USMLE Step 1 MSK
Old lady with severe right hip pain after a fall.
Current meds - low dose prenisone.
40 pack year history of smoking.
Injury to what artery is most likely to lead to osteonecrosis?
Medial circumflex femoral
Medial circumflex supplies blood to the head of the femur.
CAST Bent LEGS
What are the causes of avascular necrosis of the femoral head?
CAST Bent LEGS
Corticosteroids
Alcoholism
Sickle cell disease
Trauma
the Bends
LEggs-Calves-Perthes (childhood disorder of blood flow to the hip)
Gaucher's Disease (cerebroside metabolism)
Slipped Femoral Capital Epiphysis
Fractures of the surgical neck of the humerus damage what nerve?
axillary
Fractures of the midshaft of the humerus damage what nerve and potentially what artery?
Name one other fracture that could potentially damage this nerve?
Radial, deep brachial
Anterolateral displacement of a supracondylar ridge humerus fracture could also damage radial
1st line treatment for osteoporosis is?
,Bisphosphonates
(-dronates; Risedronate)
What is a classic difference in the presentation of Myasthenia Gravis and Lambert-Eaton
myasthenic syndrome?
MG - strength decreases with repetition
- autoantibodies to the ACh post-synaptic receptor, so more repetition = less and less ACh
available to be released from the synapse --> weakness
LEMS - strength increases with repetition
- autoantibodies to the pre-synaptic Ca++ channel, (less release of ACh). More repetition leads
to increased calcium in the pre-neuron --> more release of ACh --> strength
Patient is being treated for a Pseudomonas infection and complains of weakness and vision
deficits that occur later in the day. What is occuring?
Pt is being tx with Aminoglycosides
SE of Aminoglycosides - neuromuscular blockade (+ nephrotoxicity, + ototoxicity, +
teratogenicity)
Two main "classes" of muscle relaxers are what?
Which would be used for outpatient tx? for surgery?
1. centrally acting - outpatient
2. peripherally acting - surgery
What are the two main peripherally acting muscle relaxers and how do their MOAs differ?
Succinylcholine
"Curiums" and "Curonium"
Succinyl - DEPOLARIZING (binds to receptor, causes prolonged depolarization and eventually
relaxation)
Curiums - NON-DEPOLARIZING (competitive antagonist of ACh receptors)
What do/are the A-band, I-band, H-zone, and Z-line contain/made of?
,A-band = full length of myosin aka thick filament (dark on EM)
I-band = only actin aka thin filaments and structural elements (light on EM)
Z-line = structural support proteins aka the anchoring point for actin filaments
H-zone = only myosin filaments
What are the three findings of dermatomyositis?
Cutaneous -
- Gottron papules (red/violet, flat topped papules over joints or bony prominences)
- Heliotrope rash (red /violet edematous eruption on upper eyelids and periorbital skin
Myopathy
- proximal muscle weakness (w/ elevated CK)
Individual > 50 with dermatomyositis, what must you R/o
malignancy (adenocarcinoma)
Rickets is caused by ____
Presenting symptoms?
Labs?
vitamin D deficiency leading to excess of unmineralized osteoid matrix
Bowing of legs, frontal bossing, bead-like costochondral junctions
Increased - PTH, Alk.P
Decreased - Ca and Phosphate
What are the two steps of building bone?
1> osteoblasts lay down osteoid
2. Calicum and phophate mineralize the osteoid with the assistance of VItamin D
HLA B27 = ___
Seronegative arthropathies
, What is the mnemonic for seronegative arthropathies
PAIR
Psoriatic arthritis
Ankylosing spondylitis
IBD-associated arthritis
Reactive Arthritis
What HLA corresponds to Rheumatoid arthritis
HLA-DR4
"4 walls in a rheum"
Shitty injection into the _____quadrant of the ___ buttock results in a right hip drop when the
patient raises his right foot off of the ground?
Upper medial quadrant
Left buttock
Lesion is opposite to the hip drop and ipsilateral to the planted foot
Three first line agents for acute gout are
NSAIDs (NO SALICYLATES)
Glucocorticoids
Colchicine
Why do you not give aspirin for acute gout?
salicylates inhibit tubular secretion of uric acid and therefore worsen gout
Given indomethacin or naproxen instead
Old woman with low impact vertebral fracture
osteoporosis suspicion
d/t increased bone resorption
What are three TNF alpha inhibitors?
