MSK Flashcards
Osteosarcoma
Primary vs. secondary forms (Paget radiation). Most common primary tumor of bone (B-cell lymphoma is most common overall). Found around knee. Bimodal (10-20 and >65). Codman’s triangle = raised periosteum. Secretes osteoid. Rarely invades epiphysis.
Osteoclast mechanism?
Pump out H+ produce by carbonic anhydrase against gradient into Howship lacunae to release calcium, phosphoric acid, and carbonic acid.
Lumbar lordosis etio?
Imbalance of hip flexion > extension. Obesity, pregnancy, osteoporosis, discitis, kyphosis, spondylithesis, achondroplasia
Reiter syndrome
Triad of reactive arthritis, urethritis, and conjunctivitis 2/2 to urogenital infection (Chlamydia) or GI inf (Salmonella, Shigella, Campy, Yersinia). HLA-B27 associated.
Superficial inguinal LN’s drain what structures?
Cutaneous lymph from umbilicus to feed except posterior calf (popliteal LN’s). Includes external genitalia (e.g. scrotum) and anus up to dentate line.
Most common congenital anomaly
Accessory nipple = polythelia. Failure to involute. Usu. asymptomatic, although may become so during pregnancy or lactation.
Deep inguinal LN’s drain what structures?
Glans/clitoris + superficial inguinal LN’s
Layers of the epidermis?
Californians Like Girls in String Bikinis. Stratum Corneum, Lucidum, Granulosum, Spinosum, Basale.
At what epidermal layer are the cells starting to die?
Granulosum -> Lucidum
Zonula adherens vs. Macula adherens?
Zonula adherens is the adherent junction. Belt below the tight junction connecting actin cytoskeletons of cells with CADherins. Loss of E-cadherin promotes metastasis. Macula adherents are desmosomes (Desmoplakin; site of pemphigus vulgarism auto ab’s)
Tight junction make-up?
Claudins and occludins
Gap junction make-up?
Connexon with central channel
Integrins vs. cadherins?
Integrins on basolateral membrane with the hemidesmosomes. Cadherins with the adherents junction (belt).
Valgus vs. varus?
Varys is wide. Valgus is knock-kneed.
McMurray test?
External rotation of knee (varus stress)–> pain from MEDIAL meniscus. Pain on internal rotation (valgus stress) is LATERAL meniscus.
Where do you do a pudendal nerve block?
Ischial spine
Where is McBurneys point?
2/3 of distance from umbilicus to ASIS (right)
F(x) of supraspinatus and nerve?
Abduct arm before deltoid. Suprascapular nerve.
F(x) of infraspinatus and nerve?
Lateral rotation of arm. Suprascapular nerve.
F(x) of teres minor and nerve?
Adduction and lateral rotation of arm. Axillary nerve.
F(x) of subscapularis and nerve?
Medial rotation and adduction. Subscapular nerve.
Most common rotator cuff tear?
Supraspinatus
Ulnar nerve injury that localizes to wrist?
Probably outstretched hand. Hook of hamate.
Wrist bone most commonly fractured?
Scaphoid
Acronym for wrist bones.
So Long to Pinky, Here Comes The Thumb. Scaphoid, Lunate, Triquetrum, Pisiform. Hamate, Capitate, Trapezoid, Trapezium.
Guyon canal syndrome?
Ulnar nerve compression at wrist or hand. Classically for cyclist and handlebar pressure.
Klumpke’s palsy
Lower trunk (C8-T1) -> CLAW hand. Often 2/2 to upward traction during delivery or breaking fall with arm.
Erb palsy
Upper trunk (C5-C6) -> waiter’s tip. Unable to abduct arm (deltoid, supraspinatus), laterally rotate (infraspinatus), flex or supinate (biceps brachii)
General differences between distal and proximal median/ulnar nerve “clawing?”
Distal lesions are worse and seen with extension of the fingers/at rest (cannot extend). Proximal lesions are less pronounced and tend to be seen during voluntary flexion (cannot flex).
Distal ulnar n. vs proximal ulnar n.?
Distal ulnar nerve -> inability to extend lateral fingers = “Ulnar claw.” Proximal ulnar nerve -> inability to flex lateral fingers = OK gesture while making fist.
Distal ulnar n. vs distal median n.?
