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Pediatric Hip MCQs

Practice Set 76 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 1501

Topic: Pediatric Hip

A 6-week-old infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. After 3 weeks of strict, monitored harness wear, ultrasound confirms the hip remains entirely dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 3 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld brace)
. Perform immediate closed reduction and spica casting
. Perform open reduction and capsulorrhaphy
. Discontinue harness and observe until the child is 6 months old

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 3 weeks

Explanation

If a hip remains dislocated after 3 to 4 weeks of proper Pavlik harness treatment, the harness must be discontinued to prevent damage to the posterior acetabular wall (Pavlik harness disease). Transitioning to a rigid abduction orthosis is a recognized next step before attempting closed reduction under anesthesia.

Question 1502

Topic: Pediatric Hip

A 6-month-old infant in a Pavlik harness for developmental dysplasia of the hip (DDH) is noted to have decreased active knee extension. Which of the following harness adjustments or complications is most likely responsible?

. Excessive hip abduction causing obturator nerve palsy
. Excessive hip flexion causing femoral nerve palsy
. Inadequate hip flexion causing sciatic nerve palsy
. Excessive hip adduction causing avascular necrosis
. Tight shoulder straps causing brachial plexopathy

Correct Answer & Explanation

. Excessive hip abduction causing obturator nerve palsy

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. This manifests as decreased quadriceps function, requiring temporary adjustment or removal of the harness.

Question 1503

Topic: Pediatric Hip

A 6-week-old female infant is currently being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During her 2-week follow-up appointment, the mother reports that the infant is no longer kicking her left leg. On examination, the infant exhibits a lack of spontaneous knee extension on the left side, though ankle and toe movements are intact. What is the most appropriate next step in management?

. Adjust the anterior strap to increase hip flexion
. Adjust the posterior strap to increase hip abduction
. Remove the Pavlik harness and observe for neurologic recovery
. Transition immediately to a rigid hip abduction orthosis (e.g., Ilfeld splint)
. Schedule an emergency closed reduction and spica casting

Correct Answer & Explanation

. Adjust the anterior strap to increase hip flexion

Explanation

The clinical presentation is highly suggestive of a femoral nerve palsy, a known complication of Pavlik harness treatment caused by excessive hip flexion. The femoral nerve becomes compressed beneath the inguinal ligament, leading to decreased quadriceps function (lack of knee extension). The most appropriate management is immediate removal of the harness to allow for neurologic recovery, which typically occurs within days to weeks. Once the nerve recovers, a different method of treatment (such as a rigid orthosis or closed reduction) should be considered.

Question 1504

Topic: Pediatric Hip
An 8-year-old boy is evaluated for a painless limp and restricted hip abduction. Radiographs confirm Legg-Calvé-Perthes disease in the fragmentation stage. According to the Lateral Pillar (Herring) classification, which radiograph is evaluated, and what is the primary determinant for a 'C' classification?
. Frog-leg lateral radiograph; the anterior pillar retains >50% of its original height
. AP radiograph; the central pillar retains <50% of its original height
. AP radiograph; the lateral pillar retains <50% of its original height
. Frog-leg lateral radiograph; the lateral pillar retains <50% of its original height
. AP radiograph; the medial pillar retains >50% of its original height

Correct Answer & Explanation

. AP radiograph; the lateral pillar retains <50% of its original height

Explanation

The Lateral Pillar (Herring) classification evaluates the AP pelvis radiograph specifically during the fragmentation phase of Legg-Calvé-Perthes disease. It is divided into three groups based on the height of the lateral third of the femoral epiphysis. Group A has no lateral pillar involvement. Group B maintains >50% of lateral pillar height. Group C maintains <50% of lateral pillar height. Age >8 years at onset and a lateral pillar B/C or C grade portend a poor prognosis and typically warrant surgical containment.

Question 1505

Topic: Pediatric Hip

A 15-month-old child undergoes open reduction for a neglected developmental dysplasia of the hip (DDH) via an anterior approach. During the procedure, several intra-articular anatomical obstacles to reduction are encountered and addressed. Which of the following structures is located most inferiorly and must be incised to allow the femoral head to seat concentrically in the true acetabulum?

