MSK Path Skeletal System Flashcards
- Explain the problem in Achondroplasia and 2. what is the biochemical cause and 3. what are the two clinical signs/manifestations/effects of the disease? 4. What is the inheritance pattern? 5. What is this disease a common cause of?
- Impaired cartilage growth in the growth plate
- Activating mutation in fibroblast growth factor receptor 3. This mutation turns on the receptor, which turns off cartilage growth.
- Short extremities and normal head and chest size. This happens because intramembranous bone growth is not effected because it does not rely on pre-existing cartilage, hence head and chest normal, but endochondral bone growth is affected, short extremities, because is does rely on cartilage matrix being formed first and bone replacing it.
- Autosomal dominant
- Dwarfism
- Explain the problem with Osteogensis Imperfecta?
- What is the biochemical cause of this disease?
- Inheritance pattern
- 3 clinical effects and why?
- Congenital problem with bone formation that results in weak bones.
- Defect in type 1 collagen synthesis
- Autosomal dominant
- Multiple fractures. 2. Blue sclera because the eye has tons of type 1 collagen, so the sclera is thin and exposes the underlying choroidal veins. 3. Hearing loss because of the middle ear bones fracture easily.
- What is the problem with osteopetrosis?
- What is the most common biochemical cause and how does it lead to this condition?
- What are the 5 clinical features and why does each one occur?
- What is the treatment?
- Inherited defect of bone resorption due to poor osteoclast function so the individual has very thick, heavy bones that fracture easily.
- CLCN7 mutation. Carbonic anhydride 2 deficiency. This is significant because the bone needs an acidic environment to resorb bone and with this mutation we don’t produce hydrogen ions.
- Bone fractures
- Anemia, thrombocytopenia, leukopenia because the bone thickness takes out potential medullary space that can perform hematopoiesis.
- Vision and hearing impairment because the skull is much thicker and can compress cranial nerves.
- Hydrocephalus because of the narrowing of the foramen magnum
- Renal tubular acidosis for the same reason because of the mutation
Bone marrow transplant because the problem is back at the monocytes.
How do osteoblasts form bone?
They produce osteoid, which is then mineralized by calcium and phosphate.
What are the two most common ways we get vitamin D?
What two organs do we need to get the active form of vitamin D?
3 ways vitamin D raises serum calcium and phosphate?
4 causes of vitamin d deficiency?
Sun and diet
Liver and kidney
Increases absorption of both in intestine, increases reabsorption of both in kidney, increases resorption of both in bone.
No sunlight, poor diet, malabsorption, and renal/liver disease.
What is the problem with Rickets?
What is the biochemical cause?
What are the 4 clinical features?
What age is this seen most commonly?
Children can’t mineralize the osteoid to form bone.
Due to vitamin D deficiency
Pigeon breast deformity, big forehead, rachitic rosary (osteoid depositing in the costchondral junction), bowing of the legs.
Less than 1 year
What is the problem with osteomalacia?
What is the biochemical cause?
What are the 4 lab values associated with it?
What two places in the skeletal system are most commonly affected?
Adults not able to mineralize osteoid.
Vitamin d deficiency
Low calcium, low phosphate, high PTH, high alkaline phosphatase because you need an alkaline environment to lay down calcium.
Hip and spine (weight bearing)
What is the problem with osteoporosis?
What are the two most common forms?
Explain the risk for osteoporosis?
- Loss of bone mass so there is an increased risk for fracture
- Senile and post menopausal
- Risk is based on peak bone mass, which we get at 30 and is due to exercise, diet and inherited vitamin d receptor…and rate of bone mass loss which is increased with lack of exercise, poor diet and low estrogen.
- Big time clinical feature of osteoporosis?
- How do we screen for osteoporosis?
- What are the labs for osteoporosis and why is this significant?
- 2 treatment options and 1 med that is contraindicated for osteoporosis?
- Fractures in weight bearing areas like the hip, spine, and distal radius
- DEXA scan
- Calcium, phosphate, PTH and alkaline phosphate are all normal. This is important because it helps us distinguish it from osteomalacia.
- Give vitamin d and calcium and exercise.
Bisphosphonates, which induce apoptosis in osteoclasts.
Glucos.
What is the problem with Paget Disease of the Bone?
What are the three stages?
What is a possible etiology?
What is important to know about where this is happening in the body, what effect does it have on the bone, and what does biopsy show?
Imbalance between osteoblast and osteoclast activity. Remember, osteoclast needs permission to do its thing from the osteoblasts.
First stage is osteoclast activity only, they break down bone like crazy. Finally, the osteoblasts jump in and try to rescue the bone by laying down bone, so stage 2 is both are working. And stage 3 is osteoblast only.
Possibly viral cause
This is a localized process, it is not happening in the entire skeleton
This disease makes thick, fragile bones.
Biopsy shows mosaic pattern of lamellar bone.
5 clinical features of Paget’s disease of Bone?
2 treatment options of Paget’s?
2 complications of Paget’s?
Bone pain, Increased Hat size, hearing loss, lion like face if skull is involved, isolated elevated level of alkaline phosphate because of the osteoblast only stage.
Calcitonin and bisphosphonates
High cardiac output failure and osteosarcoma, again because that osteoblast only stage and if there is a mutation, then you can get this.
What is the problem with osteomyelitis?
What patient population does it most commonly occur in and what is the mechanism?
How does it occur in children and how does it occur in adults?
What is the most common pathogen?
Infection of bone and marrow
Most commonly seen in children and the infection spreads via blood.
In kids, bacteremia leads to the pathogen getting into the metaphysis
In adults, bacteremia from a wound, leads to the pathogen getting into the epiphysis
Staph
The following patients with specific medical conditions are more at risk to get osteomyelitis from which pathogens? Sexually active young adults? Sickle Cell? Diabetic or IV drug users? Cat or dog bite/scratch? Pott disease?
N gonorrhea Salmonella PA Pasteurella TB
What is the big time clinical symptom associated with osteomyelitis?
What do you see on X-ray with osteomyelitis?
How do we diagnose osteomyelitis?
Bone pain with systemic signs of infection
Abscess/necrotic focus surrounded by sclerosis
Blood culture
What is the problem in avascular aseptic necrosis?
4 causes?
2 complications?
Ischemic necrosis of the bone and marrow
Fracture/trauma (most common), sickle cell (dactylics), steroids, and caisson disease (gas emboli lodging in bone and killing it).
