Musculoskeletal Flashcards
Achondroplasia
No cartilage proliferation at growth plate
Due to activating mutation in FGFR3
(Turning receptor ON inhibits growth)
Autosomal dominant & sporadic
Short extremities (Affects endochondral bone formation)
Normal head & chest (Intramembranous bone formation unaffected)
Osteogenesis Imperfecta
Congenital bone deformation, weak bone
Defective collage type 1 synthesis
Autosomal dominant
Multiple fractures, BLUE sclera with exposure of choroidal veins, hearing loss
Osteopetrosis
Abnormally thick, heavy bone that fractures easily like chalk
Due to carbonic anhydrase II mutation
(Resorption requires acidic space to remove Ca++)
Multiple fractures
Anemia, thrombocytopenia, leukopenia
Vision loss, hearing loss (Compressed CN’s)
Hydrocephalus (Thickened foramen magnum)
Renal tubular acidosis
(Anemia, thrombocytopenia, leukopenia because medullary space is replaced, myelophthisic process, no room for hematopoiesis)
Tx. Bone marrow transplant, to recover hematopoiesis/ make normal monocytes & osteoclasts again
Rickets & Osteomalacia
Defective mineralization of osteoid because low vitamin D levels (Low sun exposure, poor diet, malabsorption, liver/renal failure)
Rickets - Low vit D in kids with abnormal osteoid deposition ~ Pigeon chest, frontal bossing, rachitic rosary, bowed legs
Osteomalacia - Low vit D in adults with weak bone prone to fracture & abnormal labs
-Dec serum Ca++ & phos
+Inc PTH (because Ca++ is low) & ALP
(NOTE: Alkaline environment to add Ca++)
Osteoporosis
Loss of trabecular bone mass, leaving porous bone that is painful & fractures in weight-bearing areas
Risk of fracture depends on peak bone mass at age 30 & rate of bone loss after 30
-Diet & exercise
-Inherited vit D receptor
-Estrogen levels
Post-menopausal & Senile
Monitor bone density with DEXA scan
Labs are normal!
Tx. Exercise, vit D & Ca++, Bisphosphonates, ?ERT
Glucocorticoids c/i
Paget Disease of Bone
Imbalanced osteoCLAST/osteoBLAST, involving one or more bones, NOT whole skeleton
Etiology unknown, ?viral
Seen in late adulthood
Stages
1. Clasts go crazy
2. Mixed
3. Blasts try to compensate
4. Thick sclerotic bone
Bone pain (microfractures)
Increasing hat size
Hearing loss
Lion-like facies
+++ALP
Tx. Calcitonin & Biphosphonates
Complications: High-output cardiac failure
Osteosarcoma (with mutated blasts)
Osteomyelitis
Bacterial infection of marrow space & bone, due to hematogenous spread, especially in kids
S. aureus
N. gonorrhoeae
Salmonella
Pseudomonas
Pasteurella
Mtb
Bone pain, fever, leukocytosis
Lytic
Avascular (Aseptic) Necrosis
Ischemic necrosis of marrow & bone due to trauma, fracture, steroids, SCD, Caisson Disease
Multiple fractures, osteoarthritis
Osteoma
Benign bone tumor on surface of facial bones, associated with Gardner Syndrome
Osteoid Osteoma VS. Osteoblastoma
Benign tumor of blasts
Osteoid Osteoma
-Surrounded by sclerotic, reactive bone
-Young adults <25 in cortex of long bones
-Bone pain relieved with aspirin
-Imaging shows bony mass with radiolucent core
Osteoblastoma
-Larger >2 cm
-Seen in vertebrae
-Bone pain does NOT respond to aspirin
Osteochondroma
Benign bone tumor with cartilage cap
Due to lateral projection of growth plate
***Cartilage cap can transform into chondrosarcoma
Osteosarcoma
Malignant bone tumor of blasts, especially in metaphysis of long bones like femur or proximal tibia
Two peaks of incidence, Teenagers > Elderly
Risk: Familial Rb, Paget disease, radiation exposure
Pathologic fracture, bone pain with swelling
XR shows ***
Giant Cell Tumor
Tumor of giant & stromal cells, in EPIphysis of long bones like femur or proximal tibia
Seen in young adults
XR shows “soap bubble” appearance
Locally aggressive, may recur
Ewing Sarcoma
Malignant tumor of poorly-differentiated cells from NEUROectoderm in DIAphysis of long bones
Seen in M kids with 11:22 translocation
XR shows “onion skin” appearance
Histo confused with lymphoma & osteomyelitis
(Grows in medullary cavity, ***)
Chondroma VS. Chondrosarcoma
Benign cartilage tumor in medulla of small bones in hands & feet
Malignant cartilage tumor in medulla of pelvis or central skeleton
Degenerative Joint Disease
Progressive degeneration of articular cartilage
Risk: “Wear & tear” due to age, obesity, trauma
DIP, PIP, lumbar spine, hip, knees
Morning stiffness, worsens thru the day***
- Fragments of cartilage fall into joint space
- Bone will rub against bone
- Eburnation/polishing of subchondral bone
- Reactive osteophyte formation, esp DIP/PIPs
Rheumatoid Arthritis
Synovitis causing inflamed granulation tissue & contracted scarring
+Joint space narrowing
+Loss of cartilage & bone
+Ankylosing joint
+Fever, malaise, myalgia, weight loss
(Autoimmune, associated with HLA-DR4)
Seen in middle-aged F
Morning stiffness, improves with activity
Symmetric involvement of elbows/wrists/PIPs & knees/ankles (DIPs spared)
Other features: Rheumatoid nodules in skin & viscera, vasculitis, Baker cyst, LAD, pleural effusions, interstitial lung fibrosis
Labs: IgM against Fc of IgG, “Rheumatoid Factor”
+Neutrophils & proteins synovial fluid
Complications: Anemia of chronic disease
Secondary amyloidosis
(Ankylosis = Abnormal stiffening and immobility of a joint due to fusion of the bones)
Gout
Deposition of mono-sodium-urate crystals in joints due to hyperuricemia
Primary Gout - Cause of hyperuricemia unknown
Secondary Gout
-Leukemia & Myeloproliferative Disorders
-Lesch-Nyhan Syndrome
-Renal insufficiency
ACUTE Gout
-Crystals activate neutrophils
-Great toe involvement (Podagra)
-Triggered by alcohol, meat
CHRONIC Gout
-Tophi (White, chunky crystals)
-Renal failure (Crystals in tubules)
Labs: Hyperuricemia & Needle-shaped crystals with (-) birefringence under polarized light
Dermatomyositis
Inflammation of skin & skeletal muscle
Etiology unknown
Associated with gastric carcinoma
B/l proximal weakness (“Can’t comb my hair, Can’t climb the stairs”) + Late distal weakness
Helioptrope rash (purplish, upper eyelids)
Malar rash (Also seen in lupus)
Red papules on elbows, knuckles, knees
+CK
+ANA with anti-Jo1 Ab***
+PERImysial inflammation (CD4+ cells) with perifascicular atrophy
Tx. Corticosteroids
