Fractures and Bone Healing

Question 1

Fractures of what are most common?

Answer 1

Fractures of extremities

Question 2

Are fractures more common in men or women under the age of 45?

Answer 2

Men

Question 3

Are fractures more common in men or women over the age of 45?

Answer 3

Women

Question 4

Before 75 years, fractures of what body part is most common?

Answer 4

Wrist (Colles’ and Colles’ like)

Question 5

After 75 years, fractures of what body part is most common?

Answer 5

Hip

Question 6

What does the type of fracture depend on?

Answer 6

Magnitude and direction of force

Question 7

What is meant by a closed fracture?

Answer 7

Bone fragments do not pierce skin

Question 8

What is meant by an open/compound fracture?

Answer 8

Bone fragments pierce skin

Question 9

A fracture can be open or closed, but also can be _____ or not ______.

Answer 9

Displaced

Question 10

Name some types of fractures. (8)

Answer 10

Transverse
Oblique
Spiral
Comminuated (bone fragments into different pieces)
Avulsion
Impacted
Fissure
Greenstick

Question 11

What does type of fracture could bending the bone cause? (3)

Answer 11

Greenstick, fissures or potentially transverse fractures

Question 12

What does type of fracture could compressing the bone cause?

Answer 12

Impacted fracture

Question 13

What does type of fracture could torsion cause? (2)

Answer 13

Oblique

Spiral

Question 14

What is a transverse fracture usually caused by?

Answer 14

Directly applied force to fracture site

Question 15

What type of scan is good for diagnosing scaphoid fractures?

Answer 15

CT scan

Question 16

What are spiral or oblique fractures caused by?

Answer 16

Violence transmitted through limb from a distance (twisting movements).

Question 17

With a spiral fracture, is it normally the more proximal or distal bone that breaks?

Answer 17

Proximal

Question 18

What are crush/compression fractures?

Answer 18

Fracture in cancellous bone, due to compression (e.g. osteoporosis).

Question 19

Why does osteoporosis cause crush fractures?

How do the vertebral bodies appear on x-ray?

Answer 19

Bone is unable to maintain the weight that it is being asked to take, so it is crushed underneath the weight applied to it.
Wedging and biconcave vertebral bodies because the bone mass in the centre of the bone is lost and the bone collapses in the middle section (causing biconcave cupping) or complete collapse anteriorly (wedge shape).

Question 20

Why is an MRI used in compression fractures?

Answer 20

To work out if the fracture is new or old. If the bone marrow is the same density as in a non-fractured vertebrae, then it is an old fracture as the marrow has had time to respond. If there is a hypo-intense signal, it is an acute fracture.

Question 21

Between 30 and 80 years of age, how much does the elasticity of trabecular bone decrease by? What about cortical bone?

Answer 21

64%

8%

Question 22

Between 30 and 80 years of age, how much does the strength of trabecular bone decrease by? What about cortical bone?

Answer 22

68%

11%

Question 23

Between 30 and 80 years of age, how much does the toughness of trabecular bone decrease by? What about cortical bone?

Answer 23

70%

34%

Question 24

Where and why do burst fractures occur?

Answer 24

In short bones e.g. vertebra
From strong direct pressure such as impaction of disc i.e. compression but on healthy bone, compared to crush fractures which is on bone that can’t take the weight.

Question 25

Where are burst fractures most common?

Answer 25

At thoracic/lumbar junction

Question 26

Why might burst fractures require surgery?

Answer 26

Pieces may go into the vertebral canal and compress the spinal cord – requires surgery to remove bone fragments. Anterior pieces aren’t so much the problem, but the posterior ones that impinge spinal cord.

Question 27

What are avulsion fractures caused by? What happens?

Answer 27

Traction | Bony fragment usually torn off by a tendon or ligament.

Question 28

Fracture dislocation/subluxation - what does this involve and what does it result in?

Answer 28

A joint | Results in mal-alignment of joint surfaces

Question 29

What happens in an impacted fracture? | Do these normally displace?

