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Pediatric Hip MCQs

Practice Set 4 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 61

Topic: Pediatric Hip

A 13-year-old obese boy presents with an acute inability to bear weight on his right leg after a minor fall, diagnosed as a slipped capital femoral epiphysis (SCFE). According to the Loder classification, this inability to bear weight defines the slip as unstable. What is the approximate risk of avascular necrosis in this type of SCFE?

. Less than 5%
. 10-15%
. 20-47%
. 70-85%
. Nearly 100%

Correct Answer & Explanation

. 20-47%

Explanation

The Loder classification divides SCFE into stable (able to bear weight) and unstable (unable to bear weight with or without crutches). Unstable SCFE has a dramatically higher rate of avascular necrosis, reported to be between 20% and 47%.

Question 62

Topic: Pediatric Hip

A 14-year-old boy is diagnosed with an unstable slipped capital femoral epiphysis (SCFE). To minimize the risk of avascular necrosis and optimize outcomes, what is the widely recommended surgical timing?

. Conservative management with traction
. Urgent reduction and internal fixation within 24 hours
. Delayed pinning after 1 week to allow swelling to subside
. Elective pinning within 4 weeks
. Immediate subtrochanteric osteotomy

Correct Answer & Explanation

. Urgent reduction and internal fixation within 24 hours

Explanation

Unstable SCFE is considered a surgical urgency. Prompt intervention (typically pinning and capsulotomy) within 24 hours has been shown to reduce intracapsular pressure and minimize the risk of avascular necrosis.

Question 63

Topic: Pediatric Hip
A 6-year-old boy with Legg-Calvé-Perthes disease is evaluated. According to the Herring lateral pillar classification, a Type C rating signifies which of the following?
. No involvement of the lateral pillar
. Less than 50% loss of lateral pillar height
. Greater than 50% loss of lateral pillar height
. Complete extrusion of the femoral head laterally
. Presence of a metaphyseal cyst (Gage sign)

Correct Answer & Explanation

. Greater than 50% loss of lateral pillar height

Explanation

The Herring classification assesses the height of the lateral pillar of the femoral head. Type C indicates greater than 50% collapse of the lateral pillar height, which correlates with a poor clinical and radiographic prognosis.

Question 64

Topic: Pediatric Hip

An obese 13-year-old boy presents with left knee pain and an obligatory external rotation of the left hip during flexion. Which of the following is the most appropriate initial imaging step?

. MRI of the left knee
. AP and frog-leg lateral radiographs of the pelvis
. Ultrasound of the left hip
. CT scan of the left femur
. Bone scan of the lower extremities

Correct Answer & Explanation

. AP and frog-leg lateral radiographs of the pelvis

Explanation

This is the classic presentation of a slipped capital femoral epiphysis (SCFE), which commonly presents with referred knee pain and obligatory external rotation upon hip flexion. AP and frog-leg lateral pelvis radiographs are required for diagnosis.

Question 65

Topic: Pediatric Hip

During in-situ pinning of a slipped capital femoral epiphysis (SCFE), an unrecognized intra-articular pin penetration into the anterosuperior quadrant of the femoral head most commonly leads to:

. Avascular necrosis
. Chondrolysis
. Femoroacetabular impingement
. Coxa vara
. Sciatic nerve injury

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized pin penetration into the hip joint during SCFE fixation destroys the articular cartilage, leading to severe chondrolysis. Careful fluoroscopic evaluation using the approach-withdrawal principle is required to confirm pin position.

Question 66

Topic: Pediatric Hip
In a patient diagnosed with Legg-Calvé-Perthes disease, which of the following factors is most strongly associated with a poor radiographic outcome and a spherical mismatch at skeletal maturity?
. Age at presentation of 5 years
. Catterall group I classification
. Intact lateral pillar (Herring A)
. Age at presentation over 8 years
. Presence of an ossific nucleus

Correct Answer & Explanation

. Age at presentation over 8 years

Explanation

Age at clinical onset is the most significant prognostic factor in Legg-Calvé-Perthes disease. Children presenting at age 8 or older have less time for remodeling and generally suffer worse radiographic and clinical outcomes.

