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Pediatric Hip MCQs

Practice Set 84 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 1661

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her one-week follow-up, the parents report she is not moving her right leg as much. Exam reveals decreased active knee extension on the affected side. What is the most appropriate next step in management?

. Continue the harness and re-evaluate in 1 week
. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to decrease hip abduction
. Discontinue the harness temporarily and observe
. Immediately transition to a rigid hip spica cast

Correct Answer & Explanation

. Discontinue the harness temporarily and observe

Explanation

Transient femoral nerve palsy is a known complication of excessive hip flexion in a Pavlik harness, presenting as decreased active knee extension. The harness must be discontinued temporarily to allow for nerve recovery before resuming or altering treatment.

Question 1662

Topic: Pediatric Hip

A 13-year-old obese boy with left hip pain after a minor fall is unable to bear weight, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Compared to a patient with a stable SCFE, this patient is at significantly higher risk for which of the following complications?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoroacetabular impingement
. Physeal arrest
. Premature osteoarthritis

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

An unstable SCFE is defined clinically by the inability to bear weight. It carries a markedly higher risk of avascular necrosis (AVN), reaching up to nearly 50%, due to the acute disruption of the epiphyseal blood supply.

Question 1663

Topic: Pediatric Hip

A 4-week-old female infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her leg on the affected side. On examination, there is an absence of active knee extension, but ankle and toe movements are normal. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness and re-evaluate in 1-2 weeks
. Immediately proceed to closed reduction and spica casting
. Switch to a rigid abduction orthosis

Correct Answer & Explanation

. Remove the harness and re-evaluate in 1-2 weeks

Explanation

The infant has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness must be removed temporarily until nerve function recovers to prevent permanent injury or 'Pavlik disease'.

Question 1664

Topic: Pediatric Hip

A 13-year-old boy with a BMI in the 95th percentile presents with 3 weeks of knee pain and a limp. Radiographs demonstrate a stable slipped capital femoral epiphysis (SCFE) of the left hip. He is treated with single in-situ cannulated screw fixation. Two months later, he complains of global restriction of hip motion and severe pain. Radiographs reveal diffuse joint space narrowing. Which of the following factors most significantly increases the risk of this specific complication?

. Unrecognized endocrine disorder
. Anterior positioning of the screw in the femoral head
. Unrecognized intra-articular screw penetration
. Use of a fully threaded screw
. Failure to perform a prophylactic pinning of the contralateral side

Correct Answer & Explanation

. Unrecognized intra-articular screw penetration

Explanation

Chondrolysis is characterized by diffuse joint space narrowing and stiffness after SCFE fixation. Unrecognized intra-articular hardware penetration is the most significant preventable risk factor.

Question 1665

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable, moderate Slipped Capital Femoral Epiphysis (SCFE). Six months later, he complains of increasing hip pain and profound global stiffness. Radiographs demonstrate concentric joint space narrowing of the affected hip without segmental collapse. What is the most likely etiology of this complication?

. Avascular necrosis secondary to retinacular vessel injury
. Failure of the implant to provide adequate stability
. Impingement of the femoral neck on the anterior acetabular rim
. Chondrolysis caused by unrecognized intra-articular pin penetration
. Septic arthritis introduced during the operative procedure

Correct Answer & Explanation

. Chondrolysis caused by unrecognized intra-articular pin penetration

Explanation

Chondrolysis in the setting of SCFE is strongly associated with unrecognized pin penetration into the joint space. It presents with progressive global stiffness, pain, and concentric joint space narrowing on radiographs.

Question 1666

Topic: Pediatric Hip

A 6-week-old female infant is currently being treated in a Pavlik harness for Developmental Dysplasia of the Hip (DDH). Her mother notes that the infant has stopped kicking her right leg over the past 24 hours. Physical examination reveals an absence of active knee extension on the right, but withdrawal to a needle prick remains intact. What is the most appropriate next step in management?

. Discontinue the Pavlik harness immediately to allow for neurologic recovery
. Adjust the anterior straps to increase hip flexion past 120 degrees
. Transition the patient immediately to a rigid abduction orthosis
. Order an urgent MRI of the lumbar spine
. Reassure the mother and continue the current harness settings

Correct Answer & Explanation

. Discontinue the Pavlik harness immediately to allow for neurologic recovery

Explanation

The patient is presenting with a femoral nerve palsy, the most common nerve injury associated with the Pavlik harness (often due to hyperflexion). The harness should be discontinued or modified significantly until active quadriceps function returns.