Distal ulnar n = ulnar claw when at rest. Distal median nerve = median claw when at rest (can’t extend medial fingers)
Proximal median n. vs. distal median n.?
Proximal median n. = pope’s blessing when closing the hand (medial fingers cannot flex). Distal median n. = median claw (medial fingers cannot extend)
Lumbrical muscle function?
Flex MCP, extend PIP and DIP.
Fractured surgical neck of humerus?
Axillary n. (C5-C6) injury. Posterior circumflex a.
Midshaft fracture of humerus?
Radial n. injury (C5-T1). Deep branchial artery.
Supracondylar fracture of humerus?
Median n. injury
Medial epicondyle fracture of humerus?
Ulnar n. injury
Compression of axilla injury?
Radial n. injury.
Fractured hook of hamate injury?
Ulnar n. (distal) injury.
Anterior dislocation of humerus injury?
Axillary n. injury
Axillary n. injury presentation?
Flattened deltoid, inability to abduct > 15 deg. Loss of sensation over deltoid and lateral arm.
Median n. injury presentation?
Ape hand, pope’s blessing. Loss of wrist flexion, thumb opposition. Median n. sensory loss
Ulnar n. injury presentation?
Ulnar claw
Recurrent branch of median n. presentation?
Superficial laceration of palm. Ape hand. Loss of thenar muscle group = opposition, abduction, and flexion of the thumb. NO loss of sensation.
Radial n. injury prsentation?
Rist drop. Inability to extend elbow, wrist, finger. Decreased grip strength. Radial n. distribution.
Thenar muscles and nerve?
Median n. Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis. OAF.
Hypothenar muscles and n.?
Ulnar n. Opponens digiti minimi, Abductor digit minimi, flexor digiti minimi brevis. OAF.
Dorsal vs. palmar interosseous muscles function?
Dorsals ABduct. Palmar ADDUCT. Palms add together to pray.
Common peroneal nerve injury presentation?
Foot drop. Loss of sensation on dorsum of foot.
Tibial nerve injury presentation?
Can’t curl toes (can’t stand on toes either). Loss of sole sensation. Proximal lesions -> foot eversion (Baker cyst).
Superior gluteal n. injury presentation?
Trendelenburg sign/gait. Lesion is OPPOSITE of side that drops b/c the contralateral gluteus medius and minims is supposed to hip ABduct.
Inferior gluteal n. presentation?
Difficulty climbing stairs, rising from seat. Loss of hip extension (maximus)
Obturator vs. femoral n. presentations?
Femoral n. is decreased thigh FLEXION and leg extension (Femoral n. is the kick!). Obturator n. is decreased medial thigh sensation and decreased adduction. Obturator is crossing the legs.
Popliteal fossa injury?
Tibial n. and popliteal artery.
Distal humerus/cubital fossa injury?
Median n. and branchial a.
What band of the sarcomere never changes length?
A band = myosin-only length.
Two main muscle fiber types?
Slow = type 1. Fast = type 2. (Cuz slow and steady wins the race, myoglobin, AND mitochondria). Type I requires aerobic metabolism (high myoglobin for o2 and mitochondria).
T-tubule depolarization is linked to what Ca2+-channel receptors?
Dihydropyridine receptor (T-tubule) and ryanodine receptor.
How does smooth muscle contract generally speaking?
NOT with troponin and T-tubules. A depolarization causes L-type voltage-gated Ca+ channels to open leading to increased Ca -> Ca-calmodulin binding -> activates myosin light chain kinase -> phosphorylates myosin and makes it HIGH ATPase activity -> cross-bridge cycling.
How does NO relax smooth muscle cells?
NO activates guanylate cyclase to make cGMP, which activates myosin-light-chain phosphoatase -> remove phosphate from myosin and dec. cross-bridge cycling.
Woven bone vs. lamellar bone?
Histological types. Woven bone is NOT organized and stress-oriented whereas lamellar bone. Lamellar bone is made from remodeling woven bone.
Endochondral vs. membranous ossification?
Endochondral ossification relies on a cartilaginous model of bone made by chondrocytes - axial and appendicular skeleton. Membranous ossification is woven bone made directly - calvarium and facial bones.
How does estrogen affect bone formation?
Estrogen INHIBITS osteoblast apoptosis and induces osteoclast apoptosis.
