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Pediatric Hip MCQs

Practice Set 23 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 441

Topic: Pediatric Hip

A 12-year-old obese male presents with left thigh pain and a limp. The provided radiograph is shown.

He is diagnosed with a Slipped Capital Femoral Epiphysis (SCFE). What is the most widely accepted indication for prophylactic pinning of the contralateral hip?

. Initial presentation with a severe slip angle > 50 degrees
. Age < 10 for girls or < 12 for boys, or underlying endocrinopathy
. Open triradiate cartilage at the time of presentation
. Positive family history of SCFE in a first-degree relative
. Body Mass Index (BMI) > 99th percentile for age

Correct Answer & Explanation

. Age < 10 for girls or < 12 for boys, or underlying endocrinopathy

Explanation

Prophylactic pinning of the contralateral hip is generally indicated in patients with metabolic or endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) and in patients presenting at a very young age (girls <10, boys <12) due to a substantially increased risk of a contralateral slip. Recent literature also strongly weights the modified Oxford bone age score.

Question 442

Topic: Pediatric Hip

A 12-year-old boy presents with left knee pain and an antalgic gait. Examination reveals obligate external rotation of the left hip during passive flexion.

Radiographs confirm a Slipped Capital Femoral Epiphysis (SCFE). Which of the following factors is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Patient age greater than 14 years
. Male sex
. Underlying endocrine disorder (e.g., hypothyroidism)
. High body mass index (BMI > 95th percentile)
. Southwick angle greater than 50 degrees on the affected side

Correct Answer & Explanation

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

Explanation

The risk of developing a contralateral slip in a patient with an initial unilateral SCFE ranges from 20-40% overall, but approaches 100% in patients with an underlying endocrinopathy (such as hypothyroidism, growth hormone deficiency, or panhypopituitarism) or a history of radiation therapy to the pelvis. In these specific populations, prophylactic pinning of the contralateral hip is absolutely indicated.

Question 443

Topic: Pediatric Hip

A 12-year-old obese boy presents with vague left thigh and knee pain. He is diagnosed with a Slipped Capital Femoral Epiphysis (SCFE) as seen in similar clinical scenarios.

During percutaneous in-situ fixation, unrecognized penetration of the guide wire into the hip joint occurs. What is the most likely specific complication resulting from this technical error?

. Chondrolysis
. Avascular necrosis
. Osteomyelitis
. Slipped progression
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE characterized by rapid destruction of the articular cartilage. While it can occur idiopathically, its most established iatrogenic cause is unrecognized intra-articular hardware penetration. The 'approach-withdraw' fluoroscopic technique is required during pinning to assure pins are entirely intraosseous. Avascular necrosis (AVN) is usually due to damage to the epiphyseal blood supply (retinacular vessels) secondary to the initial displacement, forceful closed reduction, or posterosuperior pin placement.

Question 444

Topic: Pediatric Hip

A 6-week-old female is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. During a follow-up visit, it is noted that the anterior straps are overly tightened, causing hyperflexion of the hips. Which of the following nerve palsies is most commonly associated with this specific positioning error?

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

Correct Answer & Explanation

. Femoral nerve

Explanation

In a Pavlik harness, excessive flexion (over-tightening of the anterior straps) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as decreased quadriceps function). Conversely, excessive abduction (over-tightening of the posterior straps) places the hip at significant risk for avascular necrosis (AVN) of the femoral head.

Question 445

Topic: Pediatric Hip

A 13-year-old obese male presents with left hip pain and an obligatory external rotation of the left hip when it is passively flexed. Radiographs confirm a severe left slipped capital femoral epiphysis (SCFE).

Which of the following patient characteristics is an absolute indication for prophylactic pinning of the contralateral asymptomatic right hip?

. Patient age greater than 14 years at presentation
. Presence of a diagnosed endocrine disorder
. Severe slip angle (>50 degrees) on the symptomatic side
. Male gender with a BMI > 95th percentile
. Inability to ambulate on the affected limb

Correct Answer & Explanation

. Presence of a diagnosed endocrine disorder

Explanation

Prophylactic pinning of the contralateral asymptomatic hip in a patient with a unilateral SCFE is controversial for standard cases, but it is unequivocally recommended for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy). These patients have an exceptionally high incidence of bilateral involvement. Other factors like young age (<10 years) or open triradiate cartilage may also sway a surgeon toward prophylactic pinning.

