Imp Tech U6a

Question 1

What are primary and secondary bone healing?

Answer 1

Primary; healing without callus formation (due to no micro movement), heals quicker but less strong (due to rigid fracture fixation)

Secondary; healing with a callus (natural bone healing)

Question 2

Describe the process of secondary bone healing

Answer 2

Callus formation de to micro movement at fracture site, late stage remodelling and disappearance of callus

Question 3

What determines the rate of healing of a bone?

Answer 3

How long it takes to re-establish a blood supply (higher energy = longer to heal)

Question 4

What are the structural benefits of callus formation?

Answer 4

Larger cross sectional area so compensates for the lower strength/rigidity of callus material

Question 5

What factors promote bone healing?

Answer 5

Physical exercise (wolffs law - exercise increases bone density and thickness - increases strength and stiffness)

Question 6

What is the process of fracture management?

Answer 6

Reduction then holding

Question 7

What are the functions of a plaster of paris cast?

Answer 7

Encasing limb in rigid exoskeleton provides support to soft tissues

3 point fixation by moulding against the fracture

(most are a combination of both - exoskeleton is more important in adults)

Question 8

Why is control of the position of a fracture important?

Answer 8

Controls length, position and rotation (prevents shortening, tilt, shift or rotation around a long axis)

Question 9

What is the disadvantage of a Plaster of Paris cast?

Answer 9

If casting prolonged then joints become stiff and muscles waste (prolongs rehab)

Impairment from immobilisation can cause loss of independence

Question 10

What is functional/cast bracing?

Answer 10

Includes a hinge at knee to allow natural movement of knee

Shaping of cast (squaring around femur, triangulation around tibia to distort soft tissues)

Question 11

What are the benefits of functional cast bracing?

Answer 11

Broken fragments held sufficiently while joints/muscles can rehab early

Question 12

What are the advantages/disadvantages of Plaster of Paris casts?

Answer 12

Pros
- cheap, easy to obtain and apply, versatile

Cons
- Messy, brittle

Question 13

When should a functional cast brace be applied?

Answer 13

2-3 weeks after fracture (when soft tissue swelling has gone down)

Question 14

What are the alternatives to plaster of paris?

Answer 14

Isopropene rubbers or polycaprolactone sheets

Glass fibre and polyurethane composites

Question 15

How does traction hold a fracture?

Answer 15

Alters muscle tone to maintain position

Question 16

How does traction help with callus formation?

Answer 16

Muscle contractions will move bone fragments back and forth inducing callus formation

Question 17

How much traction applied to lower limbs? How is it balanced/why?

Answer 17

10-100N of Bw is sufficient

Tilt bed backwards as counter force to prevent pulling out of bed

Question 18

What are the different types of traction?

Answer 18

Static: Skin in the counter force (ie Thomas splint)

Dynamic: Uses pulleys to encourage joint movement

Balanced: Use a weight to offset pressure from splints

Question 19

What are the disadvantages of traction?

Answer 19

Complications from long periods spent in bed
Requires >3 months in hospital
Expensive
Inconvenient for patients