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Pediatric Hip MCQs

Practice Set 35 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 681

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). After 3 weeks of treatment, the hip remains persistently dislocated. Which of the following ultrasonographic findings is the most significant anatomic predictor of harness failure?

. Alpha angle of 55 degrees
. Beta angle of 60 degrees
. Absence of the os acetabuli
. Interposed inverted limbus or pulvinar
. Graf Type IIa classification

Correct Answer & Explanation

. Interposed inverted limbus or pulvinar

Explanation

An interposed inverted limbus, thick pulvinar, contracted transverse acetabular ligament, or a tight iliopsoas tendon are intra-articular and extra-articular blocks to reduction. Their presence on imaging strongly predicts the failure of non-operative management (Pavlik harness) and often necessitates a closed or open reduction.

Question 682

Topic: Pediatric Hip

A 6-week-old female infant is placed in a Pavlik harness for developmental dysplasia of the hip (DDH). One week later, the parents report that the infant is no longer actively kicking her right leg. On examination, there is an absence of active knee extension on the right side. Which of the following is the most likely cause of this complication?

. Obturator nerve palsy due to hyperabduction
. Femoral nerve palsy due to hyperflexion
. Sciatic nerve palsy due to extreme extension
. Superior gluteal nerve palsy due to internal rotation
. Lateral femoral cutaneous nerve palsy due to strap pressure

Correct Answer & Explanation

. Femoral nerve palsy due to hyperflexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive flexion of the hip. The hyperflexion causes the femoral nerve to become compressed against the inguinal ligament. Presentation includes loss of active quadriceps function (lack of active knee extension). The treatment is to temporarily remove or adjust the harness to reduce flexion, and the palsy almost always resolves spontaneously.

Question 683

Topic: Pediatric Hip

When placing a single in situ screw for a slipped capital femoral epiphysis (SCFE), an incorrectly positioned starting point and trajectory can lead to catastrophic complications. Placement of the screw into which quadrant of the femoral head carries the highest risk of unrecognized joint penetration and damage to the primary blood supply, risking avascular necrosis (AVN)?

. Anterosuperior
. Anteroinferior
. Posterosuperior
. Posteroinferior
. Direct central

Correct Answer & Explanation

. Anterosuperior

Explanation

The anterosuperior quadrant of the femoral head is the 'danger zone' during SCFE pinning. Because the epiphysis slips posteriorly and inferiorly, the anterior and superior aspect of the metaphysis becomes prominent. A screw directed anterosuperiorly is likely to exit the metaphysis and penetrate the joint space unrecognized. Furthermore, the lateral epiphyseal vessels, which provide the primary blood supply to the femoral head, enter in this region; injuring them significantly increases the risk of AVN. Screws should ideally be placed in the center-center position.

Question 684

Topic: Pediatric Hip

A 3-month-old infant in a Pavlik harness for developmental dysplasia of the hip (DDH) develops decreased active knee extension on the treated side. Which of the following harness positions is the most likely cause of this complication?

. Excessive abduction
. Excessive flexion
. Insufficient abduction
. Insufficient flexion
. Excessive external rotation

Correct Answer & Explanation

. Excessive flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, presenting as decreased active quadriceps function (lack of active knee extension). It is typically caused by hyperflexion of the hip, which impinges the femoral nerve against the inguinal ligament. Treatment involves temporary removal of the harness or adjusting the anterior straps to decrease hip flexion. Excessive abduction is associated with avascular necrosis (AVN) of the femoral head.

Question 685

Topic: Pediatric Hip

A 12-year-old obese male presents with left hip pain and an obligatory external rotation of the thigh during passive hip flexion. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE) on the left. His contralateral right hip is asymptomatic and radiographically normal. Which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic right hip?

. Patient's chronologic age of 12 years
. Body Mass Index (BMI) greater than the 95th percentile
. Presentation with an underlying endocrine disorder
. A slip angle of 30 degrees on the symptomatic side
. Male sex

Correct Answer & Explanation

. Presentation with an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral asymptomatic hip in SCFE is generally indicated in patients with an underlying endocrinopathy (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency), as they have a significantly higher risk of developing a bilateral slip, approaching 100% in some series. Other accepted indications include an inability to follow up and presentation at an atypically young age (<10 years).

