Bone fracture

A bone fracture (sometimes abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a break in the continuity of the bone. A bone fracture can be the result of high force impact or stress, or trivial injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture.

Although broken bone and bone break are common colloquialisms for a bone fracture, break is not a formal orthopedic term.

Orthopedic
In orthopedic medicine, fractures are classified in various ways. Historically they are named after the doctor who first described the fracture conditions. However, there are more systematic classifications in place currently.

All fractures can be broadly described as:
 * Closed (simple) fractures are those in which the skin is intact
 * Open (compound) fractures involve wounds that communicate with the fracture, or where fracture hematoma is exposed, and may thus expose bone to contamination. Open injuries carry a higher risk of infection.

Other considerations in fracture care are displacement (fracture gap) and angulation. If angulation or displacement is large, reduction (manipulation) of the bone may be required and, in adults, frequently requires surgical care. These injuries may take longer to heal than injuries without displacement or angulation.


 * Compression fractures usually occurs in the vertebrae, for example when the front portion of a vertebra in the spine collapses due to osteoporosis (a medical condition which causes bones to become brittle and susceptible to fracture, with or without trauma).

Other types of fracture are:


 * Complete fracture: A fracture in which bone fragments separate completely.
 * Incomplete fracture: A fracture in which the bone fragments are still partially joined.
 * Linear fracture: A fracture that is parallel to the bone's long axis.
 * Transverse fracture: A fracture that is at a right angle to the bone's long axis.
 * Oblique fracture: A fracture that is diagonal to a bone's long axis.
 * Spiral fracture: A fracture where at least one part of the bone has been twisted.
 * Comminuted fracture: A fracture in which the bone has broken into a number of pieces.
 * Impacted fracture: A fracture caused when bone fragments are driven into each other.

OTA classification
The Orthopaedic Trauma Association, an association for orthopaedic surgeons, adopted and then extended the classification of Müller and the AO foundation ("The Comprehensive Classification of the Long Bones") an elaborate classification system to describe the injury accurately and guide treatment. There are five parts to the code: (1) Humerus, (2) Radius/Ulna, (3) Femur, (4) Tibia/Fibula, (5) Spine, (6) Pelvis, (24) Carpus, (25) Metacarpals, (26) Phalanx (Hand), (72) Talus, (73) Calcaneus, (74) Navicular, (75) Cuneiform, (76) Cuboid, (80) LisFranc, (81) Metatarsals, (82) Phalanx (Foot), (45) Patella, (06) Clavicle, (09) Scapula
 * Bone: Description of a fracture starts by coding for the bone involved:}}
 * Location: a code for the part of the bone involved (e.g. shaft of the femur): proximal=1, diaphyseal=2, distal=3 (at the ankle the malleolar region is considered separately due to the pre-existing Weber classification and coded as 4 ). Except at the proximal femur the distal and proximal regions of the bone are defined by a square that is as wide as the as the distance between the condyles. The diaphysis is considered to be the rest of the bone between these two squares.
 * Type: It is important to note whether the fracture is simple or multifragmentary and whether it is closed or open: A=simple fracture, B=wedge fracture, C=complex fracture
 * Group: The geometry of the fracture is also described by terms such as transverse, oblique, spiral, or segmental.
 * Subgroup: Other features of the fracture are described in terms of displacement, angulation and shortening. A stable fracture is one which is likely to stay in a good (functional) position while it heals; an unstable one is likely to shorten, angulate or rotate before healing and lead to poor function in the long term.

Other classification systems
There are other systems used to classify different types of bone fractures:


 * "Denis classification": spine


 * "Frykman classification": radius and ulna


 * "Gustilo open fracture classification"


 * "Letournel and Judet Classification": Acetabular Fractures


 * "Neer classification": humerus


 * "Seinsheimer's Classification": femur

Signs and symptoms
Although bone tissue itself contains no nociceptors, bone fracture is very painful for several reasons:


 * Breaking in the continuity of the periosteum, with or without similar discontinuity in endosteum, as both contain multiple nociceptors.


 * Edema of nearby soft tissues caused by bleeding of torn periosteal blood vessels evokes pressure pain.


 * Muscle spasms trying to hold bone fragments in place

Pathophysiology
The natural process of healing a fracture starts when the injured bone and surrounding tissues bleed, forming a fracture Hematoma. The blood coagulates to form a blood clot situated between the broken fragments. Within a few days blood vessels grow into the jelly-like matrix of the blood clot. The new blood vessels bring phagocytes to the area, which gradually remove the non-viable material. The blood vessels also bring fibroblasts in the walls of the vessels and these multiply and produce collagen fibres. In this way the blood clot is replaced by a matrix of collagen. Collagen's rubbery consistency allows bone fragments to move only a small amount unless severe or persistent force is applied.

