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Pediatric Hip MCQs

Practice Set 89 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 1761

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During a follow-up visit, the infant is noted to have decreased active extension of the knee on the treated side. What is the most likely iatrogenic cause?

. Obturator nerve palsy due to excessive abduction
. Femoral nerve palsy due to excessive hyperflexion
. Sciatic nerve palsy due to excessive extension
. Avascular necrosis of the femoral head
. Normal transient developmental reflex

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hyperflexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness if the hip is maintained in excessive hyperflexion. It presents as an inability to actively extend the knee, and the harness should be adjusted or temporarily discontinued.

Question 1762

Topic: Pediatric Hip

A 13-year-old obese male presents with left hip pain and an obligatory external rotation of the hip during active flexion. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most significant risk factor for the development of avascular necrosis (AVN) in this patient?

. Severity of the slip angle
. Duration of symptoms prior to presentation
. Instability of the SCFE (inability to bear weight)
. Patient's body mass index (BMI)
. Use of a single screw for fixation

Correct Answer & Explanation

. Instability of the SCFE (inability to bear weight)

Explanation

The stability of the slip is the most critical prognostic factor for developing AVN. Unstable SCFE, defined as the inability to bear weight even with crutches, has a significantly higher rate of AVN compared to stable slips.

Question 1763

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). Hyperflexion of the hips in the harness puts the patient at greatest risk for which of the following complications?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness (greater than 120 degrees) can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. Conversely, excessive abduction places the child at higher risk for avascular necrosis.

Question 1764

Topic: Pediatric Hip
An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At follow-up, the treating physician notes that the anterior straps are overly tightened, forcing the hips into hyperflexion (>120 degrees). The infant is at greatest risk for developing which of the following complications?
. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Sciatic nerve palsy
. Inferior hip dislocation
. Coxa vara

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

In Pavlik harness treatment, excessive hip flexion (> 120 degrees) can impinge the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as a loss of active knee extension). Conversely, excessive forced abduction places the child at high risk for avascular necrosis of the femoral head.

Question 1765

Topic: Pediatric Hip

On an anteroposterior radiograph of the pelvis, Klein’s line is drawn to evaluate for a Slipped Capital Femoral Epiphysis (SCFE). In a normal, healthy pediatric hip, how should Klein’s line interact with the femoral head?

. It should pass completely superior to the femoral head without touching it
. It should intersect the superior (lateral) portion of the femoral epiphysis
. It should pass directly through the fovea capitis
. It should bisect the exact center of the epiphysis
. It should intersect the inferior (medial) portion of the femoral epiphysis

Correct Answer & Explanation

. It should intersect the superior (lateral) portion of the femoral epiphysis

Explanation

Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In a normal hip, this line must intersect a portion of the superior/lateral aspect of the femoral epiphysis. In a SCFE, the epiphysis slips posteriorly and inferiorly, meaning the line will pass superior to the epiphysis or intersect less of it compared to the contralateral side (Trethowan's sign).

Question 1766

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a stable Slipped Capital Femoral Epiphysis (SCFE). Prophylactic pinning of the asymptomatic contralateral hip is most strongly indicated in patients presenting with which of the following profiles?

. Male gender and chronological age greater than 14 years
. Underlying endocrinopathy (e.g., hypothyroidism or panhypopituitarism)
. Body mass index consistently in the 85th percentile
. An initial slip angle of less than 30 degrees
. Strong family history of developmental dysplasia of the hip

Correct Answer & Explanation

. Underlying endocrinopathy (e.g., hypothyroidism or panhypopituitarism)

Explanation

Prophylactic pinning of the contralateral asymptomatic hip is widely recommended for SCFE patients with underlying endocrine disorders or a history of radiation therapy. These specific patients possess a significantly elevated risk of developing a subsequent bilateral slip.

Question 1767

Topic: Pediatric Hip

A 12-year-old boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE). Which of the following is an absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Patient age less than 10 years
. Male gender with a BMI over 95th percentile
. Underlying endocrine disorder such as hypothyroidism
. Slip angle greater than 50 degrees on the affected side
. Presence of a metaphyseal blanch sign of Steel

Correct Answer & Explanation

. Underlying endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with an underlying endocrinopathy (e.g., hypothyroidism, renal osteodystrophy) or prior radiation therapy. These conditions carry a much higher risk of bilateral disease compared to idiopathic SCFE.

