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Pediatric Hip MCQs

Practice Set 41 of 104

This practice set contains high-yield board review questions covering key concepts in Pediatric Hip. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 801

Topic: Pediatric Hip

A 4-week-old female infant born in breech presentation undergoes a screening hip ultrasound. The coronal view demonstrates a shallow acetabulum with an alpha angle of 45 degrees and a beta angle of 80 degrees. According to the Graf classification, what is the most appropriate management?

. Reassurance and repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Immediate closed reduction and spica casting
. Open reduction with capsulorrhaphy
. Observation with triple-diapering technique

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

An alpha angle of less than 60 degrees indicates developmental dysplasia (Graf type IIc or worse depending on specific features). A Pavlik harness is the standard of care for infants younger than 6 months with dysplastic or dislocated but reducible hips.

Question 802

Topic: Pediatric Hip

An 8-year-old boy presents with bilateral groin pain and an altered gait. Radiographs demonstrate bilateral stable slipped capital femoral epiphyses (SCFE). His height is in the 5th percentile, and his weight is in the 90th percentile. Which of the following laboratory evaluations is most critical in determining the etiology of his condition?

. Complete blood count and inflammatory markers
. Serum calcium, phosphate, and alkaline phosphatase
. TSH and Free T4
. Hemoglobin A1c
. Serum protein electrophoresis

Correct Answer & Explanation

. TSH and Free T4

Explanation

Patients presenting with SCFE under the age of 10 or with simultaneous bilateral presentation should be evaluated for underlying endocrine abnormalities. Hypothyroidism is the most common endocrine disorder associated with atypical SCFE.

Question 803

Topic: Pediatric Hip

In which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) is prophylactic in situ pinning of the contralateral hip most strongly indicated?

. A 14-year-old obese male with an acute-on-chronic slip
. A 12-year-old female with a stable slip and normal endocrine function
. An 11-year-old male with chronic renal failure and renal osteodystrophy
. A 15-year-old male with a closed triradiate cartilage
. A 13-year-old female with a strong family history of DDH

Correct Answer & Explanation

. An 11-year-old male with chronic renal failure and renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine or metabolic disorders (such as renal osteodystrophy, hypothyroidism, or panhypopituitarism) due to an exceedingly high risk of subsequent bilateral involvement.

Question 804

Topic: Pediatric Hip

Following a closed reduction of developmental dysplasia of the hip (DDH) in a 6-month-old, the child is placed in a hip spica cast. To minimize the risk of developing iatrogenic avascular necrosis (AVN), which of the following joint positions must be strictly avoided during casting?

. Extreme abduction coupled with extreme flexion
. Moderate flexion and neutral rotation
. Flexion of 100 degrees and adduction
. Flexion of 90 degrees and 45 degrees of abduction
. Flexion of 110 degrees and neutral abduction

Correct Answer & Explanation

. Extreme abduction coupled with extreme flexion

Explanation

Extreme abduction (>60 degrees) combined with extreme flexion places high tension on the medial circumflex femoral artery, significantly increasing the risk of avascular necrosis. The Ramsey 'safe zone' is utilized to balance hip stability with adequate perfusion.

Question 805

Topic: Pediatric Hip

A 4-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, she exhibits decreased spontaneous extension of the right knee and an absent patellar reflex. What is the most appropriate next step in management?

. Continue the harness and re-evaluate in 1 week
. Adjust the posterior strap to increase flexion
. Remove the harness and apply a spica cast immediately
. Remove the harness and observe for neurologic recovery
. Obtain an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Remove the harness and observe for neurologic recovery

Explanation

Femoral nerve palsy is a known complication of hyperflexion in a Pavlik harness, presenting as decreased knee extension. The harness must be discontinued immediately to allow for neurologic recovery before pursuing alternative treatments.

Question 806

Topic: Pediatric Hip

A 13-year-old boy presents with severe left hip pain and an inability to bear weight following a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most likely severe complication directly associated with this specific presentation?

. Chondrolysis
. Osteonecrosis
. Femoral-acetabular impingement
. Slipped contralateral epiphysis
. Premature osteoarthritis

Correct Answer & Explanation

. Osteonecrosis

Explanation

The inability to bear weight, even with crutches, defines an unstable SCFE. Unstable SCFE has a significantly higher rate of osteonecrosis (up to 47%) compared to stable SCFE, making it the most critical complication.

