Bone Healing

Question 0

What does haematoma formation do?

Answer 0

Initiates bone healing. Clotting factors initiate fibrin meshwork, acting as a framework for the growth of fibroblasts and capillary buds.

Question 1

Name the four stages of bone healing in order.

Answer 1

• haematoma formation
• fibrocartilaginous callus development
• ossification
• remodelling

Question 2

During haematoma formation, migrating inflammatory cells and platelets do what?

Answer 2

Release growth factors which stimulate osteoclast and osteoblast proliferation.

Question 3

1-2 days post #. Explain:

Answer 3

Haematoma begins to form from torn blood vessels in the periosteum and surrounding tissues.

Question 4

2-5 days post #. Explain:

Answer 4

Haemorrhage forms a large blood clot. By day 7 most of the clot is organised by invasion of blood vessels and early fibrosis.

Question 5

After the first week, bone formation begins. What stage is this apart of?

Answer 5

Fibrocartilaginous callus development.

Question 6

Explain fibrocartilaginous callus development.

Answer 6

Fibroblasts and osteoclasts migrate into the # site and begin to reconstruct the bone. A fibrocartilage “collar” forms to connect the bone segments.

Question 7

Explain the role of fibroblasts in the second stage of bone healing.

Answer 7

Produce collagen to connect the bone ends and secrete a collagen matrix.

Question 8

Explain osteoblasts in the second stage of bone healing.

Answer 8

Begin to deposit bone into the matrix.

Question 9

Wen does ossification begin?

Answer 9

3-4 weeks of the # healing.

Question 10

Is it safe to remove the cast during the ossification stage?

Answer 10

Yes, it is usually safe. The # site feels firm and immovable and appears united on an x-ray.

Question 11

Explain ossification.

Answer 11

Mineral salts are deposited into the callus, and mature bone gradually replaces the fibrocartilage callus. Any excess callus is reabsorbed by osteoclasts.

Question 12

What is the final stage of bone healing?

Answer 12

Remodelling.

Question 13

Explain remodelling.

Answer 13

Medullary cavity is restored. The callus matures and transmits weight bearing forces. Excess bony callus that develops in the marrow space and encircles the outside of the # site is reabsorbed.

Question 14

Name three things fracture complications are due too.

Answer 14

• loss of skeletal continuity
• injury from bone fragments
• pressure from swelling and haemorrhage (# blisters, compartment syndrome)
• involvement of nerve fibres
• development of fat emboli

Question 15

Name four things healing time depends on.

Answer 15

• the site of the #
• the condition of the # fragments
• haematoma formation
• local and host factors
• type of fracture (# of long bone, displaced and a # with less surface area heal slower)
• age of person

Question 16

Why does age affect healing time? What are the healing time frames for children, adolescents, and adults?

Answer 16

The older you are the longer it takes for your bones to heal, because the healing process slows down.

Children: 4-6 weeks
Adolescents: 6-8 weeks
Adults: 10-18 weeks

Question 17

Name four things that can impair bone healing, NOT including age.

Answer 17

• poor nutrition
• circulatory problems and coagulation
• local stress around the # site
• debilitating diseases (RA, diabetes)
• current medication
• age

Question 18

Name five factors that can affect bone healing.

Answer 18

• nature of the injury
• degree of fibrocartilage bridge formation
• amount of bone loss
• type of bone injured
• degree of immobilisation achieved
• local infection
• local malignancy
• bone necrosis

Question 19

Explain the difference between the three following things:

• malunion
• delayed union
• non-union

Answer 19

Malunion: healing with deformity, angulation or rotation (does not heal in position)
Delayed union: failure of the # to unite within normal period (does not heal in time)
Non-union: failure to produce union and cessation of the bone repair process (does not heal)