Mechanical role of the Skeleton

Question 1

What are the functions of the skeleton?

Answer 1

• Locomotion
• Lever (tongue vs limbs, intrinsic musculature= change shape)
• Respiration
• Protection (skull-brain, thorax-heart)
• Calcium store
• Haematogenetic factory

Question 2

What are the adaptions for bipedal locomotion?

Answer 2

• Spinal curves
• Shock absorption of discs
• Weight bearing axis of hip and knee
• Tripod arrangement of foot
• Shape of thorax
• Soleus slow muscle
• TA energy absorption

Question 3

What are the modes of machine failure?

Answer 3

• Perinatal
• Trauma
• Osteoarthritis/ osteoporosis

Question 4

Describe perinatal failure

Answer 4

• Failure of formation= fibula hemimelia

- Failure of segmentation= congenital scoliosis= wedge vertebra

Question 5

What does a fracture need to heal?

Answer 5

• Stable mechanical environment
• Cells, growth factors, vessels
• Metal analogy: solder, energy, flux

Question 6

Describe the mechanical environment for healing

Answer 6

Yield strain
-Granulation tissue 100%
-Fibrocartilage 17%
-Bone 2%
Surgical stabilisation/ external callus

Question 7

What are the origins of callus?

Answer 7

• External callus= periosteum, soft tissue
• Gap callus= bone marrow
• Direct/ primary= cortex

Question 8

What are the modes of failure of fractures/ mechanical role?

Answer 8

• Trauma= acute fracture
• Infection= teenage OM
• Osteoporosis

Question 9

What are the consequences of failure of fractures?

Answer 9

• Failure of skeleton
• Pain
• Muscle weakness
• Loss of function
• Time off work/ earning
• Lack of mobility/ independence
• Multiple limb injury= 2 years plus of treatment

Question 10

What is the role of mechanotransduction?

Answer 10

Many tissues to function correctly
-Must sense mechanical stimulus
-Convert to biological response= muscle, tendon, bone, cartilage/ lung, blood vessels
Creation of tissue by mechanical force (bone, skin, muscle, tendon, blood vessels, nerve)