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Pediatric Hip MCQs

Practice Set 88 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 1741

Topic: Pediatric Hip

A 9-month-old female is diagnosed with developmental dysplasia of the hip (DDH). She has a completely dislocated left hip that is reducible but unstable. Prior Pavlik harness treatment failed at 3 months of age. What is the most appropriate next step in management?

. Re-trial of Pavlik harness
. Rigid abduction bracing
. Closed reduction and spica casting under anesthesia
. Open reduction and Salter osteotomy
. Observation until age 2 followed by pelvic osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia

Explanation

For infants aged 6 to 18 months with failed harness treatment or late-presenting DDH, closed reduction with spica casting under general anesthesia is the standard of care. Open reduction is reserved for failed closed reduction or older children.

Question 1742

Topic: Pediatric Hip

A 4-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents report the infant is no longer actively extending the knee on the treated side. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Discontinue the harness immediately and switch to a rigid spica cast
. Loosen the anterior straps to reduce hip flexion
. Perform an immediate ultrasound to rule out avascular necrosis
. Continue the current harness settings and reassure the parents

Correct Answer & Explanation

. Loosen the anterior straps to reduce hip flexion

Explanation

The infant has developed a femoral nerve palsy, which is caused by excessive hip flexion in the Pavlik harness. The anterior straps should be loosened or the harness temporarily discontinued to allow nerve recovery.

Question 1743

Topic: Pediatric Hip

A 6-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after an unsuccessful 6-week trial of a Pavlik harness. Radiographs confirm a persistently dislocated right hip. What is the most appropriate next step in management?

. Continue Pavlik harness for 4 more weeks
. Transition to an abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting under general anesthesia
. Open reduction with pelvic osteotomy
. Wait until walking age for spontaneous resolution

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia

Explanation

Following the failure of a Pavlik harness in an infant, closed reduction and spica casting under general anesthesia is the standard next step. Open reduction is indicated if closed reduction is unsuccessful or in older children.

Question 1744

Topic: Pediatric Hip

A 6-year-old boy presents with a painless limp, and radiographs show sclerosis and fragmentation of the capital femoral epiphysis. According to the Herring lateral pillar classification for Legg-Calve-Perthes disease, a patient with 60% maintenance of lateral pillar height falls into which group?

. Group A
. Group B
. Group B/C
. Group C
. Group D

Correct Answer & Explanation

. Group B

Explanation

In the Herring classification, Group B is characterized by radiolucency and loss of height of the lateral pillar, but greater than 50% of the normal height is maintained. Group C indicates less than 50% of the lateral pillar height remains.

Question 1745

Topic: Pediatric Hip

A 3-month-old female with developmental dysplasia of the hip (DDH) has been treated in a Pavlik harness for two weeks. During a follow-up exam, she demonstrates an absent patellar reflex and lacks active knee extension on the treated side. What is the most appropriate next step in management?

. Loosen the anterior straps to decrease hip flexion
. Loosen the posterior straps to decrease hip abduction
. Discontinue the harness and proceed to closed reduction and spica casting
. Obtain an MRI of the lumbar spine to rule out dysraphism
. Continue the current harness settings as this is a transient normal finding

Correct Answer & Explanation

. Loosen the anterior straps to decrease hip flexion

Explanation

The patient has developed a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The appropriate management is to loosen the anterior straps (decreasing flexion) or temporarily remove the harness if the palsy does not quickly resolve. Excessive abduction (tight posterior straps) can lead to avascular necrosis of the femoral head.

Question 1746

Topic: Pediatric Hip

An obese 12-year-old boy presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following conditions is prophylactic in situ pinning of the contralateral, asymptomatic right hip most strongly indicated?

. Presentation during the summer months
. Associated primary hypothyroidism
. BMI greater than the 95th percentile
. Presence of a positive Drehmann sign on the left
. Male gender

Correct Answer & Explanation

. Associated primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine disorders (such as hypothyroidism) or renal osteodystrophy. These conditions carry a significantly higher risk for bilateral involvement.

Question 1747

Topic: Pediatric Hip
A 4-month-old infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. During follow-up, the parents report the infant is not kicking the affected leg. The physician notes the anterior straps are excessively tight, holding the hips in >120 degrees of flexion. This technical error most commonly results in which of the following complications?
. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Inferior dislocation of the hip
. Sciatic nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness (anterior straps too tight) causes compression of the femoral nerve against the inguinal ligament, leading to femoral nerve palsy (evident by a lack of active knee extension/kicking). Hyperabduction (posterior straps too tight) increases the risk of avascular necrosis.

