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Pediatric Hip MCQs

Practice Set 47 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 921

Topic: Pediatric Hip

A 6-week-old female infant is currently being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report that the child has stopped kicking her right leg. Examination reveals decreased active extension of the right knee, while ankle movements and toe flexion are intact. Which nerve is most likely affected?

. Sciatic nerve
. Femoral nerve
. Obturator nerve
. Peroneal nerve
. Tibial nerve

Correct Answer & Explanation

. Sciatic nerve

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically resulting from hyperflexion of the hips. It presents with decreased active knee extension and usually resolves completely when the harness is removed or adjusted.

Question 922

Topic: Pediatric Hip

According to the Loder classification, which of the following defines an unstable slipped capital femoral epiphysis (SCFE)?

. A physeal slip angle greater than 50 degrees
. The inability of the patient to ambulate, with or without crutches
. The presence of a hip joint effusion on ultrasound
. Symptom duration of less than 3 weeks
. Slip displacement greater than 50% of the femoral neck width

Correct Answer & Explanation

. A physeal slip angle greater than 50 degrees

Explanation

The Loder classification defines an unstable SCFE as the inability to ambulate, even with the use of crutches. Unstable slips are associated with a significantly higher rate of avascular necrosis compared to stable slips.

Question 923

Topic: Pediatric Hip

Which of the following patient profiles represents the strongest absolute indication for prophylactic in situ pinning of the contralateral hip in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. A 12-year-old boy with a stable SCFE
. An 11-year-old girl with primary hypothyroidism
. A 14-year-old boy with an unstable SCFE
. A 13-year-old boy with a body mass index > 95th percentile
. A 15-year-old girl with an acute-on-chronic SCFE

Correct Answer & Explanation

. A 12-year-old boy with a stable SCFE

Explanation

Endocrinopathies, such as hypothyroidism or renal osteodystrophy, are strong indications for prophylactic contralateral pinning in SCFE. These patients have a significantly elevated risk of developing bilateral disease.

Question 924

Topic: Pediatric Hip

In the closed or open reduction of late-presenting developmental dysplasia of the hip (DDH), which of the following factors is most strongly associated with an increased risk of developing avascular necrosis (AVN) of the femoral head?

. Release of the transverse acetabular ligament
. Concomitant psoas tenotomy
. Post-reduction immobilization in excessive hip abduction
. Capsulorrhaphy during open reduction
. Excision of the ligamentum teres

Correct Answer & Explanation

. Release of the transverse acetabular ligament

Explanation

Immobilization of the hip in excessive abduction (the "frog-leg" position) causes mechanical compression of the retinacular vessels against the acetabular rim. This is the primary iatrogenic risk factor for AVN in the treatment of DDH.

Question 925

Topic: Pediatric Hip

A 13-year-old boy undergoes single-screw in situ pinning for a stable slipped capital femoral epiphysis (SCFE). Seven months postoperatively, he complains of worsening hip stiffness and global pain. Radiographs reveal symmetric hip joint space narrowing to less than 2 mm with no signs of hardware failure. What is the most likely diagnosis?

. Avascular necrosis
. Deep surgical site infection
. Implant failure with joint penetration
. Chondrolysis
. Femoral neck stress fracture

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute cartilage necrosis, presenting with marked stiffness, pain, and symmetric joint space narrowing on radiographs. It is strongly associated with unrecognized joint penetration by the hardware.

Question 926

Topic: Pediatric Hip

A 14-year-old boy with a severe, chronic slipped capital femoral epiphysis presents with severe impingement. The surgeon plans a corrective osteotomy at the apex of the deformity to restore anatomy. Which of the following procedures is an intracapsular osteotomy of the femoral neck that provides excellent correction but historically carries the highest risk of avascular necrosis?

. Southwick osteotomy
. Imhauser osteotomy
. Kramer osteotomy
. Dunn procedure
. Salter osteotomy

Correct Answer & Explanation

. Southwick osteotomy

Explanation

The Dunn procedure is an intracapsular, cuneiform osteotomy performed directly at the femoral neck to reduce a severe SCFE. Because it is intracapsular, it disrupts the retinacular blood supply and historically has a high risk of avascular necrosis.

