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Pediatric Hip MCQs

Practice Set 31 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 601

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, the parents report she has stopped kicking her leg on the treated side. On examination, the hip is hyperflexed beyond 120 degrees in the harness, and active knee extension is absent. Which nerve is most likely affected?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Superior gluteal nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

Femoral nerve palsy is the most common nerve injury associated with Pavlik harness treatment for DDH. It is typically iatrogenic, caused by hyperflexion of the hip (usually >120 degrees), which dynamically compresses the femoral nerve against the inguinal ligament or the brim of the pelvis. Clinically, it presents with a loss of active knee extension (decreased kicking). Treatment involves immediate temporary removal or adjustment of the harness flexion straps.

Question 602

Topic: Pediatric Hip

A 12-year-old boy presents with left hip pain and an obligate external rotation during passive hip flexion. Radiographs confirm a left Slipped Capital Femoral Epiphysis (SCFE). Under which of the following conditions is prophylactic pinning of the asymptomatic contralateral hip most strongly indicated?

. Open triradiate cartilage at the time of presentation
. History of an underlying endocrine disorder
. Male gender and age greater than 14 years
. High body mass index (> 95th percentile) as an isolated risk factor
. Presence of a type II physeal configuration on lateral radiograph

Correct Answer & Explanation

. History of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or those who have undergone previous pelvic radiation. These patients have a significantly higher risk of developing bilateral disease compared to idiopathic cases.

Question 603

Topic: Pediatric Hip

A 6-week-old female infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness due to a positive Ortolani sign and an ultrasound alpha angle of 45 degrees. After 3 weeks of strictly compliant harness wear, ultrasound confirms the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 3 weeks
. Switch immediately to a rigid hip abduction orthosis (e.g., Ilfeld brace)
. Perform a surgical open reduction via an anterior approach
. Perform a closed reduction and application of a hip spica cast
. Discontinue the harness and observe until the child is 6 months old

Correct Answer & Explanation

. Perform a closed reduction and application of a hip spica cast

Explanation

If a Pavlik harness fails to achieve reduction of a dislocated hip within 3 to 4 weeks, it must be discontinued to avoid 'Pavlik harness disease' (damage to the posterior acetabular wall) and to prevent femoral nerve palsy. The standard next step for a persistently dislocated hip failing Pavlik harness treatment in an infant is closed reduction under general anesthesia and application of a hip spica cast.

Question 604

Topic: Pediatric Hip

A 12-year-old obese male presents with a 3-week history of left thigh pain and a limp. Examination shows obligatory external rotation of the hip with passive flexion. Radiographs demonstrate a mild slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk factor for developing chondrolysis in this patient?

. Prophylactic pinning of the contralateral hip
. Unrecognized penetration of the joint space with the fixation screw
. Performing an open subcapital realignment (modified Dunn procedure)
. The duration of symptoms prior to presentation
. Patient's BMI over the 95th percentile

Correct Answer & Explanation

. Unrecognized penetration of the joint space with the fixation screw

Explanation

Chondrolysis is a devastating complication of SCFE characterized by rapid destruction of the articular cartilage. While it can occur in unpinned SCFE, the most strongly associated iatrogenic risk factor is unrecognized pin penetration into the joint space. Approach and pinning technique must include multi-planar fluoroscopy (the 'approach-withdraw' technique) to ensure the screw threads stay entirely within the femoral head.

Question 605

Topic: Pediatric Hip

A 12-year-old boy presents with left groin pain and an obligatory external rotation of the hip during flexion. Radiographs confirm a moderate, stable slipped capital femoral epiphysis (SCFE). Which of the following patient characteristics is the strongest absolute indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

. BMI > 95th percentile
. Renal osteodystrophy
. Age greater than 14 years at presentation
. Family history of SCFE in a sibling
. African American descent

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in unilateral SCFE remains controversial for idiopathic cases. However, it is strongly indicated (often considered an absolute indication) in patients with underlying metabolic bone diseases (such as renal osteodystrophy) or endocrinopathies (like hypothyroidism or growth hormone supplementation), as their risk of developing a contralateral slip approaches 100%.

Question 606

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. Two weeks later at a follow-up appointment, the parents report the infant is no longer actively kicking the right leg. On examination, the infant has active ankle and toe movement but cannot actively extend the knee. Patellar reflex is diminished. What is the most likely iatrogenic cause of this presentation?

. Avascular necrosis of the femoral head due to excessive abduction
. Sciatic nerve palsy due to inadequate hip flexion
. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive external rotation
. Peroneal nerve palsy due to a tight foot strap

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically resulting from hyperflexion of the hips, which causes compression of the femoral nerve against the inguinal ligament. It manifests as an inability to actively extend the knee. The appropriate action is to temporarily loosen the anterior straps or remove the harness to allow the nerve to recover.

Question 607

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 child has stopped extending her knee on the treated side. On examination, the patellar reflex is absent, and the hip is positioned in 125 degrees of flexion. Which of the following is the most likely cause of this complication?

