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Pediatric Hip MCQs

Practice Set 29 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 561

Topic: Pediatric Hip

A 4-month-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report she has stopped kicking her right leg. Examination reveals decreased active extension of the right knee, but intact ankle and toe movements. What is the most likely cause?

. Femoral nerve palsy from excessive hip flexion
. Sciatic nerve palsy from excessive hip flexion
. Obturator nerve palsy from excessive hip abduction
. Transient synovitis of the hip
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion

Explanation

The most common nerve injury associated with the use of a Pavlik harness is femoral nerve palsy, typically caused by hyperflexion of the hips. This leads to an inability to actively extend the knee (quadriceps weakness). It usually resolves once the flexion is decreased or the harness is temporarily discontinued. Sciatic nerve palsy is exceedingly rare in this context.

Question 562

Topic: Pediatric Hip

A 13-year-old obese boy presents with left knee pain and an antalgic gait. Examination shows obligate external rotation of the left hip during passive flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). What is the primary physiological reason to perform an in-situ pinning rather than attempting an aggressive closed reduction before pinning?

. To prevent premature physeal closure
. To decrease the risk of avascular necrosis (AVN)
. To avoid limb length discrepancy
. To prevent contralateral SCFE
. To minimize the risk of chondrolysis

Correct Answer & Explanation

. To decrease the risk of avascular necrosis (AVN)

Explanation

The primary danger of forcefully reducing a slipped capital femoral epiphysis (SCFE) is the disruption of the fragile terminal branches of the medial femoral circumflex artery (retinacular vessels), which dramatically increases the risk of avascular necrosis (AVN) of the femoral head. Therefore, in-situ pinning without aggressive reduction is the standard of care for a stable SCFE.

Question 563

Topic: Pediatric Hip

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

. Age greater than 14 years in males
. Presentation with a stable SCFE
. Concomitant diagnosis of renal osteodystrophy
. Modified Oxford Bone Age Score of 22
. Closed triradiate cartilage

Correct Answer & Explanation

. Concomitant diagnosis of renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in unilateral SCFE is strongly recommended in patients with endocrine or metabolic disorders (e.g., renal osteodystrophy, hypothyroidism, panhypopituitarism) due to the exceedingly high rate of bilateral involvement (up to 100% in some series). Other indications include young chronologic age or skeletal age (modified Oxford Bone Age score <16), and history of radiation therapy. A score of 22 and closed triradiate cartilage indicate a mature skeleton with low risk of subsequent SCFE.

Question 564

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the parents report the infant is not kicking the left leg. On exam, there is an absent patellar reflex and profound weakness in knee extension on the left side. What specific positional error of the Pavlik harness is the most likely cause of this complication?

. Excessive abduction of the hip
. Inadequate flexion of the hip (less than 90 degrees)
. Excessive flexion of the hip (greater than 120 degrees)
. Excessive internal rotation of the hip
. Inadequate abduction of the hip

Correct Answer & Explanation

. Excessive flexion of the hip (greater than 120 degrees)

Explanation

The infant is presenting with an iatrogenic femoral nerve palsy, a known complication of Pavlik harness treatment. This is caused by excessive flexion of the hip (typically greater than 120 degrees), which causes the anterior strap to compress the femoral nerve against the pelvic brim. Treatment involves loosening the anterior straps to reduce flexion. Conversely, excessive abduction is associated with avascular necrosis of the femoral head.

Question 565

Topic: Pediatric Hip

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

. A 13-year-old obese male with idiopathic SCFE
. A 10-year-old female with idiopathic SCFE
. A 12-year-old male with SCFE secondary to primary hypothyroidism
. A 14-year-old male with a positive family history of SCFE
. A 15-year-old female with an acute-on-chronic SCFE

Correct Answer & Explanation

. A 12-year-old male with SCFE secondary to primary hypothyroidism

Explanation

Prophylactic contralateral pinning is highly recommended for patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy) due to the extremely high risk of bilateral involvement. Other relative indications include open triradiate cartilage or age <10 years.

Question 566

Topic: Pediatric Hip

Which of the following is considered the strongest indication for prophylactic in situ pinning of the contralateral hip in a patient presenting with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Age greater than 14 years in males
. Obesity with a BMI greater than the 95th percentile
. Presence of an underlying endocrine disorder
. Acute-on-chronic slip presentation
. Severe initial slip angle greater than 50 degrees

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with an underlying endocrine disorder (e.g., hypothyroidism, renal osteodystrophy, or growth hormone therapy) due to a near 100% risk of developing bilateral SCFE. Routine prophylactic pinning in idiopathic cases remains controversial but is less indicated than in endocrine-related SCFE.

Question 567

Topic: Pediatric Hip

In which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) is prophylactic pinning of the contralateral asymptomatic hip most strongly indicated?

. A 13-year-old male with a body mass index (BMI) in the 85th percentile
. A 14-year-old female with an acute-on-chronic slip
. A 10-year-old male with hypothyroidism
. A 15-year-old male with a severe slip (Southwick angle >60 degrees)
. A 12-year-old female with an isolated slip and closed triradiate cartilage

Correct Answer & Explanation

. A 10-year-old male with hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism) due to the high risk of bilateral involvement. It is also considered in patients presenting at a very young age (males <12, females <10) or those undergoing prior radiation therapy.

