Musculoskeletal Flashcards
Describe the changes to bone in Rickets
- Trabeculae are normal in number and size, but do not mineralize effectively
- Rim of uncalcified osteoid is much larger than normal
Are crystals in gout or pseudogout visible on x-ray?
Gout - no, they are monosodium urate crystals
Pseudogout - yes, they are calcium pyrophosphate dihydrate crystals
What are the metabolic side effects of glucocorticoids?
- hypocalcemia
- fluid retention
- hypokalemia
- hyperglycemia
- hypernatremia
Is celecoxib a sulfa drug?
YES, along with:
sulfonureas, sulfamethoxazole, sulfasalazine, and thiazide diuretics, furosemide, bumetanide
Pain at what location is pathognomonic for scaphoid fracture?
anatomic snuffbox – this should be fixed right away because risk of avascular necrosis
Which lumbricals does the median nerve innervate?
1st and 2nd (which move the 2nd and 3rd fingers–the pointer and middle finger)
What symptoms would be present in a common fibular nerve injury? What is another name for this nerve and how is it commonly injured?
Symptoms:
1. loss of sensation over dorsum of the foot (superficial fibular branch)
2. loss of dorsiflexion and toe extension (deep fibular branch)
AKA: Common peroneal nerve
Common injury: compression at the head of the fibula by bed rest, leg crossing, or hyperflexion of knee (vajrasana → “yoga foot drop”)
What type of collagen is affected in osteogenesis imperfecta? What ocular finding is present?
Type I; may present with blue sclera
Draw out the brachial plexus
see a picture to check
What is tacrolimus?
an immunosuppresant that inhibits calcineurin-mediated transcription of IL-2
Which levels innervate the anal wink?
S2-S4 via the pudenal nerve
What are the markers of osteoblast and osteoclast activity?
Osteoblast:
- bone specific alkaline phosphatase
Osteoclast:
- TRAP, urinary hydroxyproline, urinary deoxydyridinoline (most reliable)
Which gout drug has GI side effects such as nausea, vomiting, and diarrhea? What is its mechanism of action? Is it used for acute or chronic gout?
Colchicine; microtubule polymerization inhibitor; both
When overactive, this enzyme can lead to gout
PRPP (5’-phosphoribosyl-1’-pyrophosphate; increases purine production → uric acid)
What immune cell mediates the inflammation in gout?
neutrophils (they try to eat the crystals → release cytokines to recruit more neutrophils and cause inflammation)
What are the findings in alkaptonuria? What enzyme is deficient?
- Dark connective tissue (e.g. helix of ears)
- Brown pigmented sclerae
- Urine turns black on prolonged exposure to air
- Arthralgias (homogentisic acid damage to cartilage)
Deficiency = homogentisate oxidase
Pathway = Tyrosine → Fumarate
What are the top 2 causes of osteomyelitis in SS patients?
- Salmonella - most common
2. E. coli
What is Ecthyma gangrenosum?
a rapidly progressive necrotic cutaneous infection caused by Pseudomonas in immunocompromised patients
Key differences b/w polymyalgia rheumatica and fibromyalgia?
- Age: PMR is more common in ♀ > 50 vs. FM in F8 20 - 50
- Symptoms: PMR has fever and weight loss, FM has point tenderness
- Labs: PMR will have ↑ ESR, CRP, (normal CK)
- Treatment: PMR: low-dose corticosteroids vs. FM: exercise, antidepressants, anticonvulsants
Inheritance of achondroplasia?
AD
What is a common manifestation of sickle cell disease painful crisis in children?
Dactylitis (painful hand swelling)
How does Paget’s disease start?
↑ osteoclast activity
4 stages: lytic, mixed, sclerotic, quiescent
Intracellular levels of what substance activates the breakdown of glycogen?
Ca2+
What is a central joint that can be affected in reactive arthritis?
sacroiliac joint (20% of cases) → sacroiliits
What are the symptoms of polymyositis? Pathophys?
Progressive symmetric proximal muscle weakness; muscle damage → overexpression of MHC I on sarcolemma → CD8+ T cell infiltration → further damage
What is etanercept? What do you have to check before using it?
TNF-α inhibitor; See if patient has TB b/c this class of drugs predispose to infection
What are some prominent features of congenital hypothyroidism?
Pot-bellied Pale Puffy-faced (course facial features) Protruding umbilicus Protuberant tongue Poor brain development Pooped (lethargy, floppy) Poor feeding
What is Hirschsprung disease?
abnormal migration of neural crest cells into rectosigmoid colon → absence of ganglion cells in wall → abdominal distention, bilious emesis, failure to pass meconium
What viral infection can closely mimic rheumatoid arthritis? How can you tell the difference?
Parvovirus; it will self-resolve
What are the symptoms of scurvy? Who might get it?
Swollen gums,
bruising,
hemarthrosis,
anemia,
poor wound healing,
perifollicular and subperiosteal hemorrhages, “corkscrew” hair
People on “Tea and Toast” diet, homeless, alcoholics, drug users
Where is collagen (proline and lysine residues) hydroxylated by vitamin C?
RER
What is the most commonly injured structure in rotator cuff syndrome? How do you test for it?
Supraspinatus tendon because it gets impinged b/w acromion and head of humerus; “empty can” test is 90% specific (abduct arms 90 degrees, flex 30 degrees, point thumbs toward floor)
What two signals produced by osteoblasts promote osteoclastic differentiation?
- Macrophage CSF
2. RANK-L
What kind of hypersensitivity is MG?
II
What protein is defective in Marfan’s? What is its function?
Fibrillin-1 - a component of microfibrils that forms a sheath around elastin
Contrast the functions of golgi tendon organ and extrafusal fibers in the mm.
Golgi: senses when too much stretch → reflex relax
Muscle spindle (aka intrafusal fibers): mm. contracts to resist stretch
Note that golgi is in series and muscle spindle is parallel to muscle fibers
What nerve passes through the obturator foramen? What action do the innervated muscles perform?
Obturator nerve → thigh adduction
What two muscles does the median nerve pass between in the arm?
flexor digitorum superficialis and flexor digitorum profundus
Injury to this nerve and muscle causes a winged scapula
long thoracic nerve to serratus anterior
Does the PCL attach medially or laterally to the midline on the femur? What about the ACL?
PCL: medially
ACL: laterally
Why is there hypercalcemia in sarcoidosis?
Activated T cells secrete IFN-gamma → ↑ 1α-hydroxylase in Mø → ↑ vit D → ↑ absorption of Ca2+ from GI and kidneys
