MSK Gen Flashcards
What is bone composed of?
Highly vascularized, metabolically active connective tissue
Made mainly of collagen type I and hydroxyapatite crystal Ca10(PO4)6(OH)2
What happens to calcium in bone at lower pH
increase in the amt of Ca2+ leaving the bone at lower pH
Bone fns
structure
protection
locomotion
reservoir- for Ca2+, PO4- and fat
hematopoietic and immune cell prod
endocrine- GF, cytokines, FGF23 and osteocalcin
What does osteocalcin do?
↑ insulin sensitivity
↑ glucose uptake in
muscle and bones
↑ insulin secretion
↑ beta cell proliferation
↑ Testosterone and bone formation
↑ exercise capacity
osteocytes release FGF23 which ↑ phosphate excretion from kidney
kidney releases erythropoietin and ↑ RBC prod
↓ anxiety and depression
What are the 4 design features of bone?
compact (strength) vs porous (low weight and more space)
rigidity vs flexibility
durability (lamellar bone) vs speed (woven bone)
balance in bone formation and reabsorption
Describe trabecular (cancellous) bone
interior is porous to ↑ space and ↓ weight
and ↑ surface area to help Ca2+ that is leaching for homeostasis
Describe medullary cavity
holds marrow, nerves, vessels
↑ space and ↓ weight
Describe cortical bone
compact outer layer that is heavily mineralized (strong) but thin (↓ weight)
What fills the porous bone space
red bone marrow- hematopoietic cells
yellow marrow- fat (as we get older)
What bone type are vertebra mainly composed of?
trabecular bone
What bone type are long bones mainly composed of?
cortical bone
What bone type is the hip mainly composed of?
cortical bone
Where is red marrow mainly found?
in flat bones such as hip, skull, breast, ribs, vertebra, shoulder blades and cancellous bones at ends of long bones
Where is yellow marrow mainly found?
mainly in medullary cavity of long bones
Why are trabecular bones more preferentially affected by pathological conditions that disturb bone remodeling?
they are remodeled more each year than cortical bone due to being more porous to provide Ca2+ for homeostasis
Describe the structure of hydroxyapatite crystal Ca10(PO4)6(OH)2
strong and resists compression but is weak to tensile strength and shears
Describe the structure of collagen fiber type I
weak but flexible to absorb bending and shear strain, resists tensile strain but is weak to compression
What happens to hydroxyapatite crystal size in osteopetrotic individuals?
increase in size
What happens to hydroxyapatite crystal size in diabetes and Paget’s disease individuals?
decrease in size
What determines bone strength?
density size and geometry composition (cortical v trabecular) matrix material property microsctruture (lamellar vs woven)
MC cause of bone tumors
Mets from lung, breast, prostate, kidney, thyroid
Oligoarthritis
arthritis affecting two to four joints during the first six months of disease
Polyarthritis
any type of arthritis that involves 5 or more joints simultaneously usually associated with autoimmune conditions
ankylosis
abnormal stiffening and immobility of a joint due to fusion of the bones
osteophytes
a bony outgrowth associated with the degeneration of cartilage at joints
If 1 joint is painful and swollen what must you rule out?
septic arthritis
Closed Fracture (aka Simple Fracture)
Skin over the fracture is intact
Open Fracture (aka Compound Fracture)
Overlying skin is disrupted; “open wound”
Fn of Labrum in hip
Increases depth of acetabular cavity creating increased surface and strength of joint
What is the MC inj structure of the knee?
MCL
Angulated fx
Fracture fragments are malaligned at an angle
Segmental fx
Fx with at least two fracture lines that together isolate a segment of bone
Comminuted fx
Fx that results in two or more fragments
Transverse fx
Fx line forms a right angle with longitudinal axis
Rhabdomyolysis
Rapid death of striated muscle cells often with myoglobinuria or acute renal failure
ca that mets to bone
“BLT w/ pickles and ketchup”
breast lung thyroid prostate kidney
Intra Articular fx
Involving the joint space
Extra Articular fx
No involvement of joint space
Impacted fx
Fx in which one of the fragments is driven into another fragment
Compression Fracture
Vertebral collapse
Greenstick fx
One side broken; opposing side bent
Occult Fracture
Fx that does not appear on x-ray
look for hypodense area (fat pads)
Avulsion fx
Release of small portion of bone at location of tendon insertion
(tendon pulls bone and fxs it)
Stable fx
A fracture that tends to remain in alignment after reduction
Unstable fx
A fracture that tends to displace after reduction
McCarthy Test
Patient is in supine position.
Flex both hips and then extend the affected hip + a catch a labral tear is presen
FABER Test
Patient is in a supine position.
Put affected leg and on the opposite straight leg in a position of Flexion Abduction External Rotation.
Apply pressure to anterior aspect of the knee lowering the test leg into further abduction.
+ If the leg can not be lowered parallel to the opposite leg or pain
Fn of Labrum in hip
Increases depth of acetabular cavity thus, increasing surface and strength of joint
What is the MC inj structure of the knee?
MCL
Myalgia
Symptom of muscle-discomfort: muscle aches, soreness, tenderness, cramps with a normal CK
Myopathy
Muscle weakness (not due to pain), with or without an elevated CK
Myositis
Muscle inflammation
Myonecrosis
Elevated CK due to death of striated muscle cells
Rhabdomyolysis
Rapid death of striated muscle cells often with myoglobinuria or acute renal failure
ca that mets to bone
“BLT w/ pickles and ketchup”
breast lung thyroid prostate kidney
Why do most herniated lumbar discs occur posteriorly and off to one side?
Posterior longitudinal ligament is strongest in the midline and the posterior-lateral annulus may bear a large share of the axial load.
