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Pediatric Hip MCQs

Practice Set 86 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 1701

Topic: Pediatric Hip

When performing in situ pinning for a severe Slipped Capital Femoral Epiphysis (SCFE), an unrecognized pin penetration into the anterosuperior quadrant of the joint space significantly increases the risk of which of the following complications?

. Femoral neck fracture
. Chondrolysis
. Avascular necrosis
. Cam-type femoroacetabular impingement
. Labral tear

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized pin penetration into the joint space during SCFE pinning is a primary and highly morbid cause of chondrolysis. Approaching the screw from the anterior femoral neck to the posterior epiphysis increases this risk. The 'approach-withdraw' technique under live fluoroscopy while ranging the hip helps prevent it.

Question 1702

Topic: Pediatric Hip

A 12-year-old girl presents with an acute on chronic slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following circumstances is prophylactic in situ pinning of the contralateral right hip most strongly indicated?

. African American descent
. Obesity (BMI > 95th percentile)
. Male gender
. Underlying endocrinopathy
. Age greater than 14 years

Correct Answer & Explanation

. Underlying endocrinopathy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly controversial in idiopathic cases but is generally recommended for patients with underlying endocrine disorders (such as hypothyroidism or growth hormone deficiency) or metabolic bone disease, as these patients have a much higher rate of bilateral involvement (up to 100%).

Question 1703

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and a limp for 3 weeks. Examination reveals obligatory external rotation of the hip upon passive flexion. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). During in situ pinning, where should the screw be positioned within the epiphysis to minimize complications?

. Anterior-superior quadrant
. Anterior-inferior quadrant
. Posterior-superior quadrant
. Center of the epiphysis
. Posterior-inferior quadrant

Correct Answer & Explanation

. Center of the epiphysis

Explanation

In SCFE pinning, the goal is to place a single screw in the center-center position of the epiphysis on both AP and lateral radiographs. This maximizes biomechanical stability and minimizes the risk of joint penetration (which can lead to chondrolysis) or damage to the vulnerable posterior-superior retinacular vessels (which can cause avascular necrosis).

Question 1704

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department complaining of left hip and knee pain for 2 weeks. Today, after a minor slip, he is completely unable to bear weight on the left leg, even with the assistance of crutches. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant prognostic risk for this specific type of slip?

. Chondrolysis
. Premature physeal closure
. Avascular necrosis (AVN) of the femoral head
. Cam-type femoroacetabular impingement
. Subtrochanteric femur fracture

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The Loder classification defines a SCFE as 'unstable' if the patient is unable to bear weight, even with crutches. Unstable slips have a significantly higher risk of avascular necrosis (AVN) of the femoral head (approaching 20-50%) compared to stable slips, where the patient can bear weight and the AVN risk is nearly zero.

Question 1705

Topic: Pediatric Hip

A 12-year-old obese boy presents with left thigh pain and a limp for 3 weeks. Examination reveals an obligate external rotation of the left hip during flexion. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). Contralateral prophylactic in situ pinning is most strongly indicated in which of the following scenarios?

. The patient has a concurrent diagnosis of hypothyroidism
. The patient is male
. The slip angle on the affected side is greater than 50 degrees
. The patient has closed triradiate cartilages
. The patient is a competitive athlete

Correct Answer & Explanation

. The patient has a concurrent diagnosis of hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency) or those receiving radiation therapy, as they have a significantly higher risk of bilateral involvement.

Question 1706

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. Two weeks later, the parents notice she is not kicking her affected leg as much as the other. Examination reveals an inability to actively extend the knee on the affected side. This complication is most likely due to excessive:

. Hip flexion in the harness
. Hip extension in the harness
. Hip abduction in the harness
. Hip adduction in the harness
. Knee flexion in the harness

Correct Answer & Explanation

. Hip flexion in the harness

Explanation

The complication described is a femoral nerve palsy, which manifests as weakness of the quadriceps (inability to extend the knee). In a Pavlik harness, this is caused by excessive hip flexion, which stretches or compresses the femoral nerve. Excessive abduction can lead to avascular necrosis (AVN) of the femoral head.

