Growth Plate Fractures and Injuries (cont.)
How Are Growth Plate Fractures Diagnosed?
After learning how the injury occurred and examining the child, the doctor
will use x rays to determine the type of fracture and decide on a treatment
plan. Because growth plates have not yet hardened into solid bone, they don't
show on x rays. Instead, they appear as gaps between the shaft of a long bone,
called the metaphysis, and the end of the bone, called the epiphysis. Because
injuries to the growth plate may be hard to see on x ray, an x ray of the
noninjured side of the body may be taken so the two sides can be compared.
Magnetic resonance imaging (MRI), which is another way of looking at bone,
provides useful information on the appearance of the growth plate. In some
cases, other diagnostic tests, such as
computed tomography (CT) or ultrasound,
will be used.
Adapted from Disorders and Injuries of the Musculoskeletal System, 3rd
Edition. Robert B. Salter, Baltimore, Williams and Wilkins, 1999. Used with the
author's permission.
Since the 1960's, the Salter-Harris classification, which divides most growth
plate fractures into five categories based on the type of damage, has been the
standard. The categories are as follows:
Type I
The epiphysis is completely separated from the end of the bone or the
metaphysis, through the deep layer of the growth plate. The growth plate remains
attached to the epiphysis. The doctor has to put the fracture back into place if
it is significantly displaced. Type I injuries generally require a cast to keep
the fracture in place as it heals. Unless there is damage to the blood supply to
the growth plate, the likelihood that the bone will grow normally is excellent.
Type II
This is the most common type of growth plate fracture. The epiphysis,
together with the growth plate, is separated from the metaphysis. Like type I
fractures, type II fractures typically have to be put back into place and
immobilized.
Type III
This fracture occurs only rarely, usually at the lower end of the tibia, one
of the long bones of the lower leg. It happens when a fracture runs completely
through the epiphysis and separates part of the epiphysis and growth plate from
the metaphysis. Surgery is sometimes necessary to restore the joint surface to
normal. The outlook or prognosis for growth is good if the blood supply to the
separated portion of the epiphysis is still intact and if the fracture is not
displaced.
Type IV
This fracture runs through the epiphysis, across the growth plate, and into
the metaphysis. Surgery is needed to restore the joint surface to normal and to
perfectly align the growth plate. Unless perfect alignment is achieved and
maintained during healing, prognosis for growth is poor. This injury occurs most
commonly at the end of the humerus (the upper arm bone) near the elbow.
Type V
This uncommon injury occurs when the end of the bone is crushed and the
growth plate is compressed. It is most likely to occur at the knee or ankle.
Prognosis is poor, since premature stunting of growth is almost inevitable.
A newer classification, called the Peterson classification, adds a type VI
fracture, in which a portion of the epiphysis, growth plate, and metaphysis is
missing. This usually occurs with an open wound or compound fracture, often
involving lawnmowers, farm machinery, snowmobiles, or gunshot wounds. All type
VI fractures require surgery, and most will require later reconstructive or
corrective surgery. Bone growth is almost always stunted.
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