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Pediatric Hip MCQs

Practice Set 32 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 621

Topic: Pediatric Hip

A 14-year-old boy with an acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE) is treated with in-situ single screw fixation. Six months later, he presents with severe hip stiffness, pain, and loss of all hip motion. Radiographs demonstrate uniform narrowing of the joint space to less than 3 mm. Which of the following is the most established primary risk factor for this specific complication?

. Unrecognized screw penetration into the joint
. Unstable slip classification at presentation
. Body Mass Index greater than the 95th percentile
. Underlying undiagnosed hypothyroidism
. Failure to perform prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Unrecognized screw penetration into the joint

Explanation

The clinical presentation describes chondrolysis, a devastating complication of SCFE characterized by acute loss of articular cartilage and severe stiffness. The most strongly associated risk factor for chondrolysis following SCFE fixation is unrecognized pin/screw penetration into the joint space. An unstable slip is a risk factor for avascular necrosis (AVN), not primarily chondrolysis.

Question 622

Topic: Pediatric Hip

An 8-week-old female infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a routine clinical check, the orthopedic surgeon notes that the infant has decreased active extension of the knee on the affected side, and the patellar reflex is diminished. What is the most likely cause of this finding and the appropriate harness adjustment?

. Femoral nerve palsy from excessive hip flexion; loosen the anterior straps
. Sciatic nerve palsy from excessive hip flexion; tighten the posterior straps
. Obturator nerve palsy from excessive hip abduction; loosen the posterior straps
. Avascular necrosis of the femoral head from excessive hip abduction; discontinue the harness
. Normal variant of Pavlik harness use; maintain current strap settings

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion; loosen the anterior straps

Explanation

The clinical findings of decreased active knee extension and a diminished patellar reflex indicate a femoral nerve palsy. In the setting of a Pavlik harness, this is almost always caused by hyperflexion of the hips compressing the nerve. The appropriate management is to loosen the anterior straps to reduce the degree of hip flexion, which usually leads to complete resolution of the palsy.

Question 623

Topic: Pediatric Hip

A 12-year-old obese male presents with a left-sided Slipped Capital Femoral Epiphysis (SCFE). In which of the following scenarios is prophylactic in situ pinning of the contralateral asymptomatic right hip most strongly indicated?

. Male gender without other comorbidities
. Age greater than 14 years at initial presentation
. Initial presentation with a chronic slip
. Presence of an endocrine disorder such as hypothyroidism
. Slip angle less than 30 degrees on the affected side

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly considered in patients with metabolic or endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency), as these conditions present a high risk for bilateral involvement. It is also considered in patients presenting at a younger age (males <12, females <10) or those with prior radiation therapy.

Question 624

Topic: Pediatric Hip

An 8-year-old boy, who is in the 10th percentile for height and 90th percentile for weight, presents with an idiopathic unilateral slipped capital femoral epiphysis (SCFE). Given his young age, an underlying endocrinopathy is highly suspected. Which of the following laboratory profiles is most classically associated with the most common endocrine cause of SCFE in this age group?

. Elevated free T4 and low TSH
. Decreased free T4 and elevated TSH
. Elevated growth hormone and IGF-1
. Elevated serum calcium and decreased PTH
. Decreased testosterone and elevated FSH

Correct Answer & Explanation

. Decreased free T4 and elevated TSH

Explanation

SCFE in children under the age of 10 or those with atypical presentations should prompt an evaluation for an underlying endocrine disorder. Hypothyroidism is the most common endocrinopathy associated with SCFE, characterized by a low free T4 and an elevated TSH.

Question 625

Topic: Pediatric Hip

An 8-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a routine follow-up, the parents note that the child is no longer actively kicking the leg on the affected side. Upon physical examination, there is an absent patellar reflex and decreased active knee extension. Which of the following errors in harness application is the most likely cause of this complication?

. Excessive flexion of the hip
. Excessive abduction of the hip
. Excessive adduction of the hip
. Placement of the chest strap too high
. Inadequate tension on the posterior straps

Correct Answer & Explanation

. Excessive flexion of the hip

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically resulting from hyperflexion of the hips, which compresses the femoral nerve against the inguinal ligament. Excessive abduction is associated with avascular necrosis (AVN) of the femoral head.

Question 626

Topic: Pediatric Hip

In a patient presenting with a slipped capital femoral epiphysis (SCFE), which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Age older than 15 years at the time of presentation
. Male gender
. Obesity (BMI > 95th percentile)
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Moderate-to-severe slip angle (>30 degrees) on the affected side

Correct Answer & Explanation

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

Explanation

While contralateral pinning is debated in idiopathic SCFE, there is broad consensus that patients with an underlying endocrinopathy (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) have an exceptionally high risk of bilateral involvement (up to 100% in some series). Therefore, prophylactic contralateral pinning is strongly indicated in these patients. Other indications include an inability to reliably follow up or an age at presentation of less than 10 years.

Question 627

Topic: Pediatric Hip

In the evaluation of developmental dysplasia of the hip (DDH) in a 6-month-old child, the ossific nucleus of the femoral head is delayed. Which radiographic landmark combination correctly defines the normal anatomical position of the proximal femur?

