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Pediatric Hip MCQs

Practice Set 12 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 221

Topic: Pediatric Hip

A 6-month-old infant is diagnosed with DDH that failed Pavlik harness treatment. A closed reduction and spica casting are planned. Under fluoroscopy, the "safe zone" of Ramsey is evaluated. What does this zone represent?

. The arc between maximal abduction and the angle of re-dislocation
. The arc between 90 degrees of flexion and maximal extension
. The arc between maximal internal and external rotation
. The arc between the angle of subluxation and 30 degrees of adduction
. The arc between 30 and 60 degrees of hip flexion

Correct Answer & Explanation

. The arc between maximal abduction and the angle of re-dislocation

Explanation

The "safe zone" of Ramsey is the arc of hip abduction between the angle of maximal abduction (limited by adductor tightness) and the lower angle at which the hip redislocates or subluxates as it is adducted. If the safe zone is too narrow, an adductor tenotomy may be required.

Question 222

Topic: Pediatric Hip

A 7-month-old girl presents with a persistently dislocated left hip after 6 weeks of compliant Pavlik harness treatment. What is the most appropriate next step in management?

. Continue the Pavlik harness for 6 additional weeks
. Examination under anesthesia, closed reduction, and spica casting
. Immediate femoral varus derotational osteotomy
. Salter innominate osteotomy
. Switch to a rigid abduction orthosis for 12 weeks

Correct Answer & Explanation

. Examination under anesthesia, closed reduction, and spica casting

Explanation

In an infant older than 6 months or after failed Pavlik harness treatment, the next appropriate step is an examination under anesthesia and an attempted closed reduction with spica casting. Continued use of the Pavlik harness after failure increases the risk of "Pavlik harness disease" and structural damage.

Question 223

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a severe, chronic left slipped capital femoral epiphysis (SCFE). Which of the following is the most widely accepted absolute indication for prophylactic in-situ pinning of the asymptomatic contralateral hip?

. Age greater than 14 years at presentation
. Male gender
. Presence of an endocrine disorder such as hypothyroidism
. Slip angle greater than 50 degrees on the affected side
. Body mass index (BMI) greater than 35

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy) due to the exceptionally high risk of bilateral involvement. Age less than 10 years or open triradiate cartilage are also strong relative indications.

Question 224

Topic: Pediatric Hip

The following parameter is the most useful in predicting the need for surgical correction of developmental coxa vara:

. The range of active abduction
. The epiphyseal extrusion index
. The acetabular index
. The Hilgenreiner-epiphyseal angle
. Presence of a Trendelenburg gait

Correct Answer & Explanation

. The Hilgenreiner-epiphyseal angle

Explanation

The Hilgenreiner-epiphyseal angle is a measure of the shear stress on the femoral neck. A value greater than 60° is an indication for surgery. The range of abduction does not directly reflect the mechanical stresses on the femoral neck that may need correction. The epiphyseal extrusion index is a parameter used in Perthes disease. The acetabular index is used in developmental hip dysplasia. It is usually essentially within normal limits, even in severe coxa vara.

Question 225

Topic: Pediatric Hip

A 13-year-old obese male presents with right groin pain and an obligatory external rotation of the hip when it is passively flexed. If this condition is treated with forceful closed reduction, what is the most significant and devastating complication?

. Avascular necrosis (AVN) of the femoral head
. Chondrolysis of the hip joint
. Premature closure of the triradiate cartilage
. Nonunion of the proximal femur
. Septic arthritis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The presentation is classic for Slipped Capital Femoral Epiphysis (SCFE). Forceful closed reduction of a SCFE significantly increases the risk of avascular necrosis of the femoral head, which is the most devastating complication.

Question 226

Topic: Pediatric Hip

A 3-month-old infant is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). What is the most common nerve palsy associated with excessive hip flexion in this device?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Superior gluteal nerve palsy
. Pudendal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of treating DDH with a Pavlik harness when the hips are placed in excessive hyperflexion, which compresses the nerve against the inguinal ligament.

Question 227

Topic: Pediatric Hip
Which of the following is the most important prognostic factor in a patient with Legg-Calvé-Perthes disease?
. Age at the time of clinical onset
. Gender of the patient
. Duration of symptoms before diagnosis
. Presence of a positive Trendelenburg sign
. Body mass index

Correct Answer & Explanation

. Age at the time of clinical onset

Explanation

Age at clinical onset is the most critical prognostic factor in Legg-Calvé-Perthes disease. Children who develop the condition before 6 to 8 years of age have a better prognosis due to greater potential for acetabular remodeling.

