Pediatric Hip Disorders: Slipped Capital FemoralEpiphysis and Legg-Calvé-Perthes DiseaseAlexa J. Karkenny, MD,* Brandon M. Tauberg, MD,* Norman Y. Otsuka, MD*

*Montefiore Medical Center and the Children’s Hospital at Montefiore, Bronx, NY

Practice Gaps

1. The differential diagnosis for a limping child or adolescent with hip or

knee pain is broad. Delayed or missed diagnoses of slipped capital

femoral epiphysis and Legg-Calvé-Perthes disease have significant

morbidity. Clinicians should understand when to suspect these

disorders based on history, examination, and early imaging findings to

allow for timely referral to a specialist.

2. Clinicians should also have a basic understanding of the treatment

options and prognosis of these disorders to counsel patients and their

families before and during treatment by a specialist.

Objectives After completing this article, readers should be able to:

1. Identify the general anatomy relevant to slipped capital femoral

epiphysis (SCFE) and Legg-Calvé-Perthes disease (LCPD) pathology.

2. Recognize the symptoms and physical examination findings of SCFE

and LCPD.

3. Know the basic laboratory values and imaging to order to evaluate for

SCFE and LCPD when referring to a specialist.

4. Differentiate straightforward presentations of SCFE and LCPD.

5. Understand broad treatment categories and the prognoses of SCFE

and LCPD.

6. Realize the importance of timely referral to a specialist for SCFE and

LCPD.

INTRODUCTION

Pediatric hip pathology can lead to devastating complications, such as hip

instability, early arthritis, and growth abnormalities. Two of the most common

pathologies in this age group include slipped capital femoral epiphysis (SCFE)

and Legg-Calvé-Perthes disease (LCPD). The importance of early diagnosis is

paramount in both of these disorders, to allow for early treatment and attempt to

limit the potentially morbid outcomes. Because many of these children will

AUTHOR DISCLOSURE Drs Karkenny andTauberg have disclosed no financialrelationships relevant to this article. Dr Otsukahas disclosed that he is deputy editor ofthe Journal of the American Academy ofOrthopaedic Surgeons. This commentary doesnot contain a discussion of an unapproved/investigative use of a commercial product/device.

ABBREVIATIONS

AP anteroposterior

LCPD Legg-Calvé-Perthes disease

MRI magnetic resonance imaging

SCFE slipped capital femoral epiphysis

454 Pediatrics in Review

initially present to their pediatrician, recognition and early

referral to an orthopedic specialist can drastically change

their outcomes.

SLIPPED CAPITAL FEMORAL EPIPHYSIS

Background, Pathophysiology, and Relevant AnatomySlipped capital femoral epiphysis is the most common hip

pathology affecting adolescents. (1) Although a common

diagnosis, up to 20% of patients are delayed in diagnosis,

with short- and long-term consequences. (2) Contradictory

to its name, the pathologic process occurs when the femoral

head (epiphysis) of the proximal femur displaces on the

femoral neck due to weakness in the hypertrophic zone of

the growth plate (physis). Figure 1 illustrates the anatomy of

the physis and epiphysis. Factors that may contribute to this

slippage either predispose an individual to increased stress

across the physis, such as obesity, or decrease its resistance

to shear forces, such as metabolic derangements (ie, hypo-

thyroidism) that inherently weaken the physis. (1) The

pathogenesis of SCFE is likely multifactorial, with anatom-

ical, genetic, and temporal factors.

