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Pediatric Hip MCQs

Practice Set 36 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 701

Topic: Pediatric Hip
In a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is considered the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?
. Patient age greater than 14 years in males
. Obesity (BMI > 95th percentile)
. Presence of an underlying endocrine disorder
. Severe (Grade III) slip on the affected side
. African American ethnicity

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

The risk of developing a contralateral SCFE is significantly elevated in patients with an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). Bilateral involvement can approach 100% in these populations. Therefore, the presence of an endocrine disorder is a universally accepted indication for prophylactic pinning of the unaffected hip.

Question 702

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At her 2-week follow-up, the parents note that she has stopped kicking her left leg, and examination reveals a lack of active knee extension on the left side. This complication is most commonly caused by which of the following positioning errors?

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

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The infant is exhibiting signs of a femoral nerve palsy (lack of active knee extension/quadriceps function), which is a known complication of Pavlik harness treatment. It is caused by hyperflexion of the hips, which causes compression of the femoral nerve against the inguinal ligament. Excessive hip abduction, by contrast, is associated with avascular necrosis (AVN) of the femoral head.

Question 703

Topic: Pediatric Hip

A 6-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother notes that the infant has stopped kicking her right leg. Examination reveals decreased active knee extension, but active hip flexion is maintained. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Order a stat MRI of the lumbar spine
. Continue the harness as this is a normal transient finding
. Discontinue the harness temporarily to allow nerve recovery
. Switch immediately to a closed reduction and spica casting

Correct Answer & Explanation

. Discontinue the harness temporarily to allow nerve recovery

Explanation

The infant has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The diagnosis is clinical, marked by decreased active quadriceps function (lack of knee extension). The standard management is to temporarily discontinue the harness or significantly loosen the anterior straps to decrease hip flexion until nerve function returns, which typically resolves spontaneously.

Question 704

Topic: Pediatric Hip

A 13-year-old obese male presents with a 4-week history of right groin and thigh pain. Physical examination reveals obligatory external rotation of the right hip upon passive hip flexion. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). If single-screw in situ fixation is planned, what is the ideal position of the screw within the epiphysis to minimize complications?

. Anterosuperior
. Anteroinferior
. Posterosuperior
. Posteroinferior
. Center-center

Correct Answer & Explanation

. Center-center

Explanation

The ideal starting point and trajectory for a single-screw in situ fixation of a SCFE is perpendicular to the physis, terminating in the 'center-center' position of the epiphysis. Screws placed in the anterosuperior quadrant risk cutout and joint penetration. Screws placed posterosuperiorly risk injury to the lateral epiphyseal vessels, leading to avascular necrosis.

Question 705

Topic: Pediatric Hip

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

. Continue Pavlik harness for an additional 6 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint) for 4 weeks
. Closed reduction and spica casting under general anesthesia with intraoperative arthrogram
. Open reduction via an anterior approach with a Salter innominate osteotomy
. Observation until age 1 year, followed by open reduction

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia with intraoperative arthrogram

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip increases the risk of 'Pavlik harness disease' (posterior acetabular wear) and avascular necrosis. If a hip is not reduced within 3 to 4 weeks, the harness should be abandoned. The standard next step for a 6-month-old is an examination under anesthesia, arthrogram, and closed reduction with spica casting.

Question 706

Topic: Pediatric Hip

A 13-year-old obese male underwent in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he complains of severe hip stiffness and pain. Examination reveals a rigid hip with severe loss of motion in all planes. Radiographs show a concentric joint space narrowing of the affected hip to less than 3 mm. What is the most likely diagnosis?

. Avascular necrosis (AVN) of the femoral head
. Chondrolysis
. Septic arthritis
. Hardware failure
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is an acute dissolution of articular cartilage characterized by concentric joint space narrowing (typically < 3 mm) and severe global stiffness. It is a known complication of SCFE, particularly associated with unrecognized pin penetration into the joint space, severe slips, or prolonged immobilization.

Question 707

Topic: Pediatric Hip

A 6-week-old female infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. At a follow-up visit, the mother notes the baby is no longer kicking her right leg. On examination, the infant exhibits absent active knee extension on the right side. Which nerve is most likely compressed due to improper positioning in the harness?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Superior gluteal nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, usually caused by excessive hyperflexion of the hips. It presents clinically with absent active knee extension (decreased kicking). The treatment is to temporarily discontinue or loosen the harness to allow the hip to rest in less flexion until the nerve recovers.

