Bone Structure and Healing, Osteomyelitis, Septic Arthritis

Question 1

Formation of flat bones

Answer 1

Intramembranous ossification directly from mesenchyme

Question 2

Mutation in flat bone formation that leads to cleidocranial dysplasia

Answer 2

RUNX2 / Cbfa1

Question 3

Formation of short bones

Answer 3

Endochondral ossification (same as long bones)

Question 4

Portion of bone supplied by the nutrient artery

Answer 4

Inner 2/3 of cortex and the medulla

Question 5

Portion of bone supplied by the periosteal artery

Answer 5

Outer 1/3 of cortex

Question 6

Portion of bone supplied by the metaphyseal artery

Answer 6

Metaphyseal junction (poor supply in the 5th metacarpal –> fracture)

Question 7

Organization structure of cortical bone

Answer 7

Osteon/Haversian system

Question 8

Origin tissue of osteoblasts

Answer 8

Mesenchyme

Question 9

Products of osteoblasts

Answer 9

RANK
Alkaline phosphatase
TYPE 1 COLLAGEN (for bone formation)
osteocalcin (activity marker)

Question 10

Origin tissue of osteoclasts

Answer 10

Hematopoietic cells

Question 11

Products of osteoclasts

Answer 11

Tartrate resistant phosphatase (TARP)

Question 12

MoA of osteoprotegrin

Answer 12

Prevents bone resorption by binding and inhibiting RANK ligand produced by osteoblasts.
Prevents activation of osteoclasts.

Question 13

MoA of RANK-L

Answer 13

Produced by osteoblast cells to activate clasts and resorb bone

Question 14

Effect of PTH on bone

Answer 14

High, continuous levels of PTH result in bone resorption

Pulsed levels of PTH results in bone formation

Question 15

MoA of forteo

Answer 15

Acts as an artificial PTH, given in pulses to stimulate bone growth in osteoporosis

Question 16

MoA of denosumab

Answer 16

Anti-RANK-L antibodiy –> reduced bone resorption

Question 17

Forces that bone is weakest against

Answer 17

shear, then tension (strongest in compression)

Question 18

Fracture pattern seen in tensile forces or pure bending

Answer 18

Transverse

Question 19

Fracture pattern seen in compression

Answer 19

Oblique

Question 20

Fracture pattern seen in bending with an axial load

Answer 20

Butterfly with two oblique fractures on the side of compression.

Question 21

Fracture pattern seen with bone torsion

Answer 21

Spiral

Question 22

Types of epiphyses

Answer 22

Pressure and traction

Question 23

Traction epiphysis

Answer 23

FOrms at insertions of tendons

Does not lenghten bone but does influence shape

Question 24

Pressure epiphysis

Answer 24

FOrmes at areas of joint articulation

Lengthens bones

Question 25

THe three major zones of the epiphysis

Answer 25

Reverse zone Proliferative zone Hypertrophic zone

Question 26

Function of the reverse zone

Answer 26

Mainly anoxic | Produces and stores cartilaginous matrix

Question 27

Function of the proliferative zone

Answer 27

High levels of O2 and chondrocyte division | Production of ECM matrix

Question 28

Function of the hypertrophic zone

Answer 28

Preparation and calcification of matrix from the proliferative and reverse zones At the end of the hypertrophic zone, cells are no longer viable due to calcification and anoxia

Question 29

Types of epiphyseal injury most associated with future growth abnormalities

Answer 29

III, IV, and V (Crush)

Question 30

Type III epiphyseal fracture

Answer 30

fracture through the epiphysis and physis only

Question 31

Type IV epiphyseal fracture

Answer 31

Fracture through the physis, eipphysis and underlying bone

Question 32

Type V epiphyseal fracture

Answer 32

crush

Question 33

Type II epiphyseal fracture

Answer 33

fracture through physis only, often due to a chip of bone

Question 34

Type I epiphyseal fracture

Answer 34

Sliding of the epiphysis off of the physis (ex: hip dysplasia)

Question 35

Difference between osteopenia, osteomalacia, and osteoporosis

Answer 35

Osteopenia: decreased bone density during immobility Osteomalacia: decreased bone QUALITY due to poor mineralization Osteoporosis: decreased bone density (but bone of normal quality)

Question 36

Risk factors for developing osteoporosis

Answer 36

smoking (estrogens are protective?)

Question 37

Most common agents of osteomyelitis in adults

Answer 37

Staph and GNR

Question 38

Most common agents of osteomyelitis in children

Answer 38

Strep and staph

Question 39

Joints most commonly affected by osteomyelitis in children

Answer 39

growth plates

Question 40

Joints most commonly affected by osteomyelitis in adults

Answer 40

Spine, SI, sternoclavicular joints

Question 41

Most common agents of osteomyelitis in prosthetics

Answer 41

S. epidermidis

Question 42

Most common agents of osteomyelitis in bites or fist injuries related to the mouth

Answer 42

Streptococcus or anaerobes

Question 43

Most common agents of osteomyelitis in pressure or diabetic ulcers

Answer 43

Strep or anaerobes

Question 44

Most common agents of osteomyelitis in SCD

Answer 44

Salmonella

Question 45

Most common agents of osteomyelitis in trauma or diabetic lesions

Answer 45

Anaerobes

Question 46

Most common sources of Pseudomonas osteomyelitis

Answer 46

Tennis shoe Otitis (malignant) IV drug abuse

Question 47

Limitations of sinus tract culture in osteomyelitis

Answer 47

Only finds aerobes | Not necessarily correlated to organism causing osteomyelitis

Question 48

Treatment of CCO

Answer 48

Surgery is the only curative option In patients who should not get surgery, suppression with antibiotics can be done

Question 49

Treatment of acute osteomyelitis

Answer 49

Can be cured with antibiotics

Question 50

Empiric therapy of osteomyelitis

Answer 50

NOT GIVEN, must get biopsy first

Question 51

Septic arthritis therapy for patients without risk factors

Answer 51

Nafcillin

Question 52

Septic arthritis therapy for patients with risk factors

Answer 52

Nafcillin + (FQ or aminoglycoside) OR 2nd generation cephalosporin (cefuroxime, cefoxitin) Should also cover anaerobes

Question 53

Differences in reactive gonococcal arthritis and septic

Answer 53

REACTIVE: Multiple joints, rash, involves wrists/hands (can't pee, can't see, can't climb a tree) SEPTIC: Single joint, knee/hip, no rash (may have lesion on joint)

Question 54

Most common joints for SA in adults and children

Answer 54

Adults: Knee Children: Hip