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Pediatric Hip MCQs

Practice Set 24 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 461

Topic: Pediatric Hip
A 12-year-old obese boy presents with a left-sided slipped capital femoral epiphysis (SCFE). Which of the following represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?
. Age greater than 14 years
. Male gender
. Presence of an endocrine disorder
. Grade III slip on the symptomatic side
. Acute-on-chronic presentation

Correct Answer & Explanation

. Presence of an endocrine disorder

Explanation

The presence of an underlying endocrine disorder (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) is a strong risk factor for bilateral SCFE, with some studies reporting nearly 100% eventual bilateral involvement. Prophylactic pinning of the contralateral hip is highly recommended in these patients. Other indications include prior radiation therapy and age younger than 10.

Question 462

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a routine follow-up, the parents report that the child has stopped actively kicking the affected leg. On physical examination, there is an absent patellar reflex and decreased active knee extension. The harness is found to be in excessive hyperflexion. Which of the following nerves is most likely compressed?

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

Correct Answer & Explanation

. Femoral nerve

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, usually resulting from hyperflexion of the hip (anterior straps too tight). It manifests as decreased spontaneous movement of the leg, specifically decreased active knee extension (quadriceps weakness) and an absent patellar reflex. The treatment involves loosening the anterior straps or temporarily removing the harness.

Question 463

Topic: Pediatric Hip

A 6-week-old female infant is evaluated for developmental dysplasia of the hip (DDH). Ultrasound is performed, and an alpha angle of 45 degrees is noted on the right hip. She is prescribed a Pavlik harness. Which of the following complications is most likely to occur if the harness is placed in excessive hip flexion (greater than 120 degrees)?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

In the use of a Pavlik harness for DDH, excessive hip flexion (typically > 120 degrees) is known to cause femoral nerve palsy due to compression of the nerve against the inguinal ligament. Excessive abduction is associated with avascular necrosis of the femoral head.

Question 464

Topic: Pediatric Hip

A 13-year-old overweight boy presents with a 3-week history of right groin and knee pain. He walks with a limp. On examination, when his right hip is flexed, it obligatorily externally rotates. Radiographs show a slip of the proximal femoral epiphysis. Which radiographic line is used to diagnose this condition?

. Shenton's line
. Hilgenreiner's line
. Klein's line
. Perkin's line
. Ward's triangle

Correct Answer & Explanation

. Klein's line

Explanation

The clinical scenario describes Slipped Capital Femoral Epiphysis (SCFE). Klein's line is drawn along the superior edge of the femoral neck on an AP pelvic radiograph. In a normal hip, this line should intersect a portion of the lateral capital femoral epiphysis. In SCFE, the line passes superior to the epiphysis or intersects less of it compared to the contralateral normal side (Trethowan's sign).

Question 465

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp of several months' duration. Examination reveals restricted hip abduction and internal rotation. Radiographs demonstrate sclerosis and flattening of the capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. According to the Waldenström classification, what is the sequence of radiographic stages in this disease?
. Fragmentation, Initial, Reossification, Healed
. Initial, Fragmentation, Reossification, Healed
. Reossification, Initial, Fragmentation, Healed
. Initial, Reossification, Fragmentation, Healed
. Healed, Reossification, Fragmentation, Initial

Correct Answer & Explanation

. Initial, Fragmentation, Reossification, Healed

Explanation

The Waldenström classification of Legg-Calvé-Perthes disease outlines four stages: 1) Initial (infarction/necrosis) stage, characterized by sclerosis and cessation of growth; 2) Fragmentation stage, where the epiphysis appears fragmented as necrotic bone is resorbed; 3) Reossification stage, where new bone forms; and 4) Healed (residual) stage, where the bone is fully reossified, though often with a deformed head.

Question 466

Topic: Pediatric Hip

A 13-year-old obese male underwent in situ single-screw pinning for a severe, unstable slipped capital femoral epiphysis (SCFE) 6 months ago. He now complains of progressive hip stiffness and pain. Radiographs demonstrate marked concentric joint space narrowing of the affected hip without evidence of avascular necrosis.

What is the most likely diagnosis?

