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Pediatric Hip MCQs

Practice Set 34 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 661

Topic: Pediatric Hip

A 3-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. At follow-up, the mother reports the infant has stopped kicking her left leg. On examination, the infant lacks active knee extension, but passive knee range of motion is normal. Which nerve is most likely compressed, and what positioning error causes this complication?

. Sciatic nerve; hyperflexion of the hip
. Femoral nerve; hyperflexion of the hip
. Obturator nerve; excessive abduction
. Femoral nerve; excessive abduction
. Sciatic nerve; excessive extension

Correct Answer & Explanation

. Femoral nerve; hyperflexion of the hip

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and presents with decreased active knee extension. It is typically caused by excessive flexion of the hip. The treatment is temporarily loosening the anterior straps or discontinuing the harness until nerve function returns.

Question 662

Topic: Pediatric Hip

A 12-year-old obese male presents with a left-sided slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral right hip?

. Male gender
. African American ethnicity
. Presence of an underlying endocrine disorder
. Body mass index > 95th percentile
. Slip angle greater than 50 degrees on the affected side

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Endocrinopathies (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) are strong indications for prophylactic contralateral pinning in SCFE due to the very high risk (often >50%) of subsequent bilateral involvement. Age < 10 years or an open triradiate cartilage are also significant risk factors for bilaterality.

Question 663

Topic: Pediatric Hip

A 6-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). She has been strictly in the harness for 4 weeks, but a repeat ultrasound demonstrates that the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 3 weeks
. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or schedule closed reduction
. Perform an immediate open reduction and spica casting
. Switch to double-diapering
. Perform a varus derotational osteotomy (VDRO)

Correct Answer & Explanation

. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or schedule closed reduction

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip leads to 'Pavlik harness disease', characterized by erosion of the posterior acetabular wall, which makes future reduction significantly more difficult. If a hip remains dislocated after 3 to 4 weeks of strict Pavlik harness wear, the harness must be discontinued. The accepted next step is transitioning to a rigid abduction brace (e.g., Ilfeld) or proceeding to closed reduction and spica casting.

Question 664

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department complaining of right hip and thigh pain after slipping on ice. He is completely unable to bear weight on the right leg, even with crutches. Radiographs demonstrate a displaced Slipped Capital Femoral Epiphysis (SCFE) of the right hip. Based on the Loder classification, what is his primary risk regarding the natural history of this specific injury pattern?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Coxa magna
. Femoroacetabular impingement (FAI)
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

According to the Loder classification, SCFE is divided into stable and unstable. 'Unstable' is defined clinically as the inability to ambulate, even with assistive devices (crutches). The incidence of avascular necrosis (AVN) in unstable SCFE is extremely high (up to 47%), whereas it is nearly 0% in stable SCFE.

Question 665

Topic: Pediatric Hip

What is the most devastating and rapid complication specifically associated with the surgical pinning of an unstable Slipped Capital Femoral Epiphysis (SCFE)?

. Chondrolysis
. Osteonecrosis (Avascular Necrosis) of the femoral head
. Femoroacetabular impingement
. Progressive leg length discrepancy
. Premature osteoarthritis

Correct Answer & Explanation

. Osteonecrosis (Avascular Necrosis) of the femoral head

Explanation

Osteonecrosis (AVN) is the most devastating complication of SCFE, occurring at a significantly higher rate in unstable SCFE (reported up to 47%) compared to stable SCFE (almost 0%). It is typically caused by disruption of the retinacular vessels, which can be exacerbated by forceful closed reduction or hematoma accumulation.

Question 666

Topic: Pediatric Hip

When treating an infant for Developmental Dysplasia of the Hip (DDH) using a Pavlik harness, hyperflexion of the hips beyond 120 degrees places the child at significant risk for which specific complication?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion (typically >120 degrees) in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy. Excessive hip abduction, on the other hand, compromises the medial circumflex femoral artery and leads to avascular necrosis.

Question 667

Topic: Pediatric Hip

A 6-week-old female infant is undergoing an ultrasound evaluation for Developmental Dysplasia of the Hip (DDH). According to the Graf classification, what does the alpha angle measure and what is considered a normal value (Type I hip)?

. Measures the cartilaginous roof; normal is > 60 degrees
. Measures the cartilaginous roof; normal is < 55 degrees
. Measures the bony acetabular roof; normal is > 60 degrees
. Measures the bony acetabular roof; normal is < 55 degrees
. Measures the femoral head coverage; normal is > 50%

Correct Answer & Explanation

. Measures the bony acetabular roof; normal is > 60 degrees

Explanation

In the Graf classification for DDH ultrasound, the alpha angle measures the bony roof of the acetabulum (formed by the ilium). A normal alpha angle (Graf Type I) is > 60 degrees. The beta angle measures the cartilaginous roof.