Question 927

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor fall. Radiographs reveal a severe, posterior slip of the right capital femoral epiphysis. What is the recommended definitive management?

. Closed reduction and spica casting
. Gentle closed reduction and in-situ pinning with a single screw
. Open reduction and internal fixation through a surgical dislocation approach
. In-situ pinning with a single screw without reduction
. Subtrochanteric osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

Unstable SCFE has a high risk of AVN. Recent literature supports open reduction and internal fixation utilizing a surgical hip dislocation approach (modified Dunn procedure) to decompress the intracapsular hematoma and restore anatomy.

Question 928

Topic: Pediatric Hip

A 13-year-old boy undergoes in-situ pinning for a left-sided SCFE. Which of the following is the strongest indication for prophylactic pinning of the contralateral asymptomatic hip?

. Obesity (BMI > 95th percentile)
. Age greater than 14 years
. Male sex
. Endocrine disorder (e.g., hypothyroidism)
. Slips greater than 50 degrees

Correct Answer & Explanation

. Obesity (BMI > 95th percentile)

Explanation

Endocrine disorders, such as hypothyroidism or renal osteodystrophy, strongly predispose patients to bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in this population.

Question 929

Topic: Pediatric Hip

A 14-year-old boy with a history of a chronic, stable slipped capital femoral epiphysis pinned in-situ 1 year ago presents with increasing hip pain and stiffness. Radiographs show joint space narrowing and subchondral cysts in both the femoral head and acetabulum. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Pin penetration into the joint
. Cam impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is a severe complication of SCFE characterized by progressive joint space narrowing and stiffness. It is strongly associated with unrecognized intra-articular hardware penetration during pinning.

Question 930

Topic: Pediatric Hip

On an AP pelvis radiograph of a 12-year-old patient with suspected early SCFE, which line is drawn along the superior margin of the femoral neck to check for intersection with the lateral epiphysis?

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

Correct Answer & Explanation

. Shenton's line

Explanation

Klein's line is drawn along the superior aspect of the femoral neck on an AP radiograph. In a normal hip, it should intersect the lateral aspect of the femoral epiphysis.

Question 931

Topic: Pediatric Hip

In a slipped capital femoral epiphysis, the displacement of the femoral neck relative to the capital epiphysis is typically in which direction?

. Posterior and medial
. Anterior and lateral
. Posterior and lateral
. Anterior and medial
. Superior and lateral

Correct Answer & Explanation

. Posterior and medial

Explanation

In SCFE, the epiphysis stays relatively fixed in the acetabulum while the femoral neck displaces anteriorly, laterally, and externally rotates relative to the epiphysis.

Question 932

Topic: Pediatric Hip

While performing a closed reduction and spica casting for a 9-month-old with DDH, what is the optimal "safe zone" of Ramsey to ensure joint stability while minimizing the risk of avascular necrosis?

. Maximal abduction and internal rotation
. The arc between the angle of redislocation (adduction) and the angle of maximal abduction
. The arc between 0 degrees and 30 degrees of flexion
. The arc between maximal internal and external rotation
. 90 degrees of flexion and 90 degrees of abduction

Correct Answer & Explanation

. Maximal abduction and internal rotation

Explanation

The safe zone of Ramsey is the arc of abduction between the angle where the hip redislรณcates and the angle of maximal abduction. Extreme abduction dramatically increases the risk of avascular necrosis.

Question 933

Topic: Pediatric Hip

When performing in-situ percutaneous pinning of a severe slipped capital femoral epiphysis, the starting point for the guide wire on the lateral femur should be:

. Distal to the lesser trochanter
. At the level of the greater trochanteric tip
. Anterior and proximal on the femoral neck
. Anterior to the mid-axial line of the proximal femur
. At the exact center of the lateral cortex

Correct Answer & Explanation

. Distal to the lesser trochanter

Explanation

Because the femoral neck displaces anteriorly and externally rotates, the starting point for the screw must be more anterior and proximal on the femoral neck to achieve the correct trajectory.

Question 934

Topic: Pediatric Hip

A 4-month-old girl is currently being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Her mother reports that the infant has stopped actively extending her knee on the treated side. Which of the following is the most appropriate next step in management?

