Slipped Capital Femoral Epiphysis
A slipped capital femoral epiphysis (SCFE) is
defined as a posterior and inferior slippage of the proximal femoral epiphysis
on the metaphysis (femoral neck), occurring through the physeal plate during the
early adolescent growth spurt. This injury is the most common hip disorder in
adolescents, especially those that are obese.
Due to the anatomic innervation of the hip and the referred nature of the pain,
it often presents with groin, thigh, or knee pain rather than hip pain. Due to
the nature of the pain, diagnosis can be rather enigmatic. Also, due to the
nature of the pain, the diagnosis can be initially missed, delaying treatment.
Any delay in treatment can result in a very poor long-term result.
A SCFE is classified according to its stability.
Approximately 90% of all SCFE can be classified as “stable.” A stable fracture
is characterized by the ability to bear weight, with or without crutches, and
ambulate. An unstable SCFE is characterized by the inability to bear weight and
ambulate. An unstable SCFE has a poorer prognosis for a positive outcome due to
the increased risk of avascular necrosis.
Although a SCFE is more common in obese children (95th percentile of weight for
their age), it is seen in children who are not obese. The injury is
statistically more prevalent in boys than girls (60% vs. 40%), and is more
common in black or Polynesian children. SCFE occurs before the pre-pubescent
growth phase and almost never occurs in girls once menses has begun. The average
age of onset is 12.0 years for girls and 13.5 years for boys. Bilateral SCFE is
seen in between 25% to 40% of all cases.
History and Physical Exam
A stable SCFE will present with a history of intermittent limp and pain that is
poorly defined (located in the groin, thigh, or knee). These symptoms may have
been present from several weeks to several months. There may have also been a
history of a vague trauma, such as slipping on the stairs, that can be linked to
the onset of symptoms.
Physically, there may be a slight loss in internal rotation of the hip. There
may also be slight pain at the end ranges of motion. As the symptoms continue
the child’s limp will become more noticeable and specific. The gait will show a
loss of internal rotation, increases in abduction and flexion of the hip. Also,
there will be an almost automatic external rotation of the lower extremity with
hip flexion.
An unstable fracture should not be moved to minimize further displacement of the
fracture. Typically the child will not move the lower extremity and resist any
motion of the limb. The child’s preferred position is reclined on a bed with the
hip held in a position of flexion, external rotation, and abduction.
Radiographic Findings
The physician should x-ray the hip and pelvis (anteroposterior (AP) and lateral
views and the minimums) of any obese child with diffuse hip, thigh, or knee
pain, and presents with a history of a limp. Under these circumstances, a SCFE
should be assumed until proven otherwise.
The AP view seen here shows evidence of a SCFE. This
radiograph is evidence of an early SCFE with minimal slippage (arrow pointing to
slippage).
An AP radiograph may show more subtle early signs. For this reason an
orthopaedic specialist may utilize Klein’s line
to help make the determination of a SCFE. Klein’s line is a line drawn along the
superior surface of the femoral neck. The epiphysis should normally project
superiorly to it. An early SCFE will characteristically show the epiphysis flush
with the line.
Treatment
The goals of treatment should be to prevent further slippage, avascular
necrosis, and expedite physeal closure. Orthopaedic surgeons will opt for
surgical treatment of both the stable and unstable SCFE. Conservative
treatments, such as non-weight bearing on crutches or in a wheel chair or the
use of a hip spica cast have been associated with poor outcomes.
The surgical technique used for the open reduction
with internal fixation usually involves placement of a single central screw into
the neck of the femur with or without use of bone grafting. There is some debate
as to whether bone grafts should be used to expedite physeal closure.
Prognosis
Early diagnosis and treatment are paramount in achieving a positive outcome.
Complications from delayed treatment can include avascular necrosis or
chondrolysis, and degenerative hip arthritis. Early, appropriate treatment will
result in a positive outcome for the patient.
Surgical intervention has been shown to significantly improve the outcome for
this injury when compared to a more conservative approach.
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