Type III = Blue, purple or gray tint Type IV= White \*Remember; The order of best prognosis to worst is (1--\> 4 --\>3--\>2) because fuck, lets make this difficult. But yeah, remember that type 4 is less severe, so the sclera are going to be normal in color.

Osteopetrosis Aka? (2 names)

Marble bone disease Albers-Schonberg disease

What is the deficiency in **osteopetrosis?**

Carbonic anhydrase 2 (CA2)

How does **osteopetrosis** appear on Xray? Buzz word association?

Erlenmeyer flask

Inheritance pattern for **osteopetrosis?** Populations?

Autosomal recessive Mediterranean and Arab race

Common clinical features of **osteopetrosis?**

Cranial nerve deficits: Optic atrophy, **deafness**, facial paralysis

What is seen on histology with **osteopetrosis?**

No medullary cavity

What type of disease is **mucopolysaccharidoses?**

Lysosomal storage disease

What are examples of **aquired bone disorders (5)?**

Osteopenia/osteoporosis Pagets Osteomalacia/rickets Hyperparathyroidism Renal osteodystrophy

# Define **osteopenia** Define **osteoporosis**

Osteopenia = **1.0 - 2.5** standard deviations below the mean Osteoporosis = At least **2.5** SD below the mean peak bone mass in young adults

If your patient has a bone mass that is less than 2.5 SD below the mean, but you still diagnose them with **osteoporosis**, what MUST have happened?

Atraumatic or Vertebral compression fractures

What population is at risk of never obtaining their full potential bone mass due to eating disorders?

Adolescent girls (Insufficienct calcium intake during period of rapid growth **restricts their peak bone mass**)

What is a major hormonal influence on osteoporosis?

Menopause (estrogen deficiency)

Describe the appearance of **osteoporotic bone**

(Right) Loss of horizontal trabeculae

What is the method of diagnosis for osteoporosis?

DEXA-scan

Risk factors for osteoporosis?

Caucasian, light colored eyes and skin Nutrition (too much phosphorus-soda) Smokers

What spinal changes are associated with **loss of height** in osteoporosis?

Lumbar lordosis & kyphoscoliosis

Paget disease aka?

Osteitis deformans

Paget disease Characteristsics? Gene?

Polyostotic (involves multiple bones) 70yo average age Caucasians **SQSTM1 gene**

Paget disease Buzz word association with Xray appearance?

"Cotton Wool"

What is the **paget disease** morphology?

Mosaic pattern of lamellar bone Jigsaw-like

What type of fractures are associated with **paget disease?**

Chalk stick type fractures

What are the lab values associated with **paget disease?**

Elevated **ALK PHOSPHATASE** NORMAL = Calcium and phosphorous

Name a unique clinical feature of paget disease

Hyeprvascularity of paget disease **Warms the overlying skin** --\> Can lead to **high output heart failure**

Rickets and osteomalacia are manifestations of?

VITAMIN D DEFICIENCY Or it's abnormal metabolism

What is the histology associated with **hyperparathyroidism?**

Train tracks

# Define: Simple fracture

Overlying skin intact

# Define: Compound fracture

Bone communicates with the skin surface

# Define: Comminuted fracture

Bone is fragmented

# Define: Displaced fracture

Ends of the bone at the fracture site are **not aligned**

# Define: Stress fracture

Slowly developing fracture that follows a period of increased physical activity in which bone is subjected to repetitive loads nice.

# Define: Greenstick fracture

Extending only partially through the bone, common in infants when bones are soft

# Define: Pathologic fracture

Involving bone weakened by an underlying disease process such as a tumor

What is **osteonecrosis?**

**Infarction** of the bone and marrow (pretty common)

What causes most cases of **osteonecrosis?**

Fractures or **Corticosteroid tx**

What region is typically not affected in **osteonecrosis?** **Why?**

Cortex is not affected Due to **collateral flow**

Buzz word association with **osteonecrosis?**

"Creeping substitution"

What is **osteomyelitis?**

Inflammation of the bone and marrow Typically following **infection**

What are most cases of **osteomyelitis** caused by?

Pyogenic bacteria & Mycobacteria

How does **pyogenic osteomyelitis** typically spread in: Kids? Adults?

Kids = Hematogenous Adults = Complication of open fractures, surgical procedures and diabetic infections

Most common cause of **pyogenic osteomyelitis?**

Staph aureus (80-90%)

Osteomyelitis: Name the associated organism with: Sickle cell patients

Salmonella

Osteomyelitis: Name the associated organism with: MAC deficiency

Neisseria

What is: Sequestrum? Involucrum?

Sequestrum = Dead bone following abscess Involucrum = New bone

What is the histology associated with **mycobacterial osteomyelitis?**

Caseous necrosis and granulomas

What is **Pott disease?**

Aka Tuberculous spondylitis Permanent compression fractures

What are the associated bone deformities seen with **skeletal syphilis?**

Saber shin Saddle nose