Bones Path Part 1 Flashcards
When is peak bone mass achieved?
Early adulthood after cessation of skeletal growth. *teens with eating disorders
4th decade skeletal mass decreases!
RANK promotes bone growth or breakdown?
OPG?
RANK (& RANKL) promote bone breakdown! stimulate NF-kB for osteoclast propagation.
OPG promotes bone building! Prevents RANKL interaction with RANK propagating bone building
Other modulators: Estrogen, testosterone & Vit. D–breakdown or build?
PTH, IL-1, glucocorticoids?
Estrogen, testosterone & Vit. D build
PTH, IL-1, glucocorticoids breakdown
What is brachydactyly?
Short terminal phalanges of thumb and big toe. HOXD13
What is cleidocranial dysplasia?
AD, patent fontanelles, WORMIAN BONES, short height, primitive clavicles, delayed closure of the cranial sutures RUNX2
What is achondroplasia?
Dwarfism
AD, FGFR3 GoF mut.
Shortened proximal extremities, norm. trunk length & no change to longevity, intelligence or reproductive abilities.
What is thanatophoric dysplasia
Most common LETHAL form of dwarfism.
FGFR3 GoF mut. (different than achondroplasia). Die soon after birth and have a small chest cavity and head, in addition to the short limbs.
What is Osteogenesis imperfecta? What type of collagen does it affect?
OI: type 1 collage dz and most common inherited DO of connective tiss. Defined by ACCORDION LIKE SHORTENING OF LIMBS and blue sclerae.
Which type of OI is the worst and best? Describe each
Type II - is the most severe and usually fatal in utero. Resp. problems (underdeveloped lungs) with numerous fractures and sever bone deformities.
Type I - less severe, pts live normal life spans, loose joints, brittle teeth and hearing loss in 20’s-30’s. Triangular faces
Differentiate OI types III & IV
Both are of intermediate severity with IV being of less severity. Barrel chests and triangular faces with brittle teeth and hearing loss possible. Short stature
Type III - tinted sclerae, more severe bone deformity and poor muscle development
Type IV - white sclerae, mild-mod. bone deformity
What is osteopetrosis? What enzyme is deficient?
aka Marble bone or Albers-Schonberg dz
Mut. in CLCN7 gene. Deficient carbonic anhydrase 2 (CA2).
Bones lack medullary cavity (Erlenmeyer Flask) & CN compression
Can result in RTA from lack of CA2. Impaired function of osteoclasts.
In osteopetrosis, which form is the severe and which is the milder form?
AR is the severe form:
Infantile type found in Mediterranean & Arab races. Optic atrophy, DEAFNESS, and facial paralysis. Anemia and hydrocephaly
AD is the mild form:
Adolescence or adulthood characterized by repeat fractures and mild cranial n. deficits and anemia.
What is mucopolysaccharidoses?
Lysosomal storage dz, mostly acid hydrolase enzymes affected. Accumulation of mucopolysaccharides in the chondrocytes & extracellular spaces. Leads to short stature, chest wall abnormalities & malformed bones
Differentiate osteopenia from osteoporosis
Osteopenia is decreased bone mass 1-2.5 SD below the mean.
Osteoporosis is osteopenia severe enough to incr. risk of bone breaks (at least 2.5 SD). Atraumatic or vertebral compression fractures are indications. Common groups are senile & postmenopausal.
5 main contributors to osteoporosis path.
- Age related changes - senile or low turnover variant.
- Decr. physical activity - immobility, paralysis, astronauts in zero gravity
- Genetics
- Ca2+ nutritional state - Ex. adolescent girls with insufficient ca2+ intake -> restricted peak bone mass -> predisposition later in life.
- Hormonal influences - Estrogen deficiency -> high turnover variant.
If a pt was treated with Tamoxifen for breast cancer, what should we be concerned with?
Increased risk for osteoporosis
Osteoporosis morphology
Normal bone with decr. quantity.
