Orthopaedics- Trauma- The fracture process and fracture healing; Dislocations and Instability; Soft tissue injury Flashcards
What causes fractures?
What causes the majority of fractures?
Direct trauma (direct blow) Indirect trauma (due to twisting or bending forces). This causes the majority of fractures.
What is an incomplete/unicortical fracture?
A fracture in which there is a break in continuity of only one cortex
What is a complete fracture?
A fracture in which there is a break in continuity of both cortices.
Give examples of causes of a) A high energy fracture and b) A low energy fracture
a) RTA, gunshot, blast, fall from height
b) Trip, fall, sports injury
What are very low energy fractures usually due to?
An underlying weakness of the bone resulting in pathological fracture
Name the two ways in which bone can heal
Primary healing and Secondary healing
What is primary bone healing and when does it occur?
When there is minimal fracture gap (less than about 1mm)
The bone simply bridges the gap with new bone from osteoblasts.
This occurs in the healing of hairline fractures and when fractures are fixed with compression screws and plates
What is secondary bone healing and when does it occur?
Secondary bone healing occurs in the majority of fractures, when there is a gap at the fracture site which needs to be filled temporarily to act as a scaffold for new bone to be laid down.
It involves an inflammatory response with recruitment of pluripotent stem cells which differentiate during the healing process.
Describe the different stages of secondary bone healing.
After the fracture, haematome occurs with inflammation from damaged tissues.
Macrophages and osteoclasts remove debris and resorb the bone ends
Granulation tissue forms from fibroblasts and new blood vessels
Chondroblasts form cartilage (soft callus)
Osteoblasts lay down bone matrix (collagen type 1)- endochondral ossification
Calcium mineralisation produces immature woven bone (hard callus)
Remodelling occurs with organisation along lines of stress into lamellar bone
When is a)soft callus and b) hard callus normally formed by?
a) 2nd to 3rd week
b) 6th to 12-th week
What does secondary bone healing require?
A good blood supply for oxygen, nutrients and stem cells
A little movement or stress (compression or tension)
What could be the result of a lack of blood supply, no movement (internal fixation with fracture gap), too big a fracture gap or tissue trapped in the fracture gap?
Atrophic non-union
List some things which may impair fracture healing.
Smoking due to vasospasm
Vascular disease
Chronic ill health
Malnutrition
What is hypertrophic non-union and why does it occur?
There is abundant hard callus formation but too much movement to give the fracture a chance to bridge the gap.
They occur due to excessive movement at the fracture site.
What are the 5 basic fracture patterns?
Transverse fractures Oblique fractures Spiral fractures Comminuted fractures Segmental fractures
What are transverse fractures?
Fractures that occur with pure bending forces One side (the convex side) fails in compression and the other (concave) side fails in tension.
What are the effects of transverse fractures?
They may not shorten (unless completely displaced) but may angulate or result in rotational malalignment.
What are oblique fractures?
Fractures that occur with a shearing force (e.g. a fall from a height, deceleration).
How can oblique fracture patterns be fixed?
With an interfragmentary screw
What are the effects of oblique fractures?
Shortening
Angulate
What are spiral fractures?
Fractures that occur due to torsional forces
How can spiral fractures be fixed?
With an interfragmenary screw
What are spiral fractures most unstable to?
Rotational force
They can also angulate
What are comminuted fractures?
Fractures with 3 or more fragments
What are comminuted fractures usually a reflection of?
A higher energy injury or poor bone quality.
What are the effects of comminuted fractures?
substantial soft tissue swelling
periosteal damage
reduced blood supply to the fracture site which may impair healing
Are comminuted fractures stable or unstable?
Very unstable. They tend to be stabilized surgically.
What are segmental fractures?
When the bone is fractured in two separate places.
How is a fracture of a long bone described?
According to the site of the bone involved (proximal, middle or distal third)
According to the type of bone involved (diaphyseal, metaphyseal or epiphyseal)
Intra-articular or extra-articular
What are intra-articular fractures at greater risk of?
Stiffness
Pain
Post-traumatic OA, particularly if there is any residual displacement resulting in an uneven articular surface
What does the position of a fracture depend on?
The degree of displacement and angulation
What is displacement?
Displacement describes the direction of translation of the distal fragment and is described using anatomical terms.
It can be estimated with reference to the width of the bone (25%, 50%, 75% displacement)
100% displacement is referred to as an “off-ended” fracture
That is the degree of angulation?
