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Pediatric Hip MCQs

Practice Set 40 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 781

Topic: Pediatric Hip

A 6-week-old female born breech presents for evaluation of developmental dysplasia of the hip (DDH). Ultrasound of the hips reveals an alpha angle of 45 degrees and a beta angle of 78 degrees on the left side. The right hip is normal. What is the most appropriate next step in management?

. Observation with repeat ultrasound in 4 weeks
. Double diapering
. Pavlik harness application
. Closed reduction and spica casting
. Open reduction

Correct Answer & Explanation

. Pavlik harness application

Explanation

An alpha angle less than 60 degrees and a beta angle greater than 55 degrees (Graf Type IIc or worse) indicate significant acetabular dysplasia. The Pavlik harness is the gold standard for treatment of DDH in infants younger than 6 months of age.

Question 782

Topic: Pediatric Hip

A 2-year-old female who recently immigrated is brought to the clinic for a noticeable limp and leg length discrepancy. Radiographs reveal an untreated, high-riding developmental dislocation of the right hip. What is the most appropriate definitive management?

. Pavlik harness application
. Hip abduction orthosis
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Proximal femoral varus derotational osteotomy alone

Correct Answer & Explanation

. Open reduction and pelvic osteotomy

Explanation

In a child older than 18 to 24 months with an untreated DDH, closed reduction has a high failure and avascular necrosis rate. Open reduction with a concomitant pelvic osteotomy (e.g., Salter or Pemberton) is generally required to address the secondary capsular and acetabular changes.

Question 783

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe right thigh pain after a minor slip on the ice. He is completely unable to bear weight on the right leg. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the greatest risk of developing?

. Chondrolysis
. Osteonecrosis of the femoral head
. Deep space infection
. Premature osteoarthritis
. Subspine impingement

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

The patient's inability to bear weight even with crutches categorizes this as an unstable SCFE. Unstable slips carry a significantly higher risk of osteonecrosis (avascular necrosis), reaching up to nearly 50% in some series.

Question 784

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ screw fixation for a unilateral SCFE. Which of the following patient profiles represents an absolute indication for prophylactic pinning of the asymptomatic contralateral hip?

. Presence of an endocrinopathy or renal osteodystrophy
. Unilateral unstable SCFE in a 14-year-old
. Patient weight greater than the 95th percentile alone
. Male sex and tall stature
. Presence of a mild, chronic slip

Correct Answer & Explanation

. Presence of an endocrinopathy or renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is strongly indicated in patients with endocrine disorders (e.g., hypothyroidism) or renal osteodystrophy due to the extremely high risk of bilateral involvement. Other indications often include age less than 10 or inability to follow up.

Question 785

Topic: Pediatric Hip

In a typical patient with a slipped capital femoral epiphysis (SCFE), the relative displacement of the proximal femoral epiphysis in relation to the femoral neck is most accurately described as:

. Anterior and superior
. Posterior and superior
. Medial and anterior
. Anterior and inferior
. Posterior and inferior

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the epiphysis remains structurally housed within the acetabulum while the femoral neck displaces anteriorly and superiorly. Thus, the relative position of the epiphysis to the neck is posterior and inferior.

Question 786

Topic: Pediatric Hip

When evaluating an anteroposterior (AP) pelvis radiograph for a suspected SCFE, a line is drawn along the superior border of the femoral neck. In a normal hip, this line should intersect a portion of the lateral epiphysis. What is the name of this line?

. Perkin's line
. Hilgenreiner's line
. Klein's line
. Shenton's line
. Ilioischial line

Correct Answer & Explanation

. Klein's line

Explanation

Klein's line is drawn along the superior margin of the femoral neck on the AP radiograph. In a normal hip, it intersects the lateral portion of the femoral head epiphysis; in SCFE, it often passes superior to the epiphysis (Trethowan's sign).

Question 787

Topic: Pediatric Hip

A 6-week-old female with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for 4 weeks. Repeat ultrasound reveals a persistent dislocation with an alpha angle of 35 degrees. What is the most appropriate next step in management?

. Continue Pavlik harness for 4 more weeks
. Switch to a rigid abduction orthosis or perform a closed reduction
. Perform immediate open reduction
. Perform a varus derotational osteotomy
. Discontinue bracing and observe until 6 months of age

Correct Answer & Explanation

. Switch to a rigid abduction orthosis or perform a closed reduction

Explanation

If a Pavlik harness fails to reduce a dislocated hip after 3 to 4 weeks, it should be discontinued to avoid "Pavlik harness disease" (posterior acetabular wall damage). The next appropriate step is a trial of a rigid abduction orthosis (e.g., Ilfeld) or proceeding to closed reduction and spica casting.