Question 686

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an obligate external rotation of the hip during passive flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following accurately describes the anatomic displacement in SCFE?

. The epiphysis displaces anteriorly and laterally relative to the metaphysis.
. The metaphysis displaces anteriorly and externally rotates relative to the epiphysis.
. The epiphysis displaces superiorly and anteriorly.
. Klein's line intersects a larger portion of the epiphysis compared to the normal side.
. The metaphysis displaces posteriorly and medially.

Correct Answer & Explanation

. The metaphysis displaces anteriorly and externally rotates relative to the epiphysis.

Explanation

In SCFE, the femoral head (epiphysis) actually remains anatomically seated in the acetabulum. The deformity is created by the femoral neck (metaphysis) displacing anteriorly and externally rotating relative to the epiphysis. Consequently, it appears as though the epiphysis has slipped posteriorly and medially. Klein's line (drawn along the superior femoral neck) will intersect LESS of the epiphysis on the affected side.

Question 687

Topic: Pediatric Hip

A 3-year-old girl is diagnosed with late-presenting developmental dysplasia of the hip (DDH). She undergoes an open reduction and a pelvic osteotomy. The surgeon performs a redirectional, complete innominate osteotomy that hinges on the pubic symphysis to provide anterolateral coverage of the femoral head. Which osteotomy was performed?

. Pemberton osteotomy
. Dega osteotomy
. Salter osteotomy
. Chiari osteotomy
. Steel triple osteotomy

Correct Answer & Explanation

. Salter osteotomy

Explanation

The Salter osteotomy is a complete, trans-iliac redirectional osteotomy that hinges on the pubic symphysis to provide primarily anterolateral coverage for DDH. The Pemberton is an incomplete osteotomy that hinges on the triradiate cartilage, reducing acetabular volume. The Dega is also incomplete, hinging on the triradiate, but focuses on lateral and posterior coverage. The Chiari is a salvage capsular interposition osteotomy. Steel is a triple osteotomy (ilium, ischium, pubis).

Question 688

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The parents report that the child has stopped actively kicking the knee on the affected side. On examination, there is decreased active knee extension, but the patellar reflex is absent. Which of the following is the most likely cause of this complication?

. Excessive hip abduction
. Excessive hip flexion
. Inadequate hip flexion
. Excessive knee extension
. Direct pressure on the fibular head

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip flexion causing compression of the femoral nerve against the inguinal ligament. It presents with decreased active knee extension. Treatment involves loosening the anterior straps or temporarily discontinuing the harness until nerve function recovers.

Question 689

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip is most strongly indicated and routinely recommended for which of the following patients presenting with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. An 11-year-old girl with an idiopathic SCFE and closed triradiate cartilages
. A 12-year-old boy with a BMI in the 85th percentile
. A 10-year-old boy with renal osteodystrophy
. A 14-year-old boy with normal endocrine function
. A 15-year-old girl with an acute-on-chronic SCFE

Correct Answer & Explanation

. A 10-year-old boy with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is indicated in patients at high risk for a sequential slip. Endocrine or metabolic disorders (such as renal osteodystrophy, hypothyroidism, or panhypopituitarism) carry a very high risk of bilateral involvement. Open triradiate cartilage (indicating young age) is another relative indication.

Question 690

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a severe left slipped capital femoral epiphysis (SCFE) and undergoes in-situ pinning. Which of the following factors is the strongest absolute indication for performing a prophylactic pinning of the contralateral asymptomatic hip?

. Endocrine disorder (e.g., hypothyroidism)
. Male gender
. Modified Oxford Bone Age score of 18
. Body Mass Index in the 85th percentile
. Presentation with acute-on-chronic symptoms

Correct Answer & Explanation

. Endocrine disorder (e.g., hypothyroidism)

Explanation

Patients with an underlying endocrinopathy (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) have an extremely high risk of bilateral SCFE (up to 100% in some series) and often present at an atypical age. Prophylactic pinning of the contralateral hip is strongly indicated in these patients. A low Modified Oxford Bone Age score (<16) also predicts higher risk, while a score of 18 implies skeletal maturity with minimal risk.

Question 691

Topic: Pediatric Hip

Which of the following factors is the most significant clinical predictor for the development of avascular necrosis (AVN) following a slipped capital femoral epiphysis (SCFE)?

