Fractures and Bone Healing Flashcards
Fractures of what are most common?
Fractures of extremities
Are fractures more common in men or women under the age of 45?
Men
Are fractures more common in men or women over the age of 45?
Women
Before 75 years, fractures of what body part is most common?
Wrist (Colles’ and Colles’ like)
After 75 years, fractures of what body part is most common?
Hip
What does the type of fracture depend on?
Magnitude and direction of force
What is meant by a closed fracture?
Bone fragments do not pierce skin
What is meant by an open/compound fracture?
Bone fragments pierce skin
A fracture can be open or closed, but also can be _____ or not ______.
Displaced
Name some types of fractures. (8)
Transverse Oblique Spiral Comminuated (bone fragments into different pieces) Avulsion Impacted Fissure Greenstick
What does type of fracture could bending the bone cause? (3)
Greenstick, fissures or potentially transverse fractures
What does type of fracture could compressing the bone cause?
Impacted fracture
What does type of fracture could torsion cause? (2)
Oblique
Spiral
What is a transverse fracture usually caused by?
Directly applied force to fracture site
What type of scan is good for diagnosing scaphoid fractures?
CT scan
What are spiral or oblique fractures caused by?
Violence transmitted through limb from a distance (twisting movements).
With a spiral fracture, is it normally the more proximal or distal bone that breaks?
Proximal
What are crush/compression fractures?
Fracture in cancellous bone, due to compression (e.g. osteoporosis).
Why does osteoporosis cause crush fractures?
How do the vertebral bodies appear on x-ray?
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).
Why is an MRI used in compression fractures?
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.
Between 30 and 80 years of age, how much does the elasticity of trabecular bone decrease by? What about cortical bone?
64%
8%
Between 30 and 80 years of age, how much does the strength of trabecular bone decrease by? What about cortical bone?
68%
11%
Between 30 and 80 years of age, how much does the toughness of trabecular bone decrease by? What about cortical bone?
70%
34%
Where and why do burst fractures occur?
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.
Where are burst fractures most common?
At thoracic/lumbar junction
Why might burst fractures require surgery?
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.
What are avulsion fractures caused by? What happens?
Traction
Bony fragment usually torn off by a tendon or ligament.
Fracture dislocation/subluxation - what does this involve and what does it result in?
A joint
Results in mal-alignment of joint surfaces
What happens in an impacted fracture?
Do these normally displace?
Bone fragments are impacted (forced, pushed) into each other.
No
What do impacted fractures look like on x-ray?
White line, as bone is overlapping
Why are MRIs used to look at impacted fractures?
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.
What is a comminuted fracture? What causes them?
Two or more bone pieces
High energy trauma
Why do comminuted fractures take longer to heal?
Due to disruption to blood supply and as there is a whole section of bone detached.
What can cause a stress fracture? (2)
Abnormal stress on normal bone (fatigue fracture)
Normal stress on abnormal bone (insufficiency fracture)
What conditions are insufficiency fractures seen in? (2)
Osteomalacia
Paget’s
What type of fracture is a March fracture?
Fatigue fracture
What can be seen with stress fractures on plain film? Why are they difficult to pick up?
What about with bone scintigraphy?
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.
Who do greenstick fractures (only) occur in? Why?
Children Bones soft (more woven bone) and bend without fracturing completely
Who do fractures of the epiphyseal growth plate (only) occur in? What can this cause?
Children
Can cause the plate to close prematurely so interferes with growth
Why are pelvic fractures a special case?
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%).
What bone did David Beckham fracture? What type?
Fracture to second metatarsal (transverse fracture from being stamped on)
Describe the process of developing a fracture haematoma? How long does this take?
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
Describe the process of forming a fibrocartilaginous/soft callus. How long does this last?
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
Describe the formation of the bony callus. How long does this take?
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
Describe the process of bone remodelling.
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
Why does the upper limb heal faster than lower limb?
Better blood supply, more oxygenated blood