. Superior to Hilgenreiner's line and medial to Perkin's line
. Inferior to Hilgenreiner's line and medial to Perkin's line
. Inferior to Hilgenreiner's line and lateral to Perkin's line
. Superior to Hilgenreiner's line and lateral to Perkin's line
. Medial to the teardrop and superior to Hilgenreiner's line

Correct Answer & Explanation

. Inferior to Hilgenreiner's line and medial to Perkin's line

Explanation

On an AP pelvis radiograph, the normal femoral head (or its expected unossified cartilaginous analogue) should reside in the inferomedial quadrant formed by the intersection of Hilgenreiner's line (horizontal through the triradiate cartilages) and Perkin's line (vertical descending from the lateral margin of the ossified acetabulum).

Question 628

Topic: Pediatric Hip

A 12-year-old obese boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) and undergoes in-situ percutaneous screw fixation. If a prominent anterior metaphyseal bump remains, what is the most common long-term complication associated with the natural history of his hip?

. Avascular necrosis of the femoral head
. Chondrolysis
. Femoroacetabular impingement (cam-type)
. Premature osteoarthritis due to pincer impingement
. Leg length discrepancy > 3 cm

Correct Answer & Explanation

. Femoroacetabular impingement (cam-type)

Explanation

Following SCFE, the persistent retroverted orientation of the femoral head relative to the neck leaves a prominent anterior metaphyseal bump. This altered anatomy classically leads to cam-type femoroacetabular impingement (FAI) during hip flexion, which is the most common cause of premature secondary osteoarthritis in these patients.

Question 629

Topic: Pediatric Hip

A 12-year-old boy undergoes in situ pinning for a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral, currently asymptomatic hip?

. Patient age over 14 years at presentation
. Female gender
. Presence of an endocrinopathy such as hypothyroidism
. Body Mass Index > 95th percentile
. Severe slip angle (> 60 degrees) on the affected side

Correct Answer & Explanation

. Presence of an endocrinopathy such as hypothyroidism

Explanation

Patients with underlying endocrinopathies (such as hypothyroidism, growth hormone deficiency, or renal osteodystrophy) have an exceptionally high risk (up to 100% in some series) of developing bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly indicated in this population. Age < 10 or > 16 is also a relative indication, but endocrinopathy is the strongest.

Question 630

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, which of the following is considered the most significant and reliable prognostic factor regarding the long-term development of premature osteoarthritis?

. Age at the clinical onset of symptoms
. Gender of the patient
. Duration of the initial fragmentation stage
. Presence of a metaphyseal cyst on radiographs
. Degree of early joint effusion

Correct Answer & Explanation

. Age at the clinical onset of symptoms

Explanation

Age at clinical onset is the most consistently reported prognostic factor in Legg-Calve-Perthes disease. Children who develop the disease at a younger age (especially <6 years) have a significantly better prognosis for remodeling the femoral head and a lower risk of premature osteoarthritis, as they have more remaining growth potential.

Question 631

Topic: Pediatric Hip

An 18-month-old girl is evaluated for developmental dysplasia of the hip (DDH). An anteroposterior pelvic radiograph is obtained. Which of the following radiographic parameters is the most reliable metric to evaluate acetabular coverage/dysplasia at this specific age?

. Alpha angle
. Center-edge angle of Wiberg
. Reimers migration percentage
. Acetabular index
. Southwick angle

Correct Answer & Explanation

. Acetabular index

Explanation

The acetabular index (or Tonnis angle) is the standard radiographic measure of acetabular roof inclination and dysplasia in children from birth up to approximately 5 to 8 years of age. Wiberg's center-edge angle is used for older children when the femoral head center can be accurately identified. The alpha angle is an ultrasound metric for infants (<6 months).

Question 632

Topic: Pediatric Hip

Which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient diagnosed with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Male gender, age 14 years old
. Female gender, age 12 years old
. Presence of an underlying endocrinopathy (e.g., hypothyroidism or renal osteodystrophy)
. Obesity with a BMI greater than the 95th percentile
. Radiographic evidence of a severe slip angle (>50 degrees) in the ipsilateral hip

Correct Answer & Explanation

. Presence of an underlying endocrinopathy (e.g., hypothyroidism or renal osteodystrophy)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended and considered essentially absolute in patients with underlying metabolic or endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy), as their risk of bilateral disease can approach 100%. Other relative indications include young age (e.g., modified Oxford bone age score), prior radiation therapy, and inability to follow up, but endocrinopathy remains the strongest indication.

Question 633

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking the right leg. On examination, the right knee is extended, and there is an absence of active knee extension. Which of the following adjustments to the Pavlik harness is required?

. Loosen the anterior straps
. Tighten the anterior straps
. Loosen the posterior straps
. Tighten the posterior straps
. Discontinue the harness completely

Correct Answer & Explanation

. Loosen the anterior straps

Explanation

The infant presents with femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The anterior straps control the degree of hip flexion. Loosening the anterior straps reduces hyperflexion, which typically relieves the compression on the femoral nerve, leading to spontaneous recovery.

