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Pediatric Hip MCQs

Practice Set 83 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 1641

Topic: Pediatric Hip

A 38-year-old female with Crowe Type IV developmental dysplasia of the hip (DDH) is undergoing a total hip arthroplasty. The femoral head is completely dislocated superior to the true acetabulum. To place the acetabular cup in the anatomic true acetabulum while preventing sciatic nerve stretch injury, what specific surgical adjunct is most frequently required?

. Adductor tenotomy and psoas release alone
. Subtrochanteric shortening osteotomy of the femur
. Greater trochanteric advancement
. High hip center cup placement
. Prophylactic sciatic nerve decompression

Correct Answer & Explanation

. Subtrochanteric shortening osteotomy of the femur

Explanation

In Crowe IV DDH, the hip is completely dislocated, and the soft tissues have contracted over many years. Bringing the femur down to an anatomic cup in the true acetabulum stretches the sciatic nerve, with a high risk of neuropraxia or permanent injury if the limb is lengthened more than 4 cm. A subtrochanteric shortening osteotomy of the femur is required to safely reduce the hip into the true acetabulum while protecting the sciatic nerve.

Question 1642

Topic: Pediatric Hip

A 13-year-old overweight boy presents with a 3-month history of vague left knee and thigh pain. On physical examination, as the left hip is passively flexed, it obligatorily moves into external rotation. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE). What is the most appropriate definitive management?

. Closed reduction and spica casting
. In situ pinning with a single cannulated screw
. Open reduction and internal fixation with multiple screws
. Subtrochanteric derotational osteotomy
. Observation and non-weight bearing with crutches

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

The patient has a stable Slipped Capital Femoral Epiphysis (SCFE). The standard of care for a mild, stable SCFE is in situ percutaneous fixation with a single cannulated screw placed in the center of the epiphysis to prevent further slippage. Closed reduction is contraindicated due to the high risk of osteonecrosis. Multiple screws do not significantly improve biomechanical stability for stable slips and increase the risk of joint penetration.

Question 1643

Topic: Pediatric Hip

A 12-year-old obese male presents with a confirmed slipped capital femoral epiphysis (SCFE) of the left hip. During surgical planning, prophylactic pinning of the asymptomatic contralateral right hip is considered. Which of the following is an established strong indication for prophylactic pinning of the contralateral hip?

. Male sex alone
. Age older than 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. BMI > 95th percentile alone
. Bilateral hip pain with strictly normal radiographs on the right

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 universally recommended in patients with an intrinsically high risk for a subsequent contralateral slip. Established high-risk factors include underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), prior radiation therapy to the pelvis, and a very young age at presentation (typically girls <10 years or boys <12 years).

Question 1644

Topic: Pediatric Hip

A 13-year-old obese male presents with acute-on-chronic left groin pain and an obligatory external rotation of the hip during flexion. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). What is the most devastating potential complication of treating this condition with in-situ single screw fixation?

. Chondrolysis
. Osteonecrosis (AVN)
. Femoral neck fracture
. Implant failure
. Infection

Correct Answer & Explanation

. Osteonecrosis (AVN)

Explanation

Osteonecrosis is the most devastating complication of SCFE and is associated with acute unstable slips, forceful reduction, and hardware penetration into the joint. In-situ fixation aims to minimize this risk, but AVN remains a primary concern in severe or unstable cases.

Question 1645

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The mother reports that the child has stopped kicking the affected leg. On examination, there is decreased active knee extension. What is the most likely cause?

. Obturator nerve palsy
. Sciatic nerve palsy
. Femoral nerve palsy
. Tibial nerve palsy
. Common peroneal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hip. Treatment involves temporary removal or adjustment of the harness until neurologic function returns.

Question 1646

Topic: Pediatric Hip

A 28-year-old female runner complains of deep anterior hip pain. An AP pelvic radiograph demonstrates the 'crossover sign'. This radiographic finding is indicative of which pathoanatomical condition?

. Cam-type femoroacetabular impingement
. Focal or global acetabular retroversion
. Developmental dysplasia of the hip (DDH)
. Coxa profunda
. Femoral retroversion

Correct Answer & Explanation

. Focal or global acetabular retroversion

Explanation

The crossover sign occurs when the anterior wall of the acetabulum crosses lateral to the posterior wall on an AP pelvis radiograph. It is the hallmark radiographic sign of focal or global acetabular retroversion, a form of pincer impingement.

Question 1647

Topic: Pediatric Hip

Restoring the anatomical hip center during THA for developmental dysplasia of the hip (DDH) is preferred over placing the cup in a high hip center. Biomechanically, what is the primary advantage of lowering the hip center to its true anatomical location?