Question 568

Topic: Pediatric Hip

In evaluating an AP pelvis radiograph of a 6-month-old female for Developmental Dysplasia of the Hip (DDH), you draw Hilgenreiner's line and Perkin's line. In a normal, properly developing hip, the ossific nucleus of the femoral head should be located in which quadrant formed by these intersecting lines?

. Superomedial
. Superolateral
. Inferomedial
. Inferolateral
. Directly on the intersection

Correct Answer & Explanation

. Inferomedial

Explanation

On an AP pelvis radiograph, Hilgenreiner's line is drawn horizontally through the triradiate cartilages, and Perkin's line is drawn perpendicular to it at the lateral margin of the ossified acetabulum. In a normal hip, the femoral head ossific nucleus (or the medial beak of the metaphysis if unossified) should lie in the inferomedial quadrant. A subluxated or dislocated hip typically lies in the superolateral quadrant.

Question 569

Topic: Pediatric Hip

An infant being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness is noted by the parents to have decreased spontaneous movement of the right leg. On examination, the infant has an absent active knee extension but intact sensation over the leg. Which of the following nerve palsies is the most likely cause?

. Obturator nerve palsy
. Sciatic nerve palsy
. Femoral nerve palsy
. Superior gluteal nerve palsy
. Genitofemoral nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

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. It manifests as decreased active quadriceps function (absent knee extension). The treatment is modifying the harness to decrease flexion or temporarily discontinuing it.

Question 570

Topic: Pediatric Hip

A 10-year-old boy presents with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following patient profiles represents the strongest absolute indication for prophylactic percutaneous pinning of the contralateral, asymptomatic hip?

. A 12-year-old boy with a BMI in the 99th percentile
. A 10-year-old boy with Down syndrome
. A 14-year-old boy with a family history of SCFE
. An 11-year-old boy with previously diagnosed primary hypothyroidism
. A 9-year-old girl with early-onset menarche

Correct Answer & Explanation

. An 11-year-old boy with previously diagnosed primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended in patients with underlying endocrinopathies (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) or prior pelvic radiation therapy, as their risk of bilateral involvement approaches 100%. While obesity and young age are risk factors, endocrine disorders are the strongest indication.

Question 571

Topic: Pediatric Hip

The Salter innominate osteotomy is a surgical procedure used for the treatment of developmental dysplasia of the hip (DDH) to redirect the acetabulum and improve anterior and lateral coverage. Where is the functional hinge point of rotation for this specific osteotomy?

. Sacroiliac joint
. Symphysis pubis
. Triradiate cartilage
. Ischial spine
. Acetabular teardrop

Correct Answer & Explanation

. Symphysis pubis

Explanation

The Salter osteotomy is a complete, single-cut trans-iliac osteotomy extending from the sciatic notch to the anterior inferior iliac spine (AIIS). The distal segment (acetabulum) is rotated anteriorly, laterally, and inferiorly, hinging on the symphysis pubis.

Question 572

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes that the infant is no longer actively extending the knee on the treated side. What is the most likely cause of this complication?

. Excessive hip flexion causing femoral nerve palsy
. Excessive hip abduction causing obturator nerve palsy
. Excessive hip adduction causing sciatic nerve palsy
. Excessive hip flexion causing sciatic nerve palsy
. Excessive hip abduction causing avascular necrosis

Correct Answer & Explanation

. Excessive hip flexion causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, most commonly caused by excessive hip flexion, which stretches or compresses the femoral nerve. It presents as an inability to actively extend the knee. The treatment is to temporarily loosen the anterior straps to decrease hip flexion. Excessive hip abduction, on the other hand, puts the hip at increased risk for avascular necrosis (AVN) of the femoral head.

Question 573

Topic: Pediatric Hip

According to the Loder classification system, which of the following is the defining clinical characteristic of an 'unstable' slipped capital femoral epiphysis (SCFE)?

. Slip angle greater than 50 degrees on the lateral radiograph
. Presence of a significant hip joint effusion on ultrasound
. Inability of the patient to ambulate, even with the use of crutches
. Duration of prodromal hip or knee symptoms less than 3 weeks
. Radiographic evidence of severe physeal widening and metaphyseal blanching

Correct Answer & Explanation

. Inability of the patient to ambulate, even with the use of crutches

Explanation

The Loder classification divides SCFE into stable and unstable based entirely on clinical presentation. An 'unstable' SCFE is defined by the patient's inability to ambulate, either with or without crutches. This distinction is highly prognostic; unstable SCFE carries a much higher risk of avascular necrosis (AVN) of the femoral head (up to nearly 50%) compared to stable SCFE (near 0%).

