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Pediatric Hip MCQs

Practice Set 56 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 1101

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 4-week history of left groin pain and a new inability to bear weight on the left leg for the past 48 hours. On examination, his left lower extremity is externally rotated, and attempts at hip flexion result in obligate external rotation. Radiographs demonstrate a left slipped capital femoral epiphysis (SCFE). He undergoes in situ percutaneous pinning. Which of the following factors presents the highest risk for the development of avascular necrosis (AVN) of the femoral head in this patient?

. Patient age greater than 10 years
. The duration of prodromal symptoms exceeding 3 weeks
. The inability to bear weight prior to surgical intervention
. The use of a single screw rather than double screws for fixation
. The degree of initial posterior epiphyseal displacement

Correct Answer & Explanation

. The inability to bear weight prior to surgical intervention

Explanation

The inability to bear weight with or without crutches characterizes an unstable SCFE according to the Loder classification. Unstable SCFE is the single most significant risk factor for the development of avascular necrosis (AVN), carrying an AVN rate of up to 47%, compared to nearly 0% in stable SCFE. Age, duration of prodromal symptoms, degree of slip, and use of single versus double screw fixation do not predict AVN as strongly as the stability of the slip.

Question 1102

Topic: Pediatric Hip

A 6-month-old girl with a dislocated left hip is brought to the operating room for a closed reduction and spica casting. An intraoperative arthrogram is performed to assess the adequacy of reduction.

On the arthrogram, the surgeon identifies a radiolucent block traversing the inferior aspect of the acetabulum, preventing concentric seating of the femoral head. Which of the following anatomical structures is most likely causing this specific block to reduction?

. Inverted limbus
. Hypertrophied pulvinar
. Transverse acetabular ligament
. Ligamentum teres
. Iliopsoas tendon

Correct Answer & Explanation

. Transverse acetabular ligament

Explanation

The transverse acetabular ligament is located at the inferior aspect of the acetabulum and, when hypertrophied or contracted, presents as an inferior block to reduction on an arthrogram in developmental dysplasia of the hip (DDH). The inverted limbus presents as a superior/lateral block. The ligamentum teres and pulvinar present as medial blocks within the cotyloid fossa. The iliopsoas tendon causes an hourglass constriction of the joint capsule extra-articularly.

Question 1103

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease of the right hip. Anteroposterior and frog-leg lateral radiographs taken during the fragmentation stage demonstrate a >50% depression of the lateral pillar height of the capital femoral epiphysis. According to the Herring lateral pillar classification, what is his classification and the expected clinical prognosis?
. Lateral Pillar A; Excellent prognosis without surgical intervention
. Lateral Pillar B; Good prognosis with containment surgery
. Lateral Pillar B/C border; Variable prognosis depending on age
. Lateral Pillar C; Poor prognosis, with a high risk of developing an aspherical femoral head
. Lateral Pillar C; Excellent prognosis if treated aggressively with a Petrie cast

Correct Answer & Explanation

. Lateral Pillar C; Poor prognosis, with a high risk of developing an aspherical femoral head

Explanation

The Herring lateral pillar classification evaluates the height of the lateral portion of the femoral head during the fragmentation stage. A loss of >50% of the lateral pillar height is classified as Herring Group C. Patients with Group C disease, particularly those 8 years of age or older at the onset of symptoms, generally have a poor prognosis characterized by an aspherical femoral head, coxa magna, and early onset of degenerative joint disease, regardless of the treatment applied.

Question 1104

Topic: Pediatric Hip

A 13-year-old boy with a BMI of 38 presents to the emergency department unable to bear weight on his left leg after stumbling on a step. Radiographs confirm a severe, displaced slipped capital femoral epiphysis (SCFE). He is unable to walk even with crutches. Which of the following complications is most specifically associated with this patient's acute presentation compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis (AVN)
. Progressive slip
. Contralateral SCFE
. Premature hip osteoarthritis

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

This patient has an unstable SCFE, defined by the Loder classification as the inability to bear weight, even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN), ranging from 20% to 50%, compared to stable SCFE, where the risk of AVN is near 0%. The precarious blood supply to the capital femoral epiphysis (mainly the lateral epiphyseal vessels) is acutely disrupted or kinked in an unstable slip.

Question 1105

Topic: Pediatric Hip

A 3-year-old girl is evaluated for a painless limp and leg length discrepancy. Examination reveals a positive Galeazzi sign and asymmetric thigh folds. Anteroposterior pelvis radiograph shows a dislocated right hip with significant acetabular dysplasia, a false acetabulum, and increased femoral anteversion. What is the most appropriate definitive surgical intervention?

. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and femoral varus derotational osteotomy (VDRO)
. Open reduction, femoral VDRO, and pelvic osteotomy
. Pelvic osteotomy (Salter) alone

Correct Answer & Explanation

. Open reduction, femoral VDRO, and pelvic osteotomy

Explanation

In a child older than 2 to 3 years presenting with a late, untreated Developmental Dysplasia of the Hip (DDH), the hip is typically high-riding with adaptive changes including significant acetabular dysplasia and increased femoral anteversion. Comprehensive surgical reconstruction is required. This involves an open reduction to clear obstacles to reduction, a femoral shortening and varus derotational osteotomy (VDRO) to reduce pressure on the joint (reducing AVN risk) and correct version, and a pelvic osteotomy (e.g., Pemberton, Dega, or Salter) to address the acetabular dysplasia.

Question 1106

Topic: Pediatric Hip
A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD) of the right hip. Radiographs in the fragmentation stage demonstrate collapse of more than 50% of the lateral pillar of the femoral head (Herring Lateral Pillar Class C). Which of the following factors in this patient is most strongly associated with a poor radiographic and functional outcome at skeletal maturity?
. Chronological age > 8 years at the onset of symptoms
. Presence of an adduction contracture on physical examination
. Body Mass Index (BMI) in the 85th percentile
. Male gender
. Concomitant ipsilateral knee pain

Correct Answer & Explanation

. Chronological age > 8 years at the onset of symptoms

Explanation

In Legg-Calvé-Perthes disease, the two most important prognostic factors are the age of the patient at the onset of symptoms and the extent of epiphyseal involvement/collapse (specifically lateral pillar height). An age of onset older than 8 years is universally associated with a poorer prognosis because there is less remaining growth potential for the femoral head to remodel before skeletal maturity. Lateral pillar class B or C also indicates a poor prognosis, but among the choices provided, age > 8 years is the primary unmodifiable demographic risk factor dictating a poor outcome.

Question 1107

Topic: Pediatric Hip

A 13-year-old obese boy presents with severe right groin pain after a minor slip. He is unable to bear weight on the affected limb, even with the assistance of crutches. Radiographs demonstrate a right slipped capital femoral epiphysis (SCFE) with a 45-degree slip angle. According to the Loder classification, what specific clinical factor in this patient is associated with the highest risk of developing avascular necrosis (AVN) of the femoral head?

. The severity of the slip angle on the frog-leg lateral radiograph
. The patient's body mass index (BMI) > 95th percentile
. The inability to bear weight on the affected limb
. The duration of symptoms prior to the acute event
. The degree of retroversion of the femoral neck

Correct Answer & Explanation

. The inability to bear weight on the affected limb

Explanation

The Loder classification defines an unstable SCFE as one in which the patient cannot bear weight, even with crutches, regardless of the duration of symptoms. Unstable slips have a significantly higher rate of avascular necrosis (up to 47%), whereas stable slips have a very low rate of AVN (<10%). While slip angle determines severity, the functional instability (inability to bear weight) is the most critical prognostic risk factor for AVN.

Question 1108

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 3 months duration. Radiographs show sclerosis and fragmentation of the femoral head consistent with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, which of the following radiographic findings determines the poorest prognosis for subsequent femoral head sphericity?
. Involvement of the medial pillar
. Presence of the Gage sign
. >50% loss of lateral pillar height
. Presence of a subchondral crescent sign
. Metaphyseal cysts

Correct Answer & Explanation

. >50% loss of lateral pillar height

Explanation

The Herring lateral pillar classification is highly prognostic in Legg-Calvé-Perthes disease, evaluated during the fragmentation stage. Group A has no lateral pillar involvement. Group B maintains >50% of the lateral pillar height. Group C has <50% of lateral pillar height maintained. Group C (>50% loss of height) has the poorest prognosis and highest likelihood of developing an aspherical incongruent joint. Age >8 years at onset is also a poor prognostic indicator.

Question 1109

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department with acute left hip pain and an inability to bear weight after a minor fall 2 days ago. Radiographs demonstrate a severe, displaced slipped capital femoral epiphysis (SCFE) on the left side. He is completely unable to bear weight even with crutches. According to the Loder classification, this specific presentation is associated with a significantly increased risk of which of the following complications?