Question 446

Topic: Pediatric Hip



A 13-year-old obese male presents with acute-on-chronic hip and knee pain and an inability to bear weight on the affected limb. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). He is taken to the operating room for urgent in-situ pinning. What is the most significant complication associated with attempting a forceful, intentional closed reduction of this deformity prior to hardware placement?

. Chondrolysis of the hip joint
. Femoral head osteonecrosis (avascular necrosis)
. Premature closure of the greater trochanteric apophysis
. Progression of the slip post-operatively
. Anterior labral tear

Correct Answer & Explanation

. Femoral head osteonecrosis (avascular necrosis)

Explanation

An unstable SCFE (defined as the inability to bear weight even with crutches) already carries a high risk of osteonecrosis. Attempting a forceful closed reduction further disrupts the fragile retinacular vascular supply to the femoral epiphysis, significantly increasing the risk of iatrogenic avascular necrosis. Gentle reduction by positioning may occur naturally, but intentional forceful reduction is contraindicated.

Question 447

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for exactly 4 weeks. Serial ultrasounds show the left hip remains persistently dislocated and irreducible in the harness. What is the most appropriate next step in the management of this patient?

. Continue the Pavlik harness for an additional 4 weeks to allow further remodeling
. Transition immediately to a rigid hip abduction orthosis (e.g., Ilfeld splint)
. Discontinue the harness and proceed with closed reduction and spica casting under general anesthesia
. Open reduction via an anterior approach with a Salter pelvic osteotomy
. Varus derotational osteotomy of the proximal femur

Correct Answer & Explanation

. Discontinue the harness and proceed with closed reduction and spica casting under general anesthesia

Explanation

If a hip remains dislocated after 3 to 4 weeks of strict Pavlik harness use, it is deemed a failure of the harness. The harness must be discontinued immediately to prevent 'Pavlik harness disease' (erosion of the posterior acetabular wall and increased risk of avascular necrosis). The standard next step is an exam under anesthesia, arthrogram, and closed reduction with spica casting.

Question 448

Topic: Pediatric Hip

A 12-year-old obese boy presents with 3 weeks of vague knee pain and a new inability to bear weight on the right leg. On physical examination, the affected leg is resting in external rotation. What is the most significant clinical risk factor for the development of avascular necrosis (AVN) in this patient's condition?

. Duration of symptoms prior to presentation
. Degree of initial slip angle
. Unstable nature of the slip
. Patient's body mass index
. Concomitant endocrine disorder

Correct Answer & Explanation

. Unstable nature of the slip

Explanation

The patient has a Slipped Capital Femoral Epiphysis (SCFE). The inability to bear weight, even with crutches, defines an 'unstable' SCFE according to Loder's classification. Unstable SCFE carries a significantly higher risk of avascular necrosis (nearly 47%) compared to stable SCFE (less than 10%).

Question 449

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, the mother notes the infant has stopped kicking with the affected leg. On examination, active knee extension is absent, though passive motion is full. Which of the following complications has most likely occurred?

. Avascular necrosis of the femoral head
. Obturator nerve palsy
. Femoral nerve palsy
. Sciatic nerve palsy
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness if the hip is hyperflexed (usually > 120 degrees). It presents as decreased active knee extension and quadriceps firing. It is usually reversible upon decreasing the amount of hip flexion.

Question 450

Topic: Pediatric Hip

A 13-year-old obese male presents with left thigh pain and a limp. He walks with an externally rotated leg. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE) with a slip angle of 60 degrees. What is the most significant risk associated with performing an acute anatomical reduction prior to pinning?

. Chondrolysis
. Avascular necrosis of the femoral head
. Femoroacetabular impingement
. Subtrochanteric fracture
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Acute anatomical reduction of a SCFE is highly associated with stretching or kinking of the retinacular vessels, leading to avascular necrosis (AVN) of the femoral head. Therefore, in-situ pinning is the gold standard for stable slips, though unstable slips may require gentle reduction or open procedures (e.g., modified Dunn).