Question 708

Topic: Pediatric Hip

In a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is considered the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Male sex
. Age greater than 14 years at presentation
. Presence of an underlying endocrine disorder
. Mild degree of slip on the symptomatic side
. Body Mass Index (BMI) greater than the 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Patients with endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or those undergoing prior radiation have a significantly higher risk of developing bilateral SCFE (up to 100% in some series). Prophylactic pinning of the contralateral hip is highly recommended in these atypical presentations.

Question 709

Topic: Pediatric Hip

A 4-month-old infant with Developmental Dysplasia of the Hip (DDH) has been treated with a Pavlik harness for 4 weeks. Ultrasound reveals a persistently dislocated left hip. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld splint)
. Perform an immediate open reduction and spica casting
. Discontinue the Pavlik harness and proceed with closed reduction and spica casting
. Perform a femoral derotation osteotomy

Correct Answer & Explanation

. Discontinue the Pavlik harness and proceed with closed reduction and spica casting

Explanation

If a dislocated hip fails to reduce after 3 to 4 weeks of proper Pavlik harness treatment, the harness must be discontinued to prevent complications such as 'Pavlik harness disease' (erosion of the posterior acetabular wall). The next standard step is closed reduction and application of a hip spica cast under general anesthesia, usually with an arthrogram.

Question 710

Topic: Pediatric Hip

A 5-week-old female infant is treated with a Pavlik harness for developmental dysplasia of the hip (DDH) of the left side (Graf Type IV). After 4 weeks of compliant harness wear, an ultrasound demonstrates that the left hip remains completely dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld or von Rosen splint)
. Perform an immediate closed reduction and spica casting under general anesthesia
. Perform an open reduction via an anterior approach
. Recommend observation without bracing until the infant is 6 months old

Correct Answer & Explanation

. Transition to a rigid abduction orthosis (e.g., Ilfeld or von Rosen splint)

Explanation

If a Pavlik harness fails to achieve reduction after 3 to 4 weeks of compliant use in a young infant, it must be abandoned to prevent 'Pavlik harness disease' (damage to the posterior acetabular wall from the harness pushing the hip posteriorly). The next recommended step is typically a trial of a rigid abduction orthosis. If that fails, closed reduction and spica casting under anesthesia is indicated.

Question 711

Topic: Pediatric Hip

A 12-year-old obese boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) of the left hip. During surgical counseling, the parents ask about the risk to the contralateral (right) hip. Prophylactic pinning of the contralateral hip is most strongly indicated if the patient has which of the following underlying conditions?

. Down syndrome
. Panhypopituitarism
. Prader-Willi syndrome
. Legg-Calve-Perthes disease
. Achondroplasia

Correct Answer & Explanation

. Panhypopituitarism

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) significantly increase the risk of developing bilateral SCFE (approaching 100% in some endocrine subgroups compared to ~20-30% in idiopathic cases). Therefore, prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in patients with an underlying endocrine or metabolic disorder.

Question 712

Topic: Pediatric Hip

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following radiographic findings represents a Type C pillar, and what does it signify?

. >50% of the original lateral pillar height is maintained; good prognosis
. >50% of the original lateral pillar height is maintained; poor prognosis
. <50% of the original lateral pillar height is maintained; good prognosis
. <50% of the original lateral pillar height is maintained; poor prognosis
. Total collapse of the medial pillar; requires immediate surgical containment

Correct Answer & Explanation

. <50% of the original lateral pillar height is maintained; poor prognosis

Explanation

The Herring Lateral Pillar Classification is based on the height of the lateral pillar of the capital femoral epiphysis during the fragmentation stage. Type A: no involvement (100% height). Type B: >50% of lateral pillar height is maintained. Type C: <50% of lateral pillar height is maintained. Type C carries a poor prognosis and a high likelihood of a non-spherical femoral head at skeletal maturity, predisposing to early osteoarthritis.

Question 713

Topic: Pediatric Hip

A 5-year-old girl with developmental dysplasia of the hip (DDH) presents with an acetabular index of 40 degrees and primarily anterolateral deficiency. The surgeon plans an incomplete pericapsular osteotomy that relies on the flexibility of the triradiate cartilage to hinge the acetabular roof downward. Which of the following osteotomies is being described?

. Salter innominate osteotomy
. Pemberton osteotomy
. Chiari osteotomy
. Dega osteotomy
. Ganz periacetabular osteotomy

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the triradiate cartilage, reducing the volume of the acetabulum while improving anterolateral coverage. The Salter osteotomy is a complete innominate osteotomy that hinges at the pubic symphysis. The Dega osteotomy is also incomplete but typically directs the roof laterally and posteriorly, commonly used in spastic dysplasia. The Chiari is a salvage capsular interposition osteotomy.