Question 807

Topic: Pediatric Hip

An infant undergoes screening ultrasound for developmental dysplasia of the hip (DDH). The report notes an alpha angle of 45 degrees. Which of the following anatomic structures form the lines used to measure the alpha angle?

. The bony roof of the acetabulum and the ilium
. The cartilaginous roof and the ilium
. The femoral head and the triradiate cartilage
. The labrum and the joint capsule
. The ischium and the pubic bone

Correct Answer & Explanation

. The bony roof of the acetabulum and the ilium

Explanation

The alpha angle measures the bony concavity of the acetabulum and is formed by the intersection of the baseline (ilium) and the bony roof line. An alpha angle less than 60 degrees generally indicates a shallow, dysplastic acetabulum.

Question 808

Topic: Pediatric Hip

A 7-year-old boy, whose weight is in the 30th percentile, presents with a stable slipped capital femoral epiphysis (SCFE). Which of the following laboratory studies is most highly indicated for this patient?

. Complete blood count with differential
. C-reactive protein and ESR
. Thyroid-stimulating hormone (TSH) and free T4
. Rheumatoid factor
. HLA-B27

Correct Answer & Explanation

. Thyroid-stimulating hormone (TSH) and free T4

Explanation

SCFE presenting in children under 10 years old, over 16 years old, or with atypical body habitus (weight < 50th percentile) is highly associated with endocrine disorders. Hypothyroidism is a leading cause, making TSH and free T4 essential screening tests.

Question 809

Topic: Pediatric Hip

A 14-year-old boy undergoes in situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). Which of the following screw configurations provides the optimal balance of biomechanical stability and minimized complication risk?

. Two parallel screws placed in the center of the epiphysis
. One single screw placed in the center-center position
. Three divergent screws spanning the physis
. One single screw placed in the anterosuperior quadrant
. Two crossed screws engaging the posterior cortex

Correct Answer & Explanation

. One single screw placed in the center-center position

Explanation

A single screw placed in the center-center of the epiphysis provides sufficient biomechanical stability for a stable SCFE. Adding a second screw does not clinically improve stability but significantly increases the risk of articular penetration and chondrolysis.

Question 810

Topic: Pediatric Hip

Following pinning of a SCFE, a 13-year-old patient develops a stiff, painful hip with a 15-degree flexion contracture. Radiographs reveal global narrowing of the joint space to less than 3 mm. What is the most likely diagnosis?

. Osteonecrosis of the femoral head
. Septic arthritis
. Chondrolysis
. Hardware failure
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis involves the acute dissolution of articular cartilage, presenting with marked stiffness, pain, and global joint space narrowing on radiographs. It is a severe complication of SCFE, highly associated with unrecognized intra-articular hardware penetration.

Question 811

Topic: Pediatric Hip

When evaluating an AP pelvis radiograph for a suspected slipped capital femoral epiphysis (SCFE), what defines an abnormal Klein's line?

. The line drawn along the superior femoral neck intersects more of the epiphysis than the contralateral side
. The line drawn along the superior femoral neck intersects less or none of the lateral epiphysis compared to the contralateral side
. The line drawn along the inferior femoral neck fails to intersect the lesser trochanter
. The line drawn along the physeal plate intersects the fovea capitis
. The line drawn along the central neck axis passes superior to the fovea

Correct Answer & Explanation

. The line drawn along the superior femoral neck intersects less or none of the lateral epiphysis compared to the contralateral side

Explanation

Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In SCFE, the epiphysis is displaced posteriorly and inferiorly, causing Klein's line to intersect less of the lateral epiphysis (or miss it entirely) compared to the normal contralateral hip.

Question 812

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report the infant is no longer actively extending the knee on the treated side. What is the most appropriate management?

. Continue the harness and add physical therapy
. Tighten the anterior straps to increase flexion
. Remove the harness and transition to a spica cast
. Loosen the anterior straps or temporarily discontinue the harness
. Perform an immediate ultrasound to rule out hip dislocation

Correct Answer & Explanation

. Loosen the anterior straps or temporarily discontinue the harness

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. Management consists of loosening the anterior straps or temporarily discontinuing the harness until nerve function returns.

Question 813

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with a left-sided stable slipped capital femoral epiphysis (SCFE). Which of the following is considered an absolute indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?

. Age greater than 14 years
. Presence of endocrinopathy (e.g., hypothyroidism)
. Male sex
. Slit-like physis on radiograph
. Bilateral knee pain

Correct Answer & Explanation

. Presence of endocrinopathy (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior radiation therapy due to the high risk of bilateral involvement.