. Chondrolysis
. Contralateral slipped capital femoral epiphysis
. Avascular necrosis (AVN) of the femoral head
. Early-onset femoroacetabular impingement (FAI)
. Proximal femoral growth arrest

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The Loder classification categorizes SCFE into stable (patient can bear weight) and unstable (patient cannot bear weight, even with crutches). Unstable SCFE has a substantially higher risk of avascular necrosis (AVN), historically reported to be as high as 47%, compared to nearly 0% in stable SCFE.

Question 1110

Topic: Pediatric Hip
An 8-year-old boy presents with a 4-month history of a painless limp. Examination shows restricted hip abduction and internal rotation. AP and frog-leg lateral pelvis radiographs show sclerosis, flattening, and fragmentation of the right femoral head. Which of the following clinical or radiographic factors indicates the worst prognosis for this patient?
. Age of onset at 5 years
. Involvement of less than 50% of the femoral head
. Maintenance of lateral pillar height >50%
. Loss of containment with lateral subluxation of the femoral head
. Decreased hip internal rotation of 10 degrees

Correct Answer & Explanation

. Loss of containment with lateral subluxation of the femoral head

Explanation

In Legg-Calvé-Perthes disease, a poor prognosis is associated with older age at onset (typically >8 years), extensive epiphyseal involvement, loss of lateral pillar height (Herring B/C or C), and signs of a 'head at risk'. Loss of containment with lateral subluxation (extrusion) is a severe 'head at risk' sign that subjects the softened femoral head to deforming mechanical forces against the lateral acetabular rim, leading to permanent aspherical deformity and early osteoarthritis.

Question 1111

Topic: Pediatric Hip

A 12-year-old obese boy presents with sudden inability to bear weight on the left leg after a minor fall. He had been experiencing vague left thigh pain for 3 weeks prior to the fall. On physical examination, the left hip is held in external rotation and he is entirely unable to ambulate even with crutches. Radiographs show a severe posterior and inferior displacement of the proximal femoral epiphysis. He undergoes urgent in-situ pinning with a single cannulated screw. Based on his presentation, which of the following complications is he at the highest risk for developing compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis
. Contralateral slip
. Femoroacetabular impingement
. Screw cutout

Correct Answer & Explanation

. Avascular necrosis

Explanation

The patient has an unstable Slipped Capital Femoral Epiphysis (SCFE). The Loder classification dictates that an unstable SCFE is defined by the inability to bear weight, even with assistive devices. The distinction is critical because unstable SCFE has a significantly higher risk of avascular necrosis (AVN), reported to be between 10% and 47%, compared to nearly 0% in stable SCFE. Chondrolysis is typically associated with unrecognized pin penetration into the joint space. While femoroacetabular impingement is a known long-term sequela of SCFE deformity, AVN is the specific, devastating complication most closely linked to the unstable nature of the slip.

Question 1112

Topic: Pediatric Hip

A 4-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the left hip (DDH). At her 1-week follow-up visit, the mother reports that the infant is no longer kicking her left leg. On examination, the hip remains successfully reduced, but there is absent active extension of the left knee. Sensation to a light pinprick on the anterior thigh appears diminished compared to the contralateral side. What is the most appropriate management of this complication?

. Adjust the anterior strap to increase hip flexion by 10 degrees
. Adjust the posterior strap to increase hip abduction
. Discontinue the harness completely
. Switch to a rigid hip spica cast immediately
. Reassure the mother and observe without modifying the harness

Correct Answer & Explanation

. Discontinue the harness completely

Explanation

The infant has developed a femoral nerve palsy, a known complication of Pavlik harness treatment. It is primarily caused by excessive hyperflexion of the hip, which compresses the femoral nerve against the inguinal ligament. The standard of care when a femoral nerve palsy is identified is to discontinue the Pavlik harness immediately to prevent permanent nerve damage. Once the harness is removed, motor function typically recovers over days to a few weeks. After full recovery of quadriceps function, an alternative treatment method, such as a rigid abduction orthosis or careful reinstitution of the harness with less flexion, can be considered.

Question 1113

Topic: Pediatric Hip

A 12-year-old boy with chronic kidney disease presents with a stable slipped capital femoral epiphysis (SCFE) on the left. Which of the following is the strongest indication for prophylactic pinning of the contralateral right hip?