. Decreases the abductor moment arm and increases joint reactive force
. Increases the abductor moment arm and decreases joint reactive force
. Increases both the abductor moment arm and joint reactive force
. Decreases both the abductor moment arm and joint reactive force
. Shifts the center of gravity laterally, reducing superior sheer forces

Correct Answer & Explanation

. Increases the abductor moment arm and decreases joint reactive force

Explanation

Restoring the anatomical (inferior and medial) hip center increases the mechanical advantage (moment arm) of the abductor muscles. This reduces the muscle force required for pelvic stability, thereby significantly decreasing the overall joint reactive force.

Question 1648

Topic: Pediatric Hip
A 4-year-old child presents with a painless limp. Radiographs of the hip show flattening and fragmentation of the femoral epiphysis. ESR and CRP are normal. What is the most likely diagnosis?
. Septic arthritis
. Transient synovitis
. Legg-Calvé-Perthes disease
. Slipped Capital Femoral Epiphysis (SCFE)
. Juvenile Idiopathic Arthritis

Correct Answer & Explanation

. Legg-Calvé-Perthes disease

Explanation

This clinical presentation is classic for Legg-Calvé-Perthes disease, which is idiopathic avascular necrosis of the femoral head in children, typically affecting those between 4 and 8 years of age. A painless limp is a common symptom, and radiographs showing flattening and fragmentation of the femoral epiphysis are diagnostic. Normal inflammatory markers (ESR, CRP) help differentiate it from infectious or inflammatory conditions like septic arthritis or juvenile idiopathic arthritis. SCFE typically affects older, often obese, adolescents.

Question 1649

Topic: Pediatric Hip
A 5-year-old child presents with a 2-month history of a painless limp. Examination reveals limited hip abduction and internal rotation, and a positive Trendelenburg sign. Radiographs show increased density (sclerosis) and flattening of the femoral epiphysis. What is the most appropriate initial management?
. Immediate surgical epiphysiodesis
. Observation with activity restriction and protected weight-bearing
. Casting in abduction and internal rotation
. Non-steroidal anti-inflammatory drugs (NSAIDs) only
. Urgent MRI of the hip

Correct Answer & Explanation

. Observation with activity restriction and protected weight-bearing

Explanation

The clinical picture (painless limp, limited abduction/internal rotation, Trendelenburg sign) and radiographic findings (sclerosis and flattening of the femoral epiphysis) are classic for Legg-Calvé-Perthes disease (LCPD), which is osteonecrosis of the femoral head in children. The primary goal of management is to maintain the femoral head containment within the acetabulum while it revascularizes and remodels. Initial management usually involves observation with activity modification (avoiding high-impact activities), protected weight-bearing, and possibly bracing or casts to maintain abduction and internal rotation, especially for younger children or those with less severe involvement. Urgent MRI confirms the diagnosis and extent but is not the initial management. Epiphysiodesis or other surgeries are reserved for specific stages or to contain the femoral head when conservative measures fail. NSAIDs alone only address symptoms.

Question 1650

Topic: Pediatric Hip

Which of the following interventions has been shown to be most effective in reducing the risk of subsequent contralateral Slipped Capital Femoral Epiphysis (SCFE) in a patient diagnosed with a unilateral stable SCFE?

. Prophylactic pinning of the contralateral asymptomatic hip
. Intensive physical therapy and weight loss program
. Long-term oral bisphosphonate therapy
. Regular MRI surveillance of the contralateral hip
. Activity restriction for 12 months

Correct Answer & Explanation

. Prophylactic pinning of the contralateral asymptomatic hip

Explanation

For patients diagnosed with unilateral stable Slipped Capital Femoral Epiphysis (SCFE), the risk of developing SCFE in the contralateral hip is significant (reported between 20-60%), especially in younger patients and those with endocrine disorders. Prophylactic pinning of the contralateral asymptomatic hip is often recommended, particularly in skeletally immature patients, to prevent the contralateral slip. While weight loss and activity modification are important for overall health, they are not proven to prevent contralateral slips as effectively as prophylactic pinning. Bisphosphonates are not indicated. Regular MRI surveillance would detect a slip, but not prevent it.

Question 1651

Topic: Pediatric Hip

Which of the following is the most accurate radiographic sign for diagnosing an unstable slipped capital femoral epiphysis (SCFE)?

