10.1 Bones Highlights

Question 1

What makes up the 2 components of bones?

Answer 1

1) Osteoid (35%): collagen
2) Minerals (65%): phosphate + calcium (mostly)

Question 2

Define:
1) Osteoblasts
2) Osteoclasts

Answer 2

1) Synthesize bone matrix and regulate its mineralization
2) Specialized macrophages responsible for resorption

Question 3

Congenital Bone Disease: List the 3 ways Dysostoses can manifest

Answer 3

1) Aplasia (absent)
2) Supernumerary (extra bones or digits)
3) Syndactyly/ craniosynostosis (abnormal fusion)

Question 4

Congenital Bone Disease: What are 2 groups?

Answer 4

1) Dystoses
2) Dysplasias

Question 5

Dysplasias:
1) What do they arise from?
2) In this context, refers to abnormal growth, NOT a _______________ lesion

Answer 5

1) Mutations in genes that control the development of the entire skeleton
2) pre-malignant

Question 6

*List the 4 predominant features of osteogenesis imperfecta

Answer 6

1) Skeletal fragility
2) Blue sclera
3) Sensori-neural hearing loss and or conductive hearing loss
4) Dental imperfections (small misshapen bluish-yellow teeth)

Question 7

*What is THE most important Sx of Osteogenesis Imperfecta?

Answer 7

Skeletal fragility (fragile bones!)

Question 8

1) Osteogenesis Imperfecta is diverse in what way?
2) What is it the most common of?

Answer 8

1) Phenotypically diverse
2) Most common inherited disorder of connective tissue (1/20,000)

Question 9

Osteopetrosis “marble bone disease”:
1) Reduced formation or function of osteoclasts leads to what?
2) What form is severe? What can it cause and what can it lead to?
3) What can make it fatal?
4) Give 2 facts abt the adult form

Answer 9

1) Diffuse skeletal sclerosis.
2) Infantile form; Extramedullary hematopoiesis can lead to hepatosplenomegaly
3) Leukopenia
4) Autosomal dominant + Incidentally detected on radiographs

Question 10

*Osteoporisis
1) What is the physiologic average bone loss of bone mass per year with osteopenia?
2) Osteoporosis → Osteopenia severe enough to risk fracture most likely in what 2 groups?
3) List 1 of the many aspects of pathogenesis

Answer 10

1) Physiologic average bone loss 0.7% of bone mass per year
2) Geriatric + Post-menopausal
3) Hormonal influences (estrogen in particular)

Question 11

1) What 2 things can menopause lead to to cause osteoporosis?
2) What abt aging?

Answer 11

1) Decrease serum estrogen; increased osteoclast activity.
2) Reduced physical activity

Question 12

Rickets and Osteomalacia:
1) Who is rickets found in? Why?
2) Who is osteomalacia found in?
3) What is a common cause?

Answer 12

1) Children; interferes with deposition of bone in the growth plates
2) Adults; bone formed during remodeling is undermineralized
3) Vitamin D deficiency → impairment of mineralization and deposition of unmineralized matrix

Question 13

Paget disease of the bone is characterized by what kind of bone?

Answer 13

Increased, but disordered and structurally unsound bone

Question 14

Pagent disease of the Bone
1) What are 2 primary causes?
2) List 2 other manifestations and define each
3) What can develop with this condition?

Answer 14

1) a) Genetic
b) Environmental: [possibly relating to viral infection (measles) of osteoclast precursors alters vit D sensitivity or IL-6 production]
2) Leontiasis ossia “lion face”: enlargement of craniofacial skeleton
Platybasia: flattening of skull base due to weakening and ↑ weight
3) Tumor-like conditions; <1% develop into osteosarcoma
-Unless malignant transformation happens, Paget’s is usually not fatal.

Question 15

List the 4 steps of Fx healing

Answer 15

1) Hematoma (0-1 day)
2) Soft callus
3) Bony callus formation
4) Bony callus (3 weeks-months)

Question 16

*List 4 predisposing factors for AVN (osteonecrosis)

Answer 16

1) Vascular injury (trauma or vasculitis)
2) Drugs (corticosteroids
3) Systemic disease (sickle cell)
4) Radiation

Question 17

*What is the most important cause of AVN?

Answer 17

Trauma

Question 18

What are 3 mechanisms of AVN?

Answer 18

1) Mechanical disruption of vessels
2) Thrombotic occlusion
3) Extravascular compression

Question 19

*What are the 3 Sx of AVN?

Answer 19

1) Subchondral infarct-activity related pain → constant pain
2) Collapse: worse pain
3) Secondary arthritis

Question 20

*What are 2 types of osteomyelistis?

Answer 20

Pyogenic and mycobacterial (TB)

Question 21

*Pyogenic osteomyelitis: What causes it?

