9. bone injuries/repair/healing

Question 1

what happens to muscle during immobolisation?

Answer 1

• protein synthesis declines
• Unrelated to changes in phosphorylation status of the Akt/mTOR pathway
• muscle breakdown may increase but not as much as decline in synthesis

Question 2

does consuming a high protein diet increase protein synth?

Answer 2

to an extent because there is some resistant to nutrition during immobolisation

Question 3

consequences of insulin resistance in muscle

Answer 3

unable to increase blood glucose disposal in resposne to elevated glucose conc

cannot take up glucose

Question 4

effects of the localised immobilisation

Answer 4

blood is shunted across due to low metabolic rate from decreased contraction

muscle lipid accumulation- inhibits glucose uptake

Question 5

Muscle mass rehabilitation

Answer 5

resistance training

isometric strength restores strength (no dynamic contractions)

attributable to increased phosphorylation of the Akt/mTOR pathway.

muscle breakdown inhibited

nutrition and pharmacological can facilitate

Question 6

Glucose uptake during exercise is increased with high intensity

Answer 6

• Linked to GLUT4 mechanism
• Calcium release- increased translocation of GLUT4 to sarcolemma allowing glucose entry-> respiration
• This mechanism isn’t insulin dependent
• Long term training increases amount of GLUT4 in muscle

Question 7

Trauma and inflammation (and immobilisation)

Answer 7

• Combination has major atrophy of muscle
• Inflammation induces muscle wasting, which can be profound in severe cases (e.g. sepsis).
• Muscle cytokines elevated
• Muscle wasting is achieved by the marked inhibition of muscle protein synthesis AND increase in muscle protein breakdown- Suppression of mTOr signalling and upregulation of protein breakdown
• muscle become very resistant to the anabolic effects of nutrients and hormones.
• Inflammation induces muscle insulin resistance and impairs carbohydrate oxidation.
• The combination of immobilisation and inflammation represents a perfect metabolic storm

Question 8

primary bone healing

Answer 8

• Healing is through remodelling (cutting cone)
• lay down osteons directly

Absolute stability required

Need to be tight and close together because osteoclast must cross the gap

No callus

Cutting cones cross fracture site

6 months

Question 9

bone healing

Answer 9

1. Cells to aid bone healing- macrophage, stem cells, inflammatory cells to encourage neurovascular formation
2. Fibroblasts- make fibrous tissue to hold bone together
3. Bony callus made
4. (osteoblast lay down new structure)

Question 10

what promotes fracture healing

Answer 10

movement

Perren’s Strain Theory

Micro-motion promotes callus % strain between fragments Relative stability required

Question 11

indirect fracture healing

Answer 11

•Impact •Haematoma •Inflammation •Soft Callus •Hard Callus •Remodeling • Years • Wolff’s law

Question 12

what is a spiral fracture also known as

Answer 12

butterfly fracture

Question 13

Compartment syndrome

Answer 13

• Fixed compartment, bleeding, pressure goes up, decrease blood supply-> death, scars and non-functioning
• Life long scarring (skin graft)
• Fracture and soft tissue injury with lots of pain
• Patient complaining of numbness and paraesthesia
• No pulse- amputation

Question 14

Neurodegeneration:

Answer 14

• Nerves don’t grow back
• Disconnection and degeneration will not recover
• 1. Neuropraxia compression
• 2. Axonotmesis loss of sheath
• 3. Neurotmesis degeneration- need surgery (suture together)