Question 714

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE) using a single cannulated screw. If the screw inadvertently penetrates the anterosuperior quadrant of the femoral head during the procedure, the patient is at highest risk for developing which of the following complications?

. Avascular necrosis (AVN)
. Chondrolysis
. Progression of the slip
. Subtrochanteric femur fracture
. Premature physeal closure

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized joint penetration by the hardware during SCFE pinning is the leading cause of chondrolysis (rapid destruction of articular cartilage). The anterosuperior quadrant is the most common location for unrecognized penetration because the screw may appear to be within the head on standard AP and lateral views while actually protruding into the joint.

Question 715

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip. At the 1-week follow-up, the mother notes the infant has stopped kicking her left leg, and the knee remains extended. Which of the following is the most likely cause?

. Excessive flexion of the anterior straps causing femoral nerve palsy
. Excessive adduction causing obturator nerve palsy
. Excessive abduction causing avascular necrosis
. Excessive extension of the posterior straps causing sciatic nerve palsy
. Tight chest strap causing brachial plexus traction

Correct Answer & Explanation

. Excessive flexion of the anterior straps causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion when the anterior straps are too tight. It presents with decreased active knee extension. The treatment is adjusting the straps to reduce flexion, and it usually resolves spontaneously.

Question 716

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip in a patient with a unilateral Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in a patient with which of the following underlying conditions?

. Obesity (BMI > 95th percentile)
. Hypothyroidism
. Male gender
. African American descent
. Age older than 14

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or those with prior radiation therapy, as they have a significantly higher risk of bilateral involvement compared to idiopathic SCFE.

Question 717

Topic: Pediatric Hip

In the management of Slipped Capital Femoral Epiphysis (SCFE), prophylactic in situ pinning of the asymptomatic contralateral hip is widely debated. However, there is strong consensus to perform prophylactic pinning in which of the following patient presentations?

. A 14-year-old boy with a Body Mass Index (BMI) of 35
. A 12-year-old girl with primary hypothyroidism
. A 13-year-old boy with a strong family history of SCFE
. An 11-year-old girl with a unilateral acute-on-chronic SCFE
. A 15-year-old boy with open triradiate cartilages

Correct Answer & Explanation

. A 12-year-old girl with primary hypothyroidism

Explanation

Patients with underlying endocrine or metabolic disorders (such as hypothyroidism, growth hormone deficiency, or renal osteodystrophy) or a history of pelvic radiation are at a substantially higher risk for bilateral SCFE (up to 100% in some metabolic conditions). In these high-risk cohorts, prophylactic pinning of the contralateral hip is strongly recommended regardless of age or gender.

Question 718

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) after a positive Ortolani maneuver. A Pavlik harness is applied. At the one-week follow-up, it is noted that the anterior straps are excessively tight, holding the hips in over 120 degrees of flexion. Which peripheral nerve is most at risk for palsy due to this specific positioning error?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Superior gluteal nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

A common and severe complication of the Pavlik harness is femoral nerve palsy, which is typically caused by hyperflexion of the hips (excessively tight anterior straps) compressing the nerve against the inguinal ligament. Excessive abduction (tight posterior straps) is associated with avascular necrosis of the femoral head.

Question 719

Topic: Pediatric Hip

In a 20-month-old child undergoing an anterolateral (Smith-Petersen) approach for open reduction of developmental dysplasia of the hip, what is the primary extra-articular block to concentric reduction that must be released first?

. Ligamentum teres
. Transverse acetabular ligament
. Iliopsoas tendon
. Inverted limbus
. Pulvinar

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The iliopsoas tendon is a primary extra-articular obstacle to reduction in DDH as it passes over the anterior capsule, causing an hourglass constriction of the joint. It is routinely released during the Smith-Petersen approach before addressing intra-articular obstacles like the ligamentum teres, transverse acetabular ligament, and pulvinar.

Question 720

Topic: Pediatric Hip

A 12-year-old boy presents with an unstable slipped capital femoral epiphysis (SCFE) and is unable to bear weight. The surgeon performs an in-situ pinning and an open capsulotomy to decompress the joint. This capsulotomy is primarily intended to protect the terminal branches of which artery to prevent avascular necrosis?

. Lateral circumflex femoral artery
. Medial circumflex femoral artery
. Obturator artery
. Inferior gluteal artery
. Pudendal artery

Correct Answer & Explanation

. Medial circumflex femoral artery

Explanation

An unstable SCFE carries a high risk of avascular necrosis (AVN) due to kinking or tamponade of the retinacular vessels. These vessels, particularly the lateral epiphyseal artery, are terminal branches of the medial circumflex femoral artery (MCFA). Capsulotomy reduces intracapsular pressure to maintain perfusion.

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