Answer 29

Bone fragments are impacted (forced, pushed) into each other. No

Question 30

What do impacted fractures look like on x-ray?

Answer 30

White line, as bone is overlapping

Question 31

Why are MRIs used to look at impacted fractures?

Answer 31

Easier to see - disrupted blood supply so there will be bleeding, so this will be on the bone marrow signal. There will be an increased signal around the fracture site.

Question 32

What is a comminuted fracture? What causes them?

Answer 32

Two or more bone pieces | High energy trauma

Question 33

Why do comminuted fractures take longer to heal?

Answer 33

Due to disruption to blood supply and as there is a whole section of bone detached.

Question 34

What can cause a stress fracture? (2)

Answer 34

Abnormal stress on normal bone (fatigue fracture) | Normal stress on abnormal bone (insufficiency fracture)

Question 35

What conditions are insufficiency fractures seen in? (2)

Answer 35

Osteomalacia | Paget's

Question 36

What type of fracture is a March fracture?

Answer 36

Fatigue fracture

Question 37

What can be seen with stress fractures on plain film? Why are they difficult to pick up? What about with bone scintigraphy?

Answer 37

``` Periosteal reaction - cells are stimulated and differentiate to heal the bone. Bone callus starting to form. Difficult to pick up as it is the internal trabeculae network that is affected. Bone scintigraphy (shows where radioactive has ended up) becomes positive at same time or sooner than plain films. ```

Question 38

Who do greenstick fractures (only) occur in? Why?

Answer 38

``` Children Bones soft (more woven bone) and bend without fracturing completely ```

Question 39

Who do fractures of the epiphyseal growth plate (only) occur in? What can this cause?

Answer 39

Children | Can cause the plate to close prematurely so interferes with growth

Question 40

Why are pelvic fractures a special case?

Answer 40

Because the bladder, uterus, rectum, anus, major nerve supply and perineum, blood supply... all pass through the pelvis, so these fractures have a high mortality rate (10%).

Question 41

What bone did David Beckham fracture? What type?

Answer 41

Fracture to second metatarsal (transverse fracture from being stamped on)

Question 42

Describe the process of developing a fracture haematoma? How long does this take?

Answer 42

The break disrupts blood supply through Haversian canals and nutrient arteries going into marrow that communicate with trabeculae bone. Blood leaks out of damaged vessels, so a clot forms (fracture haematoma). The haematoma is characterised by hypoxia and low pH, which delays things a bit – takes 6-8 hours for the clot to form so there is some bleeding into surrounding tissue. WBCs are recruited to site of injury to deal with dead bone cells. Cytokines in the fracture haematoma that attract inflammatory cells. This means there is swelling and inflammation. HAPPENS BETWEEN DAY 0-5

Question 43

Describe the process of forming a fibrocartilaginous/soft callus. How long does this last?

Answer 43

This starts healing bone together and lasts 3 weeks. New capillaries organise fracture haematoma into granulation tissue (procallus) because hypoxia induces angiogenesis. Fibroblasts and osteogenic cells invade procallus and make collagen (type 1) fibres which connect ends of bone together. Chondroblasts begin to produce fibrocartilage that forms a scaffold for osteoblasts to take up residence and produce bone. HAPPENS BETWEEN DAY 5-16

Question 44

Describe the formation of the bony callus. How long does this take?

Answer 44

Osteoblasts have fully differentiated and are producing woven bone. Forms a bony callus (harder than fibrocartilage) – tougher and more resilient. After 3 weeks and lasts about 3-4 months HAPPENS DAY 16-21

Question 45

Describe the process of bone remodelling.

Answer 45

Take woven bone and remove it with osteoclasts, replace it with compact bone and trabecular bone. Bone looks slightly denser as you have both types of bone at this point. There is often no trace of fracture line on X-rays. Periosteum is a little swollen. HAPPENS DAY 21-35

Question 46

Why does the upper limb heal faster than lower limb?

Answer 46

Better blood supply, more oxygenated blood