Question 634

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in situ single-screw fixation for a mild, stable slipped capital femoral epiphysis (SCFE). During follow-up, he demonstrates limited hip internal rotation and pain with combined flexion, adduction, and internal rotation. Which of the following is the most likely long-term complication explaining his symptoms?

. Avascular necrosis of the femoral head
. Chondrolysis
. Femoroacetabular impingement (FAI)
. Slipped capital femoral epiphysis of the contralateral hip
. Nonunion of the physis

Correct Answer & Explanation

. Femoroacetabular impingement (FAI)

Explanation

Following in situ fixation of a SCFE, the residual prominent anterior metaphysis can abut the anterior acetabular rim during hip flexion and internal rotation. This biomechanical mismatch leads to cam-type femoroacetabular impingement (FAI), causing pain and restricted range of motion. AVN and chondrolysis are less common in mild, stable slips treated with a single screw.

Question 635

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE). Intraoperatively, an intracapsular hematoma is evacuated. What is the primary blood supply to the femoral head that is at greatest risk of injury in this condition?

. Ascending branch of the medial femoral circumflex artery
. Lateral epiphyseal artery
. Medial epiphyseal artery
. Artery of the ligamentum teres
. Inferior gluteal artery

Correct Answer & Explanation

. Lateral epiphyseal artery

Explanation

The lateral epiphyseal artery is the terminal branch of the medial femoral circumflex artery (MFCA) and provides the predominant blood supply to the femoral head in children and adolescents. It is uniquely vulnerable to stretching, kinking, or tearing in SCFE, which can result in avascular necrosis (AVN).

Question 636

Topic: Pediatric Hip

A 12-year-old obese male presents with a slipped capital femoral epiphysis (SCFE). Which of the following best describes the anatomical direction of the epiphyseal displacement relative to the metaphysis?

. Anterior and superior
. Anterior and inferior
. Posterior and superior
. Posterior and inferior
. Lateral and inferior

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the epiphysis actually remains relatively housed in the acetabulum while the femoral neck (metaphysis) displaces anteriorly and superiorly. Therefore, relative to the metaphysis, the epiphysis slips posteriorly and inferiorly.

Question 637

Topic: Pediatric Hip

A 4-month-old female is diagnosed with developmental dysplasia of the hip (DDH) and treated with a Pavlik harness. Two weeks later, the parents report she has stopped kicking her right leg. Examination reveals an inability to actively extend the knee. This complication is most directly related to which improper fitting of the harness?

. Excessive abduction
. Inadequate abduction
. Excessive hip flexion
. Inadequate hip flexion
. Constriction of the chest strap

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The patient has a femoral nerve palsy, a known complication of the Pavlik harness. It is caused by excessive hip flexion, which stretches or compresses the femoral nerve against the inguinal ligament. By contrast, excessive abduction is associated with avascular necrosis (AVN) of the femoral head.

Question 638

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, the lateral pillar classification of Herring is optimally assessed during which phase of the disease process?

. Initial (avascular) stage
. Early fragmentation stage
. Late fragmentation stage
. Reossification stage
. Residual stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The Herring lateral pillar classification is ideally applied during the early fragmentation stage of Legg-Calve-Perthes disease. This provides the most accurate prognostication based on the maintenance of the height of the lateral pillar of the capital femoral epiphysis.

Question 639

Topic: Pediatric Hip

In a patient presenting with a Slipped Capital Femoral Epiphysis (SCFE), which of the following is the most significant prognostic clinical factor for the subsequent development of avascular necrosis (AVN) of the femoral head?

. The degree of the slip angle on the frog-leg lateral radiograph.
. The patient's chronologic age at the time of presentation.
. The patient's ability to bear weight on the affected extremity at presentation.
. The specific method of surgical fixation utilized.
. The duration of symptoms prior to the definitive diagnosis.

Correct Answer & Explanation

. The patient's ability to bear weight on the affected extremity at presentation.

Explanation

The stability of the SCFE, defined clinically by the patient's ability to bear weight (with or without crutches), is the most critical prognostic factor for the development of AVN. Unstable SCFEs (inability to bear weight) have a much higher rate of AVN (up to 20-50%) compared to stable SCFEs (nearly 0%).

Question 640

Topic: Pediatric Hip

A 3-month-old female with Developmental Dysplasia of the Hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking her right leg. Examination reveals decreased active extension of the right knee. What adjustment to the harness is required to address this specific complication?

. Decrease the flexion of the anterior strap.
. Increase the flexion of the anterior strap.
. Decrease the abduction of the posterior strap.
. Increase the abduction of the posterior strap.
. Discontinue the harness and transition immediately to a rigid hip spica cast.

Correct Answer & Explanation

. Decrease the flexion of the anterior strap.

Explanation

The clinical scenario describes a femoral nerve palsy, a known complication of the Pavlik harness caused by excessive hyperflexion of the hip. The femoral nerve becomes compressed against the anterior pelvis. The management is to decrease the tension on the anterior strap to reduce the degree of hip flexion, which usually allows the palsy to resolve.

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