Old lady with severe right hip pain after a fall.
Current meds - low dose prenisone.
40 pack year history of smoking.
Injury to what artery is most likely to lead to osteonecrosis?
Medial circumflex femoral
Medial circumflex supplies blood to the head of the femur.
CAST Bent LEGS
What are the causes of avascular necrosis of the femoral head?
CAST Bent LEGS
Corticosteroids
Alcoholism
Sickle cell disease
Trauma
the Bends
LEggs-Calves-Perthes (childhood disorder of blood flow to the hip)
Gaucher's Disease (cerebroside metabolism)
Slipped Femoral Capital Epiphysis
Fractures of the surgical neck of the humerus damage what nerve?
axillary
Fractures of the midshaft of the humerus damage what nerve and potentially what artery?
Name one other fracture that could potentially damage this nerve?
Radial, deep brachial
Anterolateral displacement of a supracondylar ridge humerus fracture could also damage radial
1st line treatment for osteoporosis is?
,Bisphosphonates
(-dronates; Risedronate)
What is a classic difference in the presentation of Myasthenia Gravis and Lambert-Eaton
myasthenic syndrome?
MG - strength decreases with repetition
- autoantibodies to the ACh post-synaptic receptor, so more repetition = less and less ACh
available to be released from the synapse --> weakness
LEMS - strength increases with repetition
- autoantibodies to the pre-synaptic Ca++ channel, (less release of ACh). More repetition leads
to increased calcium in the pre-neuron --> more release of ACh --> strength
Patient is being treated for a Pseudomonas infection and complains of weakness and vision
deficits that occur later in the day. What is occuring?
Pt is being tx with Aminoglycosides
SE of Aminoglycosides - neuromuscular blockade (+ nephrotoxicity, + ototoxicity, +
teratogenicity)
Two main "classes" of muscle relaxers are what?
Which would be used for outpatient tx? for surgery?
1. centrally acting - outpatient
2. peripherally acting - surgery
What are the two main peripherally acting muscle relaxers and how do their MOAs differ?
Succinylcholine
"Curiums" and "Curonium"
Succinyl - DEPOLARIZING (binds to receptor, causes prolonged depolarization and eventually
relaxation)
Curiums - NON-DEPOLARIZING (competitive antagonist of ACh receptors)
What do/are the A-band, I-band, H-zone, and Z-line contain/made of?
,A-band = full length of myosin aka thick filament (dark on EM)
I-band = only actin aka thin filaments and structural elements (light on EM)
Z-line = structural support proteins aka the anchoring point for actin filaments
H-zone = only myosin filaments
What are the three findings of dermatomyositis?
Cutaneous -
- Gottron papules (red/violet, flat topped papules over joints or bony prominences)
- Heliotrope rash (red /violet edematous eruption on upper eyelids and periorbital skin
Myopathy
- proximal muscle weakness (w/ elevated CK)
Individual > 50 with dermatomyositis, what must you R/o
malignancy (adenocarcinoma)
Rickets is caused by ____
Presenting symptoms?
Labs?
vitamin D deficiency leading to excess of unmineralized osteoid matrix
Bowing of legs, frontal bossing, bead-like costochondral junctions
Increased - PTH, Alk.P
Decreased - Ca and Phosphate
What are the two steps of building bone?
1> osteoblasts lay down osteoid
2. Calicum and phophate mineralize the osteoid with the assistance of VItamin D
HLA B27 = ___
Seronegative arthropathies
, What is the mnemonic for seronegative arthropathies
PAIR
Psoriatic arthritis
Ankylosing spondylitis
IBD-associated arthritis
Reactive Arthritis
What HLA corresponds to Rheumatoid arthritis
HLA-DR4
"4 walls in a rheum"
Shitty injection into the _____quadrant of the ___ buttock results in a right hip drop when the
patient raises his right foot off of the ground?
Upper medial quadrant
Left buttock
Lesion is opposite to the hip drop and ipsilateral to the planted foot
Three first line agents for acute gout are
NSAIDs (NO SALICYLATES)
Glucocorticoids
Colchicine
Why do you not give aspirin for acute gout?
salicylates inhibit tubular secretion of uric acid and therefore worsen gout
Given indomethacin or naproxen instead
Old woman with low impact vertebral fracture
osteoporosis suspicion
d/t increased bone resorption
What are three TNF alpha inhibitors?
