Bone Fracture
A bone
fracture 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
termed pathological fracture.
It should be noted that
although broken bone and bone
break are common colloquialisms for a bone
fracture, break is not a formal orthopedic term.
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:
·
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.
Another type of bone fracture is
a compression fracture. It 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.
-
Compacted fracture: A fracture caused when bone fragments are driven into each
other.
-
Holstein-Lewis fracture: A fracture of the distal third of the humerus resulting in
entrapment of the radial nerve. Since the triceps brachii and all muscles distal of
the break are innervated by the radial nerve, they will be significantly affected
by the fracture.
Classification of
Fractures
The Orthopaedic Trauma Association,
an association for orthopaedic surgeons, devised an elaborate classification
system to describe the injury accurately and guide treatment.
There are five parts to the
code:
-
Bone: Description of a fracture starts by naming the bone:
-
-
-
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 bone fracture classification
systems
There are other systems used to
classify different types of bone fractures:
-
-
Denis
classification: spine
-
Seinsheimer's
Classification: femur
-
-
Signs and symptoms of bone
fracture
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.
-
Healing Process of Bone
Fracture
The natural process of healing a
fracture starts when the injured bone and surrounding tissues bleed, forming what's called 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 of bone
fractrure
A bone fracture can be diagnosed
clinically, based on the history given and the physical examination performed by a healthcare
professional. Usually there will be an area of swelling, abrasion, bruising and/or tenderness at
the suspected fracture site.
Open fractures are obvious in the
sense that bone may be exposed.
X-ray radiographs can be requested to
view the bone suspected of being fractured.
In situations where
x-ray alone is insufficient,
a computed tomograph (CT scan) may be
performed.
Treatment of bone
fracture
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 verify 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 fiberglasscast 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.
Orthopedic Surgery to Correct Bone
Fracture
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 their limited blood flow. Bone tissue is predominantly extracellular matrixrather 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 cobaltchromium 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.
Some doctors further treat bones
using electrical bone growth stimulation or osteostimulation or both.
Child Bone
Fracture
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 pediatric age
group, as fracture clavicle and supracondylar fracture of humerus.
|