. Hyperflexion causing femoral nerve palsy
. Hyperabduction causing avascular necrosis
. Hyperextension causing sciatic nerve palsy
. Hyperabduction causing obturator nerve palsy
. Strap loosening leading to recurrent dislocation

Correct Answer & Explanation

. Hyperflexion causing femoral nerve palsy

Explanation

Excessive hip flexion (typically >120 degrees) in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. This presents clinically as a loss of active knee extension and an absent patellar reflex. The treatment is to temporarily adjust the anterior straps to decrease hip flexion or remove the harness until nerve function returns. Excessive abduction, on the other hand, is associated with avascular necrosis.

Question 608

Topic: Pediatric Hip

Which of the following eponymous radiographic signs describes a crescent-shaped area of increased radiodensity in the proximal femoral metaphysis on an AP pelvis radiograph in a patient with a Slipped Capital Femoral Epiphysis (SCFE)?

. Gage's sign
. Trethowan's sign
. Blanch sign of Steel
. Waldenstrom's sign
. Sagging rope sign

Correct Answer & Explanation

. Blanch sign of Steel

Explanation

The Blanch sign of Steel is a crescent-shaped double density seen on the AP radiograph of a SCFE, caused by the superimposition of the posteriorly displaced femoral epiphysis on the metaphysis. Trethowan's sign refers to Klein's line passing completely superior to the epiphysis. Waldenstrom's sign is an increased distance between the medial epiphysis and the pelvic teardrop (effusion). The sagging rope sign is a thin sclerotic line running transversely across the metaphysis indicating severe deformity.

Question 609

Topic: Pediatric Hip

A 4-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after an ultrasound shows an alpha angle of 40 degrees and 20% coverage. She is placed in a Pavlik harness. Which complication is most closely associated with excessive hip flexion in the harness?

. Femoral nerve palsy
. Sciatic nerve palsy
. Obturator nerve palsy
. Avascular necrosis of the femoral head
. Inferior dislocation of the hip

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion (>120 degrees) in a Pavlik harness can impinge the femoral nerve against the inguinal ligament, leading to femoral nerve palsy. Excessive abduction is strongly associated with avascular necrosis (AVN) of the femoral head.

Question 610

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of right groin and thigh pain, and a limp. Examination reveals obligate external rotation of the right hip during passive flexion. Radiographs confirm a mild Slipped Capital Femoral Epiphysis (SCFE). What is the most appropriate initial management?

. Immediate weight-bearing as tolerated
. Closed reduction and spica casting
. In situ percutaneous pinning
. Open reduction and internal fixation
. Proximal femoral osteotomy

Correct Answer & Explanation

. In situ percutaneous pinning

Explanation

The gold standard treatment for a stable SCFE is in situ percutaneous pinning with a single cannulated screw to prevent further slip. Attempted closed reduction is strongly contraindicated due to the high risk of causing avascular necrosis (AVN) of the femoral head.

Question 611

Topic: Pediatric Hip
A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic signs is considered a 'head at risk' sign according to Catterall, indicating a potentially poorer prognosis?
. Gage sign
. Crescent sign
. Waldenström sign
. Sagging rope sign
. Metaphyseal blanch sign

Correct Answer & Explanation

. Gage sign

Explanation

Catterall 'head at risk' signs for Legg-Calvé-Perthes disease indicate impending collapse and poor prognosis. They include the Gage sign (a small V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), lateral calcification, lateral subluxation, a horizontal physis, and metaphyseal cysts.

Question 612

Topic: Pediatric Hip

An 18-month-old child presents with an untreated developmental dysplasia of the hip (DDH) and undergoes an open reduction and spica casting. Intraoperatively, the surgeon carefully positions the hip. Which of the following maneuvers is the most critical intraoperative factor to prevent avascular necrosis (AVN) of the femoral head?

. Extensive capsulorrhaphy technique
. Routine proximal femoral shortening osteotomy
. Complete resection of the ligamentum teres
. Avoidance of extreme abduction during casting
. Routine release of the iliopsoas tendon

Correct Answer & Explanation

. Avoidance of extreme abduction during casting

Explanation

Extreme abduction (the traditional 'frog-leg' position) causes increased mechanical pressure on the vulnerable capital femoral epiphysis and its blood supply, significantly increasing the risk of iatrogenic AVN. The safe zone of Ramsey mandates immobilizing the hip in the 'human position' (moderate abduction and flexion).

Question 613

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of left knee pain and a limp. Examination reveals obligatory external rotation of the left hip with passive flexion. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). Which of the following best describes the true anatomical displacement occurring in a SCFE?

. The epiphysis displaces anteriorly and laterally relative to the metaphysis.
. The epiphysis displaces anteriorly and medially relative to the metaphysis.
. The metaphysis displaces anteriorly and laterally relative to the epiphysis.
. The metaphysis displaces posteriorly and medially relative to the epiphysis.
. The epiphysis displaces superiorly relative to the metaphysis.

Correct Answer & Explanation

. The metaphysis displaces anteriorly and laterally relative to the epiphysis.

Explanation

In a SCFE, the capital femoral epiphysis remains essentially in its normal position within the acetabulum. The true pathology is the displacement of the femoral neck (metaphysis), which translates anteriorly and laterally (externally rotates) relative to the epiphysis. On standard radiographs, this makes the epiphysis appear to have slipped posteriorly and medially.