Question 228

Topic: Pediatric Hip

What is the approximate rate of bilateral involvement in patients presenting with Slipped Capital Femoral Epiphysis (SCFE)?

. 5-10%
. 20-40%
. 60-80%
. 85-95%
. 100%

Correct Answer & Explanation

. 20-40%

Explanation

Bilateral involvement in SCFE occurs in 20-40% of cases, with up to half presenting simultaneously. Patients with endocrinopathies or who present at an atypically young age have an even higher risk of bilaterality.

Question 229

Topic: Pediatric Hip

In the Graf classification for developmental dysplasia of the hip (DDH) using ultrasound, what does the alpha angle measure?

. The cartilaginous roof coverage
. The bony acetabular roof concavity
. The dynamic instability of the femoral head
. The distance from the femoral head to the teardrop
. The version of the acetabulum

Correct Answer & Explanation

. The bony acetabular roof concavity

Explanation

The alpha angle in Graf's ultrasound evaluation measures the concavity of the bony acetabular roof. A normal alpha angle is typically greater than 60 degrees. The beta angle assesses the cartilaginous roof.

Question 230

Topic: Pediatric Hip

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

. Age older than 14 years
. Female gender
. Presence of an endocrine disorder
. Presence of an ipsilateral joint effusion
. BMI less than 25

Correct Answer & Explanation

. Presence of an endocrine disorder

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) significantly increase the risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these patients.

Question 231

Topic: Pediatric Hip

A 4-month-old female infant is diagnosed with developmental dysplasia of the hip (DDH). Dynamic ultrasound confirms a dislocated but reducible left hip. What is the most appropriate initial management for this patient?

. Closed reduction and spica casting
. Open reduction and capsulorrhaphy
. Pavlik harness application
. Rigid hip abduction orthosis
. Observation and repeat ultrasound in 4 weeks

Correct Answer & Explanation

. Pavlik harness application

Explanation

For infants under 6 months of age with a reducible dislocated hip, a Pavlik harness is the gold standard initial treatment. It maintains the hip in flexion and abduction to promote concentric reduction and acetabular remodeling.

Question 232

Topic: Pediatric Hip
A 12-year-old boy diagnosed with slipped capital femoral epiphysis (SCFE) of the left hip undergoes in situ single-screw fixation. Prophylactic pinning of the asymptomatic contralateral right hip is most strongly indicated if the patient has which of the following?
. A body mass index (BMI) greater than the 95th percentile
. An underlying endocrine disorder or renal osteodystrophy
. A severe (Grade III) slip on the symptomatic side
. A history of previous developmental dysplasia of the hip (DDH)
. A chronologic age of 14 years or older

Correct Answer & Explanation

. An underlying endocrine disorder or renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine disorders (e.g., hypothyroidism) or renal failure. These patients have a significantly higher risk of bilateral involvement compared to idiopathic cases.

Question 233

Topic: Pediatric Hip

When evaluating an infant with suspected developmental dysplasia of the hip (DDH) using coronal ultrasound, the alpha angle is measured. What does the alpha angle represent, and what is its normal value?

. Measures the cartilaginous roof and should be less than 55 degrees
. Measures the percentage of femoral head coverage and should be greater than 50 percent
. Measures the bony acetabular roof and should be greater than 60 degrees
. Measures the acetabular anteversion and should be greater than 20 degrees
. Measures the labral inversion angle and should be less than 43 degrees

Correct Answer & Explanation

. Measures the bony acetabular roof and should be greater than 60 degrees

Explanation

In the Graf method of neonatal hip ultrasound, the alpha angle quantifies the bony concavity of the acetabulum (bony roof). An alpha angle of greater than 60 degrees is considered normal (Graf Type I).

Question 234

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 3-week history of groin pain and a limp. Examination reveals obligatory external rotation with hip flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). What is the most appropriate standard surgical management?

. Spica casting
. In situ pinning with a single cannulated screw
. Open reduction and internal fixation
. Prophylactic pinning of the contralateral hip only
. Proximal femoral osteotomy

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

The gold standard treatment for a stable SCFE is in situ percutaneous pinning using a single partially threaded cannulated screw. This prevents further slippage while minimizing the risk of avascular necrosis and chondrolysis.

