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Pediatric Hip MCQs

Practice Set 52 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 1021

Topic: Pediatric Hip

An 8-year-old boy presents with a painless limp that has progressively worsened over the past 3 months.

Radiographs confirm Legg-Calvé-Perthes disease in the fragmentation stage. The surgeon classifies the hip using the Herring Lateral Pillar classification. According to this system, which of the following radiographic criteria defines a Lateral Pillar Type B?

. Greater than 50% of the lateral pillar height is maintained
. Less than 50% of the lateral pillar height is maintained
. 100% of the lateral pillar height is maintained with only central involvement
. Complete collapse of the lateral pillar with secondary subluxation
. Sclerotic changes isolated to the medial pillar

Correct Answer & Explanation

. Less than 50% of the lateral pillar height is maintained

Explanation

The Herring Lateral Pillar classification is evaluated on the AP pelvis radiograph during the fragmentation stage of Legg-Calvé-Perthes disease. Type A: 100% of the lateral pillar height is maintained. Type B: >50% of the lateral pillar height is maintained. Type C: <50% of the lateral pillar height is maintained. Type B/C border involves exactly 50% loss or a very thin lateral pillar. Lateral pillar height is strongly prognostic for long-term hip deformity and outcomes.

Question 1022

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 99th percentile presents to the emergency department with acute severe left groin pain after a minor slip.

He refuses to bear weight on the left leg, even with the assistance of crutches. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE). According to the Loder classification, this clinical presentation is associated with a significantly increased risk of which of the following complications?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (pincer type)
. Contralateral asymptomatic slip
. Spontaneous premature physeal closure of the greater trochanter

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The Loder classification divides SCFE into stable and unstable based on the patient's ability to bear weight (with or without crutches). An unstable SCFE (patient unable to bear weight) carries a high risk of avascular necrosis (AVN) of the femoral head, historically reported as high as 47-50%, compared to nearly 0% in stable slips. Prompt recognition and careful treatment (such as urgent gentle reduction and pinning or modified Dunn procedure, often with capsular decompression) are critical in managing unstable SCFE.

Question 1023

Topic: Pediatric Hip

A 2-year-old girl is undergoing an open reduction for developmental dysplasia of the hip (DDH) via a medial approach.

The surgeon encounters several obstacles preventing concentric reduction of the femoral head into the true acetabulum. Which of the following structures is considered an extracapsular obstacle to reduction?

. Transverse acetabular ligament
. Ligamentum teres
. Iliopsoas tendon
. Inverted labrum (Neolimbus)
. Pulvinar

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In DDH, obstacles to closed or open reduction are divided into extracapsular and intracapsular structures. The iliopsoas tendon is an extracapsular obstacle that causes an hourglass constriction of the joint capsule. Intracapsular obstacles include the hypertrophied ligamentum teres, fibrofatty pulvinar, inverted labrum (neolimbus), and a contracted transverse acetabular ligament. A medial approach allows direct visualization and release of the iliopsoas tendon and transverse acetabular ligament.

Question 1024

Topic: Pediatric Hip

A 12-year-old boy is brought to the emergency department unable to bear weight on his right leg after a minor slip. He reports a 4-week history of dull, intermittent right thigh pain prior to the fall. Anteroposterior and frog-leg lateral radiographs demonstrate a severe right slipped capital femoral epiphysis (SCFE). Which of the following approaches is most strongly supported by recent literature to minimize the risk of avascular necrosis (AVN) in this unstable slip?

. In situ single-screw fixation performed electively after 7 days of bed rest
. Urgent (within 24 hours) surgical intervention with an intracapsular decompression (capsulotomy) and stable fixation
. Urgent (within 24 hours) closed reduction and spica casting
. Delayed surgical hip dislocation with a modified Dunn procedure after 2 weeks
. Skeletal traction for 3 weeks followed by in situ pinning

Correct Answer & Explanation

. Urgent (within 24 hours) surgical intervention with an intracapsular decompression (capsulotomy) and stable fixation

Explanation

The patient has an unstable SCFE, defined clinically by the inability to bear weight even with crutches. Unstable SCFE has a much higher risk of avascular necrosis (AVN) compared to stable SCFE. Literature supports urgent intervention (typically within 24 hours) utilizing intracapsular decompression (via capsulotomy) to release the tamponade effect of the fracture hematoma, followed by gentle, incidental reduction and stable internal fixation to decrease the risk of AVN.