. Widening of the physis on AP view
. Positive Klein's line on AP view
. Posterior and inferior displacement of the epiphysis on frog-leg lateral view
. Absence of a palpable pulse in the affected extremity
. Inability to bear weight on the affected extremity

Correct Answer & Explanation

. Inability to bear weight on the affected extremity

Explanation

While all options except 'absence of palpable pulse' are relevant to SCFE, the definition of an unstable SCFE is the inability to bear weight on the affected extremity, even with crutches. This clinical finding distinguishes unstable from stable SCFE and carries a significantly higher risk of complications, particularly avascular necrosis. Radiographic signs like physeal widening, positive Klein's line (metaphysis not intersecting the epiphysis), and posterior/inferior displacement are characteristic of SCFE but do not differentiate between stable and unstable slips. A palpable pulse is generally present, as vascular compromise is a complication, not a defining characteristic of instability.

Question 1652

Topic: Pediatric Hip

In a viva, you are asked to discuss the management of developmental dysplasia of the hip (DDH) in an infant. What is the most crucial aspect to convey for optimal scoring?

. That it always requires surgery.
. Ignoring family history.
. Early diagnosis through screening (Ortolani/Barlow maneuvers, ultrasound in high-risk infants), prompt initiation of treatment (e.g., Pavlik harness for reducible hips), and close monitoring for concentric reduction and acetabular development.
. Assuming it will resolve spontaneously.
. Only focusing on X-ray findings.

Correct Answer & Explanation

. Early diagnosis through screening (Ortolani/Barlow maneuvers, ultrasound in high-risk infants), prompt initiation of treatment (e.g., Pavlik harness for reducible hips), and close monitoring for concentric reduction and acetabular development.

Explanation

For DDH, early diagnosis and prompt, appropriate management are critical for optimal outcomes. A high-scoring answer will emphasize systematic screening methods (clinical exams, targeted ultrasound), the role of early intervention (e.g., Pavlik harness), and the importance of monitoring for concentric reduction and proper acetabular development. This demonstrates an understanding of growth, development, and preventative orthopedics.

Question 1653

Topic: Pediatric Hip
In a viva, you are discussing the management of a child with Legg-Calvé-Perthes disease. The examiner asks, 'What is the primary goal of treatment for Legg-Calvé-Perthes disease, regardless of whether surgical or non-surgical methods are employed?'
. To eliminate all pain immediately and completely.
. To restore normal blood supply to the femoral head to prevent avascular necrosis.
. To maintain containment of the femoral head within the acetabulum to preserve its spherical shape and prevent deformity, thereby minimizing the risk of developing early osteoarthritis.
. To accelerate the revascularization process of the femoral head.
. To prolong the disease process to allow for maximal growth before healing.

Correct Answer & Explanation

. To maintain containment of the femoral head within the acetabulum to preserve its spherical shape and prevent deformity, thereby minimizing the risk of developing early osteoarthritis.

Explanation

The primary goal of treatment for Legg-Calvé-Perthes disease, regardless of the method, is to maintain containment of the femoral head within the acetabulum. This helps to preserve the spherical shape of the femoral head as it undergoes revascularization and healing, preventing the development of a 'mushroom-shaped' deformity, which is highly predictive of early-onset osteoarthritis. While pain relief (A) and revascularization (B, D) are important, they are secondary to the goal of containment and preserving femoral head morphology. Prolonging the disease (E) is incorrect.

Question 1654

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left groin and knee pain. He walks with an antalgic limp and externally rotates the left leg during the swing phase. On physical exam, as the left hip is flexed, it obligatorily externally rotates. Radiographs confirm a Slipped Capital Femoral Epiphysis (SCFE). In which direction does the proximal femoral epiphysis anatomically displace relative to the femoral neck?

. Anterior and Superior
. Posterior and Superior
. Anterior and Inferior
. Posterior and Inferior
. Directly Medial

Correct Answer & Explanation

. Posterior and Inferior

Explanation

In a Slipped Capital Femoral Epiphysis (SCFE), the proximal femoral epiphysis remains relatively stationary within the acetabulum while the femoral metaphysis (neck) displaces anteriorly and superiorly. Thus, describing the displacement of the epiphysisrelative to the neck, it displaces posteriorly and inferiorly.

Question 1655

Topic: Pediatric Hip

In a 12-year-old boy presenting with an isolated, unilateral slipped capital femoral epiphysis (SCFE), which of the following patient factors represents the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Patient age of 14 years
. Female gender
. Presence of panhypopituitarism
. Body mass index > 95th percentile
. A Southwick angle of 20 degrees on the affected side

Correct Answer & Explanation

. Presence of panhypopituitarism

Explanation

Patients with underlying endocrine disorders (such as panhypopituitarism, hypothyroidism, or renal osteodystrophy) have a significantly higher risk of bilateral SCFE (up to 100% in some series) and are strong candidates for prophylactic pinning of the contralateral hip.