. Deep joint space infection
. Heterotopic ossification
. Chondrolysis
. Screw penetration into the joint
. Cam-type femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, characterized by acute articular cartilage destruction, concentric joint space narrowing (typically <3 mm), stiffness, and pain. It is more common in severe slips, unstable slips, and historically with spica cast immobilization or unrecognized intra-articular hardware penetration, though it can occur idiopathically post-slip.

Question 467

Topic: Pediatric Hip

A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip.

Which of the following factors is the strongest indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?

. Body Mass Index greater than the 95th percentile
. Slip angle greater than 50 degrees on the affected side
. Age greater than 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Male gender

Correct Answer & Explanation

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

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly indicated in patients with a high risk of bilateral involvement. Risk factors predicting contralateral slip include an underlying endocrine disorder (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), prior radiation therapy, or age of presentation less than 10 years (or low modified Oxford bone age score).

Question 468

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for 4 weeks.

Clinical and ultrasonographic evaluations confirm that the left hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue Pavlik harness treatment for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld or Rhino brace)
. Perform an immediate open reduction and spica casting
. Perform a proximal femoral varus derotational osteotomy
. Perform a pelvic (Salter) osteotomy

Correct Answer & Explanation

. Transition to a rigid abduction orthosis (e.g., Ilfeld or Rhino brace)

Explanation

If a Pavlik harness fails to achieve reduction within 3 to 4 weeks, its use should be discontinued to prevent complications such as 'Pavlik harness disease' (erosion of the posterior acetabular lip) and avascular necrosis. The AAOS guidelines recommend transitioning to a rigid or semi-rigid abduction orthosis as the next step before considering closed or open surgical reduction.

Question 469

Topic: Pediatric Hip

A 13-year-old obese boy presents with non-traumatic knee pain and is noted to have an obligate external rotation of his hip when it is passively flexed. Radiographs confirm the diagnosis.

He is unable to bear weight on the affected extremity. What is the primary complication associated with this presentation compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Slipped capital femoral epiphysis on the contralateral side
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The patient has an unstable slipped capital femoral epiphysis (SCFE), defined by Loder criteria as the inability to bear weight even with crutches. Unstable SCFE has a significantly higher rate of avascular necrosis (up to nearly 50% in some series) compared to stable SCFE (which has an AVN rate near 0%). Both stable and unstable SCFEs can lead to impingement or contralateral slips, but AVN is the critical distinguishing risk factor of an unstable slip.

Question 470

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with severe left thigh pain and an inability to bear weight on the left leg for the past 2 weeks, even with crutches. Radiographs demonstrate a slipped capital femoral epiphysis.

Which of the following defines this as an 'unstable' SCFE, and what is the primary associated complication risk?

. Symptom duration less than 3 weeks; high risk of chondrolysis
. Inability to bear weight; high risk of avascular necrosis (AVN)
. Slip angle greater than 50 degrees; high risk of AVN
. Open triradiate cartilage; high risk of nonunion
. Presence of an effusion on ultrasound; high risk of septic arthritis

Correct Answer & Explanation

. Inability to bear weight; high risk of avascular necrosis (AVN)

Explanation

The Loder classification defines an unstable SCFE by the patient's inability to bear weight, even with assistive devices. This distinction is critical because unstable SCFEs carry a much higher risk of avascular necrosis (AVN) of the femoral head (approaching 47%) compared to stable SCFEs (<10%). Symptom duration previously defined acute vs. chronic but doesn't dictate stability.

Question 471

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At the two-week follow-up, the mother notes that the baby is not kicking or extending the knee on the treated side, though ankle and toe movements are intact. Which of the following is the most likely cause of this finding?

. Avascular necrosis of the femoral head due to excessive abduction
. Femoral nerve palsy due to hyperflexion of the hip
. Obturator nerve palsy due to excessive abduction
. Sciatic nerve compression from the posterior harness straps
. Slipped capital femoral epiphysis caused by the harness

Correct Answer & Explanation

. Femoral nerve palsy due to hyperflexion of the hip

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment. It is typically caused by excessive hyperflexion of the hip in the anterior straps. It presents clinically as an inability to extend the knee (quadriceps weakness) or a lack of kicking on the affected side. The treatment is to temporarily loosen the anterior straps or remove the harness until nerve function returns.

