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Pediatric Hip MCQs

Practice Set 71 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 1401

Topic: Pediatric Hip

A 13-year-old obese boy presents with severe, sudden hip pain and inability to bear weight after a minor fall, superimposed on months of mild groin pain. In an unstable slipped capital femoral epiphysis (SCFE), which vessel is at greatest risk of injury leading to osteonecrosis?

. Ligamentum teres artery
. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Inferior gluteal artery
. Obturator artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery, specifically its posterosuperior retinacular branches, provides the primary blood supply to the femoral head. It is at the highest risk of disruption in an unstable SCFE.

Question 1402

Topic: Pediatric Hip

A 4-month-old female with Developmental Dysplasia of the Hip (DDH) is being treated in a Pavlik harness. During a follow-up visit, the parents note she has stopped kicking her leg on the affected side. On exam, she has an absent patellar reflex and cannot actively extend the knee. Which of the following positioning errors most likely caused this complication?

. Excessive abduction
. Excessive hip flexion
. Excessive hip extension
. Inadequate hip flexion
. Inadequate abduction

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip flexion (hyperflexion), which compresses the femoral nerve against the inguinal ligament. It presents as an inability to actively extend the knee. Excessive abduction is associated with avascular necrosis of the femoral head.

Question 1403

Topic: Pediatric Hip

A 12-year-old boy presents with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. He is scheduled for in situ screw fixation. Which of the following factors is the strongest indication for prophylactic pinning of the contralateral, asymptomatic hip?

. Age at presentation less than 10 years
. Presence of an underlying endocrine disorder
. Initial slip angle greater than 50 degrees
. Body mass index greater than the 95th percentile
. African American ethnicity

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) have a significantly higher risk of developing bilateral SCFE, approaching 100% in some series. Prophylactic pinning of the contralateral hip is highly recommended in these cases.

Question 1404

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following radiographic criteria places the hip in Group B?
. No involvement of the lateral pillar
. Greater than 50% maintenance of lateral pillar height
. Less than 50% maintenance of lateral pillar height
. Complete collapse of the entire epiphysis including the medial pillar
. Extrusion of the lateral pillar without any loss of height

Correct Answer & Explanation

. Less than 50% maintenance of lateral pillar height

Explanation

In the Herring Lateral Pillar Classification for Perthes disease: Group A has no involvement of the lateral pillar. Group B has >50% maintenance of lateral pillar height. Group C has <50% maintenance of lateral pillar height. The classification strongly correlates with long-term sphericity of the femoral head.

Question 1405

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe right hip pain after a minor fall. He is completely unable to bear weight on the right leg. Radiographs reveal a slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the primary clinical significance of this presentation?

. It implies an acute-on-chronic slip.
. It indicates a high risk for subsequent chondrolysis.
. It designates an "unstable" SCFE, which carries a much higher risk of avascular necrosis (AVN).
. It mandates immediate open reduction via surgical dislocation.
. It suggests that contralateral prophylactic pinning is unnecessary.

Correct Answer & Explanation

. It designates an "unstable" SCFE, which carries a much higher risk of avascular necrosis (AVN).

Explanation

The Loder classification divides SCFE into stable (able to bear weight) and unstable (unable to bear weight, even with crutches). Unstable SCFE has a significantly higher risk of avascular necrosis (nearly 50%) compared to stable SCFE.

Question 1406

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 99th percentile presents to the emergency department with acute-on-chronic hip pain and is unable to bear weight on the affected limb. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following defines an 'unstable' SCFE according to the Loder classification, and what is its most devastating complication?

. Displacement > 50%; Chondrolysis
. Inability to bear weight; Avascular necrosis (AVN)
. Presence of an effusion; Degenerative joint disease
. Duration of symptoms < 3 weeks; Femoral neck fracture
. Inability to ambulate without crutches; Chondrolysis

Correct Answer & Explanation

. Inability to bear weight; Avascular necrosis (AVN)

Explanation

According to the Loder classification, an unstable SCFE is defined by the patient's inability to bear weight, even with assistive devices. Unstable slips carry a significantly higher risk (up to 50%) of developing avascular necrosis (AVN) of the femoral head compared to stable slips.

Question 1407

Topic: Pediatric Hip

A 12-year-old obese male undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). Postoperatively, he develops severe hip pain and restriction of all hip movements. Radiographs show joint space narrowing without a joint effusion. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Implant failure
. Labral tear

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage and diffuse joint space narrowing. It presents with severe stiffness and pain, often linked to unrecognized intra-articular hardware penetration.