Question 1748

Topic: Pediatric Hip

In a patient presenting with an acute slipped capital femoral epiphysis (SCFE), prophylactic in situ pinning of the asymptomatic contralateral hip is most strongly indicated and routinely recommended in which of the following clinical scenarios?

. A 13-year-old obese male with an idiopathic slip
. A 12-year-old female with a severe slip angle (>60 degrees) on the affected side
. A 9-year-old male with confirmed renal osteodystrophy
. An 11-year-old male with a documented history of major pelvic trauma
. A 14-year-old male with a mild slip and a completely normal endocrine workup

Correct Answer & Explanation

. A 9-year-old male with confirmed renal osteodystrophy

Explanation

Prophylactic pinning of the asymptomatic contralateral hip in SCFE is controversial for typical idiopathic cases but is strongly recommended for patients at exceptionally high risk of a sequential slip. High-risk factors include age less than 10 years, widely open triradiate cartilage, and underlying endocrine or metabolic disorders (e.g., renal osteodystrophy, hypothyroidism, growth hormone deficiency). The 9-year-old with renal osteodystrophy possesses both a metabolic disorder and young age, putting him at near-certain risk for a contralateral SCFE.

Question 1749

Topic: Pediatric Hip

A 12-year-old boy presents with left knee pain and an obligate externally rotated gait.

Radiographs reveal a left slipped capital femoral epiphysis (SCFE). Which of the following is a recognized indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?

. Male gender
. Age older than 14 years at initial presentation
. Presence of an underlying endocrinopathy (e.g., hypothyroidism)
. Obesity greater than the 95th percentile alone
. Mild slip severity on the symptomatic side

Correct Answer & Explanation

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

Explanation

Prophylactic pinning of the contralateral asymptomatic hip in SCFE is controversial but is strictly indicated in certain high-risk groups. These include patients with underlying endocrinopathies (such as hypothyroidism or growth hormone deficiency), renal osteodystrophy, prior pelvic radiation, or patients presenting at a very young age (e.g., <10 years for girls or <11 for boys) with an open triradiate cartilage. Obesity alone is a risk factor for SCFE but not an absolute indication for prophylactic pinning.

Question 1750

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute on chronic left hip pain and inability to bear weight. Examination shows an obligatory external rotation of the hip with passive flexion. Slipped capital femoral epiphysis (SCFE) is diagnosed. What is the primary arterial supply to the femoral head that is at risk of disruption in this condition?

. Ligamentum teres artery
. Medial femoral circumflex artery (MFCA)
. Lateral femoral circumflex artery (LFCA)
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery (MFCA)

Explanation

In older children and adults, the predominant blood supply to the femoral head is the lateral epiphyseal branches of the Medial Femoral Circumflex Artery (MFCA). This precarious blood supply is at risk for disruption in a displaced or unstable SCFE, potentially leading to avascular necrosis (AVN).

Question 1751

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with acute-onset right hip pain. He is entirely unable to bear weight on the right leg, even with crutches. Radiographs demonstrate a Slipped Capital Femoral Epiphysis (SCFE). What is the most significant prognostic factor for the development of avascular necrosis (AVN) in this patient?

. The anatomical degree of the epiphyseal slip angle
. The patient's Body Mass Index (BMI)
. The clinical instability of the slip (inability to bear weight)
. Delay in surgical treatment beyond 24 hours
. Use of a single central screw for fixation

Correct Answer & Explanation

. The clinical instability of the slip (inability to bear weight)

Explanation

The most important prognostic factor for the development of AVN in SCFE is the stability of the slip. An unstable SCFE (defined by Loder as the inability to bear weight, even with crutches) has a high rate of AVN (up to 47%), whereas stable slips have an AVN rate approaching zero.

Question 1752

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, the parents report the infant is not kicking her left leg as much. On examination, there is decreased active extension of the left knee, but normal ankle movements. What is the most likely cause of this complication?

. Hyperflexion of the hip causing femoral nerve compression
. Excessive abduction of the hip causing obturator nerve compression
. Avascular necrosis of the femoral head
. Inadequate flexion of the hip leading to hip subluxation
. Ischemic contracture of the quadriceps

Correct Answer & Explanation

. Hyperflexion of the hip causing femoral nerve compression

Explanation

The most common nerve injury associated with Pavlik harness use is a transient femoral nerve palsy, typically caused by hyperflexion of the hip. This presents with decreased active extension of the knee (quadriceps weakness). Treatment involves adjusting the harness to reduce flexion; the palsy typically resolves spontaneously.