. Ligamentum teres
. Inverted limbus
. Pulvinar
. Transverse acetabular ligament
. Iliopsoas tendon

Correct Answer & Explanation

. Ligamentum teres

Explanation

Obstacles to reduction in DDH include extra-articular structures (iliopsoas tendon, adductor longus) and intra-articular structures. The intra-articular obstacles include the pulvinar (fibrofatty tissue in the cotyloid fossa), an elongated/hypertrophic ligamentum teres, an inverted acetabular labrum (limbus), and a contracted transverse acetabular ligament. The transverse acetabular ligament crosses the acetabular notch at the inferior aspect of the joint. It is often contracted in DDH and must be radially incised (not excised) to allow the femoral head to seat fully.

Question 1506

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department with severe acute left hip pain after slipping on ice. He is completely unable to bear weight, even with crutches. Radiographs show a severe left Slipped Capital Femoral Epiphysis (SCFE). Which of the following complications is he at greatest risk for compared to a patient who presents with an ability to bear weight?

. Chondrolysis
. Avascular necrosis (AVN)
. Subtrochanteric fracture
. Femoroacetabular impingement (FAI)
. Infection

Correct Answer & Explanation

. Chondrolysis

Explanation

The inability to bear weight defines an unstable SCFE according to the Loder classification. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN), reported to be up to 20-50%, compared to a nearly 0% risk in stable SCFE. Chondrolysis is more commonly associated with unrecognized hardware penetration into the joint.

Question 1507

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 is the most important radiographic parameter for determining long-term prognosis?
. Extent of epiphyseal necrosis in the anterior half of the femoral head
. Maintenance of lateral pillar height greater than 50%
. Presence of a subchondral lucency (Crescent sign)
. Extrusion of the femoral head laterally
. Premature physeal closure

Correct Answer & Explanation

. Maintenance of lateral pillar height greater than 50%

Explanation

The Herring Lateral Pillar Classification is the most reliable prognostic indicator for Legg-Calvé-Perthes disease. It assesses the height of the lateral pillar of the femoral head on an AP radiograph during the fragmentation stage. Group A (>100%), Group B (>50%), and Group C (<50%). Patients with <50% lateral pillar height (Group C) have a poor prognosis and a higher likelihood of an aspherical femoral head and early osteoarthritis.

Question 1508

Topic: Pediatric Hip

A 3-year-old girl presents with a painless limp. Examination reveals a positive Galeazzi sign and asymmetric thigh folds. Radiographs reveal a dislocated left hip with a broken Shenton's line and an acetabular index of 40 degrees. The right hip is normal. What is the most appropriate primary surgical treatment?

. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Pavlik harness application
. Shelf acetabuloplasty

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In a child older than 2 to 3 years presenting with a completely dislocated hip (Developmental Dysplasia of the Hip), closed reduction is rarely successful and carries a high risk of avascular necrosis. The standard of care is an open reduction combined with a femoral shortening osteotomy (to relieve tension on the reduced hip and decrease AVN risk) and a pelvic osteotomy (e.g., Pemberton or Dega) to address the significant acetabular dysplasia (acetabular index of 40 degrees).

Question 1509

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic findings is considered a 'head at risk' sign, portending a poorer prognosis and a higher risk of femoral head deformation?
. Medial subluxation of the femoral head
. Gage sign
. Presence of the crescent sign in the anterior 25% of the head
. Delayed skeletal age
. Decreased medial joint space

Correct Answer & Explanation

. Gage sign

Explanation

Catterall described 'head at risk' signs in Legg-Calvé-Perthes disease, which indicate a high risk for progressive subluxation and a poorer outcome. These include: Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), lateral (not medial) subluxation of the femoral head, calcification lateral to the epiphysis, diffuse metaphyseal reaction, and a horizontal physis.

Question 1510

Topic: Pediatric Hip

An 18-month-old girl with Developmental Dysplasia of the Hip (DDH) is planned for a Salter innominate osteotomy. Which of the following is an absolute prerequisite for performing this procedure?

