10.1 Bones MJ slides Flashcards
Osteogenesis imperfecta:
1) What is it the most common form of?
2) What causes it?
3) Describe the diverse phenotypes
1) Caused by deficiencies to synthesize Type I collagen
2) Predominantly misfolding of collagen peptides
3) -OI type I normal life except for susceptibility to fratures
-OI type II uniformly fatal in perinatal period or in utero.
-Severe fractures and respiratory failure
Osteogenesis imperfecta: What is the inheritance?
Autosomal dominant
Osteoporosis:
1) What does it start as?
2) How is osteoporosis defined?
3) What is the hallmark?
4) What is a challenge to treatment?
1) Osteopenia → ↓ bone mass
2) Osteopenia severe enough to risk fracture
3) Histologically normal, but ↓ amount of bone
Bones with increased surface area are affected more than others (ie vertebra
4) Uncoupling the osteoblast/osteoclast activity
Osteoporosis: What is the pathogenesis?
1) Age-related changes
2) Reduced physical activity
3) Genetic factors
4) Calcium nutritional state
5) Hormonal influences (estrogen in particular)
Avascular Necrosis (osteonecrosis)
Refers to ischemic necrosis of bone or marrow cells
Osteomyelitis: What are the 3 mechanisms of pyogenic?
1) Hematogenous spread
2) Extension from contiguous site
3) Direct implantation: via open fractures or surgical procedures
Pyogenic Osteomyelitis:
1) How does it manifest? (2 main ways)
2) What are the 2 diagnostic tests? What do you need for definitive Tx?
1) Acute systemic illness: Fever, chill, malaise, pain,
OR
Subtle: unexplained fever, unexplained local pain
2) X-rays show lytic focus w. sclerotic rim
Requires biopsy with culture for definitive tx
Mycobacterial (TB) Osteomyelitis:
1) Where is it usually seen?
2) Mechanism of inoculation?
1) Usually seen in developing countries; 1-3% of patients w/ TB will have osseus infection
2) Usually blood borne from visceral infection
-Direct extension (i.e. lung →rib)
Bone-Forming Tumors: List and describe the 2 main benign types
1) Osteoid Osteoma: <2cm in diameter
-Pain improved at night by aspirin (likely mediated by prostaglandin E)
2) >2cm in diameter Osteoblastoma: Tumor does not stimulate a large bony reaction
What is a common pathogenesis of bone-forming tumors?
Synthesize osteoid
Osteosarcoma (malignant bone forming tumor):
1) What is it? Why does it occur?
2) Who does it predominantly occur in? When?
1) Aggressive tumor of malignant osteoblasts; usually from acquired genetic abnormalities
2) Predominantly occurs in young children
-Often occurs at adolescent growth spurt, most frequently in the region of the growth plate w/ fastest growth
Tumor of Unknown Origin: Ewing Sarcoma
Is it malignant? Describe it.
Aggressive, malignant, small, round cell tumors
*Osteoarthritis: What are the 2 types? Incl. when each typically occurs
1) Age related and usually oligoarticular (i.e. injury related)
2) Younger age w. predisposing conditions like joint deformity, previous injury, or systemic disease
Gout:
1) What crystal? Why?
2) What else does it cause? Why/
1) Urate results from purine metabolism
2) Hyperuricemia; overproduction or underexcretion (most common)
Gout:
1) What do crystals precipitate in? What does this do?
2) What factors contribute to development?
1) Joints; stimulates production of cytokines & recruitment of leukocytes
2) Age, genetic predisposition. ETOH consumption, obesity, drugs (thiazides)
Pseudogout:
1) What is it also called?
2) What crystal?
3) What may it mimic?
1) Calcium pyrophosphate deposition disease
2) Calcium pyrophosphate
3) Subacute of chronic OA
Pseudogout: What are the 3 types?
1) Sporadic (idiopathic)
2) Hereditary: autosomal dominant germline mutation in pyrophosphate channel
3) Secondary: may be predisposed by previous joint damage, hyperparathyroidism, hemochromatosis, diabetes
Guillain-Barre’ Syndrome:
1) What does it result in?
2) What can it follow?
1) Rapidly progressive weakness; may result in death within days of onset secondary to failure of reparatory muscles
2) Campylobacter jejuni, EBV, CMV, HIV, and Zika
Diabetic Peripheral Neuropathy:
1) What is it and what characterizes it?
2) What does it feel like when it takes the form of Lumbosacral radiculopathy?
3) When Distal symmetric sensorimotor polyneuropathy occurs, what is more affected, sensory or motor?
1) Autonomic neuropathy; changes in bowel, bladder, cardiac, or sexual function
2) Asymmetric pain with muscular weakness +/- atrophy
Distal symmetric sensorimotor polyneuropathy
3) Sensory > Motor
Diabetic Peripheral Neuropathy: What is it the most common cause of?
Peripheral neuropathy
1) What condition can Can attack other parts of the neuromuscular junction?
2) This clinical syndrome is different; why?
1) Myasthenia gravis (MG)
2) Most other myopathic disease spares facial muscles and EOM
Dysytrophinopathies:
Caused by mutations that disrupt dystrophin ( a large structural protein) → which disrupts the dystrophin-glycoprotein complex →transient membrane tears during contraction
What does this lead to?
Myofiber degeneration outpaces the ability to repair
List + describe 3 forms of Diabetic Peripheral Neuropathy
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
What are the 2 principle dystophinopathies?
Duchenne muscular dystrophy-usually diagnosed in childhood → wheelchair bound by teens → dead by early adulthood
Becker muscular dystrophy-less common and less severe