The degree of angulation describes the direction which the distal fragment points towards.
It is measured in degrees from the longitudinal axis of the diaphysis of a long bone.
What information does the degree of displacement and angulation of a fracture give?
It gives information about the direction of forces involved in an injury and about the reversed direction of forces required to reduce a fracture.
What are possible consequences of residual displacement or angulation?
Deformity
Loss of function
Abnormal pressure on joints leading to post-traumatic OA.
May minor degrees of displacement and angulation be acceptable?
Yes, depending on the bone involved and the site of the fracture.
What is the role of the periosteum in children’s bones?
It serves to increase the width/circumference of growing long bones
What is the difference between the periosteum in children and in adults?
The periosteum in children is much thicker and tends to remain intact which can help stability and help reduction if required.
Do children’s fractures heal more quickly or more slowly than adult’s fractures?
Why?
They heal more quickly
This is due to the thicker periosteum which is a rich source of osteoblasts.
What is a benefit of the large potential of children’s bones to remodel?
Children can correct angulation up to 10 degrees per year of growth remaining in that bone.
Children’s fractures are therefore surgically stabilised less often and greater degrees of displacement or angulation can be accepted.
When are fractures treated as an adult’s fracture would be, due to the remodelling potential being less?
Once a child has reached puberty (around 12-14).
What do fractures around the physis have the potential to do?
What could this result in?
They have the potential to disturb growth.
This could result in a shortened limb or an angular deformity if one side of the physis is affected by growth arrest.
What is the name of the classification system for physeal fractures?
Salter Harris clasisfication
What is a Salter-Harris I fracture?
A pure physeal separation. This carries the best prognosis and is least likely to result in growth arrest.
What are Salter-Harris II fractures?
Similar to Salter-Harris I but a small metaphyseal fragment is attached to the physis and epiphysis.
The likelihood of growth disturbance is low.
What are Salter-Harris III and IV fractures?
Intra-articular fractures, with the fracture splitting the physis.
III- splits the physis, no attached metaphysis
IV- splits the physis and attached fragment of metaphysis/diaphysis
There is greater potential for growth arrest with these.
How should Salter-Harris III and IV fractures be managed?
These fractures should be reduced and stabilized to ensure a congruent articular surface and minimize growth disturbance.
What is a Salter-Harris V injury?
A compression injury to the physis with subsequent growth arrest.
These cannot be diagnosed with initial X-Rays and are only detected once angular deformity has occurred.
What are the commonest physeal fractures?
Salter-Harris II fractures.
What should raise the suspicion of NAI (non-accidental injury) or child abuse?
Multiple fractures of varying ages (with varying amounts of callus or healing)
Multiple trips to A&E with different injuries
+ other features
What should happen to a child considered at risk of under suspicion of NAI?
They should be admitted for safety and a full examination of the child should be carried out, and skilled history taking from parents or carers should be performed by an experienced doctor.
List some clinical signs of a fracture
Localised bony (marked) tenderness- not diffuse mild tenderness
Swelling
Deformity
Crepitus- from bone ends grating with an unstable fracture
Which X-ray views should be requested to assess a fracture?
AP and lateral views
Oblique views can be useful for complex shaped bones (e.g. scaphoid, acetabulum, tibial plateau)
What are used to diagnose mandibular fractures?
Tomograms- moving X-ray
When is CT useful in diagnosing fractures?
To assess fractures of complex bones
Can help determine the degree of articular damage and help surgical planning for complex intra-articular fractures.
When is MRI useful?
To detect occult fractures (where there is clinical suspicion of fracture but a normal X-ray
When is Technetium bone scan helpful?
To detect stress fractures as these may fail to show up on xray until hard callus begins to appear.
List early local complications of fractures.
Compartment syndrome
Vascular injury with ischaemia
Nerve compression or injury
Skin necrosis
List early systemic complications of fractures
Hypovolaemia Fat embolism Shock ARDS (acute respiratory distress syndrome) Acute renal failure SIRS (systemic inflammatory response syndrome) MODS (multi-organ dysfunction syndrome) Death
List late local complications of fractures
Stiffness Loss of function Chronic Regional Pain Syndrome Infection Non-union Malunion Volkmann's ischaemic contracture Post traumatic OA DVT
What is the main late systemic complication of fractures?
When does this tend to occur?
Pulmonary embolism
Tends to occur several days to weeks after injury but can occur much sooner