. Body mass index (BMI) over the 95th percentile
. Severe slip angle (> 50 degrees)
. Instability of the slip (inability to bear weight)
. Age of the patient at the time of onset
. Underlying endocrine dysfunction

Correct Answer & Explanation

. Instability of the slip (inability to bear weight)

Explanation

The stability of the SCFE, defined by Loder as the ability or inability to bear weight (even with crutches), is the most important prognostic factor for AVN. Unstable SCFE has an AVN rate approaching 20-50%, whereas stable SCFE has an AVN rate of nearly 0%.

Question 692

Topic: Pediatric Hip

A 4-month-old female infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). After 3-4 weeks of verified, continuous proper harness wear, ultrasound confirms the hip remains completely dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Switch to an Ilfeld splint for rigid abduction
. Abandon the harness and proceed to closed reduction and spica casting
. Perform an immediate open reduction and pelvic osteotomy
. Discontinue the harness and wait until walking age to re-evaluate

Correct Answer & Explanation

. Abandon the harness and proceed to closed reduction and spica casting

Explanation

If a hip remains dislocated after 3 to 4 weeks of proper Pavlik harness treatment, the harness must be abandoned. Continuing it increases the risk of 'Pavlik harness disease' (posterior acetabular damage) and AVN. The next standard step is closed reduction and spica casting, possibly preceded by rigid orthosis trial or traction, but closed reduction is the definitive next step.

Question 693

Topic: Pediatric Hip
A 4-week-old infant is referred for management of Developmental Dysplasia of the Hip (DDH). Which of the following conditions represents an absolute contraindication for the use of a Pavlik harness?
. Bilateral hip dislocation
. Age less than 6 weeks
. Teratologic hip dislocation (e.g., Arthrogryposis multiplex congenita)
. An alpha angle of 45 degrees on ultrasound
. A Barlow-positive, Ortolani-negative hip

Correct Answer & Explanation

. Teratologic hip dislocation (e.g., Arthrogryposis multiplex congenita)

Explanation

The use of a Pavlik harness relies on normal muscle function and active motion to achieve and maintain hip reduction. Teratologic hip dislocations (associated with syndromes such as arthrogryposis or spina bifida) exhibit severe muscle imbalance or contractures. In these cases, a Pavlik harness is absolutely contraindicated due to a high failure rate and an increased risk of complications. Other absolute contraindications include failure to achieve reduction after 3-4 weeks of use, or significant patient/family non-compliance.

Question 694

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral hip in patients presenting with a unilateral Slipped Capital Femoral Epiphysis (SCFE) is a debated topic. However, it is most strongly and universally indicated in which of the following clinical scenarios?

. A 14-year-old male with an idiopathic acute SCFE
. A 10-year-old male with a chronic SCFE and a BMI in the 85th percentile
. A 12-year-old female with SCFE and renal osteodystrophy
. A 13-year-old male with SCFE and a normal endocrine laboratory profile
. A 15-year-old female with an acute-on-chronic SCFE

Correct Answer & Explanation

. A 12-year-old female with SCFE and renal osteodystrophy

Explanation

Patients with underlying endocrine or metabolic disorders (such as renal osteodystrophy, hypothyroidism, or panhypopituitarism) are at a markedly elevated risk for developing bilateral SCFE (approaching 100% in some cohorts). Therefore, prophylactic fixation of the contralateral hip is universally recommended for these patients. Idiopathic cases have a lower bilateral rate (typically 20-40%), making prophylaxis a topic of shared decision-making rather than an absolute indication.

Question 695

Topic: Pediatric Hip
In the evaluation of a child with Legg-Calvรฉ-Perthes disease, Catterall described specific 'head at risk' clinical and radiographic signs that portend a poor prognosis and higher risk of femoral head deformation. Which of the following is considered a 'head at risk' radiographic sign?
. Metaphyseal cysts
. Medial subluxation of the femoral head
. Ossification of the lateral pillar
. Decreased teardrop distance
. Sclerosis of the acetabulum

Correct Answer & Explanation

. Medial subluxation of the femoral head

Explanation

Catterall's 'head at risk' signs indicate a high likelihood of a poor clinical outcome. The five classic signs are: 1. Gage's sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), 2. Calcification lateral to the epiphysis, 3. Lateral (not medial) subluxation of the femoral head, 4. A horizontal orientation of the growth plate, and 5. Metaphyseal cysts. These signs typically mandate more aggressive treatment.