Increased shear forces across the physis may predispose

individuals to slippage. (1)(3) Obese children tend to have

higher mechanical loads across the physis and of the prox-

imal femur, with increased retroversion. (1)(4) As child-

hood obesity continues to rise, so too does the prevalence

of SCFE. (4) Obesity and puberty may be risk factors for

SCFE due to changes in the metabolic activity of the

physis. (5) The natural history of SCFE is affected by the

acuity at presentation (ie, acute versus chronic SCFE),

degree of displacement of the femoral neck in relation to

the epiphysis, stability of the physis, and the resulting

relation of the proximal femoral metaphysis to the femoral

head. (1)

EpidemiologySlipped capital femoral epiphysis is the most common hip

pathology affecting adolescents, and the incidence con-

tinues to rise. (1)(3)(4)(6) The average age at onset is 12.7

years (13.5 years in boys and 12.0 years in girls). Unfortu-

nately, recent evidence has shown that the average age at

presentation has been dropping, which has been correlated

with the rise in pediatric obesity. (4)(7)(8)(9) The overall

prevalence of the disorder varies from 0.71 to 10.8 per

100,000 children, with boys more often affected than girls

at a ratio of approximately 1.5:1. (1)(10) Typically, SCFE

presents during puberty due to the relative weakness of

the physis during rapid growth. (5)

Loder et al (11) demonstrated that slip severity was

significantly correlated with the age of the patient and the

duration of symptoms. There is a weakly positive correlation

between slip severity and duration of symptoms. (11) Factors

that increase physeal stress or decrease resistance to shear

forces are associated with SCFE, including obesity and

metabolic abnormalities such as hypothyroidism. (5) Com-

pared with white individuals, there is a higher prevalence

in black, Hispanic, Polynesian, and Native American indi-

viduals. (12)

PresentationThe presentation of SCFE may vary, depending on the

severity and stability of the slip. Often, a child will be 10

to 14 years old, will be obese, and will present with a chief

complaint of groin/hip or knee pain. The duration of pain

may be chronic (>3 weeks) or acute (<3 weeks) in pre-

sentation and may be related to a specific event. The pain

may be an acute or chronic exacerbation. (13) The average

duration of pain before diagnosis with SCFE is 4 to 5

months. (8) Pain may be constant or occur only when

weightbearing, and the severity of the pain may differ.

Typical pain is unilateral, although bilateral pain/SCFE

may be possible and should be evaluated, especially in a

younger child (<10 years old) or a child with metabolic

abnormalities. (9)(14) Of the 18% to 63% of SCFE cases that

are bilateral, only 50% to 60% will present with pain

bilaterally. Those with bilateral SCFE presenting with uni-

lateral pain often develop bilateral symptoms within 18

Figure 1. The femoral head is known as the epiphysis. Growth of theproximal femur occurs at the growth plate, known as the physis. Thefemoral shaft is known as the diaphysis. The metaphysis is where thediaphysis transitions into the epiphysis.

Vol. 39 No. 9 SEPTEMBER 2018 455

months. (3) Patients may present with painless limp and

external rotation of the affected leg. Typically, patients have

limited hip range of motion with decreased internal rota-

tion, flexion, and abduction; they may also exhibit obligatory

external rotation with passive flexion of the hip (Fig 2). (15)

Limited internal rotation is the most commonly seen abnor-

mality on examination. (6)

Patients with stable SCFE will present with the ability to

bear weight on the affected extremity, with or without

crutches. Patients with an unstable SCFE are unable to bear

weight on the affected extremity. Unstable SCFE is associ-

ated with a high risk of osteonecrosis, with the literature

showing 10% to 60% risk. (16)(17)(18) Sankar et al (16)

reported that younger patients with a shorter period of

prodromal symptoms and unstable SCFE have a higher

rate of avascular necrosis. However, another study by Loder

et al showed that slip severity may be correlated with older

age and longer duration of symptoms. (11) The increased

risk of avascular necrosis with SCFE is directly correlated

with the risk of development of early osteoarthrosis. (1) Table

1 summarizes key features that pediatricians should re-

cognize in patients with SCFE.