Question 1768

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During follow-up, the infant shows absent active knee extension on the affected side. What is the most appropriate next step in management?

. Increase the hip flexion of the harness
. Increase the hip abduction of the harness
. Switch immediately to a rigid spica cast
. Loosen the anterior straps to decrease hip flexion
. Perform an immediate ultrasound-guided closed reduction

Correct Answer & Explanation

. Loosen the anterior straps to decrease hip flexion

Explanation

Absent active knee extension indicates a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The appropriate initial management is to loosen the anterior straps or temporarily discontinue the harness to relieve pressure on the femoral nerve.

Question 1769

Topic: Pediatric Hip

A 12-year-old obese male presents with a left-sided Slipped Capital Femoral Epiphysis (SCFE). Which of the following factors represents the strongest indication for prophylactic pinning of the contralateral, asymptomatic hip?

. Male gender
. Body Mass Index > 95th percentile
. Underlying endocrine disorder (e.g., hypothyroidism)
. Age of 12 years at presentation
. Initial slip angle > 50 degrees

Correct Answer & Explanation

. Underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency), as well as in patients outside the typical age range (girls <10, boys <11, or older teens), because they have a significantly higher rate of subsequent bilateral involvement.

Question 1770

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During a follow-up visit, the physician notes an absence of active knee extension on the treated side. Which of the following is the most likely cause of this complication?

. Hyperflexion of the hip by over-tightened anterior straps
. Excessive abduction by over-tightened posterior straps
. Inadequate flexion of the hip due to loose anterior straps
. Avascular necrosis of the femoral head
. Direct compression of the sciatic nerve by the harness

Correct Answer & Explanation

. Hyperflexion of the hip by over-tightened anterior straps

Explanation

The most common nerve palsy associated with the Pavlik harness is a femoral nerve palsy. This complication results from excessive hip flexion caused by over-tightening of the anterior straps, which stretches or compresses the femoral nerve. It presents clinically as a loss of active knee extension.

Question 1771

Topic: Pediatric Hip
A 12-year-old male presents with a unilateral left Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most widely accepted absolute indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?
. Chronological age > 14 years at presentation
. Presence of a recognized underlying endocrine disorder (e.g., hypothyroidism)
. Body mass index > 95th percentile for age
. Symptom duration of the affected side > 3 weeks
. Grade III severity (slip angle > 50 degrees) on the affected side

Correct Answer & Explanation

. Presence of a recognized underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Contralateral prophylactic pinning in SCFE is universally recommended for patients with atypical or secondary SCFE, which most commonly includes those with underlying endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or radiation therapy, as the risk of contralateral slip is extremely high (up to 100%). While age (especially <10), obesity, and open triradiate cartilage are relative indications in idiopathic SCFE, an endocrine disorder is a definitive indication.

Question 1772

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of Pavlik harness treatment for a persistently dislocated left hip. What is the most appropriate next step in management?

. Continue Pavlik harness for 6 additional weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld)
. Closed reduction and spica casting under anesthesia
. Open reduction and spica casting
. Proximal femoral derotational osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia

Explanation

For a persistently dislocated hip at 6 months of age after failed Pavlik harness treatment, closed reduction and spica casting under anesthesia is the standard next step. Prolonging harness use in a dislocated hip increases the risk of "Pavlik harness disease" (posterior acetabular erosion).

Question 1773

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, a Type C hip is characterized by what degree of height loss in the lateral pillar of the femoral head?
. No measurable height loss
. Less than 25% height loss
. Less than 50% height loss
. Greater than 50% height loss
. Complete collapse of the entire femoral epiphysis

Correct Answer & Explanation

. Less than 50% height loss

Explanation

In the Herring lateral pillar classification, Type A indicates no height loss, Type B indicates less than 50% height loss, and Type C denotes greater than 50% height loss of the lateral pillar. Type C is associated with a poor clinical prognosis.

Question 1774

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The harness is incorrectly adjusted, forcing the hip into excessive abduction. Which of the following complications is most closely associated with this positioning error?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Excessive abduction in a Pavlik harness places the medial circumflex femoral artery under tension, significantly increasing the risk of avascular necrosis of the femoral head. Excessive flexion, on the other hand, is associated with femoral nerve palsy.

