MSK Flashcards
what is osgood-schlatter disease
overuse injury of the secondary ossification center (apophysis) of the tibial tubercle
very common cause of knee pain in young adolescent athletes after a recent growth spurt
pain and swelling at the tibial tubercle, the insertion point of the patellar ligament
insertion site of the quadriceps muscles group
tibial tuberosity
by the patellar ligament
what is the psoas sign
inflammation of the psoas muscle causes pain when the hip is extended
how to tell that the alkaline phosphatase is from the bone and not placenta, liver, or intestine
two predominant contributors of alkaline phosphatase: bone and liver
can be differentiated by electrophoresis and specific monoclonal antiboies
heat denature bone-specific alkaline phosphatase
what is bone-specific alkaline phosphatase used for
reflects osteoblastic activity
mechanism of action of colchicine and side effects
second-line agent for acute gouty arthritis
inhibits tubulin polymerization and microtubule formation in leukocytes, reducing neutrophil chemotaxis an emigration to sites inflamed by tissue deposition of monosodium urate crystals
also impaired GI mucusal function by microtubule disruption–> diarrhea, nausea, vomiting, and abdominal pain
type 1 muscle fiber
slow twitch; red fibers resulting from increased mitochondria and myoglobin concentratioin (increased oxidative phosphorylation)–> sustained contraction
increased with endurance training
type 2 muscle fiber
fast twitch; white fibers from decreased mitochondria and myoglobin concentration (increased anaerobic glycolysis)
proportion increased after weight/resistance training, sprinting
CREST syndrome
- Calcinosis (subcutaneous Ca2+ deposits which may be asumptomatic or painful)
- Raynaud’s phenomenon
- Esophageal dysmotility
- Sclerodactyly (thickening of the skin of the hands and feet)
- Telangiectasias (dilated blood vessels)
associated with anti-centromere antibodies
what is ankylosing spondylitis?
inflammatory condition associated with HLA-B27 serotype
stiffness and fusion (ankylosis) of axial joints
most commonly affected joints: sacroiliac and apophyseal joints of the spine
peripheral arthritis and enthesitis (pain and swelling at the sites of tendon insertion in to bone)
complications of ankylosing spondylitis
- respiratory: limit chest wall expansion–> hypoventilation
- cardio: ascending aortitis–> dilation of aortic ring and aortic insufficiency
- eye: anterior uveitis –> pain, blurred vision, photophobia, and conjunctival erythema
characteristics of anaplastic tumors
neoplastic cells that have complete lack of differentiation–>high-grade
1) loss of cell polarity with complete disruption of normal tissue architecture; cels coalesce into islands in a disorganized, infiltrative fashion
2) significant variation in shape and size of cells and nuceli
3) large nuclei that are deep-staining with abundant, coarsely-clumped chromatin and large nucleoi
4) numerous mitotic figures
5) giant, multinucleated tumor cells
dermatomyositis
autoimmune inflammatory disease that affects muscles and skin
malar rash, Gottron papules, heliotrope rash, “shawl and face” rash, “mechanic’s hands”
increased risk of malignancy, especially lung, colorectal, and ovarian
characteristic of follicular lymphoma
most common indolent non-Hodgkin lymphoma in adults, second most common NHL overall
derives from follicular B cells
waxing and waning clinical course
middle-aged patients with painless lymph node enlargmet or ab discomfort from abdominal mass
histology: cleaved and noncleaved folllicle center cells in a nodular pattern
mutation associated with follicular lymphoma
t(14;18) translocation–> overexpression of bcl-2 oncogene that blocks programmed cell death
DIC in pregnancy is mediated by
tissue factor (thromboplastin) found in high concentration in placental trophoblast
initiate coagulatioin cascade, depleting clotting factors and platelets–> lots of bleeding
signs of thrombotic thrombocytopenic purpura
new-onset neurologic symptoms, anemia with schistocytes, thrombocytopenia, and acute kidney injury
due to deficiency of ADAMTS13, a von Willebrand factor cleaving protease
how come there is hypercalcemia in sarcoidosis
caused by PTH-independent formation of 1,25-dihydroxyvitamin D by activated macrophages
leads to increased intestinal absorption of calcium
what is rheumatoid factor
IgM antibody specific for Fc component of IgG
what does dystrophin do?