. Increase the hip flexion in the harness to improve stability
. Reassure the mother and continue the current harness settings
. Discontinue the harness temporarily or adjust to decrease hip flexion
. Switch immediately to a rigid hip spica cast
. Perform an emergent closed reduction in the operating room

Correct Answer & Explanation

. Increase the hip flexion in the harness to improve stability

Explanation

Decreased active knee extension in a Pavlik harness suggests a femoral nerve palsy, typically caused by hyperflexion of the hip. The harness should be temporarily removed or adjusted to decrease flexion until neurologic function returns.

Question 935

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with acute-onset left hip pain after tripping. He is completely unable to bear weight on the left leg, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant complication risk associated with this specific presentation?

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

Correct Answer & Explanation

. Chondrolysis

Explanation

According to the Loder classification, a SCFE is unstable if the patient cannot bear weight even with crutches. Unstable slips carry a significantly higher risk of avascular necrosis (AVN), historically reported to be up to 47%.

Question 936

Topic: Pediatric Hip

A 2-year-old girl is diagnosed with untreated developmental dysplasia of the left hip. Radiographs show a dislocated left hip with a false acetabulum and an acetabular index of 42 degrees. Which of the following surgical strategies is most appropriate for achieving a stable, concentric reduction?

. Closed reduction and spica casting
. Open reduction alone
. Open reduction with a pelvic osteotomy and possible femoral shortening
. In situ shelf arthroplasty
. Pavlik harness trial

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In a child older than 18-24 months, open reduction is typically required. Due to secondary adaptive changes like severe acetabular dysplasia and capsular laxity, a concomitant pelvic osteotomy (and often femoral shortening) is necessary to maintain stability.

Question 937

Topic: Pediatric Hip

An 11-year-old girl with chronic kidney disease secondary to focal segmental glomerulosclerosis presents with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral, asymptomatic hip in this patient?

. Her age at presentation
. Her sex
. Her underlying endocrinopathy or renal osteodystrophy
. The severity of the unilateral slip
. Presence of a positive Drehmann sign on the affected side

Correct Answer & Explanation

. Her age at presentation

Explanation

Patients with underlying metabolic or endocrine disorders (such as renal osteodystrophy, hypothyroidism, or growth hormone therapy) have a high rate of bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in these populations.

Question 938

Topic: Pediatric Hip

During the percutaneous pinning of a stable slipped capital femoral epiphysis (SCFE), the surgeon uses the approach-withdraw technique under fluoroscopy. Unrecognized pin penetration into the joint space most directly increases the risk of which of the following complications?

. Avascular necrosis
. Chondrolysis
. Implant failure
. Slip progression
. Femoral neck fracture

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized hardware penetration into the joint space is a major risk factor for chondrolysis. Fluoroscopic evaluation with continuous internal-external rotation (approach-withdraw technique) is critical to confirm the pin is completely within the bone.

Question 939

Topic: Pediatric Hip

A 6-week-old female has been treated with a Pavlik harness for 2 weeks for Developmental Dysplasia of the Hip (DDH). Her mother reports that the baby is no longer kicking her right leg. Examination reveals decreased active extension of the right knee, while toe and ankle movements remain normal. What is the most appropriate next step in management?

. Adjust the harness to increase hip flexion
. Perform immediate closed reduction and spica casting
. Adjust the harness to decrease hip abduction
. Discontinue the harness or decrease hip flexion until function returns
. Continue the current settings as this is a transient normal finding

Correct Answer & Explanation

. Adjust the harness to increase hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip hyperflexion compressing the nerve against the pelvis. The appropriate management is to temporarily discontinue the harness or significantly loosen the flexion straps until active quadriceps function returns, which usually occurs within a few days.

Question 940

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with severe acute hip pain after a minor fall and is completely unable to bear weight. Radiographs confirm a severe, displaced slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant long-term risk associated with this specific presentation?

. Avascular necrosis (AVN)
. Chondrolysis
. Cam impingement
. Premature osteoarthritis
. Slipped contralateral epiphysis

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 SCFE carries a significantly high risk of avascular necrosis (AVN), historically reported to be between 20% and 50%.

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