CLASSIFICATION OF FRACTURES AND DISLOCATIONS
the aim
To know how to investigate a patient who may have a fracture or dislocation
• To be able to describe a fracture or dislocation concisely and correctly
• To understand the principles of reduction and holding a fracture or dislocation
• To know the common complications of fractures and dislocations, and how to check for them
• To understand the basic pathophysiology of fracture healing
SIGNIFICANCE OF FRACTURES AND DISLOCATIONS
Fractures (breaks) and dislocations are failures of the skeleton to cope with the load put upon It. When they do occur other structures may also fail, this may not be so obvious but may have much more serious consequences. After the initial trauma. tissues tend to spring back into place. Nerves and blood vessels may also have been stretched far beyond their physiological limit at the time of trauma. It the nerve has been disrupted and the ends have separated. surgery may improve the prognosis dramatically. If the blood supply to that limb has been disrupted, then it is a surgical emergency to restore that circulation.
The check for neurovascular damage in a traumatized is, if any thing. more important than the diagnosis of the fracture or dislocation.
IMPORTANCE OF THE HISTORY
The history gives important clues to the type of trauma likely. The energy of trauma is related to the mass and the square of the
velocity. i.e.
E= 1|2 MV2
The direction of the trauma will also affect the injury that you are looking for. The important thing to remember is that. If the trauma was severe enough to fracture or dislocate the skeleton it is highly likely that there was enough energy to cause a second or even a third dislocation or a fracture.
Do not relax once you have found the fracture or dislocation start looking for more
PATTERNS OF INJURY
The history of the injury will give a clue to the pattern of the injury. A fall from a height with the casualty landing on his or her
EXAMINATION
The musculoskeletal examination is described before .
The key feature is to make sure that the patient's overall condition stable by checking the airway. breathing and circulation before concentrating on the musculoskeletal injuries. The examination should then be systematic from top to bottom of the body. with complete exposure and care taken to check the patient's back as well as front. For each limb, be sure to check the distal circulation and neurology. Finally. it is important to record these findings. Mean while. be careful not to let the patient get too cold.
Investigation of a patient with a limb injury
• First perform ABC, then a quick general survey
• Then check distal neurovascular status on any injured limb
• Estimate the energy from the square of the velocity
• you find one fracture then look for another
• Seek for a pattern of injuries that fits with the history of the accident
DESCRIBING A DISLOCATION OR FRACTURE Dislocations and subluxations
A dislocation is a complete disruption of a joint. The articular surfaces are no longer in contact with each other. A subluxation is a partial dislocation. Some of the articular surface is in contact, but the congruence of the two joints has been lost. For either a dislocation or subluxation. the joint needs to be named. and the direction of the disruption should be described (e.g. an inferior glenohumeral dislocation.
Fractures
Classification by quality of bone in relation to load
Fractures occur when the load to which they are subjected exceeds their intrinsic strength which may be.
Traumatic fracture
This occurs when an excessive load is applied to normal bone.
Pathological fracture
This is produced when the strength of the bone is reduced by disease. In this case. a force that is within normal limits leads to a fracture. The disease could be generalised osteoporosis or a localized lytic lesion from a metastasis
Stress fracture
This occurs if bones are subjected to a very large number of loads, none of which alone would be enough to break the bone but which mean that the mechanical structure of the bone can grad usually fatigue. The bone will then break at a load far lower than it could normally with stand. This is particularly a problem for people playing high-level sport.
Partial or green-stick fractures
These occur because bones in young people or child are very flexible. They bend and then may buckle or partially break. instead of breaking cleanly when overloaded (as bones in adults do). One characteristic of a green-stick fracture is that there may be a discontinuity in one cortex of the bone but not in the other.
Classification by direction of force
Compression fractures
If the load applied along the length of a bone exceeds that of its strength then it may collapse into itself. This is especially common in elderly patients whose bones are osteoporotic and therefore less able to resist a heavy load. The fracture may be difficult to see.
There may only be a small overlap of the cortical margins of the
fracture, while the medulla may look diffusely radiopaque white
because the trabeculae have collapsed into each other. overall, the bone will be shortened and may also be angulated, A common example is the crush fracture of the vertebral body in a patient who slips and lands hard on his or her bottom.