Question 1753

Topic: Pediatric Hip

In the pathogenesis of Slipped Capital Femoral Epiphysis (SCFE), the classic displacement of the capital femoral epiphysis relative to the femoral neck is in which direction?

. Anterior and superior
. Posterior and inferior
. Anterior and inferior
. Posterior and superior
. Directly medial and un-rotated

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the capital femoral epiphysis is held within the acetabulum while the femoral neck displaces anteriorly and superiorly. Thus, relative to the neck, the epiphysis "slips" posteriorly and inferiorly.

Question 1754

Topic: Pediatric Hip

A 13-year-old overweight boy sustains an unstable slipped capital femoral epiphysis (SCFE) and is unable to bear weight. He undergoes urgent in-situ pinning. Which of the following complications is he at the highest risk for compared to a patient with a stable SCFE?

. Chondrolysis
. Avascular necrosis (AVN)
. Nonunion
. Heterotopic ossification
. Implant failure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

An unstable SCFE (defined clinically as the inability to bear weight even with crutches) is associated with a much higher rate of avascular necrosis (AVN), historically reported up to 20-50%, compared to a stable SCFE where AVN is extremely rare (<1%).

Question 1755

Topic: Pediatric Hip

An infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. If the harness is applied with excessive hip flexion (greater than 120 degrees), which nerve is at greatest risk of palsy?

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

Correct Answer & Explanation

. Femoral nerve

Explanation

Excessive flexion of the hip (> 120 degrees) in a Pavlik harness can impinge the femoral nerve against the inguinal ligament, leading to a compressive femoral nerve palsy. This manifests as an inability to extend the knee.

Question 1756

Topic: Pediatric Hip

A 9-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after an abnormal physical exam. She has received no prior treatment. Radiographs confirm a dislocated left hip. What is the most appropriate initial management?

. Pavlik harness application
. Rigid abduction orthosis (e.g., Ilfeld brace)
. Closed reduction and spica casting
. Open reduction and spica casting
. Femoral derotational osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

For a child presenting between 6 and 18 months of age with a dislocated hip, the standard initial treatment is an examination under anesthesia (EUA), arthrogram, and attempted closed reduction followed by spica casting. A Pavlik harness is typically reserved for infants under 6 months of age and has a high failure rate if initiated after 6 months. Open reduction is indicated if closed reduction fails to achieve a stable, concentric reduction.

Question 1757

Topic: Pediatric Hip

A 12-year-old male is treated for a slipped capital femoral epiphysis (SCFE). The risk of developing a contralateral SCFE is significantly elevated in patients with which of the following underlying conditions?

. Achondroplasia
. Hypothyroidism
. Type 1 Diabetes Mellitus
. Down syndrome
. Marfan syndrome

Correct Answer & Explanation

. Hypothyroidism

Explanation

Patients with endocrine disorders, particularly hypothyroidism, growth hormone deficiency, and panhypopituitarism, have a high incidence of atypical SCFE and a markedly elevated risk of bilateral involvement (up to 100% in some series of endocrine-related SCFE). Prophylactic pinning of the contralateral hip is strongly considered in patients with an underlying endocrinopathy.

Question 1758

Topic: Pediatric Hip

An overweight 13-year-old boy presents with groin pain and an obligate external rotation of the hip with passive flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). What is the classic direction of displacement of the femoral neck relative to the epiphysis?

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

Correct Answer & Explanation

. Anterior and superior

Explanation

In SCFE, the epiphysis stays within the acetabulum while the femoral neck displaces anteriorly and superiorly. This anatomical shift results in the classic clinical finding of obligate external rotation upon hip flexion.

Question 1759

Topic: Pediatric Hip

A 6-week-old infant is treated with a Pavlik harness for developmental dysplasia of the hip. If the harness places the hip in excessive flexion, which nerve is at the greatest risk of compression neuropathy?

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

Correct Answer & Explanation

. Femoral nerve

Explanation

Excessive hip flexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a temporary palsy. Excessive abduction is avoided due to the higher risk of avascular necrosis of the femoral head.

Question 1760

Topic: Pediatric Hip

A 13-year-old obese male presents with acute worsening of chronic groin pain and inability to bear weight. Radiographs demonstrate a severe slipped capital femoral epiphysis (SCFE). If an unstable SCFE is aggressively anatomically reduced prior to fixation, the patient is at highest risk for developing which of the following complications?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement
. Leg length discrepancy
. Septic arthritis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

Forceful or anatomic closed reduction of an unstable SCFE significantly increases the risk of avascular necrosis (AVN) due to disruption of the vulnerable retinacular blood supply. Gentle, in-situ fixation is generally preferred to minimize this risk.

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