Question 67

Topic: Pediatric Hip

A 4-week-old female undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). The Graf alpha angle is reported as 65 degrees. What does this indicate?

. A normal, mature infant hip
. Mild dysplasia requiring a Pavlik harness
. A subluxated hip requiring closed reduction
. A completely dislocated hip
. A teratologic dislocation

Correct Answer & Explanation

. A normal, mature infant hip

Explanation

In the Graf ultrasound classification for DDH, an alpha angle greater than 60 degrees indicates a normal, mature hip (Type I). No treatment is required.

Question 68

Topic: Pediatric Hip

A newborn is diagnosed with arthrogryposis multiplex congenita and bilateral developmental dysplasia of the hip. Why is a Pavlik harness contraindicated in the management of this patient?

. High risk of severe skin ulceration
. High failure rate and risk of iatrogenic contractures or fractures
. High risk of sudden infant death syndrome
. Inability to properly size the harness
. Spontaneous resolution is expected

Correct Answer & Explanation

. High failure rate and risk of iatrogenic contractures or fractures

Explanation

The Pavlik harness relies on active spontaneous movement to achieve and maintain reduction. In teratologic dislocations (like arthrogryposis), the hips are rigid, leading to extremely high failure rates and risks of iatrogenic fractures or skin necrosis.

Question 69

Topic: Pediatric Hip

In which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) is prophylactic pinning of the contralateral hip most strongly indicated?

. A 12-year-old boy with a BMI in the 90th percentile
. A 10-year-old girl with renal osteodystrophy
. A 14-year-old boy with a history of minor trauma
. A 13-year-old boy with an acute-on-chronic slip
. An 11-year-old girl with isolated hip pain for 2 weeks

Correct Answer & Explanation

. A 10-year-old girl with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated for patients with underlying metabolic or endocrine disorders (e.g., renal osteodystrophy, hypothyroidism) due to the extremely high risk of bilateral involvement.

Question 70

Topic: Pediatric Hip

A 5-year-old boy presents for examination. He is diagnosed with developmental dysplasia of the hip. Recommended treatment includes:

. Closed reduction and cast application
. Traction, closed reduction, and cast
. Femoral osteotomy and closed reduction
. Open reduction and iliac osteotomy
. Open reduction, femoral osteotomy, and iliac osteotomy

Correct Answer & Explanation

. Open reduction, femoral osteotomy, and iliac osteotomy

Explanation

At age 5, traction or closed reduction is not likely to produce a stable joint. Femoral shortening is indicated to reduce pressure, reducing the likelihood of avascular necrosis or redislocation. The most likely option to produce a stable joint is open reduction with femoral and iliac osteotomy.

Question 71

Topic: Pediatric Hip

This radiograph (Slide) shows an 11-month-old girl with a Tonnis 3 developmental dislocation of the hip. Recommended treatment includes:

. Pavlik harness
. C losed reduction and spica cast application
. Open reduction and spica cast application
. Open reduction with femoral shortening derotation osteotomy
. Open reduction with Salter osteotomy

Correct Answer & Explanation

. C losed reduction and spica cast application

Explanation

Closed reduction and spica cast application is the best treatment for this patient with a Tonnis 3 developmental dislocation of the hip. Open reduction and spica cast application introduces additional risks of infection and vascular compromise and should not be performed unless closed reduction and spica cast application fails. This patient is too old to be controlled by a Pavlik harness.

Question 72

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip has been managed in a Pavlik harness for 4 weeks with no ultrasound evidence of reduction. What is the next best step in management?

. Continue the harness for 4 more weeks
. Switch to a rigid abduction orthosis
. Perform closed reduction and spica casting
. Proceed to immediate open reduction and pelvic osteotomy
. Perform varus derotational osteotomy

Correct Answer & Explanation

. Perform closed reduction and spica casting

Explanation

If a Pavlik harness fails to achieve reduction within 3 to 4 weeks, it should be discontinued to avoid 'Pavlik harness disease' (posterior wear of the acetabulum). The next appropriate step is closed reduction and spica casting under general anesthesia.