Question 1667

Topic: Pediatric Hip

An 8-year-old boy with a BMI in the 50th percentile (normal weight) presents with a 2-month history of a left-sided limp and obligatory external rotation when the left hip is flexed. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Given the patient's presentation, which of the following laboratory evaluations is most critical?

. Thyroid stimulating hormone (TSH) and free T4
. Complete blood count (CBC) and erythrocyte sedimentation rate (ESR)
. Rheumatoid factor (RF) and Anti-CCP antibodies
. Serum protein electrophoresis (SPEP)
. Hemoglobin A1c and fasting blood glucose

Correct Answer & Explanation

. Thyroid stimulating hormone (TSH) and free T4

Explanation

SCFE occurring in a child under the age of 10 or outside the typical demographic (non-obese) should raise high clinical suspicion for an underlying endocrine disorder, most commonly hypothyroidism or renal osteodystrophy.

Question 1668

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). His radiographs demonstrate that the lateral pillar of the femoral head has maintained approximately 60% of its original height. When determining his long-term prognosis and likelihood of developing early osteoarthritis, which of the following is considered the most critical independent prognostic factor?
. His gender
. His age at the onset of symptoms
. His weight and body mass index
. The duration of symptoms prior to diagnosis
. The presence of a subchondral fracture line (Crescent sign)

Correct Answer & Explanation

. His age at the onset of symptoms

Explanation

In Legg-Calvé-Perthes disease, age at clinical onset is the most significant independent prognostic factor. Children diagnosed after the age of 8 typically have much poorer remodeling potential and clinical outcomes compared to younger children.

Question 1669

Topic: Pediatric Hip

In a 12-year-old obese male presenting with a stable slipped capital femoral epiphysis (SCFE), what is the most significant iatrogenic risk factor for the development of chondrolysis following treatment?

. Failure to perform a prophylactic pinning of the contralateral hip
. Use of a single cannulated screw for fixation
. Unrecognized intra-articular hardware penetration
. Performing a subtrochanteric osteotomy
. Delay in surgical fixation greater than 24 hours

Correct Answer & Explanation

. Unrecognized intra-articular hardware penetration

Explanation

Chondrolysis is a devastating complication of SCFE, most commonly associated with unrecognized intra-articular penetration of hardware during in situ pinning. Meticulous fluoroscopic evaluation (approach-withdrawal technique) is required to ensure the screw has not breached the joint.

Question 1670

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During follow-up, the mother notes the child is no longer kicking her knee straight on the treated side. Which aspect of harness positioning is the most likely cause of this complication?

. Excessive abduction
. Excessive hyperflexion
. Inadequate abduction
. Excessive internal rotation
. Excessive extension

Correct Answer & Explanation

. Excessive hyperflexion

Explanation

Excessive hyperflexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy. This manifests as an inability to actively extend the knee.

Question 1671

Topic: Pediatric Hip

A 9-year-old male presents with a slipped capital femoral epiphysis (SCFE). Given his young age, an endocrine etiology is suspected. Which of the following endocrinopathies is most frequently associated with atypical SCFE?

. Hyperthyroidism
. Hypothyroidism
. Cushing's syndrome
. Addison's disease
. Hyperparathyroidism

Correct Answer & Explanation

. Hypothyroidism

Explanation

Hypothyroidism is the most common endocrine disorder associated with SCFE. An endocrine workup is strongly indicated in SCFE patients presenting outside the typical age range (under 10 or over 16) or with bilateral involvement.

Question 1672

Topic: Pediatric Hip

A 4-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. At the 2-week follow-up, the parents report the infant has stopped kicking the affected leg. Examination reveals absent active knee extension and no response to plantar stimulation on that side. What is the most appropriate next step in management?

. Switch immediately to a rigid hip spica cast
. Discontinue the harness and observe
. Adjust the harness to increase hip flexion
. Perform an immediate diagnostic ultrasound
. Schedule for urgent open reduction

Correct Answer & Explanation

. Discontinue the harness and observe

Explanation

Femoral nerve palsy is a known complication of excessive hyperflexion in a Pavlik harness. The standard management is to remove the harness and observe; nerve function typically recovers spontaneously within days to a few weeks.

Question 1673

Topic: Pediatric Hip

In evaluating a child with Legg-Calve-Perthes disease, the Herring lateral pillar classification is used during the fragmentation stage to predict long-term outcomes. Which group is associated with the poorest prognosis for achieving a spherical, congruent hip joint?

. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group C

Explanation

The Herring lateral pillar classification determines prognosis based on the height of the lateral portion of the capital femoral epiphysis. Group C, characterized by >50% collapse of the lateral pillar height, carries the poorest prognosis and highest risk of aspherical femoral head development.