Question 1025

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal that he is in the fragmentation stage. According to the Herring Lateral Pillar classification, which of the following radiographic findings places this patient in Lateral Pillar Group C, portending a poorer prognosis?

. Maintenance of 100% of the lateral pillar height with no radiolucency
. Maintenance of greater than 50% but less than 100% of the lateral pillar height
. Maintenance of less than 50% of the lateral pillar height
. Involvement confined to the anterior half of the epiphysis on the frog-leg lateral view
. Calcification lateral to the epiphysis indicating hinge abduction

Correct Answer & Explanation

. Maintenance of less than 50% of the lateral pillar height

Explanation

The Herring Lateral Pillar classification assesses the height of the lateral portion of the capital femoral epiphysis on an AP radiograph during the fragmentation stage of Legg-Calvé-Perthes disease. Group A: no loss of height in the lateral pillar. Group B: maintenance of >50% of lateral pillar height. Group C: maintenance of <50% of lateral pillar height. Group C has the poorest prognosis and often goes on to develop an aspherical femoral head and early osteoarthritis.

Question 1026

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ pinning of a stable slipped capital femoral epiphysis (SCFE) of the right hip. Six months postoperatively, he presents with worsening right hip pain, a significant limp, and severely restricted range of motion in flexion and abduction. Radiographs demonstrate severe diffuse joint space narrowing, generalized osteopenia around the joint, but no evidence of segmental collapse or sclerosis of the femoral head. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Septic arthritis
. Cam-type femoroacetabular impingement
. Implant failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, particularly associated with unrecognized intra-articular pin penetration, though it can occur idiopathically. It presents with progressive pain, severe global stiffness, and diffuse joint space narrowing on radiographs. Avascular necrosis (AVN) would typically present with sclerosis, subchondral radiolucency (crescent sign), and eventual segmental collapse of the femoral head, rather than isolated uniform joint space narrowing.

Question 1027

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease.

Which of the following radiographic findings is considered one of Catterall's 'head at risk' signs, indicating a potentially poorer prognosis and an increased likelihood of epiphyseal extrusion?

. Medial subluxation of the femoral head
. Calcification lateral to the epiphysis
. Vertical orientation of the physeal plate
. Sclerosis of the central epiphysis
. Hypertrophy of the greater trochanter

Correct Answer & Explanation

. Calcification lateral to the epiphysis

Explanation

Catterall identified several 'head at risk' signs that correlate with a poorer prognosis and impending lateral extrusion of the femoral head in Legg-Calvé-Perthes disease. These include: lateral (not medial) subluxation of the femoral head, Gage's sign (a V-shaped radiolucency in the lateral portion of the epiphysis and metaphysis), calcification lateral to the epiphysis, diffuse metaphyseal radiolucencies, and a horizontal (not vertical) orientation of the growth plate.

Question 1028

Topic: Pediatric Hip

A 6-month-old infant with developmental dysplasia of the hip (DDH) was treated with a Pavlik harness starting at age 4 weeks. After 4 weeks of harness wear, the hip remained dislocated, and the harness was discontinued. Currently, ultrasound confirms persistent dislocation. What is the most appropriate next step in management?

. Restart the Pavlik harness for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Varus derotational osteotomy (VDRO)

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

Pavlik harness failure occurs in about 10% of cases. Continuing the harness past 3-4 weeks if the hip remains dislocated increases the risk of 'Pavlik harness disease' (damage to the posterior acetabular wall) and avascular necrosis. The next appropriate step is closed reduction and spica casting, often preceded by an arthrogram or an adductor tenotomy.

Question 1029

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with knee pain. He walks with a limp and his foot is externally rotated. Examination shows obligatory external rotation with hip flexion. AP and frog-leg lateral radiographs of the pelvis show a mild left slipped capital femoral epiphysis (SCFE) and a normal right hip. What is the most appropriate management?