Question 574

Topic: Pediatric Hip

A 12-year-old male presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Radiographs of the right hip are completely normal. Which of the following conditions represents an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

. Obesity with BMI > 95th percentile
. Hypothyroidism
. Male gender
. African American ethnicity
. Age greater than 14 years

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended for patients with endocrine disorders (such as hypothyroidism, growth hormone deficiency, or panhypopituitarism) and patients undergoing radiation therapy, due to the extremely high risk of bilateral involvement in these systemic conditions. While obesity and young age are risk factors for bilaterality, they remain relative indications depending on the surgeon's and family's shared decision-making, whereas endocrinopathies are considered strong/absolute indications.

Question 575

Topic: Pediatric Hip

During a reconstructive pelvic osteotomy for developmental dysplasia of the hip (DDH) in a 6-year-old child, the surgeon performs an incomplete cut starting anteriorly just superior to the AIIS and extending posteriorly down to the ilioischial limb of the flexible triradiate cartilage. The osteotomy is then hinged open to decrease acetabular volume and improve anterior and lateral coverage. Which specific osteotomy was performed?

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

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage (specifically the ilioischial limb). It alters the morphology of the acetabulum, decreasing its volume while improving anterolateral coverage. The Salter is a complete innominate osteotomy that hinges at the pubic symphysis, redirecting the entire acetabulum without changing its volume. The Dega also hinges on the triradiate cartilage but typically relies on the central/posterior portion, commonly used for posterior coverage in neuromuscular dysplasia.

Question 576

Topic: Pediatric Hip

In which of the following scenarios is prophylactic in situ pinning of the contralateral hip most strongly indicated in a patient presenting with an acute slipped capital femoral epiphysis (SCFE)?

. A 14-year-old male with a BMI of 25
. A 10-year-old female with primary hypothyroidism
. A 13-year-old male with a stable SCFE and a positive Klein's line on the contralateral side
. A 15-year-old male with a history of minor hip trauma
. A 12-year-old female with an acute-on-chronic SCFE pattern

Correct Answer & Explanation

. A 10-year-old female with primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation) due to the high risk (up to 100% in some series) of developing bilateral SCFE. It is also considered for patients of very young age or those unable to follow up.

Question 577

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 12-year-old male with a BMI of 30
. A 10-year-old female with an idiopathic slip
. A 13-year-old female with a history of DDH
. A 14-year-old male with renal osteodystrophy
. A 15-year-old male with a sports-related acute slip

Correct Answer & Explanation

. A 14-year-old male with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients with an underlying endocrine or metabolic disorder (such as renal osteodystrophy, hypothyroidism, or prior pelvic radiation) due to the high risk of a contralateral slip, which can approach 100% in these populations.

Question 578

Topic: Pediatric Hip

A 13-year-old boy undergoes in-situ pinning of a severe, unstable slipped capital femoral epiphysis (SCFE). Postoperatively, he has significantly decreased hip motion and pain, and radiographs reveal diffuse narrowing of the joint space. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Undiagnosed contralateral SCFE
. Septic arthritis
. Cam impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis (acute cartilage necrosis) is a serious complication of SCFE, presenting with progressive stiffness, pain, and marked joint space narrowing on radiographs. Risk factors include severe slips, unrecognized pin penetration into the joint, and spica cast immobilization.

Question 579

Topic: Pediatric Hip

According to the Loder classification, an unstable Slipped Capital Femoral Epiphysis (SCFE) is defined by which of the following clinical criteria, and what is the primary risk associated with it?

. Displacement greater than 50%; high risk of chondrolysis
. Inability to ambulate even with crutches; high risk of avascular necrosis
. Duration of symptoms less than 3 weeks; high risk of contralateral slip
. Presence of an effusion on ultrasound; high risk of septic arthritis
. Slip angle greater than 60 degrees; high risk of osteoarthritis

Correct Answer & Explanation

. Inability to ambulate even with crutches; high risk of avascular necrosis

Explanation

The Loder classification divides SCFE into stable and unstable categories based strictly on the clinical ability of the patient to bear weight (with or without crutches). An unstable SCFE means the patient cannot bear weight. This is highly clinically relevant because unstable SCFEs carry a substantially higher risk of developing avascular necrosis (AVN) of the femoral head (often approaching 50%).

Question 580

Topic: Pediatric Hip

During the surgical treatment of a severe, unstable slipped capital femoral epiphysis (SCFE) using in situ pinning, the surgeon performs an anterior capsulotomy of the hip. What is the primary biomechanical or physiologic benefit of this adjunctive procedure?

. Reduces the risk of postoperative chondrolysis
. Reduces intracapsular pressure and the risk of avascular necrosis (AVN)
. Improves direct visualization to achieve anatomical reduction
. Facilitates the placement of a completely intra-epiphyseal screw
. Prevents the future development of cam-type femoroacetabular impingement

Correct Answer & Explanation

. Reduces intracapsular pressure and the risk of avascular necrosis (AVN)

Explanation

In an unstable SCFE, there is often an intracapsular hematoma that raises the pressure within the joint space. This increased pressure can compromise the tenuous retinacular vessels supplying the femoral epiphysis, increasing the risk of avascular necrosis (AVN). An anterior capsulotomy decompresses the hematoma, lowering intracapsular pressure and mitigating the risk of AVN.

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