At this stage, some of the fibroblasts begin to lay down bone matrix (calcium hydroxyapatite) in the form of insoluble crystals. This mineralization of the collagen matrix stiffens it and transforms it into bone. In fact, bone is a mineralized collagen matrix; if the mineral is dissolved out of bone, it becomes rubbery. Healing bone callus is on average sufficiently mineralized to show up on X-ray within 6 weeks in adults and less in children. This initial "woven" bone does not have the strong mechanical properties of mature bone. By a process of remodeling, the woven bone is replaced by mature "lamellar" bone. The whole process can take up to 18 months, but in adults the strength of the healing bone is usually 80% of normal by 3 months after the injury.

Several factors can help or hinder the bone healing process. For example, any form of nicotine hinders the process of bone healing, and adequate nutrition (including calcium intake) will help the bone healing process. Weight-bearing stress on bone, after the bone has healed sufficiently to bear the weight, also builds bone strength. The bone shards can also embed in the muscle causing great pain. Although there are theoretical concerns about NSAIDs slowing the rate of healing, there is not enough evidence to warrant withholding the use of this type analgesic in simple fractures.

Diagnosis
A bone fracture can be diagnosed clinically, based on the history given and the physical examination performed by to view the bone suspected of being fractured.

In situations where x-ray alone is insufficient, a computed tomograph (CT scan) may be performed.

Pain management
In arm fractures in children, ibuprofen has been found to be equally effective as the combination of acetaminophen and codeine.

Immobilization
Since bone healing is a natural process which will most often occur, fracture treatment aims to ensure the best possible function of the injured part after healing. Bone fractures are typically treated by restoring the fractured pieces of bone to their natural positions (if necessary), and maintaining those positions while the bone heals. Often, aligning the bone, called reduction, in good position and verifying the improved alignment with an X-ray is all that is needed. This process is extremely painful without anesthesia, about as painful as breaking the bone itself. To this end, a fractured limb is usually immobilized with a plaster or fiberglass cast or splint which holds the bones in position and immobilizes the joints above and below the fracture. When the initial post-fracture edema or swelling goes down, the fracture may be placed in a removable brace or orthosis. If being treated with surgery, surgical nails, screws, plates and wires are used to hold the fractured bone together more directly. Alternatively, fractured bones may be treated by the Ilizarov method which is a form of external fixator.

Occasionally smaller bones, such as phalanges of the toes and fingers, may be treated without the cast, by buddy wrapping them, which serves a similar function to making a cast. By allowing only limited movement, fixation helps preserve anatomical alignment while enabling callus formation, towards the target of achieving union.

Splinting results in the same outcome as casting in children who have a distal radius fracture with little shifting.

Surgery
Surgical methods of treating fractures have their own risks and benefits, but usually surgery is done only if conservative treatment has failed or is very likely to fail. With some fractures such as hip fractures (usually caused by osteoporosis or osteogenesis Imperfecta), surgery is offered routinely, because the complications of non-operative treatment include deep vein thrombosis (DVT) and pulmonary embolism, which are more dangerous than surgery. When a joint surface is damaged by a fracture, surgery is also commonly recommended to make an accurate anatomical reduction and restore the smoothness of the joint. Infection is especially dangerous in bones, due to the recrudescent nature of bone infections. Bone tissue is predominantly extracellular matrix, rather than living cells, and the few blood vessels needed to support this low metabolism are only able to bring a limited number of immune cells to an injury to fight infection. For this reason, open fractures and osteotomies call for very careful antiseptic procedures and prophylactic antibiotics.

Occasionally bone grafting is used to treat a fracture.

Sometimes bones are reinforced with metal. These implants must be designed and installed with care. Stress shielding occurs when plates or screws carry too large of a portion of the bone's load, causing atrophy. This problem is reduced, but not eliminated, by the use of low-modulus materials, including titanium and its alloys. The heat generated by the friction of installing hardware can easily accumulate and damage bone tissue, reducing the strength of the connections. If dissimilar metals are installed in contact with one another (i.e., a titanium plate with cobalt-chromium alloy or stainless steel screws), galvanic corrosion will result. The metal ions produced can damage the bone locally and may cause systemic effects as well.

Electrical bone growth stimulation or osteostimulation has been attempted to speed or improve bone healing. Results however do not support its effectiveness.

Complications
Some fractures can lead to serious complications including a condition known as compartment syndrome. If not treated, compartment syndrome can result in amputation of the affected limb. Other complications may include non-union, where the fractured bone fails to heal or mal-union, where the fractured bone heals in a deformed manner.

In children
In children, whose bones are still developing, there are risks of either a growth plate injury or a greenstick fracture.
 * A greenstick fracture occurs due to mechanical failure on the tension side. That is, since the bone is not as brittle as it would be in an adult, it does not completely fracture, but rather exhibits bowing without complete disruption of the bone's cortex in the surface opposite the applied force.
 * Growth plate injuries, as in Salter-Harris fractures, require careful treatment and accurate reduction to make sure that the bone continues to grow normally.
 * Plastic deformation of the bone, in which the bone permanently bends but does not break, is also possible in children. These injuries may require an osteotomy (bone cut) to realign the bone if it is fixed and cannot be realigned by closed methods.
 * Certain fractures are known to occur mainly in the pediatric age group, such as fracture of the clavicle & supracondylar fracture of the humerus.