Question 1674

Topic: Pediatric Hip

In the evaluation and management of Legg-Calve-Perthes disease, which of the following represents the most significant prognostic factor for the long-term congruency of the hip joint?

. Age of the patient at the onset of the disease
. Gender of the patient
. Duration of the initial limp
. Body mass index
. Presence of bilateral involvement

Correct Answer & Explanation

. Age of the patient at the onset of the disease

Explanation

The age at disease onset is the most critical prognostic factor in Perthes disease. Children under the age of 6 at onset have a greater potential for remodeling and generally achieve better long-term outcomes than older children.

Question 1675

Topic: Pediatric Hip

During an anterolateral (Smith-Petersen) open reduction of a developmental dysplasia of the hip (DDH) in an 18-month-old child, the surgeon encounters an extra-articular block to reduction. Which structure must be formally isolated and released to safely expose the inferior capsule?

. Ligamentum teres
. Transverse acetabular ligament
. Iliopsoas tendon
. Reflected head of the rectus femoris
. Gluteus medius

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The iliopsoas tendon crosses the anterior joint capsule and restricts inferior access and reduction. It must be released or lengthened to allow adequate exposure of the capsule and to facilitate a concentric reduction.

Question 1676

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient with a unilateral Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 12-year-old obese male with idiopathic SCFE
. A 14-year-old female with a strong family history of SCFE
. An 11-year-old male with renal osteodystrophy
. A 15-year-old male competitive athlete
. A 10-year-old female with an acute-on-chronic slip

Correct Answer & Explanation

. An 11-year-old male with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, previous radiation therapy, growth hormone deficiency), as these patients have a much higher risk (approaching 100% in some conditions) of developing a contralateral slip.

Question 1677

Topic: Pediatric Hip

A 12-year-old boy presents with left knee pain and a limp. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most widely accepted absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Patient age greater than 14 years
. Presence of an underlying endocrine or metabolic disorder
. Female sex
. Mild degree of slip on the symptomatic side
. Presence of a metaphyseal blanch sign on the AP radiograph

Correct Answer & Explanation

. Presence of an underlying endocrine or metabolic disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy) due to the extremely high risk (up to 100%) of bilateral involvement. Other indications include prophylactic treatment in patients under 10 years of age or those who cannot be reliably followed.

Question 1678

Topic: Pediatric Hip

A 10-year-old boy presents with bilateral slipped capital femoral epiphyses (SCFE). His weight is in the 40th percentile. Which of the following endocrine disorders is most commonly associated with this presentation?

. Hyperparathyroidism
. Hypothyroidism
. Growth hormone deficiency
. Panhypopituitarism
. Diabetes insipidus

Correct Answer & Explanation

. Hypothyroidism

Explanation

Hypothyroidism is the most common endocrine disorder associated with SCFE, particularly in patients presenting outside the typical age range (under 10 or over 16) or with atypical body habitus (e.g., non-obese). Endocrine workup is highly recommended for SCFE in these patient demographics or when bilateral involvement is present at initial presentation.

Question 1679

Topic: Pediatric Hip

A 12-year-old obese male is diagnosed with a unilateral stable slipped capital femoral epiphysis (SCFE). In which of the following scenarios is prophylactic in situ pinning of the contralateral asymptomatic hip most strongly indicated?

. Age greater than 14 years at presentation
. Male gender
. Associated hypothyroidism
. Grade I slip
. Presence of a metaphyseal blanch sign

Correct Answer & Explanation

. Age greater than 14 years at presentation

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with a high risk of bilateral disease. Risk factors include endocrinopathies (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation), prior radiation therapy, or presentation at an abnormally young age (typically under 10 years).

Question 1680

Topic: Pediatric Hip

An infant treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH) is noted to have an absent patellar reflex and decreased spontaneous extension of the knee on the affected side. This complication is most likely due to which of the following improper harness adjustments?

. Excessive abduction of the hips
. Inadequate abduction of the hips
. Excessive flexion of the hips
. Inadequate flexion of the hips
. Prolonged use of the harness beyond 6 weeks

Correct Answer & Explanation

. Excessive flexion of the hips

Explanation

The clinical signs point to a femoral nerve palsy. In the context of a Pavlik harness, femoral nerve palsy is typically caused by hyperflexion of the hips, which acutely compresses the femoral nerve against the inguinal ligament. Excessive abduction is instead associated with an increased risk of avascular necrosis of the femoral head.

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