Back, Joint, and Extremity Pain - Case 5-3: 14-Year-Old Boy
I. History of Present Illness
A 14-year-old boy presented to the emergency department complaining of left knee
pain. Three days before this visit, he noted left knee pain after playing
basketball and began to limp. This knee pain improved over the next few days.
While walking across a wooden floor on the evening of his emergency department
presentation, he slipped and fell. As soon as he stood up, he noted pain in his
left knee again that occasionally radiated to the left hip. He did not strike
his head. There was no other bone pain. There was no headache, blurry vision,
or loss of consciousness. There was no fever, weight loss, myalgias, or
malaise.
II. Past Medical History
The patient had required hospitalization at 8 years of age for disorientation
after a car accident; his symptoms resolved, and he was discharged the next
day. At 10 years of age, he developed poststreptococcal glomerulonephritis. He
had been treated with a short course of corticosteroids but had not required
specific therapy since that time. He did not report taking any medications.
There was no family history of endocrine or autoimmune disorders.
III. Physical Examination
T, 37.1°C; RR, 24/min; HR, 105 bpm; BP, 125/80 mm Hg
Weight, 101 kg
Physical examination revealed an obese boy without visible evidence of head
trauma. He was alert and cooperative. Heart and lung sounds were normal. The
abdomen was soft without organomegaly. There was no deformity of either lower
extremity. Passive flexion of the left hip accompanied by internal and external
rotation significantly worsened the left knee pain. Internal rotation of the
left hip was limited compared with that of the right hip. There was no
tenderness, swelling, or erythema of the left knee. There was full range of
motion of the left knee without discomfort when this joint was tested in
isolation. There was no sign of knee ligament instability. The right lower
extremity was normal. He was able to ambulate but clearly preferred not to
place too much weight on the left leg.
IV. Diagnostic Studies
The complete blood count revealed the following: 8,600 WBCs/mm3 (65% segmented neutrophils, 30% lymphocytes, and 5% monocytes); hemoglobin,
13.1 g/dL; and 204,000 platelets/mm
3. The CRP concentration was 0.7 mg/dL, and the ESR was 12 mm/hour. Serum
electrolytes and calcium were normal.
V. Course of Illness
Radiographs of the left knee were normal. Hip radiographs revealed the diagnosis
(Fig. 5-3).
Discussion: Case 5-3
I. Differential Diagnosis
Diagnosing the cause of knee pain in an adolescent can be difficult. Because
knee pain may actually be pain referred from the hip via the obturator nerve,
diagnostic considerations should include problems involving either the knee or
the hip. In this case, although the patient was adamant in his complaint of
pain localized to the knee, examination of the knee was normal. The lack of
physical findings localized to the knee made septic arthritis of the knee and
fracture of the distal femur, patella, proximal tibia, or fibula unlikely.
Antecedent trauma raised the possibility of knee hyperextension or patellar
dislocation, but the normal knee examination placed these possibilities lower
on the differential diagnosis. Osgood-Schlatter disease typically manifests
with localized tenderness and swelling over the tibial tuberosity, findings
that were absent in this case.
Hip disorders to consider in an adolescent boy include avascular necrosis of the
femoral head, septic arthritis of the hip, femoral or pelvic osteomyelitis,
femoral neck fracture, chronic developmental hip dysplasia, inguinal hernia,
slipped capital femoral epiphysis, Ewing sarcoma, and osteogenic sarcoma.
Avascular necrosis of the femoral head can be caused by corticosteroid use and
also occurs in children with SCD and idiopathically (Legg-Calv
é Perthes disease). The absence of fever, combined with normal CRP and ESR
values, makes acute septic arthritis and osteomyelitis unlikely. In this case,
radiographs of the hip narrowed the differential diagnosis even further.
II. Diagnosis
Anteroposterior radiographs of the hip (see Fig. 5-3) demonstrated inferior
displacement of the left femoral head relative to the femoral neck. On the
lateral frog leg view, this displacement appeared posterior and medial relative
to the femoral neck.
These findings confirmed the diagnosis of slipped capital femoral epiphysis
(SCFE).
The patient underwent percutaneous screw fixation (Fig. 5-4). Prophylactic screw
fixation of the contralateral hip was also performed.
III. Incidence and Epidemiology of Slipped Capital Femoral Epiphysis
The term SCFE refers to displacement of the femoral head relative to the femoral neck through
the physis (growth plate). This displacement results from either cumulative
normal stresses acting on a weakened physis or the effect of an acute traumatic
event on a normal or previously weakened physis. SCFE occurs with an annual
incidence of 2 to 3 cases per 100,000 persons. It typically develops during the
adolescent growth spurt, occurring in boys 10 to 16 years of age and girls 10
to 13 years of age. The incidence is approximately 2.5 times greater in boys
than in girls. The incidence is also higher in African-Americans than in
Caucasians. Obesity is a clear predisposing factor. One-half to two-thirds of
children with SCFE have weight-for-height profiles greater than the 95th
percentile. Obesity may contribute by creating increased shear forces across
the weakened physis during ambulation. Underlying endocrine or metabolic
disorders that delay skeletal maturation, such as primary or secondary
hypothyroidism, panhypopituitarism, or hypogonadism, should be suspected in
children who are outside the typical age or weight range for SCFE. In this
case, the corticosteroids the patient received at 10 years of age were not
thought to be a contributing factor in the development of SCFE.