Question 696

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 98th percentile undergoes in situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). During advancement of the single cannulated screw, the surgeon observes an 'approach-withdraw' phenomenon on the lateral fluoroscopic view. What severe complication is most strongly associated with failure to recognize and correct this intraoperative finding?

. Avascular necrosis of the femoral head
. Chondrolysis of the hip joint
. Iatrogenic femoral neck fracture
. Premature physeal closure with severe leg length discrepancy
. Subtrochanteric fracture

Correct Answer & Explanation

. Chondrolysis of the hip joint

Explanation

The 'approach-withdraw' phenomenon occurs when a screw penetrates the articular surface of the femoral head. As the screw is advanced and the hip is rotated, the screw tip appears to approach and then withdraw from the subchondral bone on fluoroscopy due to the spherical shape of the head. Unrecognized joint penetration is a primary cause of chondrolysis following SCFE fixation.

Question 697

Topic: Pediatric Hip

An 8-month-old female presents with a persistently dislocated left hip after an unsuccessful 6-week trial of a Pavlik harness initiated at age 5 months. Ultrasound confirms continued posteroclavicular dislocation. What is the most appropriate next step in management?

. Re-application of the Pavlik harness for an additional 4 weeks
. Transition to a rigid hip abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting under general anesthesia
. Open reduction with femoral shortening osteotomy
. Observation until skeletal maturity to perform a salvage osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia

Explanation

In children older than 6 months with Developmental Dysplasia of the Hip (DDH), or those who fail a Pavlik harness, closed reduction and spica casting under general anesthesia with an arthrogram is the next standard step. A rigid abduction brace is sometimes used for Pavlik failure in infants <6 months, but at 8 months, closed reduction is indicated. Open reduction is reserved for failure of closed reduction.

Question 698

Topic: Pediatric Hip

A 12-year-old obese male presents to the emergency department unable to bear weight on his right leg for the past 24 hours after a minor fall. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the highest risk for developing compared to a patient with a stable SCFE?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Slipped capital femoral epiphysis of the contralateral hip
. Premature physeal closure leading to leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

An unstable SCFE is defined by the inability of the patient to bear weight, even with crutches (Loder classification). Unstable SCFE has a notoriously high rate of avascular necrosis (AVN) of the femoral head, ranging from 20-50%, compared to stable SCFE, where AVN is extremely rare (<1%).

Question 699

Topic: Pediatric Hip

A 13-year-old boy is diagnosed with a stable Slipped Capital Femoral Epiphysis (SCFE) of the left hip. He undergoes in situ percutaneous pinning. What is the ideal position of the single screw in the epiphysis to provide maximum stability and minimize the risk of joint penetration?

. Center-center
. Anterior-superior
. Posterior-inferior
. Anterior-inferior
. Posterior-superior

Correct Answer & Explanation

. Center-center

Explanation

The ideal starting point and trajectory for in situ pinning of a SCFE is on the anterior aspect of the femoral neck, directed perpendicular to the physis, to end in the center-center position of the epiphysis. This position reduces the risk of in-out-in joint penetration and provides the most biomechanically stable construct for the displaced epiphysis.

Question 700

Topic: Pediatric Hip

A 13-year-old obese male presents with left groin pain and a limp. Examination reveals obligate external rotation with hip flexion. Radiographs demonstrate a severe Slipped Capital Femoral Epiphysis (SCFE) on the left side. The right hip is asymptomatic and radiographically normal. Under which of the following circumstances is prophylactic in situ pinning of the contralateral (right) hip most strongly indicated?

. Severe displacement (>50%) on the symptomatic side
. Male sex and body mass index > 99th percentile
. Presence of an underlying endocrine disorder or renal osteodystrophy
. Age greater than 14 years at the time of presentation
. A history of previous physeal fractures

Correct Answer & Explanation

. Presence of an underlying endocrine disorder or renal osteodystrophy

Explanation

While the decision to perform prophylactic contralateral pinning in SCFE is debated in idiopathic cases, the absolute indication universally recognized is the presence of an underlying endocrine or metabolic disorder (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or previous radiation therapy. These patients have an extremely high risk (>50-80%) of bilateral involvement. Other relative indications often include young age (e.g., <10 for boys) or inability to follow up reliably.

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