. Age greater than 4 years
. Preoperative skeletal traction
. A concentrically reduced hip
. A significantly dysplastic opposite hip
. Femoral head ossification center must be absent

Correct Answer & Explanation

. Age greater than 4 years

Explanation

A Salter osteotomy is a redirectional pelvic osteotomy that hinges through the symphysis pubis. A concentric reduction of the hip joint is an absolute prerequisite for the procedure to provide adequate anterolateral coverage.

Question 1511

Topic: Pediatric Hip

A 14-year-old obese male presents with left groin pain and an altered gait. Radiographs reveal a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant clinical predictor for the development of subsequent avascular necrosis (AVN)?

. Magnitude of the slip angle
. Duration of symptoms prior to presentation
. Patient's body mass index (BMI)
. Inability to ambulate with or without crutches
. Contralateral hip involvement

Correct Answer & Explanation

. Magnitude of the slip angle

Explanation

The inability to bear weight defines an unstable SCFE according to the Loder classification. Instability is the paramount risk factor for developing AVN, carrying a risk of up to 50% compared to near 0% in stable slips.

Question 1512

Topic: Pediatric Hip

A 4-week-old female infant is evaluated for developmental dysplasia of the hip (DDH). Ultrasound shows an alpha angle of 45 degrees and a beta angle of 65 degrees. According to the Graf classification, what is the appropriate management?

. Reassurance and repeat ultrasound in 4 weeks
. Pavlik harness application
. Rigid abduction orthosis
. Closed reduction and spica cast
. Open reduction and capsulorrhaphy

Correct Answer & Explanation

. Reassurance and repeat ultrasound in 4 weeks

Explanation

An alpha angle of 45 degrees indicates a Graf type IIc or worse (dysplastic hip). The standard of care for a dysplastic but reducible hip in an infant under 6 months is treatment with a Pavlik harness.

Question 1513

Topic: Pediatric Hip

A 14-year-old male with a BMI of 35 presents with acute-on-chronic left knee pain and an inability to bear weight. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following is the most significant preventable risk factor for developing chondrolysis in this patient?

. The severity of the slip at presentation
. Acute presentation of the slip
. Unrecognized pin penetration into the joint
. The patient's obesity
. Delay in surgical intervention

Correct Answer & Explanation

. The severity of the slip at presentation

Explanation

Unrecognized hardware penetration into the joint space is the most significant preventable risk factor for chondrolysis following in situ pinning of a SCFE. Intraoperative fluoroscopy with approach-withdrawal views is essential to confirm extra-articular pin placement.

Question 1514

Topic: Pediatric Hip
A 7-year-old boy presents with a painless limp. Radiographs reveal fragmentation of the left capital femoral epiphysis. Physical exam shows a loss of hip internal rotation and abduction. What is the primary overarching goal of treatment for this condition?
. Immediate surgical pinning to prevent further epiphyseal slip
. Containment of the femoral head within the acetabulum
. Eradication of occult infection with intravenous antibiotics
. Percutaneous lengthening of the Achilles tendon to improve gait
. Strict complete non-weight bearing for 2 years

Correct Answer & Explanation

. Containment of the femoral head within the acetabulum

Explanation

In Legg-Calvé-Perthes disease, the primary goal of treatment is containment of the inflamed, plastic femoral head within the acetabulum. This maintains a spherical head shape during the remodeling phase and minimizes future joint incongruity.

Question 1515

Topic: Pediatric Hip
A 6-week-old female infant is evaluated for developmental dysplasia of the hip. An ultrasound is performed on the right hip. An alpha angle of 55 degrees and a beta angle of 60 degrees is noted on the coronal view. According to the Graf classification, what is the most appropriate management at this stage?
. Observation and repeat ultrasound in 4 weeks
. Immediate Pavlik harness application
. Closed reduction and spica casting
. Open reduction
. Reassurance and discharge from clinic

Correct Answer & Explanation

. Observation and repeat ultrasound in 4 weeks

Explanation

This infant has a Graf Type IIa hip, which is defined by an alpha angle between 50-59 degrees in an infant under 3 months of age. This represents physiologic immaturity, and the vast majority of these hips will resolve spontaneously. The most appropriate management is observation and follow-up ultrasound in 2-4 weeks. A Pavlik harness is indicated for Graf Type IIb (same angles but older than 3 months), III, and IV hips.