Answer 21

Almost always bacterial, rarely fungal
-Staph aureus (80-90%)

Question 22

*2 major types of benign bone forming tumor are?

Answer 22

Osteoid Osteoma + osteoblastoma

Question 23

*Define Osteosarcoma (malignant)

Answer 23

Aggressive tumor of malignant osteoblasts

Question 24

List 3 cartilage-forming tumors and specify which is malignant

Answer 24

1) Osteochondroma
2) Chondroma
3) Chondrosarcoma (malignant)

Question 25

Give an example of a tumor of unknown origin. What is unique about this one?

Answer 25

Ewing Sarcoma; have the youngest average age presentation

Question 26

True or false: Metastatic tumors greatly outnumber primary tumors of the bone

Answer 26

True

Question 27

1) Rheumatoid Arthritis is a chronic ______________ inflammatory disease 2) Caused by cell mediated and humoral immunity response against ______________. 3) List 2 characteristics. 4) TNF and IL1 from macrophages stimulate what?

Answer 27

1) Chronic autoimmune inflammatory disease 2) self-antigens 3) Synovial hyperplasia + pannus formation 4) Synovial cells to secrete proteases and destroy hyaline cartilage.

Question 28

*Crystal-Induced Arthritis: List 2 kinds and what the crystals are made of

Answer 28

1) Gout: urate 2) Pseudogout: calcium pyrophosphate (mnemonic: pseudo starts with p, pyro starts w p; gout likes great toe)

Question 29

Infectious Arthritis: 1) List 3 mechanisms of infectious arthritis spread 2) Suppurative infectious arthritis usually has what kind of spread?

Answer 29

1) a. Hematogenous dissemination b. Direct inoculation through skin c. Contiguous spread from soft tissue abscess of osteomyelitis 2) Usually, hematogenous spread

Question 30

Infectious Arthritis: 1) What are the suppurative pathogens [by age] of infectious arthritis in general? 2) What causes Lyme arthritis? 3) What are the stages of Lyme arthritis?

Answer 30

1) Children <2: H. influenza Children & older adults: Staph aureus Gonococcal: late adolescent through early adulthood. 2) Spirochete : Borrelia burgdorferi 3) Early = skin -Early disseminated = skin, cranial nerves, heart, and meninges -Arthritis occurs weeks or months after inoculation (usually knee; migratory arthritis is aka Lyme arthritis)

Question 31

Peripheral Nerve Disorders: What are the 2 types of injury?

Answer 31

1) Axonal- (Wallerian degeneration=secondary loss of myelin sheath) 2) Demyelinating

Question 32

*1) Guillain-Barre’ Syndrome is Rapidly progressive affecting the ________ of the motor axons 2) When is it triggered medically? 3) What else can it follow? Give an example

Answer 32

1) myelin 2) when injection of vaccine breaks down self-tolerance → autoimmune response 3) Campylobacter jejuni

Question 33

*What is the most common cause of peripheral neuropathy?

Answer 33

Diabetic Peripheral Neuropathy

Question 34

*Diabetic Peripheral Neuropathy: List at least 3 forms

Answer 34

1) **Autonomic neuropathy:** Characterized by changes in bowel, bladder, cardiac, or sexual function 2) **Lumbosacral radiculopathy:** Asymmetric pain with muscular weakness +/- atrophy 3) **Distal symmetric sensorimotor polyneuropathy:** Sensory affected > Motor

Question 35

*Diabetic Peripheral Neuropathy 1) What is the kind we've heard about before? 2) What is most affected?

Answer 35

1) Distal symmetric sensorimotor polyneuropathy 2) Sensory > Motor

Question 36

* **Myasthenia Gravis 1) Autoantibodies that target what? 2) List 3 clinical manifestations**

Answer 36

1) Post-synaptic acetylcholine receptor 2) **Ptosis (drooping eyelid) Diplopia (double vision) EOM weakness**

Question 37

List 3 Inherited disorders of skeletal muscle

Answer 37

1) Muscular dystrophies (dystrophinopathies) 2) Congenital muscular dystrophies 3) Congenital myopathies

Question 38

*Dysytrophinopathies 1) Most common dystrophies are _______-linked. 2) What causes it? (pathophys/ chain of events)

Answer 38

1) X-linked 2) Mutations that disrupt dystrophin ( a large structural protein) → which disrupts the dystrophin-glycoprotein complex →transient membrane tears during contraction

Question 39

*What are the 2 principle dystrophy diseases?

Answer 39

1) **Duchenne muscular dystrophy:** usually diagnosed in childhood → wheelchair bound by teens → dead by early adulthood 2) **Becker muscular dystrophy:** less common and less severe

Question 40

Define myotonia

Answer 40

Sustained involuntary contraction of a group of muscles