Question 235

Topic: Pediatric Hip

A 13-year-old obese boy presents with an insidious onset of knee pain and a limp. A pelvic radiograph is obtained.

Which of the following radiographic lines is most appropriate to evaluate for Slipped Capital Femoral Epiphysis (SCFE)?

. Shenton's line
. Klein's line
. Hilgenreiner's line
. Perkin's line
. Skinner's line

Correct Answer & Explanation

. Klein's line

Explanation

Klein's line is drawn along the superior margin of the femoral neck on an AP and frog-leg lateral radiograph. In a normal hip, it intersects the lateral portion of the femoral epiphysis; in SCFE, the epiphysis falls below this line.

Question 236

Topic: Pediatric Hip

An obese 13-year-old boy presents with left knee pain and an obligate external rotation of the hip during flexion. The radiograph is shown below.

When treating this condition with in situ percutaneous pinning, what is the most significant iatrogenic risk factor for the development of chondrolysis?

. Prophylactic pinning of the contralateral hip
. In situ fixation using a single fully-threaded screw
. Unrecognized intra-articular hardware penetration
. Delayed surgical intervention beyond 4 weeks
. Starting the screw on the anterior aspect of the femoral neck

Correct Answer & Explanation

. Unrecognized intra-articular hardware penetration

Explanation

In Slipped Capital Femoral Epiphysis (SCFE), unrecognized intra-articular screw penetration is a major risk factor for chondrolysis. Surgeons must use the "approach-withdraw" fluoroscopic technique to confirm the screw tip is entirely within the femoral head.

Question 237

Topic: Pediatric Hip

A 6-month-old infant with developmental dysplasia of the hip (DDH) failed Pavlik harness treatment and is scheduled for a closed reduction and spica casting. During the procedure, the surgeon assesses the "safe zone" of Ramsey. How is this zone defined?

. The arc of motion between maximum adduction and maximum internal rotation
. The arc of motion between maximum abduction and the angle of re-dislocation in adduction
. The arc between maximum hip flexion and full extension
. The degree of coverage of the femoral head by the acetabulum measured fluoroscopically
. The alpha angle measured dynamically on intraoperative ultrasound

Correct Answer & Explanation

. The arc of motion between maximum abduction and the angle of re-dislocation in adduction

Explanation

Ramsey's safe zone is the arc of motion between maximum abduction (limited by the adductors) and the angle at which the hip re-dislocates as it is adducted. Immobilization within this zone prevents both avascular necrosis (from excessive abduction) and re-dislocation.

Question 238

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of right groin pain and a slight limp. On physical examination, as the right hip is passively flexed, it obligatorily deviates into external rotation. What is the eponymous name of this clinical sign?

. Ortolani sign
. Barlow sign
. Galeazzi sign
. Drehmann sign
. Trendelenburg sign

Correct Answer & Explanation

. Drehmann sign

Explanation

The Drehmann sign is the obligatory external rotation of the hip during passive flexion. It is a classic and highly indicative physical examination finding in patients with a slipped capital femoral epiphysis (SCFE).

Question 239

Topic: Pediatric Hip

A 4-month-old girl is placed in a Pavlik harness for developmental dysplasia of the hip. At a follow-up visit 2 weeks later, the parents report the infant has stopped kicking her left leg. On exam, she lacks active knee extension on the left. What is the most likely cause?

. Obturator nerve palsy due to excessive abduction
. Femoral nerve palsy due to excessive hip flexion
. Sciatic nerve palsy due to excessive extension
. Avascular necrosis of the femoral head
. Incarcerated labrum

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Excessive hip flexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament. Treatment involves loosening the anterior straps or temporarily discontinuing the harness.

Question 240

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of right groin pain and a limp. He walks with an externally rotated foot. AP and frog-leg lateral pelvis radiographs confirm a mild stable slipped capital femoral epiphysis (SCFE) on the right. What is the most appropriate management?

. Spica cast immobilization
. Closed reduction and internal fixation
. In situ pinning with a single cannulated screw
. Open reduction and subcapital osteotomy
. Core decompression

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

The gold standard treatment for a stable SCFE is in situ pinning with a single, centrally placed cannulated screw. Attempting closed reduction increases the risk of avascular necrosis.

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