Bone Physiology

Question 1

What is the function of PTH?

Answer 1

When serum Ca2+ low = increased PTH released —> 1) increased GI absorption, 2) increased bone resorption, 3) increased kidney resorption

Question 2

What is the function of calcitonin?

Answer 2

Calcitonin acts opposite to PTH —> it inhibits osteoclasts activity & promotes osteoblast activity (released by the thyroid when serum Ca2+ levels too high)

Question 3

What role does estrogen have on bone?

Answer 3

Estrogen promotes the fusion of the epiphyseal growth plate.

Also stimulates inhibits apoptosis of osteoblasts & stimulates apoptosis of osteoclasts

This is why osteoporosis is more of an issue in post menopausal women

Question 4

What role do bisphosphonates have in bone health?

Answer 4

Inhibits osteoclasts

Question 5

What role do corticosteroids have on bone health?

Answer 5

Increase the lifespan of osteoclasts

Question 6

What role does Vitamin D have on bone health?

Answer 6

Activates osteoblasts

Question 7

What are different factors that can affect fracture healing?

Answer 7

• smoking
• obesity
• excessive movement
• endo: DM, parathyroid disease
• thermal/chemical burns
• old age
• anemia
• infection
• poor blood supply to area

Question 8

What are the 4 classifications of fracture?

Answer 8

1) traumatic —> excessive force or injury to healthy bone
2) Pathologic —> low intensity force to diseased bone(e.g. fragility fracture in osteoporosis, Paget’s disease, bone Mets)
3) Salter-Harris —> fracture involving the epiphyseal growth plate
4) Stress —> low intensity/repetitive forces exerted on bone & soft tissue before they have time to accommodate (e.g. runners)

Question 9

How to describe a fracture?

Answer 9

1) name injured bone
2) open or closed (integrity of soft tissue)
3) part of bone involved (epiphyseal, metaphysical, diaphyseal, physis)
4) type of fracture (complete - transverse, oblique, spiral, segmental, comminuted, incomplete - intra-articular, avulsion, compression/impacted, torus, green stick, pathologic)
5) displacement of fracture (direction relative to proximal fragment) ~ non displaced, displaced, distracted, impacted, angulated~virus/valgus , translated/shifted, rotated
6) angulation (dorsal/palmar, Varus/valgus, radial/ulnar, lateral/medial, anterior/posterior
7) vascular and neuro impairment of injury

Question 10

What is considered a stable fracture vs. Unstable fracture?

Answer 10

Stable fracture - remains aligned, no neuro deficits, usually anterior portion of the spine, structural integrity of spine intact

Unstable fracture - mid or posterior aspect of vertebrae, 2 or more pieces of spine can move independently - risk for spinal cord, structural stability not intact

Question 11

Wha are fracture red flags?(7)

Answer 11

Compartment syndrome

Fever

Severe associated injuries

Neuro deficits

Open fracture with lots soft tissue injury

Circulatory compromise/hemorrhage

Cauda equina

Question 12

What is the classic triad of a fat emboli and what is this a complication of?

Answer 12

Complication of fracture

Triad: SOB, decreased LOC, petechial rash

Question 13

What are complications associated with fractures?

Answer 13

Fat emboli

DVT, PE

Muscle atrophy

Non-union, joint stiffness, a vascular necrosis

Vascular injury

Question 14

What carcinomas most frequently metastasize to bone?

What is most common site for skeletal metastasis?

Answer 14

Lung
Breast
Thyroid
Renal
Prostate

Spine, proximal femur, pelvis

Buy, The, Kid, Long, Pants