IV. Clinical Presentation
Several studies have documented considerable delays in the diagnosis of SCFE.
Patients frequently complain of symptoms for 3 to 4 months before the diagnosis
is made. Therefore, clinicians should have a high level of suspicion for the
diagnosis of SCFE even in adolescents with vague complaints of hip, thigh, or
knee pain.
Patients with SCFE usually complain of pain in the affected hip or groin. Pain
perceived in the medial thigh and knee is caused by referred hip pain along the
sensory distribution of the femoral and obturator nerves. Isolated knee pain is
the sole presenting feature in up to 15% of children diagnosed with SCFE. Early
in the course, pain is usually associated with exercise, but as the slip
progresses, the symptoms become more persistent and severe.
On physical examination, patients complain of pain with rotation of the hip. The
pain is most prominent at the extremes of rotation. Internal rotation may be
noticeably decreased. Furthermore, as the hip is flexed, the thigh rotates
externally. This finding, when present, is almost pathognomonic for SCFE in an
obese adolescent. Thigh or gluteal muscle atrophy occurs with long-standing
symptoms and disuse.
V. Diagnostic Approach.
Anteroposterior and frog leg lateral hip radiographs. On the anteroposterior view, a line drawn along the superior femoral neck (Klein's line) normally intersects a portion of the femoral head. In SCFE, the femoral
head is located below this line. On the frog leg lateral view, the femoral head
is displaced posterior and medial to the femoral neck. In the early stages of
SCFE, the only finding may be a widened and blurred physis. In chronic cases
(symptom duration, longer than 3 weeks), radiographs may reveal bony remodeling
along the posterior and medial aspects of the femoral neck. Both hips should be
examined, because SCFE is bilateral in 25% of cases. Approximately 20% to 50%
of those patients with known unilateral involvement ultimately develop SCFE in
the contralateral hip. Radiographs also allow exclusion of conditions with
similar manifestations, such as femoral neck fracture.
Additional imaging. Hip ultrasound, computed tomography, and MRI have been used to confirm the
diagnosis in radiographically equivocal cases.
Other studies. Consider evaluating thyroid and pituitary function in children outside the
typical age range for SCFE. Loder et al. reviewed 85 patients with endocrine
disorders and SCFE. Only those with previously undiagnosed hypothyroidism or
growth hormone deficiency presented before 10 years of age. Complete blood
count, CRP, and ESR determinations should be obtained if the diagnosis of
osteomyelitis or septic arthritis is being considered.
VI. Treatment
The goals of treatment are to prevent further slippage and to restore function.
The patient should not be allowed to bear weight on the affected extremity once
the diagnosis has been confirmed. An untreated stable slip may progress to a
more severe unstable slip, leading to increased morbidity. The most common
surgical treatment involves percutaneous fixation of the displaced femoral head
with one or more metallic pins or screws.
Prophylactic treatment of the asymptomatic contralateral hip is controversial.
Given the high incidence of eventual bilateral involvement (20% to 50% of
cases), some surgeons have advocated treatment of the contralateral hip at the
time of initial surgery. Other orthopedic surgeons recommend fixation of an
asymptomatic contralateral hip only in those patients who are at highest risk
of developing SCFE of the contralateral hip, such as those with known endocrine
or metabolic disorders.
Outcome after repair is generally good but depends on the degree of abnormality
before repair. Subsequent avascular necrosis of the femoral head complicates
15% of cases. Avascular necrosis is most often a consequence of vascular injury
associated with initial femoral head displacement rather than a consequence of
the repair. Patients with a moderate or severe degree of femoral head
displacement at presentation are also more likely to develop associated
osteoarthritis. Chondrolysis or destruction of cartilage may occur after pin
placement but has also occurred in patients without any surgical therapy. Leg
length discrepancy may result from incomplete reduction, avascular necrosis, or
chondrolysis. Early recognition and treatment of SCFE prevents many of these
complications.
VII. References
1. Kehl DK. Slipped capital femoral epiphysis. In: Morrissy RT, Weinstein SL,
eds.
Lovell and Winter's pediatric orthopaedics, 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2001:999–1033.
2. Ledwith CA, Fleisher GR. Slipped capital femoral epiphysis without hip pain
leads to missed diagnosis.
Pediatrics 1992;89:660–662.
3. Loder RT, Wittenberg B, DeSilva G. Slipped capital femoral epiphysis
associated with endocrine disorders.
J Pediatr Orthop 1995;15:349–356.
4. Matava MJ, Patton CM, Luhmann S, et al. Knee pain as the initial symptom of
slipped capital femoral epiphysis: an analysis of initial presentation and
treatment.
J Pediatr Orthop 1999;19:455–460.
5. Perron AD, Miller MD, Brady WJ. Orthopedic pitfalls in the ED: slipped
capital femoral epiphysis.
Am J Emerg Med 2002;20:484–487.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2008 Williams & Wilkins.
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