Question 788

Topic: Pediatric Hip

Which of the following patients diagnosed with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated for prophylactic pinning of the contralateral hip?

. A 12-year-old boy with a BMI in the 95th percentile
. A 14-year-old girl with an acute, unstable slip
. A 10-year-old boy with renal osteodystrophy
. A 13-year-old boy with a 40-degree chronic slip
. A 15-year-old girl who has begun menstruating

Correct Answer & Explanation

. A 10-year-old boy with renal osteodystrophy

Explanation

Prophylactic contralateral pinning is highly recommended for patients with underlying endocrinopathies, metabolic disorders (like renal osteodystrophy), or previous radiation therapy due to the extremely high risk of bilateral involvement. Idiopathic cases have a lower risk, and contralateral pinning is assessed on a case-by-case basis.

Question 789

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department unable to bear weight on his left leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the highest risk for developing compared to a patient with a stable SCFE?

. Chondrolysis
. Femoroacetabular impingement
. Osteonecrosis
. Leg length discrepancy
. Premature osteoarthritis

Correct Answer & Explanation

. Osteonecrosis

Explanation

An unstable SCFE (defined by the inability to bear weight even with crutches) has a significantly higher risk of osteonecrosis (up to 50%) compared to a stable SCFE. Urgent but careful reduction and fixation, or a modified Dunn procedure, is often required.

Question 790

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 complains of left knee pain for 2 months. Knee examination is normal. When his left hip is passively flexed to 90 degrees, the thigh deviates into obligatory external rotation. What is the pathomechanics of the underlying disorder?

. Anterior and superior displacement of the femoral neck relative to the epiphysis
. Posterior and inferior displacement of the femoral neck relative to the epiphysis
. Anterior and superior displacement of the epiphysis relative to the femoral neck
. Posterior and superior displacement of the epiphysis relative to the acetabulum
. Anterolateral displacement of the epiphysis relative to the femoral neck

Correct Answer & Explanation

. Anterior and superior displacement of the femoral neck relative to the epiphysis

Explanation

In a Slipped Capital Femoral Epiphysis (SCFE), the epiphysis remains securely positioned in the acetabulum while the metaphysis (femoral neck) displaces anteriorly and superiorly. This spatial shift results in the characteristic obligatory external rotation during hip flexion.

Question 791

Topic: Pediatric Hip

An infant treated with a Pavlik harness for DDH develops a femoral nerve palsy. Which of the following positioning errors is the most likely cause?

. Excessive abduction
. Inadequate abduction
. Excessive flexion
. Inadequate flexion
. Excessive internal rotation

Correct Answer & Explanation

. Excessive flexion

Explanation

Excessive flexion in a Pavlik harness (typically >120 degrees) can cause compression of the femoral nerve against the inguinal ligament, leading to a temporary palsy. Excessive abduction is associated with a different severe complication: avascular necrosis.

Question 792

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. During a follow-up visit, the parents report that the child is not actively kicking her left leg. On examination, the knee lacks active extension, but ankle motion is intact. What is the most likely cause of this finding?

. Avascular necrosis of the femoral head
. Femoral nerve palsy due to hyperflexion
. Obturator nerve palsy due to hyperabduction
. Sciatic nerve palsy due to extreme extension
. Inferior dislocation of the hip

Correct Answer & Explanation

. Femoral nerve palsy due to hyperflexion

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the rim of the pelvis, leading to transient femoral nerve palsy. Hyperabduction is historically associated with avascular necrosis.

Question 793

Topic: Pediatric Hip

Which of the following conditions is considered an absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip in a patient presenting with unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Obesity with a BMI > 95th percentile
. Age greater than 14 years at presentation
. Renal osteodystrophy
. Male gender
. African American descent

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Endocrinopathies and metabolic disorders, such as renal osteodystrophy and hypothyroidism, carry a nearly 100% risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in these populations.