Question 73

Topic: Pediatric Hip

A 12-year-old overweight boy presents with sudden inability to bear weight on his right leg after a minor fall. Radiographs show a slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant risk associated with this specific presentation?

. Chondrolysis
. Avascular necrosis (AVN)
. Leg length discrepancy
. Premature osteoarthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight even with crutches defines an unstable SCFE according to the Loder classification. Unstable slips carry a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips.

Question 74

Topic: Pediatric Hip
In a patient with Legg-Calvé-Perthes disease, the Herring lateral pillar classification is used for prognosis. Which of the following describes a Herring Group B classification?
. No involvement of the lateral pillar
. Greater than 50% of the lateral pillar height is maintained
. Less than 50% of the lateral pillar height is maintained
. Total collapse of the epiphysis
. Extrusion of the lateral pillar beyond the acetabulum

Correct Answer & Explanation

. Greater than 50% of the lateral pillar height is maintained

Explanation

In the Herring classification, Group B indicates that the lateral pillar maintains >50% of its normal height. Group C indicates <50% height maintained, which corresponds to a worse prognosis and a higher risk of aspherical head development.

Question 75

Topic: Pediatric Hip

A 6-week-old female infant undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). What is the minimum normal alpha angle according to the Graf classification?

. 40 degrees
. 50 degrees
. 60 degrees
. 70 degrees
. 80 degrees

Correct Answer & Explanation

. 60 degrees

Explanation

In the Graf classification for developmental dysplasia of the hip, an alpha angle of 60 degrees or greater indicates a mature, normal hip (Type I). The alpha angle measures the bony acetabular roof depth.

Question 76

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the infant is noted to lack active knee extension on the treated side. Which of the following is the most likely cause?

. Avascular necrosis of the femoral head
. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive hip abduction
. Inferior hip dislocation
. Sciatic nerve compression

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Hyperflexion of the hip in a Pavlik harness (typically >120 degrees) can compress the femoral nerve against the pubis, leading to femoral nerve palsy and loss of active knee extension. The harness must be adjusted to reduce flexion.

Question 77

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). Radiographs demonstrate that less than 50% of the lateral pillar height is maintained. According to the Herring classification, which type does this represent and what is the expected outcome?
. Type A, excellent outcome
. Type B, favorable outcome with conservative care
. Type C, poor outcome with early onset osteoarthritis
. Type B/C border, variable outcome
. Type D, requires immediate arthrodesis

Correct Answer & Explanation

. Type C, poor outcome with early onset osteoarthritis

Explanation

Herring Type C is defined by the lateral pillar maintaining less than 50% of its original height. This indicates severe collapse and is associated with a poor prognosis, often leading to early osteoarthritis.

Question 78

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE) and is unable to bear weight even with crutches (unstable SCFE). What is the most significant complication he is at risk for following in situ pinning?

. Chondrolysis
. Avascular necrosis (AVN)
. Infection
. Femoral shaft fracture
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE. Urgent but careful reduction and stabilization are critical to minimize this risk.

Question 79

Topic: Pediatric Hip

Which of the following clinical scenarios most strongly indicates the need for prophylactic in situ pinning of the contralateral hip in a patient presenting with unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Male gender, aged 13 years
. Patient with an underlying endocrine disorder (e.g., hypothyroidism)
. Body mass index > 95th percentile
. African American descent
. Presence of a stable, mild slip on the affected side

Correct Answer & Explanation

. Patient with an underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Patients with underlying endocrinopathies, metabolic disorders, or those undergoing radiation therapy have an extremely high rate of bilateral SCFE (up to 100%), making prophylactic pinning of the contralateral hip highly recommended.

Question 80

Topic: Pediatric Hip

An obese 13-year-old boy presents with left knee pain and an antalgic gait. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE).

What is the most appropriate initial treatment for a stable, moderate SCFE?

. In situ single screw fixation
. Spica cast application
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Closed reduction and pinning

Correct Answer & Explanation

. In situ single screw fixation

Explanation

In situ fixation with a single cannulated screw placed in the center of the epiphysis is the gold standard for stable SCFE to prevent further slip. Closed reduction increases the risk of avascular necrosis and should be avoided.

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