Question 472

Topic: Pediatric Hip

A 6-week-old female is diagnosed with a completely dislocated left hip (Graf IV) and treated with a Pavlik harness. After 4 weeks of compliant wear, dynamic ultrasound shows the hip remains persistently dislocated.

What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld) or proceed to closed reduction and spica casting
. Perform an open reduction via a medial approach
. Perform a proximal femoral varus derotational osteotomy
. Observe and reassess at 6 months of age

Correct Answer & Explanation

. Transition to a rigid abduction orthosis (e.g., Ilfeld) or proceed to closed reduction and spica casting

Explanation

According to established AAOS guidelines for Developmental Dysplasia of the Hip (DDH), failure of a Pavlik harness to reduce a dislocated hip after 3-4 weeks is an indication to discontinue the harness to prevent 'Pavlik harness disease' (acetabular damage/erosion). The appropriate next step is transitioning to a rigid abduction orthosis or proceeding directly to a closed reduction and spica casting in the operating room.

Question 473

Topic: Pediatric Hip

A 12-year-old obese male presents with a mild, stable right slipped capital femoral epiphysis (SCFE).

Which of the following conditions is an absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 14 years at presentation
. Obesity (BMI > 95th percentile)
. Presence of an underlying endocrine disorder
. African American race
. Male sex

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

The risk of developing a contralateral SCFE is approximately 20-40% overall. However, prophylactic pinning of the contralateral asymptomatic hip is strongly indicated in patients with underlying endocrinopathies (e.g., hypothyroidism, growth hormone deficiency), renal osteodystrophy, prior pelvic radiation therapy, or an unusually young age at presentation (<10 years), as their risk of bilateral involvement approaches 100%.

Question 474

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in situ pinning for a stable slipped capital femoral epiphysis (SCFE). During the procedure, the screw is inadvertently placed in the anterosuperior quadrant of the femoral head. What is the most likely complication associated with this specific pin position?

. Chondrolysis
. Osteonecrosis
. Slip progression
. Femoral neck fracture
. Labral tear

Correct Answer & Explanation

. Osteonecrosis

Explanation

The blood supply to the femoral head relies heavily on the lateral epiphyseal branches of the medial femoral circumflex artery, which enter the femoral head posterosuperiorly. Pin placement in the anterosuperior quadrant of the femoral head directly endangers this blood supply, significantly increasing the risk of iatrogenic osteonecrosis (avascular necrosis). The ideal screw position is in the center of the epiphysis.

Question 475

Topic: Pediatric Hip

A 6-month-old female is diagnosed with Developmental Dysplasia of the Hip (DDH). An anterior-posterior radiograph of the pelvis is evaluated. Which of the following radiographic parameters specifically indicates superior (proximal) displacement of the femoral head?

. A broken Shenton's line
. The femoral head ossific nucleus lies medial to Perkin's line
. The femoral head ossific nucleus lies inferior to Hilgenreiner's line
. An acetabular index of 20 degrees
. A center-edge angle of Wiberg of 35 degrees

Correct Answer & Explanation

. A broken Shenton's line

Explanation

Shenton's line is a continuous curve formed by the medial border of the femoral neck and the superior border of the obturator foramen. A break in this line indicates proximal (superior) displacement of the femur relative to the pelvis. Normal position requires the ossific nucleus to be medial to Perkin's line (evaluates lateral displacement) and inferior to Hilgenreiner's line.

Question 476

Topic: Pediatric Hip

A 12-year-old boy presents with left thigh pain and an antalgic gait. Radiographs confirm a mild left slipped capital femoral epiphysis (SCFE). He is subsequently evaluated for potential contralateral disease. Which of the following is considered the strongest absolute indication for prophylactic in-situ pinning of the contralateral right hip?

. Open triradiate cartilage
. Underlying endocrine disorder
. Body mass index > 95th percentile
. Initial slip angle > 50 degrees
. Male gender

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in patients with SCFE is highly recommended and considered essentially an absolute indication for patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism) due to the exceedingly high risk of bilateral involvement, approaching 100% in these conditions. Young age (<10 years) and open triradiate cartilage are relative indications.