Question 1408

Topic: Pediatric Hip
The lateral pillar classification (Herring) is widely used for prognostication in Legg-Calvé-Perthes disease. In a Herring Group C hip, what is the radiographic appearance of the lateral pillar of the femoral head?
. No radiolucency in the lateral pillar
. Greater than 50% maintenance of lateral pillar height
. Exactly 50% maintenance of lateral pillar height
. Less than 50% maintenance of lateral pillar height
. Complete extrusion of the lateral pillar

Correct Answer & Explanation

. Less than 50% maintenance of lateral pillar height

Explanation

The Herring classification evaluates the height of the lateral portion of the femoral head on an AP radiograph during the fragmentation phase. Group C is defined as less than 50% maintenance of normal lateral pillar height, and it carries the worst prognosis.

Question 1409

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant exhibits decreased spontaneous extension of the knee on the treated side. What is the most likely cause?

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

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, classically caused by hyperflexion of the hip. It presents with decreased active knee extension. The harness must be adjusted (decreasing flexion) or temporarily discontinued to allow nerve recovery. Excessive abduction is linked to avascular necrosis.

Question 1410

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is an accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Patient age over 15 years
. Male gender
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. An initial slip angle of less than 30 degrees
. Presence of a closed triradiate cartilage

Correct Answer & Explanation

. Presence of an underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is recommended for patients at high risk of bilateral disease. High-risk factors include underlying endocrine/metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism), prior radiation, or very young age (open triradiate cartilage). Older age and closed triradiate cartilage are lower risk.

Question 1411

Topic: Pediatric Hip

A 13-year-old obese male presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) and is unable to bear weight. He is scheduled for in-situ pinning. What is the primary proposed advantage of performing an incidental hip capsulotomy during the surgical fixation of this unstable SCFE?

. To directly visualize and anatomically reduce the slipped epiphysis.
. To repair the torn labrum commonly associated with acute SCFE.
. To reduce intracapsular tamponade pressure and theoretically decrease the risk of avascular necrosis (AVN).
. To promote faster fusion of the physis by introducing inflammatory mediators.
. To retrieve loose chondral fragments from the joint space.

Correct Answer & Explanation

. To reduce intracapsular tamponade pressure and theoretically decrease the risk of avascular necrosis (AVN).

Explanation

In unstable SCFE (defined by the inability to bear weight), the risk of avascular necrosis (AVN) is significantly higher (up to 50%). Performing an anterior capsulotomy decompresses the intracapsular hematoma, reducing tamponade effect on the delicate retinacular vessels, thereby theoretically decreasing the risk of AVN.

Question 1412

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, she demonstrates an inability to actively extend the knee on the treated side. Which of the following harness positioning errors is the most likely cause?

. Excessive hip flexion
. Excessive hip abduction
. Inadequate hip flexion
. Excessive knee flexion
. Excessive hip adduction

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and is typically caused by excessive hip flexion, which stretches or compresses the femoral nerve. Excessive hip abduction, on the other hand, is associated with a higher risk of avascular necrosis (AVN) of the femoral head.

Question 1413

Topic: Pediatric Hip
The Herring lateral pillar classification is used to predict the prognosis in Legg-Calvé-Perthes disease. This classification relies on assessing the height of the lateral pillar on an AP pelvic radiograph. During which stage of the disease must this assessment be made for it to be prognostically valid?
. Initial (Necrosis) stage
. Fragmentation stage
. Reossification stage
. Healed (Residual) stage
. Pre-symptomatic stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring lateral pillar classification evaluates the height of the lateral portion of the capital femoral epiphysis. To be prognostically accurate, it must be determined during the early fragmentation stage of Legg-Calvé-Perthes disease, when the extent of epiphyseal involvement is maximally apparent.

Question 1414

Topic: Pediatric Hip
A 4-month-old female is evaluated for asymmetric thigh folds. Ultrasound of the hip reveals an alpha angle of 40 degrees and a beta angle of 80 degrees. According to the Graf classification for Developmental Dysplasia of the Hip (DDH), what is the appropriate interpretation and recommended next step?
. Graf Type I: Normal hip, no treatment needed
. Graf Type IIa: Physiologic immaturity, repeat ultrasound in 4 weeks
. Graf Type IIb: Mild dysplasia, observe
. Graf Type III: Subluxated hip, initiate Pavlik harness treatment
. Graf Type IV: Dislocated hip, requires immediate open reduction

Correct Answer & Explanation

. Graf Type III: Subluxated hip, initiate Pavlik harness treatment

Explanation

According to the Graf classification, a Type III hip (subluxated) is characterized by an alpha angle of less than 43 degrees and a beta angle greater than 77 degrees, indicating no cartilaginous roof coverage. The appropriate next step in a 4-month-old is conservative treatment with an abduction orthosis, such as a Pavlik harness.