Avulsion or distraction fracture
Here, the two fragments of bone are pulled apart. In young patients, a ligament or tendon may be stronger in tension than the bone into which it inserts. If the load is excessive. the bone tears apart. These fractures are particularly common where strong muscles insert into small bones. Examples are the patella the quadriceps muscle), the olecranon (triceps) and the fifth metatarsal head peroneus tertius .
Spiral fractures
If a long bone is twisted along its axis, a spiral fracture may result. The length of the spiral is easy to underestimate. It is especially important to determine whether there is any extension into the articular surface of the bone. The tibia is particularly susceptible to spiral fractures when the foot is firmly fixed to the ground (by studs or another player's foot) and the player's body continues to twist.
Transverse fractures
If a long bone is bent along its long axis then a transverse fracture may result
Butterfly fractures
If a bone is struck a direct blow, it is common for a more complex fracture to result where two break lines spread out obliquely from the point of contact of the blow, producing a free-floating 'butter fly' fragment between the two fractures .
Comminuted fractures
Comminuted fractures occur when a large amount of energy is dissipated into a bone. The bone breaks into fragments which may impact into each other or separate and become displaced .
Classification by anatomical site
A long bone is divided into three main zones and a surface.
The diaphysis. This is the narrow part of the main shaft. It usually has a thick cortex and a medulla filled with trabecular bone.
The metaphysis. The flare at each end between the diaphysis
and the epiphyseal (growth) plate is the metaphysis. It has thinner cortical bone and Its medulla is, again, filled with trabecular bone.
The epiphysis. The ends of a long bone beyond the epiphyseal
plate are called the epiphysis (singular epiphysis). They are
covered mainly by articular cartilage but may have a cuff of thin cortical bone. In infants and children, in whom the bones are still growing, the epiphyseal plate will be open. The plate is weaker than the bone around and so fractures tend to track along It or even across it. Epiphyseal fractures are important because they can haw a poor prognosis.
The articular surface. Fractures into the joint (articular fractures ) are also important because they carry a very poor prognosis if they are not carefully reduced and held a displacement of more than 2mm in the articular surface is thought to make the onset of early traumatic
.arthritis inevitable
Classification of epiphyseal fractures
The Salter-Harris classification of epiphyseal fractures is the simplest and the most common used .
Tabl show The Salter-Harris classification of fractures involving the epiphyseal plate fracture type Anatomy Frequency
prognosis
|
frequency
|
anatomy
|
fracture
type
|
good
|
rare |
runs
along epiphyseal plate
|
1
|
good
|
very
common
|
metaphyseal fragment |
2
|
poor
if not reduced
|
rare |
extends
into epiphysis
|
3
|
poor
if not reduced
|
rare |
cross
epiphyseal plate
|
4
|
very
poor
|
very
rare
|
crushes
epiphyseal plate
|
5
|
Grade 2 The fracture line again travels along the metaphyseal side of the plate but, before reaching the far cortex, it breaks out and tracks down into the metaphysis. This is by far the most common epiphyseal fracture and, for the reason given above, has a good prognosis. Even if the fracture is markedly displaced, the prognosis remains good. In children, the bone will remodel and grow straight over the next year, especially if no rotatory abnormality is involved. In fact, one of the greatest risks in a grade 2 fracture is causing growth arrest by damaging the growth plate while reducing the fracture, especially if this is attempted after a few days. when the fracture may already be uniting .
Grade 3 The fracture line does not run along the epiphyseal plate at all. It crosses from the metaphysis to the epiphysis. If it is displaced. it may heal with a step in the epiphyseal plate. Bony union may occur across the epiphyseal plate and block further growth, causing a most disfiguring progressive deformity of the limb if it is not promptly released. The key to the management of this type of fracture is anatomical reduction if it is displaced. This type of epiphyseal plate fracture is rare.
Grade 4 The fracture line travels along the distal (epiphyseal) side of the growth plate, affecting both the blood supply and the anatomical integrity of the germinal cells. The fracture line does not travel the whole length of the epiphyseal plate but deviates into the epiphysis itself and out on the articular surface. This is a second reason why this fracture has a poor prognosis. Not only is the growth plate likely to be damaged, but the articular surface may he incongruent. This predisposes the joint to early arthritis. The key to successful management of this type of fracture is anatomical reduction. This is best performed under open surgery. Once again, this type of fracture is rare.