Question 794

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department with severe groin pain after a minor fall and is completely unable to bear weight. Radiographs confirm a slipped capital femoral epiphysis. According to the Loder classification, what is the primary complication associated with his inability to bear weight?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Premature physeal closure
. Coxa vara

Correct Answer & Explanation

. Avascular necrosis

Explanation

The inability to bear weight defines an unstable SCFE in the Loder classification. Unstable slips carry a much higher risk of avascular necrosis (up to 50%) compared to stable slips.

Question 795

Topic: Pediatric Hip

On a coronal ultrasound of a 6-week-old infant's hip, the alpha angle measures 48 degrees and the beta angle measures 70 degrees. According to the Graf classification, what does this alpha angle indicate?

. Normal hip development
. Shallow acetabular roof (dysplasia)
. Superior subluxation
. Irreducible dislocation
. Labral inversion

Correct Answer & Explanation

. Shallow acetabular roof (dysplasia)

Explanation

An alpha angle less than 60 degrees indicates a shallow bony acetabular roof, typical of developmental dysplasia. A normal alpha angle is 60 degrees or greater.

Question 796

Topic: Pediatric Hip

A 14-year-old boy underwent in situ pinning for a stable SCFE 6 months ago. He now presents with progressive hip stiffness. Examination shows severe restriction of all hip motions. Radiographs show a 2 mm joint space symmetrically but no evidence of AVN. What is the most likely diagnosis?

. Septic arthritis
. Hardware failure
. Chondrolysis
. Femoroacetabular impingement
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE, characterized by progressive joint space narrowing and marked global stiffness. It is strongly associated with unrecognized pin penetration into the joint space.

Question 797

Topic: Pediatric Hip

A 2-year-old boy is being followed after closed reduction and spica casting for DDH at age 8 months. Which radiographic finding is considered the earliest indicator of avascular necrosis of the femoral head in this patient?

. Enlargement of the femoral head
. Coxa magna
. Failure of appearance or asymmetric ossification of the capital femoral epiphysis
. Femoral neck lengthening
. Acetabular overcoverage

Correct Answer & Explanation

. Failure of appearance or asymmetric ossification of the capital femoral epiphysis

Explanation

The earliest radiographic sign of AVN in a treated DDH patient is the failure of the ossific nucleus to appear, or its asymmetric, delayed appearance compared to the normal, unaffected side.

Question 798

Topic: Pediatric Hip

During an anterior open reduction for a developmental dislocation of the hip in a 14-month-old, the surgeon notes an hour-glass constriction of the joint capsule. Which structure is directly responsible for creating this specific capsular constriction?

. Ligamentum teres
. Transverse acetabular ligament
. Iliopsoas tendon
. Gluteus medius
. Reflected head of the rectus femoris

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The iliopsoas tendon crosses the anterior aspect of the hip capsule. In a chronically dislocated DDH, it creates a tight hour-glass constriction, acting as a major mechanical block to concentric reduction.

Question 799

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report that the child has stopped kicking the left leg. On examination, there is an absence of active knee extension on the left side, but withdrawal to painful stimuli on the plantar foot is intact. What is the most appropriate next step in management?

. Immediate transition to a rigid hip spica cast
. Removal of the Pavlik harness and observation for neurological recovery
. Immediate closed reduction under general anesthesia
. Adjusting the harness to increase hip flexion
. Urgent MRI of the lumbar spine to rule out dysraphism

Correct Answer & Explanation

. Removal of the Pavlik harness and observation for neurological recovery

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by hyperflexion of the hips. Management consists of temporarily discontinuing the harness or significantly reducing flexion until the nerve recovers, which usually resolves spontaneously.

Question 800

Topic: Pediatric Hip

A 13-year-old boy with a BMI in the 98th percentile presents to the emergency department unable to bear weight on his right leg after tripping over a rug. Radiographs confirm a slipped capital femoral epiphysis (SCFE). According to the Loder classification, which of the following is the most significant consequence of his inability to bear weight?

. A 50% or greater risk of developing chondrolysis
. A high likelihood of requiring a prophylactic contralateral pinning
. An increased risk of developing avascular necrosis (AVN) up to 47%
. An indication for an immediate subtrochanteric osteotomy
. A reduced risk of further posterior physeal displacement

Correct Answer & Explanation

. An increased risk of developing avascular necrosis (AVN) up to 47%

Explanation

The Loder classification defines an unstable SCFE by the inability to bear weight, even with assistive devices. Unstable SCFE has a significantly higher rate of avascular necrosis (AVN), reported to be up to 47%, compared to nearly 0% in stable slips.

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