stabilize interaction between sarcolemma and the intracellular contraction apparatus
disruption to this protein–> membrane damage and myonecrosis
ankylosing spondylitis
chronic inflammatory disorder of the sacroiliac joints and axial skeleton
–> spine x-rays reveal sclerosis, ligamentous calcification, and vertebral fusion (“bamboo spine”)
seronegative spondyloarthropathies diseases
ankylosing spondylitis, reactive arthritis, arthritis associated with inflammatory bowel disease, and psoriatic arthritis
all don’t have serum rheumatoid factor
patients with these disease have higher incidence of the HLA-B27 allele
what is serum sickness
type III hypersensitivity reaction to nonhuman proteins characterized by vasculitis resulting from tissue deposition of circulating immune complexes
fever, pruritic skin rash, arthralgias, and low serum C3 and C4 complement levels
osteoarthritis vs rheumatoid arthritis
focused on osteoarthritis
osteoarthritis:
- increases with age, >40
- involves knees, hips, DIP and 1st CMC joint
- non or brief (<30 min) morning stiffness
- no systemic symptoms
- hard, bony enlargement of joints
osteoarthritis vs rheumatoid arthritis
focused on RA
- 40-40, often younger
- MCP, PIP and wrist joints
- prolonged morning stiffness
- fever, fatigue, and weight loss
- soft/spongy, warm joints
what is heteroplasmy in inheritance pattern?
presence of both normal and abnormal mitochondrial DNA –> variable expression of an mitochrondrially inherited disease
anti-Jo-1
anti-histidyl-tRNA synthetase
found in dermatomyositis and polymyositis
production of which cytokines plays a huge role in the severity and progression of giant cell arteritis
IL-6
breast cancer med that also decrease risk of both bone fractures and breast cancer
selective estrogen receptor modulators exhibit estrogen antagonist and agonist properties in a tissue-specific manner
Raloxifene- estrogen agonist activity on bone and estrogen antagonist effect on breast tissue and uterus so doesn’t increase risk of endometrial cancer
tamoxifen
selective estrogen receptor modulator that has strong estrogen antagonist activity in the breast and in used in the treatment of estrogen receptor-positive breast cancer
agonist activity on the uterus increaes risk of endometrial hyperplasia/cancer
relationship between TNF-alpha and latent tuberculosis
TNS-alpha is necessary for effective sequestration of mycobacteria within granulomas
so TNF-alpha inhibitors promote reactivation of latent tuberculosis–> increased risk of disseminated disease
signs and symptoms of femoral neuropathy
weakness involving the quadriceps muscle group and weakening of iliopsoas with more proximal nerve injuries
difficulty with stairs and frequent falling secondary to “knee buckling”
diminished patellar reflex
sensory loss over anterior and medial thigh and medial leg
characteristic of SLE
loss of immune self-tolerance with production of autoantibodies against nuclear antigens–> deposition of immune complexes in tissues and consumption of complement
drug-induced lupus erythematosus (DILE)
abrupt onset of lupus symptoms (eg, fever, arthralgias, pleuritis) with positive anti-histone antibodies
associated wtih drugs that are metabolized by N-acetylation in the liver (eg, procainamide, hydralazine, isoniazid)
people who are slow acetylators are at greater risk for developing DILE
what do you find in synovial fluid of pseudogout
rhomboid-shaped calcium pyrophosphate crystals
positive birefringent
marfan syndrome
defect in fibrillin-1= extracellular glycoprotein that acts as a scaffold for elastin
fibrillin are abundant in zonular fibers of lens, periosteum, and aortic media
–> aortic root dilation with dissection and rupture=common cause of death
first-line treatment for acute gouty arthrtis
NSAIDs
rotator cuff muscles and their function
- supraspinatus: abduction
- infraspinatus: external rotation
- teres minor: adduction and external rotation
- subscapularis: adduction and internal rotation
presenting features of osteonecrosis
most common site: femoral head: chronic, progressive groin and hip pain that is exacerbated by weight bearing
restricted movement in the affectd join, with no swelling, erythma, or warmth in the surrounding area
microscopic analysis: wedge-shaped zone of affected bone–> dead bony trabeculae (empty lacunae) and fat necrosis
common causes of osteonecrosis
sickle cell disease–> thrombotic occlusion of arteries
-glucocorticoid therapy, vasculitis, and alcoholism
what is defective in osteogenesis imperfecta
defective synthesis of type 1 collagen in osteoid by osteoblasts
muscles used when siting up from supine position:
external abdominal obliques, rectus abdominis, and hip flexors (psoas major, psoas minor, and iliacus)
side effects of methotrexate
stomatitis, bone marrow suppression, and liver function abnormalities
