Bone Pathology

Question 1

Dysostoses

Answer 1

Abnormalities in a bone or a single group of bones

-arise from defects in migration and condensation of mesenchyme

Question 2

Disorders of bones are catagorized by what?

Answer 2

Specific Genetic defect

Question 3

Osteopetrosis

Answer 3

Autosomal recessive genetic disorder in deficient CA2 metabolic enzyme.

Often fatal in uterine and if not develops cranial nerve defects and leukopenia

Affected infants have cranial nerve defects and increased infections due to leukopenia.

Question 4

Treatment of osteopetrosis

Answer 4

Steam cell treatments generate new osteoclasts which can reverse the marble bone build up.

Question 5

Mucopolysaccharidoses

Answer 5

Lysosomal storage disease disorder

Defect In degrading dermatan, heparan, keratan sulfates

mucopolysaccharides accumulate in chondrocytes and cause premature apoptosis and structural defects in cartilage.

• marked by short stature, chest wall abnormalities and malformed bones.

Question 6

Dysplasia

Answer 6

Global disorganization of bone and/or cartilage

Question 7

Acquired disorders of bone

Answer 7

Osteopenia and osteoporosis

Paget disease

Osteomalacia

Hyperparathyroid

Renal ostodystrophy

Question 8

Osteopenia vs osteoporosis

Answer 8

Osteopenia: decease bone mass with between 1-2.5 SD below average mean

Osteoporosis: decrease bone mess with less than 2.5 SD below average mean
- increases fracture risk

Question 9

Osteoporosis pathogenesis

Answer 9

Often caused by menopause and natural aging.

Menopause

• Decreased estrogen and increased RANK/RANKL
• Also increased IL-1/6 and TNF levels

Aging
-decreases osteoprogenitor replication and synthetic osteoblast activity

Question 10

Senile osteoporosis

Answer 10

Core thinned by superiosteal and endosteal respiration.

Haversian systems are widened and can resemble cancellous bone.

Question 11

Clinical outcomes of osteoporosis

Answer 11

Loss of height, increased kyphosis of kyphosis regions, decreases lumbar lordosis

• can develop PE and pneumonia
• marked by 40-50% bone loss (when it can actually be detected)

Question 12

Common preventative measures for osteoporosis

Answer 12

• Exercise
• Ca+ and Vitamin D supplements
• Bisphosphonate suppliments
• hormonal therapy (only when caused by postmenopause)

Question 13

Paget disease

Answer 13

Increased but disordered bone mass

Possess three phases

• osteolytic phase
• mixed osteoclastic-osteoblast is phase
• burned out quiescent osteosclerotic phase

Question 14

Paget disease morphology

Answer 14

Mosaic pattern of lamellar bone (commonly seen in sclerotic phase)

Question 15

Clinical signs of Paget disease

Answer 15

• Pain and enlarged skin as well as osteoarthritis often accompany
• most commonly found in femur or axial skeleton.
• can be accompanied by excess heat in skin, increased blood flow, and tumor-like conditions
• can lead to heart failure
• have elevated alkaline phosphate but normal calcium levels

Question 16

Treatment of Paget disease

Answer 16

Calcitonin and biphosphates

Question 17

Rickets and osteomalacia causes

Answer 17

Vitamin D deficiencies

• marked by impairment of mineralization of the matrix.

Rickets = children and affects growth plates directly

Osteomalacia = adults and affects bone modeling directly

Question 18

Hyper parathyroidism

Answer 18

• Increases osteoclast activity
• reabsorption of calcium in the kidney
• increased urinary excretion of phosphates and synthesis of active vitamin D

Question 19

Renal Osteodystrophy

Answer 19

Tubular dysfunction and generalized renal failure causes decreased secreted factors.

• increases bond resorption by high amounts and ultimately can causes osteopenia, osteoporosis and osteomalacia, and growth retardation.

Question 20

Hyperparathyrodism secondary pathology

Answer 20

often causes osteoporosis, brown tumors and osteitis fibrosis cystica

Question 21

Simple fracture

Answer 21

Fractures within skin that keep overlying skin intact

Question 22

Compound fractures

Answer 22

Bone fracture that pierces skin and communicates directly with skin surface

Question 23

Comminuted fractures

Answer 23

Bone fractures that cause bone to be fragmented

Question 24

Displaced fracture

Answer 24

Bone fracture in which the ends of bones at the fracture site do not align.

• need to be surgically put in place.

Question 25

Stress fracture

Answer 25

Bone fractures that are slow developing fractures that follow increased physical activity and repetitive loads of stress.

Question 26

Green stick fractures

Answer 26

Bone fractures that extend incompletely through the bone (often resembling twisting a green health tree branch)

• most commonly seen in soft bones (especially infants)

Question 27

Pathogenic fracture

Answer 27

Bone fracture caused by weakened bone by an underlying disease process

Question 28

Osteonecrosis

Answer 28

Infarction of bone and bone marrow.

• occurs in medullary cavity and can directly affect cortex or medulla.

Most commonly caused by bone fractures or corticosteroids

Question 29

Vascular insufficiency causes

Answer 29

Injury to blood vessels

Thromboembolism

External pressure on veins

Venous occlusion

Question 30

Osteonecrosis morphology

Answer 30

Yellow often edge shaped empty lacunae with necrotic adipocytes.

• creates insoluble soaps in the bone
• subcontractors infants in tandem also causes collapse of necrotic bone.

Question 31

Clinical signs of osteonecrosis

Answer 31

Pain associated with activity and eventually becomes constant.

Often osteoarthritis occurs after osteonecrosis.

A lot of osteonecrosis is clinically silent.

Question 32

Osteomyelitis

Answer 32

Inflammation of bone and marrow

• always secondary to primary infection in the bone.

All microorganisms can cause this infection, however mycobacterium and pyogenic bacteria are the most common.

• especially potent in immunosuppressive population

Question 33

Pyogenic osteomyelitis infections

Answer 33

Arise at bone via

• hemagoenous spread
• direct implantation
• in adults usually occurs via open fractures and diabetic infections of feet.
• S. Aureus is the most common bacteria. (80-90%)

Question 34

Other possible pyogenic osteomyelitis infections

Answer 34

E. coli, klebsiella, Pseudomonas in adults

Neonates: haemophilus influenza and B strep.

Sickle cell patients: salmonella

Question 35

Sites of pyogenic osteomyelitis

Answer 35

Infants: frequent infection in metaphysis or epiphysis of long bones.

Children: metaphysis infections most common

Adults epiphyses and subchondral regions most common.

Question 36

Pyogenic osteomyelitis morphology

Answer 36

Three stages: acute, subacute, chronic

• Dead bone = sequestrum*
• new bone = involucrum*

Question 37

Acute pyogenic osteomyelitis morphology

Answer 37

Proliferation, neutrophilic inflammation and necrosis within 48 hrs.

Question 38

Mycobacterium osteomyelitis

Answer 38

Most common in immunosuppressive population and can occur in TB patients.

• histologically shows caseous necrosis of bone and granulomas.
• more destructive and harder to control than pyogenic osteomyelitis

Question 39

Skeletal syphilis

Answer 39

Syphilis and yaws infections that tend to occur in Endochondral ossification and periosteum areas.

Causes areas of bone to not fuse properly and can leave holes upon xrays/CTs

Question 40

Brachydactyly types D and E affected gene

Answer 40

HOXD13

Question 41

Achondroplasia and thanatophoric dysplasia gene affected

Answer 41

FGFR3

Both are related to limb shortening and bowing or bones