Question 1707

Topic: Pediatric Hip

A 13-year-old obese boy presents with knee pain and a limp. Examination reveals obligate external rotation of the hip during passive flexion. What is the typical displacement of the femoral neck relative to the capital femoral epiphysis in this condition?

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

Correct Answer & Explanation

. Posterior and inferior

Explanation

In Slipped Capital Femoral Epiphysis (SCFE), the capital femoral epiphysis typically stays relatively stationary in the acetabulum, while the femoral neck displaces anteriorly and superiorly (externally rotating). This creates the radiographic appearance of the epiphysis 'slipping' posteriorly and inferiorly.

Question 1708

Topic: Pediatric Hip

Which of the following is the strongest clinical indication for prophylactic in situ pinning of the contralateral hip in a 12-year-old male presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. Age greater than 14 years
. Male sex
. African American descent
. Underlying endocrine disorder
. Body mass index > 95th percentile

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior radiation therapy have a significantly higher risk of bilateral SCFE. In these atypical presentations, prophylactic pinning of the contralateral hip is highly recommended.

Question 1709

Topic: Pediatric Hip

A 4-week-old female is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. Two weeks later, the parents report she has an inability to actively extend her knee on the treated side. What is the most likely cause?

. Hyperflexion of the hip in the harness
. Hyperextension of the hip in the harness
. Excessive abduction in the harness
. Inadequate abduction in the harness
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Hyperflexion of the hip in the harness

Explanation

An inability to extend the knee points to a femoral nerve palsy, a known complication of the Pavlik harness. It is caused by excessive hyperflexion of the hip, which stretches or compresses the femoral nerve. Excessive abduction in the harness, by contrast, is associated with avascular necrosis.

Question 1710

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. Three weeks later, her mother notes the infant has decreased active extension of the left knee. What is the most likely iatrogenic cause?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hips. It presents with decreased active quadriceps function and usually resolves with temporary adjustment or removal of the harness.

Question 1711

Topic: Pediatric Hip

A 4-month-old female infant is diagnosed with developmental dysplasia of the hip (DDH). Ultrasound shows an alpha angle of 45 degrees. The infant is placed in a Pavlik harness. Which of the following positions is most likely to cause iatrogenic avascular necrosis (AVN) of the femoral head in this device?

. Excessive hip flexion
. Excessive hip extension
. Excessive hip abduction
. Excessive hip adduction
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip abduction

Explanation

The primary risk factor for avascular necrosis of the femoral head during Pavlik harness treatment is excessive hip abduction. Conversely, excessive hip flexion primarily causes femoral nerve palsy.

Question 1712

Topic: Pediatric Hip

A 4-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, she is noted to lack active knee extension on the affected side. What is the most likely cause?

. Avascular necrosis of the femoral head
. Excessive flexion of the anterior straps causing femoral nerve palsy
. Excessive abduction causing obturator nerve palsy
. Improper harness sizing leading to sciatic nerve palsy
. Development of a transient knee effusion

Correct Answer & Explanation

. Excessive flexion of the anterior straps causing femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness (>120 degrees) impinges the femoral nerve against the inguinal ligament, leading to an acute compressive neuropathy. It typically resolves with appropriate adjustment of the anterior straps.

Question 1713

Topic: Pediatric Hip

A 12-year-old obese male presents with acute, severe left hip pain and inability to bear weight after a minor fall. He reports a 3-month history of mild, intermittent left groin pain. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following factors most significantly increases the risk of avascular necrosis (AVN) in this patient?

. Chronicity of the slip prior to the fall
. Inability to bear weight on the affected limb
. Degree of posterior slip angle on the lateral radiograph
. Patient's BMI percentile
. Concomitant hypothyroidism

Correct Answer & Explanation

. Inability to bear weight on the affected limb

Explanation

According to the Loder classification, an unstable SCFE is defined by the inability to bear weight, even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 1714

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip. At the two-week follow-up, the parents report the infant is no longer actively kicking her left leg, and physical exam reveals absent active knee extension on that side. What is the most appropriate management?