The average time from the onset of symptoms to diag-

nosis is approximately 8 weeks. This is due to delay in

seeking medical care, initial complaint of knee pain, and

insurance status. (19) The average time for a patient to see

an orthopedist versus a general provider is 91 days versus

27 days, respectively. (19)

EvaluationAnteroposterior (AP) and frog-leg lateral radiographs of

both hips are of utmost importance when evaluating a

patient for SCFE. Knee pain in the immature patient

demands critical evaluation of hip motion to rule out hip

pathology. The Klein line, the metaphyseal blanch sign of

Steel, and epiphysiolysis are helpful radiographic findings

to aid diagnosis. (20) Other radiographic measurements

may be beyond the scope of this review. The Klein line is

evaluated on the AP pelvic radiograph and is a line extended

from the lateral cortex of the femoral neck, which should

intersect the femoral epiphysis. Epiphyseal location medial

to the Klein line is a sign of SCFE. The blanch sign of Steel

arises from the overlapping of the posteriorly positioned

femoral head in relation to the metaphysis. Epiphysiolysis,

which is widening of the growth plate, may be seen com-

pared with the opposite uninvolved hip. (20) Figure 3 shows

these measurements and radiologic signs.

Magnetic resonance imaging (MRI) is typically not indi-

cated unless findings are not obvious on radiography and

SCFE is still suspected or there is a need to evaluate the

contralateral hip in a patient at risk for another slip. (18) In

early cases of SCFE, MRI is more sensitive than plain

radiographs. (20) Also, MRI may be used to assess bone

quality/blood supply of the femoral head in an unstable slip.

Computed tomography is typically not needed except for

presurgical planning in patients who may require surgical

dislocation or osteotomy. (18)

Figure 2. A. The patient’s left hip remains in neutral rotation as the hip is flexed to 90°. B. The patient’s right hip demonstrates obligatory externalrotation: the hip rotates externally as it is flexed to 90°.

456 Pediatrics in Review

Laboratory values in patients with SCFE should be ob-

tained for children younger than 10 years, children whose

weight is less than the 50th percentile, or those with other

suspected endocrine abnormalities. Included in the evalu-

ation should be triiodothyronine, thyroxine, and thyrotropin

levels to evaluate thyroid function and blood urea nitrogen

and creatinine levels to evaluate for osteodystrophy of

chronic renal failure. (21)(22)

Treatment and PrognosisTreatment for SCFE typically involves stabilization of the

physis to prevent worsening slippage. Stabilization is pri-

marily performed via percutaneous in situ fixation (Fig 4),

with a single screw being placed through the growth plate

from the metaphysis into the epiphysis. (3)(13)(18)(23)(24)

The decision whether to prophylactically fix the contralateral

side has been largely debated. Bilateral slips occur in as

many as 63% of patients. (3) The current indications for

contralateral fixation are for patients at high risk for slip-

page, which includes age younger than 10 years, metabolic

abnormality, extreme obesity, or unreliable follow-up. (14)

(25) Figure 5 shows a child with hypothyroidism who re-

quired bilateral SCFE fixation.

Approximately 61% to 95% of children with endocrine

abnormalities had a contralateral slip, which should sug-

gest the need for prophylactic fixation at the time of initial

presentation. (21)(26) Severe, chronic slips may also be

treated with hip capsule decompression, proximal femoral

osteotomies, or epiphyseal reduction/pinning. (23)(27) De-

spite pinning, there remains a risk of leg length discrepancy,

osteonecrosis of the femoral head, osteoarthrosis, and slip

progression, although rare. (3)(28)(29) In addition, residual

proximal femur deformity may occur, causing impingement

due to failure of remodeling. (30)

Patients with SCFE are at increased risk for arthritis;

approximately 45% of children with a SCFE are estimated to

require a total hip arthroplasty by 50 years after their slip.

(31) The femoral neck may deform and cause impingement

on the acetabulum, contributing to arthritis. (32) Patients

with SCFE may present with progressive loss of hip motion

TABLE 1. Key Features of Slipped Capital Femoral Epiphysis that thePediatrician Can Recognize

• Age at presentation typically 10 to 14 y (puberty)

• More common in obese patients

• Usually unilateral pain, although may be bilateral

• Typically groin/hip pain, although 15%–23% may present with knee pain

• Walk with limp

• Family history of slipped capital femoral epiphysis

• Obligatory external rotation with flexion

• Can the patient bear weight?

