Bone Adaptation to Load

Question 1

How does bone mass vary between males and females with age?

Answer 1

Women have a much lower peak bone mass and experience a steady plateau of bone mass during the reproductive years whereas men start to decline after reaching the peak. Women have a sharp decrease in bone mass during the menopause and then reach the fracture threshold much sooner than men.

Question 2

What things contribute to the efficiency of bone to bear load whilst minimising weight?

Answer 2

1. Mineral properties
2. Geometry of the bone
3. The trabecular bone architechture.

Question 3

How should bone mass be distributed for optimal strength?

Answer 3

New mass is added to the edge of the bone, furthest away from the axis through which load is experienced.

Question 4

What label is used to measure bone activity?

Answer 4

Calcein

Question 5

If loads of physiological magnitude are applied to a bone, how can osteogenesis be stimulated?

Answer 5

By applying it in a novel way. If application of load is normal, the load would need to be supra-physiological in magnitude.

Question 6

How are fractures prevented in normal bone?

Answer 6

The bone bends at many different points (think crumple zones of a car)

Question 7

How does an adaptive response to changes in load bearing come about?

Answer 7

1. Mechanotransduction = changing a mechanical signal to a cellular one.
2. Communication between cells
3. Coordination of the response.

Question 8

What cell is thought to transduce and coordinate the responses to loading?

Answer 8

Osteocytes (communicate through cannaliculli)

Question 9

Is bone strength always a result of the loads applied to it?

Answer 9

No, the skull remains strong even though it is rarely subject to loading of any significant proportions.

Question 10

Is there a genetic component to bone adaptation?

Answer 10

Yes, think chickens,