Osteoblasts and osteoclasts differentiate from what cells?
Osteoclasts (Eaters) differentiate from monocytes/macrophages. Osteoblasts (builders) differentiate from mesenchymal stem cells of periosteum.
Achondroplasia
Activation of FGFR3 inhibits chondrocyte proliferation leading to failure of long-bone growth (endochondral oss) -> short limbs. Mostly sporadic and associ. with adv. paternal age.
Two types of osteoporosis?
Type I is post-menopausal. Type II is senile > 70.
Ppx for osteoporosis?
Regular wt-bearing exercise, Ca, Vitamin D.
Treatment for osteoporosis?
Bisphosphonates, PTH, SERMs. Denosumab (monoclonal antibody AGAINST RANKL). Calcitonin rarely.
Osteopetrosis
Osteoclast failure (e.g. CA II mutation) -> dense, thick bones prone to fracture + no bone marrow -> pancytopenia and extramedullary hematopoiesis. Nerve impingement, CN. Tx = bone marrow transplant to make new osteoclasts (From monocytes)
Osteomalacia and lab values?
Vitamin D deficiency in adults -> defective mineralization of osteoid. Lab finds = dec. Ca, inc. PTH, dec. phosphate
Paget disease of bone mech and labs
Bone remodeling disorder characterized by increased osteoblastic and clastic activity. Normal lab values BUT increased alkaline phophatase. Mosaic pattern of bone.
Paget disease of bone presentation
Long bone chalk-stick fractures. High-output HF 2/2 AV shunts. Risk of osteogenic sarcoma.
4 stages of Paget disease
Lytic (clast), Mixed, Sclerotic (blast), Quiescent (minimal activity)
Etios of osteonecrosis (avascular necrosis)?
Trauma, high-dose corticosteroids, alcoholism, sickle cell. Most common site is femoral head 2/2 medial circumflex artery
Osteitis fibrosa cystica?
As a consequence of hyperparathyroidism (primary OR secondary), bone resorption + blastic activity -> fibrous replacement of bone often with hemorrhagic debris (“brown tumors”)
Names of benign primary bone tumors?
Giant cell tumor and osteochondroma
Treatment for osteosarcoma?
Surgical en bloc resection and chemo.
Pathology of Ewing’s sarcoma?
Anaplastic small blue cell malignant tumor. Onion skin in bone.
Ewing’s sarcoma presentation?
Boys < 15. Often in diaphysis of long bones, pelvis, scapula, ribs. Associated with t(11;22) translocation.
Predisposing factors for osteosarcoma?
Paget disease of bone, bone infarcts, radiation, familial retinoblastoma, Li-Fraumeni
Giant cell tumor presentation?
Soap bubble appearance. Typically around knee (epiphyseal ends of long bones). 20-40 yrs old.
Chondrosarcoma path?
Expansile glistening mass within MEDULLA.
Chondrosarcoma presentation?
Men 30-60. Pelvis, spine, scapula, humerus, tibia, femur.
Osteochondroma?
An exotosis of mature bone with cartilaginous cap. Most common benign tumor. Males < 25 y/o. Rarely transforms into chondrosarcoma.
RA etiology?
Autoimmmune inflammatory destruction of joints mediated by cytokines and type III (IC) and type IV (delayed T-cell) HS reactions.
Joint findings in OA?
Subchondral cysts, osteophytes (bone spurs), eburnation (polished appearance of bone). Heberden (DIP) and Bouchard (PIP) nodes. NO MCP.
Joint findings in RA?
Pannus formation in joints (MCP, PIP), SQ rheumatoid nodules (fibrinoid necrosis), ulnar deviation of fingers, subluxation. Baker cyst. NO DIP.
Predisposing factors for RA?
F>M. Rheumatoid factor (which is an anti-IgG antibody). Anti-cyclic citrullinated peptide is specific. DR4.
Tx for OA vs. RA?
Both use NSAIDS. OA use intra-articular glucocorticoids. RA use systemic glucocorticoids and DMARDS (methotrexate, sulfasalazine, TNF-alpha inhibitors [infliximab, adalimumab])
Lab findings of Sjogren’s?
SS-A and/or SS-B (anti-Ro/La).
Presentation of Sjogren’s?