• Males > females (1.5�)

Figure 3. A. Evaluation of a 13-year-old girl with a left-sided slippedcapital femoral epiphysis (SCFE). Klein lines are drawn on both sides,illustrating its intersection with the epiphysis on the right side whilebeing lateral to it on the side with the SCFE. B. A 14-year-old boywith left-sided SCFE with metaphyseal blanch sign of Steel showinga crescent-shaped area of increased density over the metaphysis(arrow).

Figure 4. A 13-year-old boy after an in situ single-screw pinning of aleft-sided stable slipped capital femoral epiphysis.

Vol. 39 No. 9 SEPTEMBER 2018 457

due to chondrolysis, or cartilage breakdown. The diagnosis

can be confirmed with radiographs showing decreased joint

space, and up to 7% of patients may develop this condition,

although they tend to do better than patients with SCFEwho

develop osteonecrosis. (3) Studies have shown that patients

who are diagnosed and treated with pinning more than 2

months after initiation of pain tend to have developed more

severe slips and thus are at higher risk for complications in

the future. (19)

LEGG-CALVÉ-PERTHES DISEASE

Background, Pathophysiology, and Relevant AnatomyLegg-Calvé-Perthes disease (LCPD) was first described in

1910 by several independent physicians, including Arthur

Thornton Legg, Jacques Calvé, Georg Perthes, and Henning

Waldenström. (33)(34) This disease constitutes idiopathic

osteonecrosis of the femoral capital (head) epiphysis occur-

ring in otherwise healthy young children. (35)(36) Disrup-

tion to the femoral head blood supply first results in growth

arrest and later a pattern of healing that includes bone

resorption, femoral head weakening and flattening (coxa

plana), reossification, and, finally, growth resumption. (34)

The cause of the initial vascular insult is unknown and the

subject of debate; proposed mechanisms include genetic

mutations in type II collagen, coagulation abnormalities,

repetitive hip loading and extreme flexion as seen with

gymnasts, second-hand smoke exposure, venous conges-

tion, and hyperactive behavior. (37)(38)(39)(40)(41)(42)(43)

(44)(45)(46)(47)

EpidemiologyThe incidence of LCPD is lowest in East Asian populations,

ranging from as low as 0.9 per 100,000 up to 21.1 per

100,000 in Liverpool. (34)(48) Patients classically present

with symptoms between 4 and 8 years of age but can present

from 18 months of age to skeletal maturity. (34)(49) Male to

female ratios of 3:1 up to 5:1 have been reported, and bilateral

disease occurs in 10% to 15% of patients. (34)(50)

PresentationPatients usually present with a painless limp for a few weeks

to months. Patients may or may not report pain from

antecedent trauma. However, pain may or may not be

present, and when present, the location can be variable.

Due to the innervation ofmultiple nerves about the hip, pain

may be referred to the knee (femoral nerve), medial thigh

(obturator nerve), or buttock (sciatic nerve). (33) The diag-

nosis may, in fact, be delayed when a patient with LCPD

notes persistent pain referred to the knee. On physical

examination, limited hip abduction and internal rotation

(which is best tested with the hip extended) are the most

Figure 5. A 6-year-old girl who presented with 3 weeks of groin pain was found to have right hip slipped capital femoral epiphysis. Laboratory findingsshowed an elevated thyrotropin level, and she was indicated for bilateral hip in situ screw fixation.

458 Pediatrics in Review

consistent signs of LCPD. (33) Patients may appear to have

shortening of the affected extremity in unilateral cases.

Patients often have weak quadriceps and hip abductors,

with muscle atrophy.

