A fracture is a broken bone or skeletal injury. Other types of skeletal injuries include dislocation and subluxation. While mild strains and sprains can often be treated at home, an injury that causes a bone fracture, dislocation or subluxation needs professional medical care. You can usually tell you have a broken bone because the area is swollen, twisted, or bent out of shape (deformed or abnormal position), a bone is poking through the skin, the area is black and blue, or the pain is so bad that you cannot use the limb normally—for example you can’t walk or put weight on your leg or foot. In addition to a bone fracture, you can also have a fracture/dislocation. A fracture/dislocation is a fracture in or near a joint that results in a complete or partial dislocation of the joint.
In a dislocation, the bony components of a joint that articulate with are no longer in contact with each other. The joint no longer works. In subluxation, the bony parts of the joint partially touch each other, and the joint doesn’t work exactly as it should.
Before you read any further, you need to know more about bones and some medical terminology.
Long axis of the bone.
Cortex. The cortex is the compact part of the long bone. The strength of the bone which allows it to withstand stress is mainly due to this cortex.
Distal bone fragment: The more (or most) distant part of two (or more) bone fragments to the center of the body. For example, the distal end of the thigh bone is the end at the knee joint.
Proximal bone fragment: The closest to the center of the body of two (or more) bone fragments. For example, the proximal end of the the thigh bone is the end at the hip joint.
, fracture fragment.
Types of Bone Fractures
How Bone Fracture are Described
Fractures are described based on:
- If one of the bone fragments is outside the body
- The relationship of the bone fragments to each other as well as how many bone fragments there are
- The direction of the fracture line—transverse, diagonal or oblique, longitudinal, spiral
There are a number of different ways to describe bone fractures.
- Open versus closed. A closed fracture is one which the skin is intact where the fracture occurs and an open fracture, also called compound, is one where the skin is broken.
- Simple versus comminuted. A simple fracture is one where there are only 2 major bone fragments and one fracture line. A comminuted fracture is one where there are multiple bone fragments and multiple fracture lines.
- Complete versus incomplete. A complete fracture means that the fracture line goes completely across the bone — through the cortex. Incomplete fractures usually seen in children, have a fracture line that only crosses part of the bone. Types of incomplete fractures are greenstick and torus. In a Greenstick fracture the break is through one cortex. In a torus fracture there is a buckling of the cortex.
Fractures often cause deformities (abnormal positions). The deformities can be in any one of 3 possible anatomical planes. Fractures can also be described based on the relationship of the fractured bone fragments to each other. Most fractures have more than one of these abnormal positions. To be consistent in describing these deformities, they are based on the relationship of the distal fracture fragment to the proximal fracture fragment.
- Displacement or Shortening. This is where the 2 fragments are in 2 different planes. Displacement fractures include overriding, where 2 fragments are shortened in relation to one another due to overlapping of the proximal and distal fragments. Shortening is described by the number of centimeters of overlap. Distraction is where the bony ends are pulled apart as in lateral displacement. Both displacement and shortening can be present in the fracture.
- Angulation. This happens when the 2 fragments are not aligned and an angular deformity is present. In alignment means that the axis of the proximal and distal fragments are parallel to each other and the joint above and below are in the normal relationship. The angle is usually defined by which way the break points—medial, lateral, distal, etc.—and is based on the angle made between the distal fragment and the proximal fragment after the break and where the distal fragment would be if in alignment.
- Rotation. This is where torsion or rotation happens between the 2 bone fragments. Rotation fractures are almost always in the long bones like the humerus and femur.
Bone Fracture Patterns
There are several different fracture patterns that happens when bones break.
1. Transverse: the fracture line is perpendicular to the long axis of the bone, caused by force in the direction of the fracture
2. Spiral: the fracture line is twisted and the fracture line is a twisting fracture caused by a twisting injury such as a break in your leg that happens when your foot is planted but your leg keeps turning
3. Oblique or Diagnonal: the fracture line is on the diagonal and usually caused by force applied in the same direction as the long axis of the bone.
4. Impacted, compressed or longitudinal: fracture line and force is in the same direction as the long axis of the bone
5. Avulsion: An avulsion fracture is a bone fracture which occurs when a fragment of bone tears away from the main bone mass as a result of physical trauma.
6. Torus (buckle)
The significance of fracture patterns is they help us to determine the amount of force that was applied to the bone. Knowing how much force was applied to the bone can tell us how much soft tissue damage there may be around the fracture.
Mechanical Causes (Force) of Bone Fractures
Analyzing the forces or pressure that causes a bone fracture—the mechanical cause—provides a great deal of information as to how the injury happened, the type of injury and the extent of the injury. Using this information, the fracture patterns can be further categorized into patterns and abnormal positions (deformity).
1. Putting too much force on the bone so that it bends produces a transverse fracture.
2. A twisting or torsion pressure on the bone produces a spiral fracture.
3. Put force on the long axis of the bone produces a compression or impacted fracture.
4. Tensile force on the bone produces and a motion fracture.
5. Combining forces—such as bending the bone and putting force on the long axis—produce an oblique fracture.
fracture of the distal radius with dorsal angulation
fracture of the distal radius with palmar angulation resulting from a fall on a flexed hand
fracture of head of the 5th metatarsal; easily missed avulsion fracture caused by a pull of the peroneus brevis tendon
fracture of the head of the 5th metacarpal with palmar angulation which most often results from punching a person or a wall
Healing of Fractures
- Indistinct fracture line
- Bony callous production
- Bridging of the fracture
- Remodeling of bone
Soft Tissue Injuries From Bone Fractures
There are a number of soft tissues that can be damaged when a fracture happens including blood vessels, nerves, muscles, tendons and ligaments. The amount of soft tissue damage is related to the type of fracture—a greenstick fracture has much less soft tissue damage than a compound fracture.
- Vascular Injury
Vascular injury is relatively uncommon with a fracture but when it does occur, it is an emergency situation. The most common vascular injury is compartment syndrome, which is increased pressure on a fascial compartment where the compartment cannot be stretched. This pressure from an increase in fluids caused by the trauma can cause death of the muscle(s) in the compartment in a relatively short period of time. A correct diagnosis of compartment syndrome is essential. Once the diagnosis is confirmed, immediate surgical release of the compartment with a fasciotomy (cutting away of the fascia to relieve pressure by allowing the muscle tissue in the compartment to swell) is necessary.
- Arterial Injury
- Nerve Damage
- Muscle and Tendon
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