dystonia
syndrome of prolonged, repetitive muscle contraction
may result from impaired function of basal ganglia
common types of focal dystonia: cervical dystonia (spasmodic torticollis), blepharospasm (involuntary closure of eyelids), and writer’s cramp
myoclonus
sudden, brief, sometimes severe (shock-like) muscle contraction
ex) hiccups and hypnic jerks (occur when falling asleep)
pathologic: epilepsy and Creutzfeldt-Jakob disease
what ligament is torn and displaced in radial head subluxation (nursemaid’s elbow)
annular ligament
bone mineral density with thiazide diuretics
thiazide diuretics increase calcium absorption in the distal convoluted tubules within the nephron
associated with increased bone mineral density and are recommended for treatment of hypertension in patients at risk for osteoporosis
loop diuretics increase urinary calcium loss
what happens to serum calcium, phosphorus, and PTH levels in primary osteoporosis (osteoporosis that is not due to an underlying medical disorder)
they are all normal
parvovirus B19 causes 2 primary syndrome in immunocompetent patients
erythema infectiosum: primarily in children, bright red rash on cheecks with circumoral pallor and fever
acute arthropathy: in adults, symmetric polyarthritis involves the proximal interphalangeal, metacarpal, knee, and ankle joints, arthritis is self-limited and nondestructive
contracture
condition of shortening and hardening of muscles, tendons, or other tissues–> rigidity and deformity of joints
due to excessive matrix metalloproteinase activity and myofibroblast accumulation in the wound margins
can produce deformities of the wound and surrounding tissues, most often on palms, soles, and anterior thorax, or at serious burn sites
leukocyte adhesion deficiency (LAD)
autosomal recessive disorder characterized by absence of CD18 antigens, which are necessary for the formation of integrins (essential for leukocyte adhesion to endothelial surfaces and migration to peripheral tissues in response to infection or inflammation)–> recurrent skin and mucosal infections without purulence, delayed separation of the umbilical cord, and persistent leukocytosis (elevated levels of WBC)
what does FGFR3 do?
normally responsible for limiting chondrocyte proliferation during endochondral ossification
in achondroplasia, FGFR3 is mutated and is activated, causing exaggerated inhibition of chondrocyte proliferation that results in bone shortening and craniofacial abnormalities
what artery provides the majority of the blood supply to the femoral head and neck
medial femoral circumflex artery and its branches
what ligament is injured in a lateral ankle sprain due to inversion of the food
anterior talofibular ligament
which artery is most likely to be injured with midshaft fractures of the humerus
deep brachial (profunda brachii) artery
it runs with radial nerve along the posterior aspect of the humerus
which part of the spine is also involved in rheumatoid arthritis
cervical spine–> can lead to spinal instability with potential radiculopathy/cord compression
how does the body prevent damage to the musculoskeletal system when a muscle exerts too much force
golgi tendon organs inhibit contraction of the muscle, causing sudden muscle relaxation
what is the golgi tendon organs sensitive to and insensitive to
sensitive to increases in muscle tension
insensitive to passive stretch
medications associated with osteoporotic fractures
- anticonvulsants that induce cytochrome P450 (increase vitamin D catabolism)
- aromatase inhibitors (decrease estrogen)
- medroxyprogesterone (decrease estrogen)
- GnRH agonists (decrease testosterone and estrogen)
- proton pump inhibitors (decrease calcium absorption)
- glucocorticoids (decrease bone formation)
triad clinical features of McCune-Albright syndrome
- peripheral precocious puberty
- irregular cafe-au-lait macules
- polyostotic fibrous dysplasia (multiple osteolytic-appearing lesions of the hip and pelvis)
due to activating mutation in the G protein/CAMP/adenylate cyclase signaling pathway
ATP’s role in muscle contraction
need ATP to detach myosin crossbridge from actin
when you take off the ATP and it is just the ADP-phosphate complex, then there is a cross-bridge between myosin and actin
acute rheumatic fever
migratory arthritis, new-onset murmur, fever, and a positive anti-streptolysin O titer
acute morbidity is most likely due to pancarditis (inflammation of the endocardium, myocardium, and epicardium)
where is the superior gluteal nerve located
superomedial quadrant of the buttock
treatment of rheumatoid arthritis
because disease-modifying antirheumatic drugs (hydroxychloroquin, methotrexate, minocycline, and sulfasalazine) takes several weeks to take effect, NSAIDs and glucocorticoid can provide rapid symptom relief in the interim
