Salter-Harris fracture is a common injury in children that
involves the growth plates. 15% of all fractures in children involves the
growth plate, and it occurs more in boys than in girls. The growth plate
injuries occur more distal than proximal, such as distal radius, distal tibia,
and distal phalanges. Growth plate injuries in children are common in the bones
of the lower (tibia and fibula). It is important to diagnose these fractures as
they may affect the growth of the bone if not diagnosed and treated properly.
There are generally five types of Salter-Harris fractures. The higher of the
type number, the more complications associated with the fracture and worse
prognosis. Growth plates produce the longitudinal growth bones. The reserve
zone of the growth plate is the inactive zone. The proliferating zone of the
growth plate has cellular proliferation and longitudinal growth, and this zone
makes a person tall or short. The hypertrophic zone of the growth plate has
maturation, degeneration, and provisional calcification. The majority of growth
plate injuries occur in the hypertrophic zone. The hypertrophic zone is weak.
In fact, the hypertrophic zone is weaker than the ligaments, and it provides a
cleavage zone for the fracture to occur. Type I Salter-Harris fracture is
difficult to diagnose; 5% of fractures are Type I. The fracture occurs through
the growth plate, and there may not be an obvious displacement. Sometimes the
diagnosis is a clinical one. Fracture occurs through the weak zone of
provisional calcification. Type I is known by fast healing and rare
complication rate. Type II is a fracture through the growth plate and the
metaphysis, sparring the epiphysis. 75% of fractures are Type II. The corner of
the metaphysis separates (Thurston-Holland Sign). With Type II, the fragment
usually stays with the epiphysis while the rest of the metaphysis will
displace. Healing is fast and growth is usually okay. Injury to the distal
femur will cause a high rate of growth abnormality. Type III is a fracture
through the growth plate and epiphysis, sparring the metaphysis. The fracture
splits the epiphysis. 10% of the fractures are Type III. Fracture extends into
the articular surface of the bone (intraarticular fracture). It requires
anatomic reduction of the joint and internal fixation. An example of Type III
is the Tillaux fracture of the distal tibia. CT scan may be needed to diagnose
this fracture. Type IV fracture passes through the epiphysis, the growth plate,
and the metaphysis; 10% of fractures are Type IV. It can cause complications
such as growth disturbances and angular deformity. Type V is uncommon; about 5%
are Type V. It is a compression or crush injury of the growth plate. There is
no associated fractures of the epiphysis or metaphysis. Initial diagnosis may
be difficult. Type V has the highest incidence of growth arrest and
disturbance. Type I and Type II usually do not require surgery and will have a
better prognosis than Type III, Type IV, and Type V. In Type I and Type II, the
reduction of the fracture may not be anatomic. Despite this, the prognosis is
usually good. In Type III and Type IV, the fracture is usually intraarticular
and anatomic reduction is necessary. Type III and Type IV do not require
surgery and the prognosis is usually fair. Type V is rare and has a poor
prognosis. In general, the distal femur contributes to approximately 9-10mm of
growth per year. The proximal tibia contributes to approximately 6mm of growth
per year. Girls complete growth at the age of 14 years. Boys complete growth at
the age of 16 years. In situations of child abuse, you may find growth plate
injury or physeal separation as you can see in transepiphyseal separation of
the distal humerus in children.