. Unilateral left in situ percutaneous pinning
. Bilateral in situ percutaneous pinning
. Left proximal femoral osteotomy
. Spica cast immobilization
. Open reduction and internal fixation of the left hip

Correct Answer & Explanation

. Unilateral left in situ percutaneous pinning

Explanation

Unilateral idiopathic SCFE is typically treated with unilateral in situ percutaneous pinning using a single central screw. Prophylactic pinning of the contralateral hip is generally reserved for patients with endocrine or metabolic disorders, radiation therapy, or those who cannot reliably follow up, given the surgical risks (AVN, chondrolysis, fracture) outweighing the benefits in healthy patients.

Question 1030

Topic: Pediatric Hip

An 8-year-old boy presents with a limp. Radiographs confirm Legg-Calvé-Perthes disease with fragmentation of the femoral head and more than 50% collapse of the lateral pillar. According to the Herring lateral pillar classification, which of the following best describes his prognosis and indicated management?

. Group A, good outcome without surgery
. Group B, good outcome with surgery
. Group C, poor outcome, and surgery has not been shown to significantly improve the result compared to nonoperative treatment
. Group B, poor outcome without surgery
. Group C, excellent outcome with proximal femoral varus osteotomy

Correct Answer & Explanation

. Group C, poor outcome, and surgery has not been shown to significantly improve the result compared to nonoperative treatment

Explanation

The Herring lateral pillar classification determines the prognosis in Legg-Calvé-Perthes disease based on the height of the lateral pillar on AP radiographs during the fragmentation stage. Group C indicates >50% loss of lateral pillar height. In children over 8 years of age, Group C hips have a poor prognosis, and studies show that surgical containment does not significantly improve outcomes compared to nonoperative treatment in this specific older cohort.

Question 1031

Topic: Pediatric Hip

An 11-year-old obese boy presents with right hip pain and a limp. Radiographs confirm a unilateral right slipped capital femoral epiphysis (SCFE), which is treated with in situ single-screw fixation. The parents ask about the risk of the left hip developing the same condition. Which of the following radiographic findings is the strongest predictor for a subsequent contralateral slip and most justifies prophylactic pinning of the asymptomatic left hip?

. Open triradiate cartilage
. Southwick slip angle greater than 50 degrees on the affected side
. Alpha angle greater than 50 degrees on the asymptomatic side
. Symptom duration greater than 6 months prior to initial presentation
. Intersection of Klein's line with the lateral epiphysis on the asymptomatic side

Correct Answer & Explanation

. Open triradiate cartilage

Explanation

The status of the triradiate cartilage is a crucial indicator of skeletal maturity and the strongest predictor for the development of a contralateral SCFE. An open triradiate cartilage indicates significant remaining skeletal growth, placing the patient at high risk (up to 60-80% in some series, especially in younger or obese patients) for a subsequent contralateral slip. The modified Oxford Bone Age scoring system, which assesses the iliac crest, triradiate cartilage, and proximal femoral epiphysis, is often utilized to quantify this risk. A high Southwick angle describes the severity of the current slip but does not predict the contralateral side. Klein's line intersection is a normal finding; failure to intersect would indicate an already existing slip.

Question 1032

Topic: Pediatric Hip

An 9-year-old boy presents with a 5-month history of a painless limp and right hip stiffness. Radiographs demonstrate Legg-Calvé-Perthes disease in the fragmentation stage.

Which of the following factors is the most reliable predictor of a poor long-term radiographic and clinical outcome, often necessitating surgical containment?

. Age of onset greater than 8 years
. Limitation of hip internal rotation to 10 degrees
. Presence of a subchondral fracture line (Crescent sign) involving 20% of the epiphysis
. Increased medial joint space on the anteroposterior radiograph
. Herring Lateral Pillar Class A

Correct Answer & Explanation

. Age of onset greater than 8 years

Explanation

Age at disease onset is one of the most critical prognostic factors in Legg-Calvé-Perthes disease. Children who develop the disease after the age of 8 years have less potential for remodeling and typically experience worse long-term outcomes (higher risk of severe residual deformity and early-onset osteoarthritis). According to the multicenter prospective studies by Herring et al., patients older than 8 years at onset who have Lateral Pillar B or B/C border hips benefit significantly from surgical containment (e.g., proximal femoral varus osteotomy or pelvic osteotomy) compared to non-operative treatment. Lateral Pillar Class A has a universally good prognosis regardless of age.

