9. Fractures and bone healing (Robson) Flashcards
When are men and when are women more at risk of bone fractures and why?
Men - younger age bracket - take part in mores stress related conditions e.g. contact sport
Women - older age bracket - OP - lack of oestrogen - bone becomes thinner and weaker
What is a Colles fracture?
Fracture of the distal part of the radius, within 2cm of the most distal end
What is a Colles like fracture?
Colles fracture of the radius also involving the ulnar
What is the most common presentation of a fracture to the neck of the femur (hip fracture)?
The leg shortens (compared to other) and is externally rotated
What are the two main groups of fractures?
Closed - the bone fragments do not pierce the skin
Open/compound - the bone fragments pierce the skin - tend to be due to higher force
What is the difference between a displaced and undisplaced fracture?
Displaced - there is some movement of the bone pieces relative to each other - no longer in their normal anatomical alignment
Undisplaced - the fractured bone has not moved too far out of normal alignment
SO how are bone fractures classified?
Either open or closed and then either displaced or undisplaced
What is a transverse fracture?
Horizontal fracture through the bone
What are spiral/oblique fractures and how do these occur?
(Don’t need to differentiate between these two)
Almost diagonal fracture
These are created by twisting movements of the bone e.g. by trauma
Why are spiral/oblique fractures particularly dangerous?
Can create sharp edges - nerve or blood supply damage - oedema
What is a crush/compression fracture?
When WEAKENED vertebral bone is crushed from force
In what bone do crush/compression fractures occur?
Cancellous bone due to compression
In what condition are crush/compression fractures common?
Osteoporosis as a result of compression - bone cannot carry the weight
How do crush/compression fractures typically present on an x-ray?
Wedging of the bone
Biconcave structure of the vertebrae
How do crush/compression fractures present on a CT or bone scan and why?
Whiter bone - there will be an increased density in the central part of the bone e.g. the vertebra
What type of investigation can be used to see whether a crush/compression fracture is old or new?
MRI - to visualise the bone marrow
Which fracture type can result in oedema in a muscle compartment?
Spiral fracture - sharp edges - can damage nerves or blood vessels
Why do crush/compression fractures occur?
Due to reduced bone mass e.g. as seen in osteoporosis
Thin trabeculae bone loses elasticity, strength and toughness
Between 30-80 years of age, by what percentage does the elasticity of trabeculae bone decrease?
64%
Between 30-80 years of age, by what percentage does the strength of trabeculae bone decrease?
68%
Between 30-80 years of age, by what percentage does the toughness of trabeculae bone decrease?
70%
Between 30-80 years of age, by what percentage does the strength of cortical bone decrease?
10%
What is a burst fracture?
This is a crush/compression fracture of healthy vertebrae
What causes a burst fracture?
When there is a heavy force on the IV disc that is stronger than the strength of the bone
What is the main concern with burst fractures?
Burst of the IV disc can result in compression of the spinal cord from compressed bone
What part of the vertebrae can most commonly impinge on the spinal cord from a burst fracture? (posterior or anterior)
The posterior region
What is an avulsion fracture?
This is caused by traction i.e. something pulling on the bone causing the attachment point to break off
What can pull on the bone in a traction fracture?
Ligament or tendon - ligament/tendon attachment point breaks off
What is a fracture dislocation/subluxation and when can this occur?
This occurs if a fracture occurs very close to a joint
This results in a malalignment of the joint surfaces - results in disruption and instability of the joint
What is an impact fracture?
This is when bone fragments are forced/pushed/impacted into each other
Are impact fractures typically displaced or undisplaced and why?
Tend to be undisplaced - stable fractures - bones are just pushed into each other rather than out of place
How can you identify an impact fracture from a scan?
Look for a white line where the bone is overlapping - more slerotic/white
What type of scan is useful to identify an impact fracture and why?
MRI scan - bleeding may occur and this will show the bone marrow
What is a comminuted fracture?
This is where a fracture results in two or more bone pieces due to high energy trauma
These can be other fractures e.g. spiral/transverse but then become a comminuted if there are two or more bone pieces
What is the main concern with comminuted fractures?
These can disrupt the blood supply to the bone - osteonecrosis
How can comminuted fractures be fixed?
Will require internal fixation to reapply the bone together and to reestablish the blood supply
What is a stress fracture?