. Continue harness and observe
. Adjust the anterior straps to increase hip flexion
. Discontinue the harness immediately
. Switch to a rigid hip spica cast
. Perform an emergent ultrasound

Correct Answer & Explanation

. Discontinue the harness immediately

Explanation

The clinical picture describes a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness must be discontinued immediately to prevent permanent nerve injury and allow for neurological recovery.

Question 1715

Topic: Pediatric Hip

A 13-year-old obese boy presents with right groin and knee pain, and an obligatory external rotation of the hip during passive flexion. He is diagnosed with a slipped capital femoral epiphysis (SCFE). Which of the following is a generally accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Male gender
. Age greater than 14 years
. Underlying endocrine disorder
. Body Mass Index > 30
. Bilateral knee pain

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is generally recommended for patients with underlying metabolic or endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) due to the high risk of bilateral involvement. It may also be considered in patients who are highly unlikely to follow up.

Question 1716

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up, she exhibits decreased active knee extension on the affected side. What is the most likely cause?

. Avascular necrosis of the femoral head
. Obturator nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hyperflexion
. Sciatic nerve palsy from excessive extension
. Common peroneal nerve compression from the anterior strap

Correct Answer & Explanation

. Femoral nerve palsy from excessive hyperflexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip hyperflexion that compresses the nerve. It presents as decreased active knee extension.

Question 1717

Topic: Pediatric Hip

An obese 13-year-old boy presents with an inability to bear weight on his right leg after a minor fall. Radiographs confirm an acute, unstable slipped capital femoral epiphysis (SCFE). If the surgeon attempts a forceful, anatomic closed reduction prior to internal fixation, the patient is at highest risk for which of the following complications?

. Chondrolysis
. Coxa magna
. Femoral neck fracture
. Avascular necrosis (AVN)
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Forceful or anatomic reduction of an unstable SCFE dramatically increases the risk of avascular necrosis. This occurs due to disruption or tensioning of the fragile posterior retinacular blood supply to the femoral head.

Question 1718

Topic: Pediatric Hip

A 6-week-old female infant undergoes a screening ultrasound of the hip due to a family history of developmental dysplasia of the hip (DDH). The sonographer reports an alpha angle of 50 degrees. According to the Graf classification, what does this alpha angle represent?

. Normal acetabular bony roof
. Dysplastic acetabular bony roof
. Normal cartilaginous roof coverage
. A completely dislocated hip resting outside the labrum
. A mature hip requiring no further follow-up

Correct Answer & Explanation

. Dysplastic acetabular bony roof

Explanation

In the Graf ultrasound evaluation for DDH, the alpha angle measures the concavity of the bony acetabular roof. An alpha angle less than 60 degrees (such as 50 degrees) indicates a dysplastic or shallow bony roof, typically classifying as a Graf Type II hip.

Question 1719

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of right-sided groin pain and an antalgic gait. Physical examination reveals an obligatory external rotation of the right hip during passive hip flexion. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE). What is the most appropriate definitive management?

. Spica cast immobilization
. Closed reduction and internal fixation
. In situ single screw fixation
. Proximal femoral osteotomy
. Observation with strict non-weight bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The gold standard treatment for a stable slipped capital femoral epiphysis (SCFE) is in situ fixation using a single partially threaded cannulated screw. Attempting a closed reduction is contraindicated as it severely increases the risk of avascular necrosis of the femoral head.

Question 1720

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an obligatory external rotation of the hip during active flexion. Radiographs show a posterior and inferior displacement of the proximal femoral epiphysis. Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Endocrine disorder (e.g., hypothyroidism)
. Moderate displacement (Southwick angle 30-50 degrees)
. BMI > 35
. Presentation with acute on chronic symptoms

Correct Answer & Explanation

. Endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in Slipped Capital Femoral Epiphysis (SCFE) is highly recommended in patients with endocrine disorders (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) and in children presenting at a very young age (< 10 years), due to the high risk of bilateral involvement.

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