Question 1415

Topic: Pediatric Hip

A 12-year-old obese boy undergoes in-situ percutaneous single screw fixation for a stable slipped capital femoral epiphysis (SCFE). Which of the following screw positions on fluoroscopy places the hip at the highest risk for unrecognized joint penetration and subsequent chondrolysis?

. Anterior-superior quadrant of the femoral head
. Anterior-inferior quadrant of the femoral head
. Posterior-superior quadrant of the femoral head
. Posterior-inferior quadrant of the femoral head
. Direct central position

Correct Answer & Explanation

. Anterior-superior quadrant of the femoral head

Explanation

The primary cause of chondrolysis following SCFE fixation is unrecognized pin/screw penetration into the joint space. The 'blind spot' during fluoroscopic imaging (AP and frog-leg lateral) is the anterior-superior quadrant of the femoral head. Screws placed in this quadrant can appear to be within bone on standard views despite actually penetrating the articular cartilage.

Question 1416

Topic: Pediatric Hip

A 12-year-old obese male presents with an acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE). Which of the following is considered an absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Female gender
. Presence of an endocrine disorder
. Body mass index > 95th percentile
. Bilateral hip pain on presentation

Correct Answer & Explanation

. Presence of an endocrine disorder

Explanation

The presence of an endocrinopathy (such as hypothyroidism or renal osteodystrophy) is an absolute indication for prophylactic pinning of the contralateral hip due to the high risk of bilateral involvement.

Question 1417

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Hyperflexion of the hips in the harness puts the patient at highest risk for which complication?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can compress the femoral nerve against the inguinal ligament, causing a transient femoral nerve palsy. Excessive abduction increases the risk of avascular necrosis.

Question 1418

Topic: Pediatric Hip

A 13-year-old obese boy presents with 3 weeks of insidious onset left groin and thigh pain. He walks with a limp and exhibits an externally rotated foot progression angle. On examination, as the left hip is flexed, it obligately externally rotates. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following represents the primary mechanism of displacement?

. The epiphysis displaces anteriorly and superiorly relative to the metaphysis
. The metaphysis displaces anteriorly and superiorly relative to the epiphysis
. The epiphysis displaces anteriorly and inferiorly relative to the metaphysis
. The metaphysis displaces posteriorly and inferiorly relative to the epiphysis
. The epiphysis displaces posteriorly and superiorly relative to the metaphysis

Correct Answer & Explanation

. The metaphysis displaces anteriorly and superiorly relative to the epiphysis

Explanation

In SCFE, the epiphysis actually remains relatively tethered within the acetabulum while the femoral neck (metaphysis) displaces anteriorly and superiorly relative to the epiphysis.

Question 1419

Topic: Pediatric Hip

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

. Body mass index greater than the 95th percentile
. Male gender
. Diagnosis of an underlying endocrine disorder (e.g., hypothyroidism)
. Initial slip angle greater than 50 degrees
. Presentation with an acute-on-chronic slip

Correct Answer & Explanation

. Diagnosis of an underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with an underlying endocrinopathy (such as hypothyroidism or panhypopituitarism), renal osteodystrophy, or prior radiation therapy, due to a significantly elevated risk of developing bilateral disease compared to idiopathic SCFE.

Question 1420

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents note that the infant has stopped kicking her left leg. Examination reveals active hip flexion is absent, but hip adduction and ankle movements are intact. Which of the following is the most likely cause of this complication?

. Excessive abduction of the hip in the harness
. Excessive flexion of the hip in the harness
. Inadequate flexion of the hip leading to re-dislocation
. Ischemic necrosis of the capital femoral epiphysis
. Entrapment of the sciatic nerve

Correct Answer & Explanation

. Excessive flexion of the hip in the harness

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and presents with decreased active hip flexion and knee extension. It is typically caused by excessive hip flexion in the harness, and management involves adjusting the straps to reduce flexion or temporarily discontinuing the harness.

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