Question 1033

Topic: Pediatric Hip

A 12-year-old boy weighing 95 kg presents to the emergency department with severe left hip pain and inability to bear weight after tripping two days ago. He reports mild, intermittent left knee pain over the preceding month. Radiographs demonstrate a severe left slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant risk factor for developing avascular necrosis (AVN) in this patient?

. The severity of the slip angle exceeding 50 degrees
. The prolonged duration of his prodromal knee pain
. The clinical inability to bear weight with or without crutches
. The use of a single-screw construct rather than double-screw fixation
. The delay in surgical intervention beyond 12 hours from the injury

Correct Answer & Explanation

. The clinical inability to bear weight with or without crutches

Explanation

The Loder classification categorizes Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable based on the patient's clinical ability to bear weight (with or without crutches). An unstable SCFE (inability to bear weight) is associated with a much higher rate of avascular necrosis (AVN), historically reported as up to 47%, compared to nearly 0% in stable SCFE. Thus, instability is the most profound prognostic factor for AVN in these patients.

Question 1034

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. AP and frog-leg lateral pelvis radiographs show the hip is currently in the fragmentation stage. According to the Herring lateral pillar classification, which of the following radiographic features is the most critical for determining the long-term prognosis?

. The extent of the subchondral fracture (crescent sign)
. The degree of height loss in the lateral portion of the capital femoral epiphysis
. The presence and size of metaphyseal cysts
. The degree of extrusion of the femoral head lateral to the margin of the acetabulum
. The involvement and collapse of the medial column of the femoral head

Correct Answer & Explanation

. The degree of height loss in the lateral portion of the capital femoral epiphysis

Explanation

The Herring Lateral Pillar Classification is evaluated on the AP radiograph during the fragmentation stage of Legg-Calvé-Perthes disease and is widely considered the most reliable prognostic indicator for future sphericity of the femoral head. It specifically evaluates the degree of height loss in the lateral pillar (the lateral 15% to 30% of the femoral head). Group A has no height loss, Group B has less than 50% height loss, and Group C has greater than 50% height loss (which carries the worst prognosis).

Question 1035

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp. Examination demonstrates a positive Trendelenburg sign on the left and a leg length discrepancy. Pelvic radiographs confirm a completely dislocated left hip with an acetabular index of 42 degrees and a broken Shenton's line.

What is the most appropriate definitive management?

. Application of a Pavlik harness for 6 weeks
. Closed reduction and spica casting
. Arthroscopic reduction and labral repair
. Open reduction, pelvic osteotomy, and femoral shortening osteotomy
. Observation until skeletal maturity followed by total hip arthroplasty

Correct Answer & Explanation

. Open reduction, pelvic osteotomy, and femoral shortening osteotomy

Explanation

In a child of ambulatory age (typically > 18 months) presenting with a missed or late-diagnosed Developmental Dysplasia of the Hip (DDH) that is completely dislocated, secondary adaptive changes such as severe soft tissue contractures, acetabular dysplasia, and excessive femoral anteversion/coxa valga have occurred. An open reduction is typically necessary to clear obstacles (e.g., inverted limbus, hypertrophied pulvinar, intact transverse acetabular ligament). A femoral shortening osteotomy is frequently performed to decompress the joint, allowing reduction without excessive pressure on the cartilage, thereby minimizing the risk of avascular necrosis (AVN). A concurrent pelvic osteotomy (e.g., Salter or Pemberton) is necessary to correct the severe acetabular dysplasia (acetabular index of 42 degrees).

Question 1036

Topic: Pediatric Hip

A 2.5-year-old girl is brought in for a persistent, painless limp. Physical examination reveals asymmetric thigh folds, limited abduction of the left hip, and a positive Galeazzi sign on the left. Radiographs confirm a dislocated left hip with an acetabular index of 42 degrees and a delayed ossification center of the femoral head.