Presentation will vary depending on the age of the patient

and stage of LCPD. For example, a young child in an early

stage of LCPD may present with a subtle limp and hip pain

only during mildly limited range of motion, whereas an

older child with a later stage of LCPD or a younger child with

severe LCPD may present with a notable limp and inability

to bear weight unassisted. The LCPD presentation may be

atypical in females, with later age at onset and increased

severity of involvement, especially in gymnasts and dancers

subject to repetitive microtrauma at the hip. (37) There has

been some discrepancy, with other authors reporting sim-

ilar presentations to males. (51) Table 2 summarizes key

features of LCPD that pediatricians can recognize.

EvaluationAn evaluation for LCPD should start with a detailed history

and physical examination, as well as radiographs of the

pelvis and hips. If the pediatrician is ordering initial imag-

ing, an AP pelvic radiograph with bilateral frog-leg lateral

views (hips flexed and abducted) should be obtained. A

single hip radiograph is not adequate because comparison

with the contralateral hip cannot be made and bilateral

diseasemay bemissed. (52) Early radiographic signs include

flattening of the femoral head and subchondral sclerosis

(Fig 6). (52) Later signs include extrusion of the femoral

head laterally such that it is not contained, or covered, by the

acetabulum (Fig 7). In most cases, changes in the shape of

the femoral head are accompanied by acetabular remodel-

ing. (34)

The classification systems for LCPD are based on radio-

graphic findings. Waldenström described 4 stages charac-

terizing the appearance of the femoral head: initial,

fragmentation (Fig 8), reossification, and healed. (34)(50) In

another classification described by Stulberg et al, (53) the

severity of femoral head deformity at skeletal maturity

correlates with the risk of osteoarthritis at mean follow-

up of 40 years.

The role of MRI in LCPD diagnosis, management, and

prognostication is still evolving. (50) Magnetic resonance

imaging has been shown to be more accurate in the early

diagnosis of LCPD and to provide earlier and more reliable

detail on the extent of femoral head necrosis and proximal

femoral physeal involvement as well as the configuration of

femoral head andacetabulardeformities. (34)(54)More recently,

perfusion (Fig 9), diffusion, and delayed gadolinium-enhanced

MRI have been used to better understand the pathophysi-

ology and prognosis of this disease. (55)(56)

Legg-Calvé-Perthes disease is a diagnosis of exclusion.

Other diseases causing osteonecrosis of the femoral head

must first be ruled out before assigning a diagnosis of

LCPD. A detailed medical history and family history, as

well as medication list, facilitates that. Sickle cell disease,

chronic systemic disease such as lupus, chemotherapy, and

long-term corticosteroid use can result in osteonecrosis of

the femoral head. In addition, radiographic mimickers of

LCPD include multiple epiphyseal dysplasia and Gaucher

disease, both of which typically affect both hips. (50)(57)

TABLE 2. Key Features of Legg-Calvé-Perthes Disease that the PediatricianCan Recognize

• Onset most commonly between ages 4 and 8 y

• Male prevalence (4–5� more likely than females)

• Bilateral involvement in 10%–15% of patients

• Symptoms: pain in the groin, greater trochanter, proximal thigh, or knee; limp exacerbated by activity; possible history of trauma

• Signs: Trendelenburg gait, decreased hip range of motion (especially with abduction and internal rotation)

Adapted from Herring JA, ed (34)

Figure 6. A. An anteroposterior radiograph of the pelvis shows earlyradiographic signs of Legg-Calvé-Perthes disease in the left hipcompared with the right hip, including flattening of the femoral headand subchondral sclerosis. B. These features are again seen on thelateral view.

Vol. 39 No. 9 SEPTEMBER 2018 459

Treatment and PrognosisThe best strategy for treating and managing LCPD is early

referral to a pediatric orthopedist when there is a suspicion

for LCPD. It is important for pediatricians to have a general

understanding of the treatment of LCPD to counsel patients

and families both when referring patients for suspected

LCPD and when following patients long-term who are

known to have the disease.

Our knowledge of the etiology and optimal treatment of

LCPD continues to evolve, and currently there is no cure.