Question 1656

Topic: Pediatric Hip

A 9-month-old girl undergoes an attempted closed reduction for developmental dysplasia of the hip (DDH). An intraoperative arthrogram reveals an 'hourglass' constriction preventing concentric reduction. Which of the following anatomic structures is responsible for this specific arthrographic appearance?

. Hypertrophied pulvinar
. Thickened ligamentum teres
. Iliopsoas tendon
. Contracted transverse acetabular ligament
. Inverted limbus

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In Developmental Dysplasia of the Hip (DDH), an 'hourglass' constriction seen on an intraoperative arthrogram is classically caused by the iliopsoas tendon tightly crossing and compressing the redundant capsule. While the pulvinar, ligamentum teres, transverse acetabular ligament, and inverted limbus can all act as physical blocks to concentric reduction, the iliopsoas tendon specifically produces the hourglass sign. A medial dye pool (>5mm) typically indicates intervening pulvinar or ligamentum teres.

Question 1657

Topic: Pediatric Hip

A 12-year-old boy presents with right knee pain and a limp. He walks with an externally rotated gait. Radiographs reveal a widened and irregular right proximal femoral physis, with Klein's line failing to intersect the lateral epiphysis. Which of the following represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Obesity (BMI > 95th percentile)
. Male gender
. Hypothyroidism
. Age of onset at 14 years
. Grade 1 slip severity on the affected side

Correct Answer & Explanation

. Hypothyroidism

Explanation

Endocrine disorders (such as hypothyroidism, renal osteodystrophy, and growth hormone deficiency) represent a very strong risk factor for bilateral slipped capital femoral epiphysis (SCFE). Patients with these metabolic conditions, as well as those with prior pelvic radiation, typically warrant prophylactic prophylactic pinning of the contralateral hip due to the unusually high incidence of a subsequent slip. Chronologic age < 10 is also an indication.

Question 1658

Topic: Pediatric Hip
A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs show that the lateral pillar of the femoral head has maintained approximately 60% of its original height. According to the Herring lateral pillar classification, what is his grade, and what is the expected outcome of surgical containment compared to non-operative management?
. Herring A; excellent prognosis without surgery
. Herring B; expected to have a better outcome with surgical containment
. Herring B; expected to have a better outcome with non-operative management
. Herring C; expected to have a better outcome with surgical containment
. Herring C; expected to have a better outcome with non-operative management

Correct Answer & Explanation

. Herring B; expected to have a better outcome with surgical containment

Explanation

This patient has Herring Group B Perthes disease (lateral pillar height between 50% and 100%). Based on the multicenter prospective study by Herring et al., children over the age of 8 years at the onset of symptoms with Group B or B/C border disease have significantly better radiographic outcomes when treated with surgical containment (e.g., femoral or pelvic osteotomy) compared to non-operative treatment.

Question 1659

Topic: Pediatric Hip

An 8-year-old boy with Legg-Calve-Perthes disease is evaluated.

Radiographs obtained during the fragmentation phase demonstrate that only 40% of the lateral pillar of the femoral head has maintained its normal radiolucent height. According to the Herring Lateral Pillar Classification, what is the assigned grade, and what is the expected prognosis?

. Group B; excellent prognosis with conservative care
. Group B; fair prognosis, requires surgical containment
. Group C; poor prognosis regardless of treatment modality
. Group C; excellent prognosis with timely femoral varus osteotomy
. Group B/C; excellent prognosis with bracing

Correct Answer & Explanation

. Group C; poor prognosis regardless of treatment modality

Explanation

Herring Lateral Pillar Group C indicates that less than 50% of the lateral pillar height is maintained during the fragmentation phase. These hips have a poor prognosis for spherical congruency (often developing Stulberg IV or V outcomes) and generally perform poorly regardless of the chosen treatment modality, especially in children older than 8 years.

Question 1660

Topic: Pediatric Hip

A 12-year-old boy weighing 95 kg presents with a unilateral stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in-situ pinning of the asymptomatic, normal contralateral hip?

. Patient age less than 13 years
. Male gender
. Initial slip angle of 40 degrees
. Presence of an underlying endocrinopathy
. Body mass index greater than the 95th percentile

Correct Answer & Explanation

. Presence of an underlying endocrinopathy

Explanation

While young age (boys <12, girls <10) and open triradiate cartilage increase the risk for contralateral SCFE, the strongest absolute indication for prophylactic pinning is an underlying endocrinopathy (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or prior pelvic radiation therapy, as the risk of a contralateral slip approaches 50-100% in these populations.

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