Question 451

Topic: Pediatric Hip



An 8-year-old child presents with a limp and poorly localized knee pain. Radiographs confirm a unilateral slipped capital femoral epiphysis (SCFE). Given the patient's age, an endocrine workup is indicated. Which of the following is the most common underlying endocrine abnormality associated with SCFE in this patient population?

. Hyperparathyroidism
. Hypothyroidism
. Growth hormone deficiency
. Panhypopituitarism
. Testosterone deficiency

Correct Answer & Explanation

. Hypothyroidism

Explanation

While idiopathic SCFE typically occurs during the adolescent growth spurt (ages 10-14 for girls, 12-16 for boys), patients who present 'out of age range' (< 10 years or > 16 years) or whose weight is less than the 50th percentile have a high association with endocrine disorders. Hypothyroidism is the most commonly associated endocrine disorder in patients with SCFE. Other causes include panhypopituitarism, growth hormone supplementation, and renal osteodystrophy.

Question 452

Topic: Pediatric Hip

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

. 12-year-old male with idiopathic SCFE
. 14-year-old female with obesity
. 10-year-old male with hypothyroidism
. 15-year-old male with acute-on-chronic SCFE
. 13-year-old female with a positive Klein's line intersection

Correct Answer & Explanation

. 10-year-old male with hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is generally indicated in patients at high risk for bilateral disease. Risk factors for bilateral SCFE include young age at presentation (< 10 years for girls, < 11 years for boys), endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy), and previous radiation therapy. Thus, the 10-year-old male with hypothyroidism represents the highest risk among the choices.

Question 453

Topic: Pediatric Hip

A 6-month-old female is evaluated for developmental dysplasia of the hip (DDH). Radiographs are obtained.

Which radiographic line is drawn vertically downwards from the lateral edge of the acetabulum to assess hip subluxation?

. Hilgenreiner's line
. Perkin's line
. Shenton's line
. Klein's line
. Southwick's angle

Correct Answer & Explanation

. Perkin's line

Explanation

Perkin's line is a vertical line drawn downward from the lateral margin of the acetabulum, perpendicular to Hilgenreiner's line (which is drawn horizontally through the triradiate cartilages). In a normal hip, the ossific nucleus of the femoral head should sit in the lower medial quadrant created by the intersection of these two lines.

Question 454

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe acute groin and thigh pain after a minor slip. He is unable to bear weight on the affected limb, even with the assistance of crutches. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). Which of the following complications is most specifically associated with this patient's clinical presentation compared to a patient who can bear weight?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Premature physeal closure
. Femoroacetabular impingement (FAI)
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The inability to bear weight with or without crutches defines an 'unstable' SCFE according to the Loder classification. Unstable SCFE has a significantly higher rate of avascular necrosis (AVN) of the femoral head, with rates historically reported between 20% and 50%. Stable SCFE (where the patient can bear weight) has a very low risk of AVN (<10%).

Question 455

Topic: Pediatric Hip

A 6-week-old female infant is undergoing treatment for Developmental Dysplasia of the Hip (DDH) with a Pavlik harness. During a routine follow-up, her mother notes that the baby has stopped kicking her right leg. On examination, there is an absence of active knee extension on the right side, but ankle and toe movements are intact. What is the most appropriate management step to address this complication?

. Adjust the posterior straps to decrease hip abduction
. Adjust the anterior straps to decrease hip flexion
. Immediately abandon the Pavlik harness and transition to a hip spica cast
. Obtain an urgent MRI of the lumbar spine
. Reassure the mother and continue the current harness settings

Correct Answer & Explanation

. Adjust the anterior straps to decrease hip flexion

Explanation

The infant is presenting with a femoral nerve palsy, a known complication of Pavlik harness treatment. It is caused by excessive flexion of the hip, which compresses the femoral nerve against the inguinal ligament or pelvic brim. The immediate management is to adjust the anterior straps to slightly decrease the amount of hip flexion. The condition is usually transient and resolves once the hyperflexion is corrected. Adjusting the posterior straps addresses abduction (excessive abduction risks AVN, not femoral nerve palsy).