What are the two different types?
When stress on the bone results in it to fracture
Fatigue fracture - when abnormal stress on normal bone causes a fracture
Insufficiency fracture - where normal stress on abnormal bone causes a fracture
How can you identify a stress fracture on a scan?
Will see a white haziness around the fracture - this is the periosteal reaction forming a bone callous during healing
What is the periosteal reaction in a stress fracture?
This is a white haziness that will be visible on a bone scan
This is where the bone attempts to heal itself - cells of the bone differentiate and heal the bone - results in bone callous formation
What conditions are insufficiency fractures common seen in?
Osteomalacia
Paget’s disease
What is Paget’s disease?
Where the bone is soft and bends and may potentially break
Why are stress fractures difficult to pick up on scans?
Because it is the internal trabeculae network that is affected rather than the outer cortical bone
How does a stress fracture heal generally?
Most of these will heal on their own - will not require any intervention
How does a high intensity stress fracture heal?
Should tell the patient to rest and not put much pressure on the fracture
What type of scan can be used to see stress fractures?
Bone scintigraphy - becomes positive sooner than plain film
What is a greenstick fracture?
Where there is a bending force on the bone - the bone bends but does not fracture completely
In whom does a green stick fracture occur and why?
In children - more woven bone - soft and bending bone
In whom does a fracture of the epiphyseal growth plate occur?
Children
What is the most adverse effect of a fracture of the epiphyseal growth plate?
Can interfere with bone
Why do fractures of the epiphyseal growth plate occur?
Mainly cartilage here - this is soft and is not designed to take the same forces as bone can
How can epiphyseal growth plate fractures affect growth?
Can cause the growth plate to close prematurely and to stop producing new bone eg. may close at the radius but not at the ulnar - pushes hand towards the raidal side
Why is a fracture to the pelvis so clinically significant?
There are so many important organs being protected by the pelvis - so this fracture has a very high complication rate
There is very important blood supply passing through the pelvis which all run very close to the bone
What is the mortality rate from pelvic fractures?
10-12%
What is a fracture haematoma and when does this occur?
This is the first thing that occurs when a bone fractures
Fracture results in a leak of blood from the blood vessels in the Haversian canals - clot formation occurs - this is a fracture haematoma
How long after a fracture foes a fracture haematoma occur?
6-8 hours following fracture
Why does it take so long for a fracture haematoma to form?
Hypoxic tissue with low pH
What occurs at the site of the fracture immediately after the fracture?
Swelling and inflammation will occur to the dead bone cells at the fracture site
What is the second stage of bone healing?
Fibrocartilaginous callus formation
How long does the fibrocartilaginous callus last for?
About three weeks
How does the fibrocartilaginous callus form?
The clot tissue is remodelled into granulation tissue - new capillaries reorganise and grow and there is hypoxia induced angiogensis
What cells produce the tissue in the fibrocartilaginous callus and why?
Fibroblasts - these differentiate quickly to act temporarily in the time space that it takes for the osteoblasts to differentiate
Also chondroblasts
What collagen type forms the fibrocartilaginous callus?
Collagen type 1 (fibroblasts)
What is the role of the collagen in the fibrocartilaginous callus?
Used to glue the ends of the bone together
Why are fibroblasts and chondroblasts producing the fibrocartilaginous callus rather than osteoblasts?
Because it takes a while for osteoblasts to differentiate
What other cells appear at the site of the fibrocartilaginous callus?
Inflammatory cells
What do the fibroblasts differentiate into in the fibrocartilaginous callus?
Chondrocytes
What is the purpose of the chondrocytes in the fibrocartilaginous callus?
The chondrocytes produce type I collagen - this acts to bridge the fracture site cartilage and the laid down trabeculae bone
What is the third stage of bone healing?
Bony callus
How long does the bony callus last for?
3-4 months
What cell is responsible for the production of the bony callus?
Osteobolasts - these have now fully differentiated
What is the bony callus composed of?
Woven bone - remember this is the first form of bone that is formed
What is the fourth stage of bone healing?
Bone remodelling
What is involved in the process of bone remodelling?
Osteoclasts are present - remodel the woven bone into compact and trabeculae bone
In what order do the stages of bone healing occur?
All of these stages are all overlapping with each other all at the same time - do not have one and then move onto the other - instead they are all together