Question 668

Topic: Pediatric Hip

A 12-year-old obese male presents with a unilateral left-sided Slipped Capital Femoral Epiphysis (SCFE) and undergoes in situ pinning. When evaluating the risk of a contralateral slip to determine the need for prophylactic pinning, which of the following radiographic parameters is the strongest predictor of a future contralateral slip?

. Initial left-sided slip angle > 50 degrees
. Southwick slip angle of the normal right hip > 10 degrees
. Klein's line intersecting less than 20% of the epiphysis on the right
. Modified Oxford bone age score of 16 or less at initial presentation
. Widening of the right proximal femoral physis > 5 mm

Correct Answer & Explanation

. Modified Oxford bone age score of 16 or less at initial presentation

Explanation

The modified Oxford bone age score uses AP pelvis radiographs to evaluate the maturation of the ilium and the triradiate cartilage. A score of 16 or less indicates significant remaining skeletal growth and has been proven in multiple studies (such as those by Stasikelis et al. and Popejoy et al.) to be a strong independent predictor of subsequent contralateral slip, thus strongly supporting the decision for prophylactic pinning.

Question 669

Topic: Pediatric Hip

On an anteroposterior (AP) radiograph of the pelvis in a 6-month-old infant being evaluated for Developmental Dysplasia of the Hip (DDH), Hilgenreiner's line and Perkin's line are drawn to assess the position of the femoral head. In a normal, non-dysplastic hip, the ossific nucleus of the proximal femur should be located in which of the following quadrants?

. Superomedial quadrant
. Superolateral quadrant
. Inferomedial quadrant
. Inferolateral quadrant
. Centered directly on the intersection of the two lines

Correct Answer & Explanation

. Inferomedial quadrant

Explanation

Hilgenreiner's line is drawn horizontally through the triradiate cartilages. Perkin's line is drawn perpendicularly downwards from the lateral margin of the acetabulum. In a normal hip, the ossific nucleus of the femoral head (or the medial beak of the metaphysis if unossified) sits in the inferomedial quadrant.

Question 670

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvรฉ-Perthes disease. During the fragmentation stage, an AP pelvis radiograph demonstrates that the lateral pillar of the affected femoral head maintains 40% of its original height. According to the Herring Lateral Pillar classification, which group does this hip fall into?
. Group A
. Group B
. Group C
. Group B/C border
. Group D

Correct Answer & Explanation

. Group C

Explanation

The Herring Lateral Pillar classification assesses the height of the lateral pillar of the femoral head on an AP radiograph during the fragmentation stage. Group A has no loss of height. Group B maintains > 50% of lateral pillar height. Group C maintains < 50% of the lateral pillar height. A height of 40% clearly places the hip in Group C, which is associated with a poor prognosis regardless of treatment, especially in older children (> 8 years).

Question 671

Topic: Pediatric Hip

A 12-year-old overweight boy presents with an antalgic gait. Radiographs confirm a mild left Slipped Capital Femoral Epiphysis (SCFE). Which of the following is an accepted and strongly supported indication for prophylactic in situ pinning of the contralateral right hip?

. Male gender
. Obesity alone
. Modified Oxford bone age score of 16 or lower
. Southwick angle greater than 50 degrees on the affected side
. Open triradiate cartilage

Correct Answer & Explanation

. Open triradiate cartilage

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but widely indicated in patients at high risk for a subsequent slip. Known strong risk factors for a contralateral slip include an open triradiate cartilage (indicating significant skeletal immaturity), underlying endocrine disorders (e.g., hypothyroidism), and very young age (girls <10, boys <12).

Question 672

Topic: Pediatric Hip

A 12-year-old male is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. Which of the following represents the strongest absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 14 years at presentation
. A slip angle of less than 30 degrees (Grade 1) on the affected side
. Closure of the triradiate cartilage
. Male sex and athletic participation
. Presence of underlying endocrine disorders (e.g., hypothyroidism)

Correct Answer & Explanation

. Presence of underlying endocrine disorders (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is universally recommended for patients with underlying endocrinopathies (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), previous radiation therapy, or presentation at an atypically young age (< 10 years). These populations have an exceptionally high risk of developing a contralateral slip.

Question 673

Topic: Pediatric Hip

In a 12-year-old boy presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following endocrine disorders is the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Type 1 Diabetes Mellitus
. Hypothyroidism
. Hyperparathyroidism
. Cushing's syndrome
. Congenital adrenal hyperplasia

Correct Answer & Explanation

. Hypothyroidism

Explanation

Atypical SCFE occurs in patients with endocrine disorders (such as hypothyroidism, growth hormone deficiency, and panhypopituitarism) or in children outside the typical age range. These patients have a significantly higher rate of bilateral involvement, approaching 100% in some series for certain endocrinopathies. Hypothyroidism is a classic and strong indication for prophylactic pinning of the contralateral hip.

Question 674

Topic: Pediatric Hip

A 3-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents note that the infant is no longer actively extending the knee on the affected side. What is the most appropriate immediate management?