What is the most appropriate surgical management for this patient?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, pelvic osteotomy, and spica casting
. Observation until age 4 to allow for maximum spontaneous acetabular remodeling
. Varus derotational osteotomy (VDRO) alone

Correct Answer & Explanation

. Open reduction, pelvic osteotomy, and spica casting

Explanation

By the age of 2.5 years, conservative measures such as a Pavlik harness or closed reduction are inappropriate due to the severity of adaptive changes and capsular constriction. This patient has Developmental Dysplasia of the Hip (DDH) with significant acetabular dysplasia (acetabular index > 30 degrees). The standard of care for a walking child older than 18-24 months is an open reduction combined with a pelvic osteotomy (e.g., Salter or Pemberton) to correct the dysplasia and provide anterior/lateral coverage, often accompanied by a femoral shortening osteotomy depending on the degree of proximal migration.

Question 1037

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) of the left hip. He denies any right hip pain. Which of the following is considered the most widely accepted absolute indication for prophylactic in-situ pinning of his contralateral asymptomatic right hip?

. Patient age greater than 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Male gender
. Patient BMI > 95th percentile for age
. Radiographic evidence of a physeal angle greater than 30 degrees

Correct Answer & Explanation

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

Explanation

While prophylactic pinning of the contralateral hip in SCFE is controversial for idiopathic cases, there is broad consensus that patients with atypical SCFE—specifically those with underlying endocrine disorders (e.g., hypothyroidism, panhypopituitarism, renal osteodystrophy) or prior radiation therapy—should undergo prophylactic contralateral pinning. These patients have a significantly higher risk of bilateral involvement (up to 100% in some endocrine cohorts) compared to those with idiopathic SCFE.

Question 1038

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the modified lateral pillar (Herring) classification, which of the following radiographic findings signifies the poorest prognosis for long-term hip congruency?

. Maintenance of >50% but <100% of the lateral pillar height
. Maintenance of <50% of the lateral pillar height
. A subchondral radiolucent line (Crescent sign) involving <50% of the femoral head
. The presence of a positive Gage sign
. Fragmentation of the medial pillar alone

Correct Answer & Explanation

. Maintenance of <50% of the lateral pillar height

Explanation

The Herring (Lateral Pillar) classification evaluates the height of the lateral pillar of the femoral head during the fragmentation stage of Legg-Calvé-Perthes disease. Group A has 100% height maintenance, Group B has >50% maintenance, and Group C has <50% maintenance of the lateral pillar height. Group C carries the worst prognosis for maintaining a spherical, congruent hip joint at skeletal maturity, particularly in patients who present over the age of 8. Group B/C (the modified addition) also represents a borderline poor prognosis.

Question 1039

Topic: Pediatric Hip

A 6-week-old female infant is placed in a Pavlik harness for a dislocated left hip. After 3 weeks of proper wear, ultrasound demonstrates that the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for 3 more weeks
. Transition to a rigid abduction orthosis
. Perform an open reduction and spica casting
. Discontinue the harness and perform closed reduction and spica casting
. Obtain an MRI to evaluate for interposed tissue

Correct Answer & Explanation

. Discontinue the harness and perform closed reduction and spica casting

Explanation

Continuation of a Pavlik harness in a persistently dislocated hip beyond 3 to 4 weeks increases the risk of 'Pavlik harness disease' (damage to the posterior wall of the acetabulum) and avascular necrosis. The harness should be discontinued, and the infant should be scheduled for a closed reduction and spica casting.

Question 1040

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 undergoes in situ pinning of a stable slipped capital femoral epiphysis (SCFE) with a single cannulated screw. Postoperatively, he has persistent severe pain, limited range of motion, and joint stiffness. Radiographs show joint space narrowing and subchondral radiolucencies. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Screw cutout
. Septic arthritis
. Impingement syndrome

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage, leading to rapid joint space narrowing, stiffness, and severe pain. It is associated with unrecognized screw penetration into the joint. Avascular necrosis typically presents with sclerosis, cysts, and eventual collapse of the femoral head rather than diffuse joint space narrowing early on.

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