Question 614

Topic: Pediatric Hip

Which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) has the strongest clinical indication for prophylactic pinning of the contralateral, asymptomatic hip?

. A 14-year-old boy with a BMI in the 90th percentile
. A 10-year-old girl with primary hypothyroidism
. A 13-year-old boy with a 45-degree unilateral slip
. An 11-year-old girl with a sudden onset of symptoms after jumping
. A 15-year-old boy with a BMI in the 99th percentile

Correct Answer & Explanation

. A 10-year-old girl with primary hypothyroidism

Explanation

Endocrine disorders (such as hypothyroidism, renal osteodystrophy, and growth hormone deficiency) carry a very high risk (up to 100% in some series) for the development of bilateral SCFE. Patients with these underlying conditions or very young patients (<10 years old) have the strongest indication for prophylactic contralateral pinning.

Question 615

Topic: Pediatric Hip
In the management of Legg-Calvé-Perthes disease, the Herring lateral pillar classification is widely used to determine prognosis and guide treatment. During which stage of the disease must this classification be assessed to accurately predict outcome?
. Initial (Necrosis) stage
. Fragmentation stage
. Reossification stage
. Remodeling stage
. Healed stage

Correct Answer & Explanation

. Fragmentation stage

Explanation

The Herring lateral pillar classification is most accurate and prognostically significant when assessed during the early fragmentation stage of Legg-Calvé-Perthes disease, as it determines the height of the preserved lateral pillar which is crucial to preventing femoral head extrusion.

Question 616

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. Two weeks later, the parents report the infant is not kicking the affected leg. On exam, the anterior straps are noted to be excessively tight, positioning the hip in greater than 120 degrees of flexion. Which complication has most likely occurred?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Sciatic nerve palsy
. Inferior hip dislocation
. Obturator nerve palsy

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Excessive flexion in a Pavlik harness (typically > 120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a temporary femoral nerve palsy (manifested by decreased knee extension/kicking). Excessive abduction (tight posterior straps) increases the risk of avascular necrosis.

Question 617

Topic: Pediatric Hip

Which of the following clinical scenarios is the most widely accepted indication for prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient with a slipped capital femoral epiphysis (SCFE)?

. A 12-year-old boy with a stable SCFE and a normal body mass index
. A 14-year-old boy with an acute, unstable SCFE
. An 11-year-old girl with renal osteodystrophy and a stable SCFE
. A 13-year-old girl with idiopathic unilateral SCFE and bilateral knee pain
. A 10-year-old boy with a post-traumatic SCFE

Correct Answer & Explanation

. An 11-year-old girl with renal osteodystrophy and a stable SCFE

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients with underlying endocrine or metabolic disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) due to an exceedingly high risk (up to 100% in some series) of bilateral involvement. Routine prophylactic pinning in idiopathic SCFE remains controversial, though it is sometimes considered in very young patients (e.g., <10 years old) or those likely to be non-compliant.

Question 618

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The harness is adjusted, but the anterior straps are inadvertently pulled too tight, placing the hips in excessive flexion (greater than 120 degrees). What is the most likely neurologic complication resulting from this specific positioning error?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Avascular necrosis of the femoral head
. Superior gluteal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

The Pavlik harness must be carefully adjusted. Excessive flexion of the hips (anterior straps too tight, >120 degrees of flexion) compresses the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy. The clinical sign is an absence of active knee extension. Avascular necrosis (AVN) is the most devastating complication overall and is associated with excessive abduction (posterior straps too tight). Sciatic nerve palsy is rare in this context.

Question 619

Topic: Pediatric Hip

During in situ pinning of a slipped capital femoral epiphysis (SCFE), unrecognized pin penetration into the hip joint space is most directly associated with which of the following postoperative complications?

. Avascular necrosis
. Chondrolysis
. Coxa vara
. Femoroacetabular impingement
. Premature osteoarthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized pin penetration into the hip joint during in situ fixation of a SCFE is the most common cause of chondrolysis. It causes rapid loss of articular cartilage, leading to severe stiffness, pain, and a narrowed joint space on radiographs.

Question 620

Topic: Pediatric Hip

In the ultrasonographic evaluation of developmental dysplasia of the hip (DDH) using the Graf method, the alpha angle is used to assess acetabular development. Which of the following anatomical landmarks are used to measure the alpha angle?

. The bony roof of the acetabulum and the straight portion of the iliac bone
. The cartilaginous roof of the acetabulum and the iliac bone
. The triradiate cartilage and the labrum
. The femoral head and the iliac bone
. The labrum and the joint capsule

Correct Answer & Explanation

. The bony roof of the acetabulum and the straight portion of the iliac bone

Explanation

In the Graf method for DDH, the alpha angle measures the concavity of the bony roof. It is formed by the intersection of the baseline (drawn along the straight portion of the ilium) and the bony roof line (drawn from the lower edge of the iliac bone at the triradiate cartilage tangent to the osseous rim). A normal alpha angle is greater than or equal to 60 degrees.

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