(36) Treatment options vary based on age at presentation,

deformity present during active disease, and residual defor-

mity. The goal of treatment is to maintain a spherical

femoral head and a concentrically reduced hip through

the reossification stage of the disease to prevent eventual

degenerative changes while preserving hip range of motion.

The treatment of early disease includes the use of non-

steroidal anti-inflammatory medications, protected weight-

bearing, limited physical activity, and physical therapy for

range of motion. For the patient who does not improve with

these initial conservative measures, surgery to contain the

femoral head is the next option, to position the femoral head

deeper in the acetabulum (Fig 10), and to improve the

coverage on the femoral head. (36)

Multicenter cohort studies out of Norway and the Perthes

Study Group have provided the highest level of evidence to

date to guide treatment and have shown a difference in

outcome depending on patient age at disease onset. (58)(59)

A large retrospective study of patients younger than 6 years

old indicated that 80% of hips have good results with

Figure 7. An anteroposterior radiographic of the pelvis shows flatteningand extrusion of the right femoral head. Approximately one-third ofthe lateral aspect of the femoral head is not contained, or covered, bythe acetabulum.

Figure 8. A. An anteroposterior radiograph of the pelvis shows Legg-Calvé-Perthes disease affecting the bilateral hips, with fragmentation ofbilateral femoral heads. B. Fragmentation is again seen on a lateral viewof the left hip.

Figure 9. A perfusion-weighted magnetic resonance image of bilateralhips shows changes consistent with Legg-Calvé-Perthes disease of theright hip, including flattening and lateral extrusion of the femoral headrelative to the acetabulum, decreased contrast uptake in the rightfemoral head (dark signal), and a hip joint effusion (bright signal).

Figure 10. Postoperative anteroposterior pelvic radiograph status postproximal femoral varus osteotomies bilaterally.

460 Pediatrics in Review

symptomatic or nonsurgical management only. (60) In

children younger than 6 years old with greater than 50%

femoral head involvement, no significant differences have

been seen among treatment with physical therapy, an ortho-

sis, or proximal femur varus osteotomy, whereas children

older than 6 years with greater than 50% femoral head

involvement showed significantly better results with sur-

gery. (58) Long-term follow-up suggests that more than 50%

of patients with LCPD develop disabling arthritis by the

sixth decade of life. (61) A 2012 prospective cohort series

documenting pain and function in 56 adults who were

treated nonoperatively for LCPD reported a 5% rate of total

hip replacement at 20-year follow-up. (62)

Table 3 lists the distinguishing features of SCFE and

LCPD.

References for this article are at http://pedsinreview.aappubli-

cations.org/content/39/9/454.

TABLE 3. Distinguishing Slipped Capital Femoral Epiphysis (SCFE) andLegg-Calvé-Perthes Disease (LCPD)

FEATURE SCFE LCPD

Age at onset Usually pubertal age (10–14 y) Usually 4–8 y (but can be anywhere from 18 mo toskeletal maturity)

Onset Variable – acute (<3 wk) versus chronic (>3 wk) Weeks to months

Previous trauma Sometimes Sometimes

Associated diseases Obesity, endocrinopathy Coagulopathy, hyperactivity, genetic mutations in typeII collagen

Gait Variable – may be weightbearing (stable) or not ableto tolerate weightbearing (unstable)

Usually limping, sometimes with a Trendelenburg gait

Pain Variable – note that pain can be in the groin,lateral hip, thigh, or referred to the knee

Range of motion Restricted – classically, with obligatory external rotationwhen the hip is flexed

Restricted – classically, loss of internal rotation andabduction

Unilateral or bilateral 18%–63% bilateral 10%–15% bilateral

To view teaching slides that accompany this article,

visit http://pedsinreview.aappublications.

org/content/39/9/454.supplemental.

Summary• Slipped capital femoral epiphysis (SCFE) and Legg-Calvé-Perthesdisease (LCPD) may present with classic history and physicalexamination findings that may aid the pediatrician in makingan early diagnosis.