Xeropthalmia (dec. tear production -> corneal damage), xerostomia (Decreased saliva production), b/l parotid enlargement. Complications include caries, MALTs, lymphoma
Treatment of gout?
Acute attack treat with NSAIDs, glucocorticoids, and colchicine. Chronically, use xanthine oxidase inhibitors like allopurinol and febuxostat.
Gout crystal characteristics?
Negatively birefringent (yellow on parallel, blue on perp.). Needles. Monosodium urate crystals NOT uric acid crystals!!!
Overproduction of uric acid etiologies of gout?
Lesch-Nyhan (HGRPT), PRPP excess, tumor lysis syndrome, von Gierke disease (Glucose-6-phosphatase)
Tophus formation where?
MTP of big toe (podagra), external ear, olecranon bursa, Achilles tendon
Gout vs. pseudogout?
Uric acid vs. calcium pyrophosphate. Needle neg-birefring vs. basophilic rhomboid weakly pos-birefring. Small joints vs. large joints.
What are the seronegative spondyloarthropathies?
Arthritis w/o RF. HLA-b27 associated. PAIR - Psoriatic arthritis, Anklyosing spondylitis, Inflammatory bowel disease, Reactive arthritis/Reiter syndrome.
Ankylosing spondylitis clinical features?
Chronic inflammation of spine, sacroiliac. Uveitis. Aortic regurgitation.
Lab tests with good sensitivity for SLE?
ANA. Anti-histone for DRUG-induced.
Lab tests with good specificity for SLE?
Anti-dsDNA (poor prognosis). Anti-Smith = Anti-snRNP (not prognostic).
Type of glomerular disease in lupus nephritis?
Diffuse proliferative glomerulonephritis and membranous glomerulonephritis.
Why do SLE patients get positive VDRL/RPR?
Because of anti-cardiolipin antibodies.
Sarcoidosis lab findings?
Elevated serum ACE. Hypercalcemia 2/2 to increased 1-alpha-hydroxylase activity in macrophages -> vitamin D activation
Polymyalgia rheumatica?
Pain and stiffness of shoulders and hips with fever, malaise, WT loss w/o muscle weakness associated with temporal arteritis. Inc. ESR and CRP but NOT CK. Tx with low-dose steroids.
Mechanistic differences between polymyositis and dermatomyositis?
Polymyositis has endomysial (around fiber) inflammation of CD8+ cells whereas dermatomyositis has PERImysial (around fascicle) inflammation and atrophy with CD4+ cells.
Exam findings on dermatomyositis?
Malar rash, gottron papules, heliotrope rash, “shawl and face.” Progressive symmetric proximal muscle weakness.
Lab findings in poly/dermatomyositis?
inc. CK. Positive ANA, anti-Jo-1, anti-SRP, anti-Mi2.
Mechanistic differences between myasthenia gravis and Lambert-Eaton?
Autoab’s against post-synaptic Ach receptor vs. autab’s against pre-synaptic Ca2+ receptor (to decrease Ach release)
What test would differentiate between MG and LE?
Edrophonium (AChE inhibitor) test. MG would reverse. LE would not.
Differences in associated conditions between MG and LE?
MG associated with thymoma and thymic hyperplasia whereas LE is associated with small cell lung cancer.
Myositis ossificans?
After muscular trauma, a metaplasia of skeletal muscle INTO BONE.
CREST syndrome?
Calcinosis, Raynaud, Esophageal dysmotility, sclerodactyly (thickening and tightness of skin around fingers and toes -> ulceration), Telangectasia. Associated with anti-Centromere antibody.
Diffuse scleroderma vs. limited scleroderma?
Diffuse is more widespread, rapid, associated with anti-Scl-70 (topoisomerase I). Limited is CREST and associated with anti-centromere.
Acanthosis vs. acantholysis?
Acanthosis is epidermal hyperplasia (spinosum layer) while acantholysis is separation of epidermal cells. Acanthosis nigricans vs. pemphigus vulgaris
What is spongiosis?
The accumulation of edematous fluid in intracellular spaces.
Etiologies of albinism?
Decreased melanin production 2/2 bad tyrosinase activity or defective tyrosine transport. OR failure of neural crest cell migration (meaning low numbers of melanocytes)
Verrucae?
= Warts 2/2 HPV.
Ephelis?
= Freckle. Has increased melanin pigment.
