The anatomy of the pediatric musculoskeletal system is unique
and reflects the active growth and development that occurs during
childhood. Fracture classification, treatment approach, and types
of complications are directly related to this unique anatomy. Perhaps
the most helpful way to divide pediatric musculoskeletal injuries
is those occurring before and after fusion of the physes (growth
plates). In general, both injury patterns and treatment approaches
in children in whom closure of the physes has already occurred is
similar to those of the adult. Therefore, the major focus of this
chapter is directed at injuries occurring in the prepubescent child.
In addition, diseases specific to children that cause nontraumatic musculoskeletal
complaints are also covered.
The long bones of children consist of discrete anatomic areas.
The physis is an area of growth cartilage and may occur at one (e.g.,
the phalanges) or both (e.g., the tibia and the femur) ends of a
long bone. The area of bone between a physis and the adjacent joint
is termed the epiphysis. An apophysis is a type
of growth plate that occurs at the end of a bone when there are
no bones on the other side (e.g., calcaneous) and often serves as
a point for muscle or ligament attachment. The midshaft of a long
bone is referred to as the diaphysis. The metaphysis of
a long bone represents the area between the diaphysis and the physis
(Figure 133-1; see Chapter 264, Initial Evaluation and Management of Orthopedic Injuries).
The anatomy of the pediatric long bone as demonstrated
by the femur. Longitudinal growth occurs at the physes (growth plates)
located at either end. Bony prominences that serve as sites of muscular
or ligamentous attachment are known as apophyses (e.g., greater
and lesser trochanteric apophysis).
The long bones of children are less dense and more porous than
the long bones of adults. Pediatric long bones respond to mechanical
stress by bowing and buckling, rather than fracturing through and
through, as in adults. The periosteum of the diaphysis and the metaphysis
is thick in children and is continuous from the metaphysis to the
epiphysis, surrounding and protecting the mechanically weaker physis.
The weakness of the physis is, in part, related to the reduced oxygen
tension found in the hypertrophic zone of the physis. This hypertrophic
zone is the location of frequent fractures within the physis. The
physis is also sensitive to alterations in the blood supply, and
physeal injuries can result in growth disturbance.
The growth of the musculoskeletal system and its response to
injury are also influenced by the growth of muscle and connective
tissue. The ligaments of children are stronger and more compliant
than in adults, and ligaments tolerate mechanical forces better
than the weaker physis. Therefore, apophyseal detachments or epiphyseal
fractures are much more common than ligamentous injuries during
The weakest layer of the physis is the hypertrophic cell zone.
This area is susceptible to shearing and bending, and the hypertrophic
cell zone is the layer of the physis that is most consistently fractured.
Vascular supply of the hypertrophic cell zone of the physis derives
from the epiphyseal vasculature. When physeal injury occurs, the
reserve and proliferative cartilage cells usually remain with the
epiphysis, and blood supply remains intact.
Compression forces alone may also affect bone growth. This is
particularly true when compression forces are applied to the epiphyseal
side of the physis. The injury to bone growth caused by compression
results from interruption of the epiphyseal circulation to the reproductive
cells of the physis.
Perhaps the easiest way to divide pediatric orthopedic injuries
is into those occurring in children who are skeletally immature
with open physes, and those whose physes have closed. The type of
injury in the skeletally immature child is usually described with
relation to the physis. The Salter and Harris classification system
(see Figure 264-7 and Chapter 264, Initial Evaluation and Management of Orthopedic Injuries) is
based on the relationship of the fracture line to the physis and
the prognosis for growth disturbance.
Type I Fractures
Type I physeal injuries occur when the epiphysis separates from
the metaphysis. The cleavage is through the hypertrophic cell zone
of the physis, with the reproductive cells of the physis remaining
with the epiphysis. There are no associated fragments of bone, as
the thick periosteal attachments surrounding the physis remain intact.
The epiphysis may, however, somewhat displace from the metaphysis. Type
I injuries have a low incidence of growth disturbances.
Suspect a Salter-Harris type I injury when there is point tenderness
over a physis. Radiographic findings are typically subtle or absent,
and soft tissue swelling or a joint effusion may be the only abnormality.
Epiphyseal displacement can usually be appreciated on x-rays in
one or more views (Figure 133-2); however,
in the absence of epiphyseal displacement, the diagnosis is a clinical
Salter-Harris type I fracture of distal radius. Anteroposterior
radiograph showing widened physeal line of distal radius (arrow).
(Courtesy of Wake Medical Center, Raleigh, NC.)
Treatment of most type I fractures consists of immobilization
of the suspected fracture using an appropriate splint, cold compresses,
and elevation to limit swelling. Refer to an orthopedic surgeon
for monitoring of bone growth disturbances. Type I fractures of
the distal fibula are exceptions because they are not associated
with growth arrest and can be followed by a primary care physician
Type II Fractures
In a type II injury, the fracture line extends a variable distance
along the hypertrophic cell ...