. Reassure the parents and observe while continuing the harness
. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to decrease hip abduction
. Immediate cessation of the Pavlik harness
. Switch to a hip spica cast immediately

Correct Answer & Explanation

. Immediate cessation of the Pavlik harness

Explanation

Decreased active knee extension in an infant wearing a Pavlik harness is the classic presentation of a femoral nerve palsy, typically caused by excessive hip flexion. The standard of care is the immediate cessation of the Pavlik harness and observation. The palsy usually resolves within days to a couple of weeks, after which alternative bracing or casting can be considered.

Question 675

Topic: Pediatric Hip

An 11-year-old boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Prophylactic in situ pinning of the asymptomatic contralateral right hip is most strongly indicated in patients with which of the following clinical profiles?

. Age 13 years
. Male sex
. African American descent
. History of hypothyroidism or renal osteodystrophy
. Body Mass Index (BMI) > 95th percentile

Correct Answer & Explanation

. History of hypothyroidism or renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in a patient with a unilateral SCFE is highly recommended for patients with endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), patients who have had prior radiation therapy, or patients who are relatively young (often defined as <10 years for girls and <11-12 years for boys) or have open triradiate cartilages. These factors significantly increase the risk of a subsequent contralateral slip.

Question 676

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip. At a follow-up visit, the mother notes the infant is no longer actively kicking her affected leg. Physical examination reveals decreased active knee extension but normal sensation. Which of the following is the most likely cause?

. Transient synovitis
. Excessive hip flexion in the harness
. Excessive hip abduction in the harness
. Undiagnosed septic arthritis
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment and is caused by excessive hip flexion. The anterior strap should be adjusted to decrease flexion. Excessive abduction in the harness is classically associated with an increased risk of avascular necrosis (AVN) of the femoral head.

Question 677

Topic: Pediatric Hip

A 12-year-old obese male presents with a left slipped capital femoral epiphysis (SCFE). Which of the following patient profiles most strongly indicates the need for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Age greater than 14 years
. Presentation with a chronic slip
. Female gender
. Presence of an underlying endocrine disorder
. Slip angle less than 30 degrees

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is generally recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or prior radiation therapy due to a very high risk (often >50%) of developing a bilateral slip.

Question 678

Topic: Pediatric Hip

A 3-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents note decreased spontaneous movement of the affected leg. Examination reveals active toe movement but profound weakness in knee extension. What is the most likely cause of this complication?

. Excessive hip abduction in the harness
. Excessive hip adduction in the harness
. Excessive hip flexion in the harness
. Excessive hip extension in the harness
. Inadequate hip flexion in the harness

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment and is most commonly caused by excessive hip flexion, which stretches or compresses the femoral nerve against the inguinal ligament or pelvic brim. The clinical presentation is an absence of active knee extension. Treatment involves immediate adjustment of the harness or temporary removal until nerve function recovers. Excessive abduction, conversely, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 679

Topic: Pediatric Hip

A normal-weight 10-year-old girl presents with a unilateral slipped capital femoral epiphysis (SCFE). Given her atypical demographic profile for this condition, which underlying endocrine disorder is most commonly associated with SCFE and should prompt consideration for prophylactic pinning of the contralateral hip?

. Hyperthyroidism
. Hypothyroidism
. Type 1 Diabetes Mellitus
. Hyperparathyroidism
. Addison's disease

Correct Answer & Explanation

. Hypothyroidism

Explanation

While idiopathic SCFE typically occurs in overweight adolescents during their growth spurt (males 12-16, females 10-14), patients presenting outside of this typical age or weight demographic (e.g., <10 years old, or normal weight) have a high likelihood of an underlying endocrine or metabolic disorder. Hypothyroidism is the most common endocrine disorder associated with SCFE. Other conditions include renal osteodystrophy and growth hormone deficiency. These patients are at very high risk for contralateral disease, often necessitating prophylactic pinning.

Question 680

Topic: Pediatric Hip

A 13-year-old obese male undergoes in-situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE). Four months postoperatively, he develops severe hip stiffness, worsening pain, and a 30-degree flexion contracture. Radiographs show a 50% reduction in the joint space globally compared to the contralateral hip. What is the most significant risk factor for this specific complication?

. Performing a base of neck capsulotomy
. Unrecognized hardware penetration into the articular joint
. Patient's elevated BMI
. Use of a single partially threaded screw instead of two
. Early postoperative weight bearing

Correct Answer & Explanation

. Unrecognized hardware penetration into the articular joint

Explanation

The clinical picture describes chondrolysis, a devastating complication of SCFE characterized by acute cartilage destruction and global joint space narrowing. The most strongly associated iatrogenic risk factor is unrecognized pin penetration into the hip joint during fixation. The use of live fluoroscopy (approach-withdraw technique) is critical to confirm the pin is completely within the femoral head.

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