Grade 5 This is a rare and difficult fracture to diagnose. The injury is a severe crush of the epiphyseal plate. The radiograph may look abnormal only in retrospect, and indeed this is how this type of fracture is usually diagnosed. The consequence of complete disruption of the growth plate is complete growth arrest there is little that can he done to prevent this, or indeed deal with it, once it has occurred.
Open fractures At the time of a fracture, the soft tissues over the bone will also be damaged. If the skin is broken there is a high probability that, at some time during the accident, the fracturing bone came into contact with the outside world, and so could be contaminated with bacteria. If there is no broken skin anywhere near a fracture, the fracture can be assumed ro be closed and the initially will be free of infection. If, however, there is any break in the skin anywhere near the fracture, it is important that the fracture is classified as open and treated as such. The bone will need to be exposed and a careful search made to allow all dead or contaminated tissue to be removed. The wound will also need washed out and should be left open. It is always best to err on the safe side and, if there is any doubt whatsoever, to treat the fracture
Open versus closed fractures
• Open fractures have a break in the skin near to the fracture
• The fracture must be assumed to connect with this and to be contaminated
• The bone ends and soft tissues must be surgically excised if osteomyelitis is to be avoided
Classification by position
Bones have a very strong covering (the periosteum) that is invisble on radiography. When a bone breaks, the periosteum is torn but it is unusual for the it to be completely disrupted. This is very important for othopaedic surgeons, because the periosteum be used to obtain a good position when reducing a fracture. It even act before that. Its elasticity may serve to reduce the fracture after the trauma. The fact that a fracture is seen to be undisplaced on radiographs does not necessarily mean that it was never displaced, just that much of the periosteum is intact. Even displaced fractures usually have at least part of the sleeve of periosteum intact (on the side of concave curvature), but, once again, the displacement at the time of trauma was always greater than that seen afterwards. This is why apparently innocuous-looking, minimally displaced, fractures with a small puncture wound over them should be assumed to be open, and to be potentially unstable untill otherwise proven.
Classification by management
Deciding whether a fracture is stable or unstable is yet another
type of classification, classification by management
Stable fractures are those that are unlikely to move further
Unstable fractures are those that will continue to displace if
is not taken to hold the fracture secure. There is a gradation stability which depends on the following factors
Site. Fractures in weight-bearing bones are more likely • displaced by 'normal' loads those in bones which can
easily be protected from load. such as the long bones of the arm
Shape. Spiral fractures tend to be unstable, whereas impacted fractures tend to be very stable.
Displacement .undisplaced fractures may have the periosteum intact and are therefore stable. The more displaced the
fracture. the more unstable it is likely to be.
• Behaviour of the patient. Patients who are prepared to be careful can maintain the position of a fracture that would become displaced in another patient who is not prepared to take care
International classifications
The Arbeitsgemeinschaft fur Osteosvnthesefragen (AO) classification is an internationally agreed classification of fractures using a simple alphanumeric code. The first number relates to the bone (humerus is 1. radius and ulna are 2. etc.). The second number relates to the position of the fracture on the bone (1 is proximal .2 diaphyseal and 3 distal). The position number is followed by a letter that defines the severity of the fracture. For proximal and distal fractures (types 1 and 3)., A is extra-articular B is partial articular and C is intra-articular, For diaphyseal fractures (type 2) A is a simple fracture. B is a wedge or butterfly type and C is comminuted or complex. This letter is followed by a further number that classifies the fracture still further. Charts are available to help you to decide the exact classification of each fracture .
The advantage of this classification is that it is international
and has been carefully validated to make sure that. as far as possible, everyone looking at the same fracture would classify it in the same way.The disadvantage is that a string of numbers is not very memorable. if you say to most trauma surgeons that a fracture is a 32B 3.2, it is unlikely that they would immediately know that you were talking about a distal third comminuted fracture of the femur.A second problem is that for a classification to be useful it should point to both treatment and prognosis. One of the key features which determines treatment. and indeed prognosis. in a fracture is soft-tissue damage (especially whether the fracture is displaced or not as this may make a big difference to any decision on management in the AO classification
tags:fractures,dislocations,classification
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