• Pediatricians should refer patients with abnormal physicalexamination findings, abnormal imaging findings, or persistenthip, knee, or groin pain despite normal imaging findings to apediatric orthopedist.

• Based on strong research evidence, there are adult consequencesof SCFE and LCPD, including chondrolysis and secondary

osteoarthritis resulting in a need for total hip arthroplasty. (3)(14)(25)(61)(62)

• Treatment of SCFE and LCPD remains under debate. (3)

Vol. 39 No. 9 SEPTEMBER 2018 461

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1. A 13-year-old boy with a medical history of mild persistent asthma presents to thepediatrician’s office for evaluation of a 6-week history of right thigh and knee pain. He playslinebacker on the middle school football team but has not been to practice this week dueto worsening discomfort. He denies fever, recent illnesses, or trauma. His medicationsinclude inhaled albuterol and fluticasone. His surgical history is significant for a right tibialfracture at 3 years of age. Family history is significant for osteoarthritis in the maternalgrandmother. On physical examination he is noted to have a body mass index of 28 andan antalgic gait. He lies on the bed with his right leg externally rotated and hasdecreased range of motion with internal rotation of the right hip. Which of thefollowing risk factors most contributed to his condition?

A. Family history of osteoarthritis.B. Inhaled corticosteroid use.C. Obesity.D. Participation in contact sports.E. Previous right tibial fracture.

2. You advise the patient in question 1 to refrain from weightbearing and orderanteroposterior (AP) and frog-leg lateral radiographs of the hips. In addition, you referthe patient to a pediatric orthopedic surgeon for immediate evaluation. Which of thefollowing findings do you expect to see on the AP and frog-leg lateral radiographs?

A. Deformity of the acetabulum.B. Flattening of the femoral head.C. Focal femoral lytic lesion.D. Narrowing of the femoral growth plate.E. Posterior dislocation of the femoral epiphysis.

3. A 14-year-old obese girl with a medical history of hypothyroidism is diagnosed as havingslipped capital femoral epiphysis and undergoes percutaneous in situ fixation of theright femoral head and prophylactic fixation of the contralateral hip. Which of thefollowing is the most likely long-term complication of her condition?

A. Growth failure.B. Hemarthrosis.C. Osteoarthritis.D. Osteomyelitis.E. Recurrent fractures.

4. A 6-year-old boy is brought to the emergency department for evaluation of left hippain. The pain began initially 2 months ago after a fall at school and resolvedspontaneously. Today he states that the pain has worsened over the past month andis localized to the left hip and knee. His mother also states that he began limping1 week ago. On physical examination, he has limited hip abduction and internalrotation and mild atrophy of the quadriceps. Both AP and frog-leg lateralradiographs demonstrate flattening of the femoral head and subchondral sclerosis.Which of the following best describes the pathophysiology of this patient’scondition?

A. Displacement of the proximal femoral epiphysis.B. Disruption of the blood supply to the femoral head.C. Fracture involving the femoral epiphysis, growth plate, and metaphysis.D. Inflammatory bony destruction caused by chronic infection.E. Malignant invasion leading to abnormal osteoid formation.

462 Pediatrics in Review

5. A 5-year-old boy presents to the pediatric orthopedic surgeon’s office for evaluation of a2-month history of intermittent right hip pain and a limp. He was seen by his primarycare physician last week, who ordered hip radiographs, which demonstrated findingsconsistent with avascular necrosis of the femoral head. On physical examination, thepatient is observed to have an asymmetrical gait and painwith internal rotation of the righthip. Which of the following is the next best step in management?

A. Biopsy of the femoral head.B. Broad spectrum antibiotic therapy.C. Nonsteroidal anti-inflammatory medications and physical therapy.D. Percutaneous in situ fixation.E. Surgical reconstruction of the acetabulum.

Vol. 39 No. 9 SEPTEMBER 2018 463