Question 814

Topic: Pediatric Hip
In a 7-year-old child diagnosed with Legg-Calvé-Perthes disease, which of the following radiographic classifications is most prognostic for long-term hip joint congruency and outcome?
. Catterall classification
. Salter-Thompson classification
. Herring Lateral Pillar classification
. Stulberg classification
. Tonnis classification

Correct Answer & Explanation

. Herring Lateral Pillar classification

Explanation

The Herring Lateral Pillar classification, assessed during the fragmentation phase, is the most accurate prognostic indicator for long-term outcomes in Legg-Calvé-Perthes disease based on the height of the lateral pillar of the femoral head.

Question 815

Topic: Pediatric Hip

A 13-year-old boy is brought to the ED after sudden onset of severe groin pain following a minor slip. He is unable to bear weight on the affected limb. Radiographs confirm a severe slipped capital femoral epiphysis. What is the most significant complication associated with this specific injury pattern?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Coxa magna
. Femoroacetabular impingement (FAI)
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The inability to bear weight defines an "unstable" SCFE. Unstable SCFE has a significantly higher rate of avascular necrosis (AVN) of the femoral head (up to 47%) compared to stable SCFE.

Question 816

Topic: Pediatric Hip

Prophylactic pinning of the contralateral, asymptomatic hip is most strongly indicated in which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. A 12-year-old boy with idiopathic SCFE
. A 13-year-old girl with trauma-induced SCFE
. A 10-year-old girl with renal osteodystrophy
. A 14-year-old obese boy
. A 15-year-old boy with acetabular retroversion

Correct Answer & Explanation

. A 10-year-old girl with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is indicated in patients with metabolic or endocrine disorders (e.g., renal osteodystrophy, hypothyroidism) due to an extremely high incidence of bilateral involvement.

Question 817

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the anterior straps are found to be adjusted such that the hips are held in 130 degrees of flexion. The infant is noted to have decreased active knee extension. What is the most likely complication?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Avascular necrosis of the femoral head
. Inferior hip dislocation

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hip in a Pavlik harness (>120 degrees) can compress the femoral nerve against the inguinal ligament, causing a femoral nerve palsy characterized by decreased active knee extension.

Question 818

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 98th percentile is diagnosed with a unilateral stable slipped capital femoral epiphysis (SCFE) and treated with in situ pinning. Prophylactic pinning of the contralateral asymptomatic hip is most strongly indicated in which of the following clinical scenarios?

. The patient is male.
. The patient is African American.
. The patient has underlying hypothyroidism.
. The patient has a slip angle greater than 50 degrees.
. The patient's physis is wide.

Correct Answer & Explanation

. The patient has underlying hypothyroidism.

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior radiation, as they have a very high risk of bilateral involvement.

Question 819

Topic: Pediatric Hip

An 8-month-old infant with developmental dysplasia of the hip (DDH) undergoes a closed reduction and spica casting. To minimize the risk of iatrogenic avascular necrosis (AVN), the hip must be positioned within the 'safe zone' of Ramsey. Which of the following best describes this optimal position?

. Extreme abduction and internal rotation
. 90 to 100 degrees of flexion and mild to moderate abduction
. Extension, adduction, and external rotation
. 120 degrees of flexion and maximal abduction
. Neutral flexion with 60 degrees of adduction

Correct Answer & Explanation

. 90 to 100 degrees of flexion and mild to moderate abduction

Explanation

The safe zone of Ramsey defines the position where the hip is reduced without excessive capsular tension. Immobilization in extreme abduction forces the femoral head against the acetabulum, severely increasing the risk of AVN. The ideal position is ~90-100 degrees of flexion and mild to moderate abduction.

Question 820

Topic: Pediatric Hip
When evaluating a 7-year-old child with Legg-Calvé-Perthes disease, which of the following radiographic findings during the fragmentation stage is associated with the worst long-term prognosis?
. Crescent sign covering 20% of the femoral head
. Intact lateral pillar > 50% of original height
. Lateral pillar involvement leaving < 50% of the original height intact
. Mild metaphyseal cysts
. Sclerosis of the central epiphysis

Correct Answer & Explanation

. Lateral pillar involvement leaving < 50% of the original height intact

Explanation

The Herring Lateral Pillar classification during the fragmentation stage is highly prognostic. A Lateral Pillar Group C classification (where the lateral pillar is <50% of its original height) is associated with the worst outcomes, often resulting in an aspherical, incongruent hip.

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