Postmenopausal has incr. osteoclast activity. Vertebral bodies have thinned/perforated trabeculae causing microfractures and vertebral collapse. Thinning of the cortex.
A 60 yo post-menopausal woman presents to the office with co loss of height. She is fair skinned and looks for have some lumbar lordosis or kyphoscholiosis. There is a SH of drinking lots of soda and smoking. What are you concerned of and what tests would you order?
Osteoporosis risk. DEXA-scan and blood tests for secondary causes.
What is Paget Dz?
aka Osteitis deformans
Disordered increase in bone mass.
Majority of cases are polyostotic (involves mult. bones). Avg. age of dx is 70 yo. 40-50% is inherited. Sporadic form has SQSTM1 gene mut.
What would you see on imaging and labs for a pt with Paget’s dz?
Mosaic pattern on lamellar bones in jig-saw like appearance with prominent cement lines. Chalk stick fractures of long bones. Incr. serum alk phos., norm. serum Ca2+ & Pi
3 phases of Paget dz
- Initial lytic phase - large osteoclasts with 100 nuclei
- Mixed phase - clasts persist but many more blasts.
- Final - coarsely thickened trabeculae & cortices. Soft & porous lacking structure or stability. Sarcomatous transformation possible.
How to tx Paget’s?
Calcitonin & bisphosphonates
What is the difference between Rickets and Osteomalacia?
Same condition of Vit. D deficiency/abnormal metabolism, diff. populations.
R - Pediatric form. Rachitic rosary of ribs
O - Adult form
What is hyperparathyroidism & the difference between 1° and 2°?
Too much PTH! Normally, PTH incr. [Ca2+]serum when levels are low by activating osteoclasts and renal tubules for Ca2+ resorption, incr. Pi excretion and incr. Vit D synthesis.
1° - parathyroid autonomous PTH secretion
2° - underlying renal dz
Hyperparathyroidism morph (3 skeletal abn)
Osteoporosis - most sever in phalanges, vertebrae & proximal femur
Brown tumors - microfractures from bone loss with infiltrative mac’s, hemosiderin dep. and hemorrhage -> mass of reactive brown tissue
Osteitis fibrosa cystica - clasts tunnel length of trabeculae (railroad tracks)
Another name for osteonecrosis, common causes and what does the necrotic bone look like?
aka Avascular necrosis
From fractures or corticosteriod tx. Sickle cell pts can experience spontaneous medullary osteonecrosis.
Subchondral infarcts are triangular or wedge shaped
Osteomyelitis most common cause & by demographics
Almost always a bacterial causation (STAPH A. in 80-90% of cases!)
Kids - hematogenous spread from trivial mucosa injuries or minor skin infections
Adults - Complications of open fractures or diabetic foot infections.
Osteomyelitis gram (-) agents
E. coli, Pseudomonas, Klebsiella - UTI or IV drug abusers
Mixed bacteria - surgery or open fractures
H. Influenzae & Group B Strep
Salmonella - sickle cell pts
Neisseria - Pt’s with MAC deficiencies
Osteomyelitis infection terms. Acute infection
Subperiosteal abscesses (kids)
Sequestrum - dead bone following subperisoteal abscess
Septic/suppurative arthritis in infants
Osteomyelitis infection terms. Chronic infection
Chronic after first week.
Involucrum - newly deposited bone
Brodie abscess - small interosseous abscess usually, in the cortex, walled off by reactive bone.
Sclerosing osteomyelitis of Garre - mainly in children and young adults affecting the mandible. Often ass. with dental carries
Mycobacterial osteomyelitis
Blood borne, bone infec may persist for years before detected.
Sx of low grade fevers, chills, wt loss.
*Histo: Caseous necrosis and granulomas
What is another name for Pott’s dz?
Tuberculosis spondylitis
mycobacterial osteomyelitis, usually in the spine, breaks through bone and soft tissue. Causes permanent compression fractures
What deformities are seen in congenital v. acquired syphilis?
Congenital syph. - saber shins
Acquired syph. - saddle nose