Question 456

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department unable to bear weight on his left leg after a minor twisting injury. Radiographs show a slipped capital femoral epiphysis (SCFE).

According to the Loder classification, what is the most significant risk associated with this patient's injury type?

. 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

The Loder classification divides SCFE into stable (patient can bear weight with or without crutches) and unstable (patient is unable to bear weight even with crutches). Unstable SCFE has a high rate of avascular necrosis (AVN), ranging from 20% to 50%, whereas stable SCFE has an AVN rate of nearly zero.

Question 457

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an altered gait.

Based on the presumed diagnosis of slipped capital femoral epiphysis (SCFE) shown in the representative radiograph, which of the following is the primary blood supply to the femoral head that is at highest risk for iatrogenic injury during percutaneous in situ pinning if the pin is placed in the posterosuperior quadrant?

. Anterior ascending branch of the lateral circumflex femoral artery
. Posterosuperior retinacular vessels from the medial circumflex femoral artery
. Foveal artery from the obturator artery
. Inferior gluteal artery branches
. Medial epiphyseal artery

Correct Answer & Explanation

. Posterosuperior retinacular vessels from the medial circumflex femoral artery

Explanation

The primary blood supply to the capital femoral epiphysis in children over the age of 3 is the posterosuperior retinacular vessels (lateral epiphyseal artery), which are terminal branches of the medial circumflex femoral artery (MCFA). During in situ pinning for SCFE, placement of the pin in the posterosuperior quadrant of the femoral neck/head places these extracapsular vessels at extreme risk of injury, potentially leading to avascular necrosis (AVN). Pins should ideally be placed in the center-center position to minimize this risk.

Question 458

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp. Radiographs show sclerosis and early fragmentation of the capital femoral epiphysis, consistent with Legg-Calvรฉ-Perthes disease. According to Catterall, which of the following is considered a radiographic 'head at risk' sign?
. Medial subluxation of the femoral head
. Vertical orientation of the proximal femoral physis
. A V-shaped radiolucent defect in the lateral portion of the epiphysis and adjacent metaphysis (Gage sign)
. Sclerosis of the acetabular dome
. Varus angulation of the femoral neck greater than 15 degrees

Correct Answer & Explanation

. A V-shaped radiolucent defect in the lateral portion of the epiphysis and adjacent metaphysis (Gage sign)

Explanation

Catterall described five clinical and radiographic 'head at risk' signs for Legg-Calvรฉ-Perthes disease that correlate with a worse prognosis and higher risk of femoral head deformation. These include: 1) Gage's sign (a V-shaped radiolucent defect in the lateral epiphysis/metaphysis), 2) Calcification lateral to the epiphysis, 3) Lateral (not medial) subluxation of the femoral head, 4) A horizontal (not vertical) growth plate, and 5) Metaphyseal cysts.

Question 459

Topic: Pediatric Hip

A 13-year-old obese boy presents with 3 weeks of left groin pain and a limp. Examination reveals obligatory external rotation of the left hip during passive flexion. A radiograph is provided.

What is the recommended definitive management for a stable slipped capital femoral epiphysis (SCFE)?

. Closed reduction and spica casting
. Open reduction and internal fixation
. In situ single screw fixation
. Proximal femoral osteotomy
. Observation and non-weight bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

A stable SCFE is characterized by the patient's ability to bear weight (with or without crutches). The standard of care for a stable SCFE is in situ fixation with a single cannulated screw placed centrally within the epiphysis. Closed reduction is contraindicated due to the high risk of avascular necrosis.

Question 460

Topic: Pediatric Hip

A 4-month-old female infant is treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During treatment, what is the most significant risk associated with excessive abduction of the hips in the harness?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In Pavlik harness treatment, excessive abduction of the hips places the medial circumflex femoral artery at risk of compression against the iliopsoas tendon, leading to avascular necrosis of the femoral head. Excessive flexion is associated with femoral nerve palsy.

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