Question 477

Topic: Pediatric Hip
A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. The treating orthopedist relies on the Herring Lateral Pillar classification to determine the child's prognosis and guide treatment. Which of the following accurately describes a Herring Lateral Pillar Group B hip?
. No involvement of the lateral pillar, maintaining 100% height
. > 50% maintenance of normal lateral pillar height
. < 50% maintenance of normal lateral pillar height
. Complete 100% collapse of the lateral pillar
. Central pillar collapse with perfectly intact lateral and medial pillars

Correct Answer & Explanation

. < 50% maintenance of normal lateral pillar height

Explanation

The Herring Lateral Pillar Classification evaluates the height of the lateral aspect of the capital femoral epiphysis. Group A: No involvement of the lateral pillar. Group B: >50% of the lateral pillar height is maintained. Group C: <50% of the lateral pillar height is maintained. A Group B/C classification was later added for borderline cases where the pillar is approximately 50% of normal height or poorly ossified. Prognosis significantly worsens from A to C.

Question 478

Topic: Pediatric Hip



A 12-year-old boy presents with left thigh pain and an antalgic gait for 4 weeks. Radiographs confirm a stable left slipped capital femoral epiphysis (SCFE). Prophylactic in situ pinning of the contralateral asymptomatic right hip is most strongly indicated if the patient has which of the following concomitant conditions?

. A chronologic age of 14 years at presentation
. A body mass index (BMI) tracking in the 50th percentile
. A diagnosis of hypothyroidism or panhypopituitarism
. A slip angle of 20 degrees on the symptomatic left side
. A modified Oxford bone age score of 22

Correct Answer & Explanation

. A diagnosis of hypothyroidism or panhypopituitarism

Explanation

Patients with endocrine disorders (such as hypothyroidism, growth hormone deficiency) or renal osteodystrophy are at a significantly elevated risk for bilateral slipped capital femoral epiphysis (SCFE). In these populations, prophylactic pinning of the contralateral hip is highly recommended, regardless of their chronological age.

Question 479

Topic: Pediatric Hip

A 12-year-old boy presents with left thigh pain, an antalgic gait, and an externally rotated left lower extremity. Radiographs demonstrate the pathology shown.

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

. Obesity (BMI > 95th percentile)
. Male gender
. Underlying endocrine disorder (e.g., hypothyroidism)
. Age greater than 14 years at presentation
. Black race

Correct Answer & Explanation

. Underlying endocrine disorder (e.g., hypothyroidism)

Explanation

SCFE is characterized by a displacement of the proximal femoral epiphysis. Prophylactic pinning of the contralateral hip is somewhat controversial but generally recommended in patients with a high risk of subsequent contralateral slip. Absolute indications or highly strong recommendations for prophylactic contralateral pinning include an underlying endocrine disorder (such as hypothyroidism or growth hormone deficiency), renal osteodystrophy, previous radiation therapy, and presentation at a very young age (e.g., < 10 years). Endocrine disorders dramatically increase the risk of bilateral involvement, often occurring simultaneously or sequentially.

Question 480

Topic: Pediatric Hip

A 6-week-old female infant is treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At the second weekly follow-up, the parents report the infant is no longer moving her right lower extremity. Clinical examination reveals an absence of active knee extension on the right. What is the most likely iatrogenic cause of this finding?

. Avascular necrosis of the femoral head
. Femoral nerve palsy due to excessive hyperflexion
. Obturator nerve palsy due to excessive abduction
. Sciatic nerve palsy due to hyperflexion
. Common peroneal nerve palsy from the posterior foot strap

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hyperflexion

Explanation

Femoral nerve palsy is the most common nerve palsy associated with Pavlik harness treatment and is typically caused by excessive flexion of the hips. Hyperflexion compresses the femoral nerve against the inguinal ligament, leading to decreased quadriceps function (loss of active knee extension). The treatment is to temporarily adjust or remove the harness; the palsy typically resolves spontaneously within days to weeks.

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