Skin changes in psoriasis?
Acanthosis with parakeratotic scaling (nuclei still in corneum). Thickened stratum spinosum but DEC stratum granulosom.
Leser-Trelat sign?
The sudden appearance of many seborrheic keratoses indicating an underlying malignancy
What is cellulitis an infection of exactly?
Dermis and SQ tissue. Strep pyogenes (GAS) or Staph aureus.
Pemphigus vulgaris
IgG against desmoglein -> flaccid intraepiderma bullae caused by acantholysis. Affects mucosa. + nikolksy
Path findings of pemphigus vulgarism vs. bullous pemphigoid?
Pemphigus vulgarism with net-like pattern on IF whereas linear pattern at epiderma-dermal junction for bullous pemphigoid.
Bullous pemphigoid
IgG against hemidesmosomes. TENSE blisters with EOS. NEG nikolsky.
Dermatitis herpetiformis
PRURITIC papulse, vesicles, bullae. IgA deposides at tip of dermal papillae. Celiac disease
Erythema multiforme look?
Target lesions (rings and dusky center of epithelial disruption)
Erythema multiforme associations?
Mycoplasma, HSV, sulfa drugs, Beta-lactamas, phenytoin, ca, auotimmune
Stevens-Johnson syndrome
Fever, bulla formation, skin sloughing, HIGH mortality rate. Associated with mucosa. If > 30% of body surface area, called “toxic epidermal necrolysis.”
Erythema nodosum?
PAINFUL inflammatory lesions of SQ fat usu. on ant. shins. Associated with sarcoid, coccidiodomycosis, histoplasmosis, TB, strep, leprosy, Crohn
Lichen Planus
Pruritic, Purple, Polygonal Planar Papulse and Plaques. Sawtooth infiltrate of LYMphocytes at derma-epidermal border.
Pityriasis rosea
Herald patch -> christmas tree pattern of plaque.
Tanning vs. Suburn?
UVA in tanning and photoaging. UVB in sunburn.
Molecular aspects of melanoma?
Often driven by BRAF activating mutation. If V600E, could use vemurafenib (BRAF kinase inhibitor)
Histology differences between basal cell and squamous cell carcinoma?
Palisading nuclei vs. keratin pearls
Leukotriene functions?
LTB4 is for neutrophils chemotaxis. C4,D4,E4 for bronchoconstriction.
TXA2?
TAXI’s are congested. Thromboxane for inc. PLT aggregation, vasoconstriction, and bronchoconstriction.
Zileuton?
Inhibits lipooxygenase to decrease leukotrienes.
Mechanism of action for aspirin?
Irreversible inhibition of COX-1 &2 via acetylation.
Usage of COX-2 inhibitors?
RA, OA. Patients with gastritis or ulcers benefit because TXA2 production is dependent on COX-1.
Acetaminophen mechanism?
Reversibly inhibits cycloxygenase mostly in the CNS b/c inactivated peripherally.
Toxicity of bisphophonates?
Corrosive esophagitis. Therefore, pt’s need to take with water and remain upright for THIRTY minutes.
Allopurinol drug interactions?
Will increase concentrations of azathioprine and 6-MP b/c xanthine oxidase metabolizes these drugs.
Probenacid?
Inhibits resorption of uric acid in PCT. Also inhibits secretion of penicillin (stronger concentration)
Etanercept vs. infliximab/adalimumab
Cept is a receptor for TNF-alpha fused with IgG Fc = decoy receptor. Used for RA, psoriasis, akylosing spondylitis. Inflix/ada used for IBD + others.
Hypothyroid myopathy
Muscle pain, cramps, and weakness of proximal muscles along with features of hypothyroidism. CK is high. TSH high. Myoedema.
Topical vitamin D analogs?
Calcipotriene, calcitriol, and tacalcitol. Bind vitamin D receptor (nuclear transcription factor ) -| KERATINOCYTE proliferation and stimulates their differentiation. Also mediates T-cells. Used for Psoriasis.
Juvenile hemangioma
“Strawberry hemangioma”. 1/200. Initially GROW in proportion to child, then regress at or before puberty. (usu. before age 7)
Jaw pain that starts in the middle of a meal?
Think temporal arteritis. During meal, arteries cannot respond to increased blood requirement. Tongue pain may occur during means = tongue claudication.