Question 1775

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During a follow-up visit, the mother notes the child is not actively moving her leg. Examination reveals an inability to actively extend the knee on the affected side. This complication is most directly related to which improper harness setting?

. Excessive hip abduction
. Excessive hip flexion
. Inadequate hip abduction
. Inadequate hip flexion
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The most common nerve injury associated with the Pavlik harness is transient femoral nerve palsy, which manifests as an inability to extend the knee. This is typically caused by excessive hip flexion in the anterior straps, compressing the nerve against the inguinal ligament.

Question 1776

Topic: Pediatric Hip

An 8-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after failing Pavlik harness treatment for 6 weeks. Physical examination reveals a reducible but unstable hip. What is the most appropriate next step in management?

. Continue Pavlik harness treatment for another 4 weeks.
. Initiate a program of physical therapy and observation.
. Proceed with closed reduction and hip spica cast application.
. Schedule for an open reduction with potential femoral shortening.
. Order a CT scan to assess hip morphology more precisely.

Correct Answer & Explanation

. Proceed with closed reduction and hip spica cast application.

Explanation

For DDH, if Pavlik harness treatment fails in an infant between 6-18 months of age (and sometimes earlier), closed reduction under general anesthesia followed by hip spica cast immobilization is the next standard of care. The goal is to achieve and maintain a concentric reduction. Open reduction is typically reserved for cases where closed reduction is unsuccessful or if there are specific anatomical impediments. CT scans are usually performed post-reduction in a spica cast to confirm reduction rather than as a primary diagnostic step to guide the next treatment after failed Pavlik.

Question 1777

Topic: Pediatric Hip

A 9-year-old male presents with right hip pain and a limp. BMI is in the 90th percentile. Radiographs reveal a mild right slipped capital femoral epiphysis (SCFE). What is the most appropriate routine screening indicated for this patient?

. Renal ultrasound
. Thyroid function tests
. DEXA scan
. Genetic testing for COL1A1
. Bone marrow biopsy

Correct Answer & Explanation

. Thyroid function tests

Explanation

Patients presenting with SCFE at an atypical age (less than 10 or greater than 16 years old) or with a weight less than the 50th percentile should be evaluated for endocrine disorders. Hypothyroidism is the most common associated endocrine abnormality in this population.

Question 1778

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Which of the following is the most devastating complication associated specifically with this presentation?

. Chondrolysis
. Avascular necrosis (AVN)
. Leg length discrepancy
. Coxa magna
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight defines an unstable SCFE. Unstable slips carry a notoriously high risk of avascular necrosis (AVN) of the femoral head, approaching 47%, which is the most devastating complication in this scenario.

Question 1779

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute exacerbation of chronic left knee pain and an inability to bear weight. Radiographs demonstrate a severe slipped capital femoral epiphysis (SCFE). He undergoes in situ pinning. What is the most devastating complication associated with an acute-on-chronic SCFE treated with pinning?

. Chondrolysis
. Osteonecrosis of the femoral head
. Femoroacetabular impingement
. Slipped contralateral epiphysis
. Premature physeal closure

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

Osteonecrosis (avascular necrosis) is the most devastating complication of SCFE. It is significantly more common in unstable slips (where the patient cannot bear weight) and its risk is exacerbated by forceful reduction or improper pin placement in the posterosuperior quadrant.

Question 1780

Topic: Pediatric Hip

When evaluating developmental dysplasia of the hip (DDH) via Graf's ultrasound method, the alpha angle is measured. What does the alpha angle represent, and what is the normal value for a 6-week-old infant?

. Measurement of the cartilaginous roof; normal is > 60 degrees
. Measurement of the bony roof; normal is > 60 degrees
. Measurement of the bony roof; normal is < 55 degrees
. Measurement of the cartilaginous roof; normal is < 55 degrees
. Measurement of the bony roof; normal is > 43 degrees

Correct Answer & Explanation

. Measurement of the cartilaginous roof; normal is > 60 degrees

Explanation

The alpha angle in Graf's ultrasound classification evaluates the concavity and depth of the bony acetabular roof. A normal alpha angle (Type I hip) is 60 degrees or greater. The beta angle measures the cartilaginous roof and normally is < 55 degrees.

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