Question 1516

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department refusing to bear weight on his right leg after a minor twisting injury. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE). Because he cannot bear weight even with crutches, this is classified as an unstable SCFE. Which of the following complications is significantly more likely in this patient compared to a patient with a stable SCFE?

. Chondrolysis
. Avascular necrosis of the femoral head
. Premature physeal closure
. Femoral acetabular impingement
. Slipped capital femoral epiphysis of the contralateral hip

Correct Answer & Explanation

. Chondrolysis

Explanation

Unstable SCFE is defined by the inability to bear weight on the affected extremity and carries a much higher risk (up to 50%) of developing avascular necrosis (AVN) of the femoral head. Stable SCFE has a very low risk of AVN. Chondrolysis can occur in both, often related to prominent hardware.

Question 1517

Topic: Pediatric Hip

A 13-year-old overweight boy presents with a 3-week history of right groin pain and a limp. Examination reveals obligatory external rotation of the hip with passive flexion. What is the most appropriate initial management?

. Strict bed rest and serial radiographs
. Immediate closed reduction and spica casting
. In situ percutaneous pinning of the right hip
. Bilateral prophylactic pinning
. Open reduction and internal fixation through a surgical dislocation approach

Correct Answer & Explanation

. Strict bed rest and serial radiographs

Explanation

The presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). The standard of care for a stable SCFE is in situ percutaneous pinning with a single cannulated screw in the center of the epiphysis.

Question 1518

Topic: Pediatric Hip

In the evaluation of developmental dysplasia of the hip (DDH) in a 6-month-old infant, which of the following imaging modalities is most appropriate to confirm the diagnosis and assess severity?

. Dynamic ultrasound of the hip
. Anteroposterior (AP) and frog-leg lateral radiographs of the pelvis
. Non-contrast MRI of the pelvis
. Computed tomography (CT) scan of the hips
. Bone scintigraphy

Correct Answer & Explanation

. Dynamic ultrasound of the hip

Explanation

By 4 to 6 months of age, the capital femoral ossific nucleus begins to ossify. This makes AP and frog-leg pelvis radiographs the preferred and reliable imaging modality for evaluating DDH, replacing ultrasound.

Question 1519

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left knee pain and an antalgic gait. Examination reveals limited internal rotation of the left hip. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE) on the left. Prophylactic pinning of the contralateral asymptomatic hip is most strongly indicated if the patient has which of the following concomitant conditions?

. Down syndrome
. Endocrine disorder such as hypothyroidism
. Type 1 diabetes mellitus
. Pre-existing avascular necrosis
. Marfan syndrome

Correct Answer & Explanation

. Down syndrome

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but widely recommended in patients with underlying endocrine or metabolic disorders. These conditions, such as hypothyroidism or renal osteodystrophy, significantly increase the risk of bilateral involvement.

Question 1520

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left knee pain and an antalgic gait. He is able to bear weight into the examination room with a noticeable limp. Radiographs demonstrate a posterior and inferior displacement of the proximal femoral epiphysis. According to the Loder classification, what is the primary prognostic significance of his ability to bear weight?

. It determines the risk of subsequent chondrolysis
. It dictates the absolute need for a prophylactic contralateral pinning
. It accurately predicts the risk of avascular necrosis (AVN)
. It defines whether an open reduction via a surgical hip dislocation is mandatory
. It strictly correlates with the likelihood of future femoroacetabular impingement (FAI)

Correct Answer & Explanation

. It determines the risk of subsequent chondrolysis

Explanation

The Loder classification is the most clinically relevant system for Slipped Capital Femoral Epiphysis (SCFE) and is based entirely on the patient's ability to bear weight (with or without crutches). A 'stable' SCFE is defined as the patient being able to bear weight, while an 'unstable' SCFE is defined by an inability to bear weight. The primary prognostic importance of this classification is the risk of avascular necrosis (AVN). Stable slips have a very low risk of AVN (<10%), whereas unstable slips have a high rate of AVN, historically reported up to 50%.

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