. Age younger than 10 years
. Presence of renal osteodystrophy
. Severe obesity with BMI > 95th percentile
. Male gender
. Open triradiate cartilage

Correct Answer & Explanation

. Presence of renal osteodystrophy

Explanation

Patients with endocrine disorders or renal osteodystrophy are at a highly elevated risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these patients due to the high incidence of subsequent slip.

Question 1114

Topic: Pediatric Hip
In a patient diagnosed with Legg-Calvé-Perthes disease, which of the following is considered the most significant prognostic factor for long-term hip joint congruency and function?
. Gender
. Age at onset of symptoms
. Body mass index (BMI)
. Bilateral involvement
. Presence of a positive Trendelenburg sign

Correct Answer & Explanation

. Age at onset of symptoms

Explanation

The age at the onset of Legg-Calvé-Perthes disease is the most reliable prognostic indicator. Children who develop the disease before age 6 to 8 generally have a much better capacity for remodeling and superior long-term outcomes than older children.

Question 1115

Topic: Pediatric Hip

A 13-year-old male presents with acute thigh pain and inability to bear weight after a minor fall. He had mild groin pain for 3 months prior. Radiographs confirm a displaced slipped capital femoral epiphysis (SCFE). He undergoes urgent in-situ pinning. Which of the following factors is most predictive of developing avascular necrosis (AVN) in this patient?

. Degree of epiphyseal slip
. Patient age at presentation
. Duration of prodromal symptoms
. Instability (inability to bear weight)
. Female sex

Correct Answer & Explanation

. Instability (inability to bear weight)

Explanation

Instability, defined by Loder as the inability to bear weight even with crutches, is the most significant risk factor for AVN in SCFE, with rates up to 47% compared to near 0% in stable slips.

Question 1116

Topic: Pediatric Hip

A 5-month-old female has been treated in a Pavlik harness for developmental dysplasia of the hip (DDH) for 4 weeks. A follow-up ultrasound demonstrates the femoral head remains dislocated out of the acetabulum. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Transition to an abduction orthosis (e.g., rigid brace)
. Discontinue the harness and proceed with closed reduction and spica casting
. Perform an immediate open reduction and femoral shortening osteotomy
. Switch to double-diapering technique

Correct Answer & Explanation

. Discontinue the harness and proceed with closed reduction and spica casting

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip increases the risk of 'Pavlik harness disease' (posterior acetabular wear). If reduction is not achieved within 3-4 weeks, the harness should be abandoned for closed reduction and spica casting.

Question 1117

Topic: Pediatric Hip

A 12-year-old girl is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following underlying conditions represents the strongest indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

. Obesity (>95th percentile BMI)
. Trisomy 21
. Renal osteodystrophy
. Type 1 diabetes mellitus
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is strongly indicated in patients with underlying endocrinopathies or metabolic disorders, such as renal osteodystrophy or hypothyroidism, due to the high risk (up to 100%) of bilateral involvement.

Question 1118

Topic: Pediatric Hip

A 12-year-old boy presents with a 2-day history of severe left hip pain and is unable to bear weight. Radiographs demonstrate a left slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following factors most strongly correlates with the development of avascular necrosis in this patient?

. Number of screws used for fixation
. Timing of surgery exceeding 48 hours
. Inability to bear weight prior to surgery
. Concomitant endocrine disorder
. Open triradiate cartilage

Correct Answer & Explanation

. Inability to bear weight prior to surgery

Explanation

Unstable SCFE, defined clinically by the inability to bear weight even with crutches, is the most significant risk factor for AVN, with rates up to 47%.

Question 1119

Topic: Pediatric Hip

A 4-month-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the left hip. During a follow-up visit, the mother reports the infant has stopped moving the left leg. Examination reveals decreased active extension of the left knee, but sensation and perfusion are intact. What is the most appropriate next step in management?

. Obtain an MRI of the lumbar spine
. Switch to a rigid hip spica cast
. Release the anterior straps of the harness
. Release the posterior straps of the harness
. Perform an immediate open reduction

Correct Answer & Explanation

. Release the anterior straps of the harness

Explanation

The clinical picture describes femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. Management requires loosening the anterior straps or discontinuing the harness temporarily to allow nerve recovery.

Question 1120

Topic: Pediatric Hip

A 13-year-old obese boy presents with acute-on-chronic left hip pain and an inability to bear weight. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE), and he is classified as having an unstable slip. What is the primary theoretical advantage of performing an urgent open reduction and capsulotomy (e.g., modified Dunn procedure) rather than in situ pinning?

. To decrease the risk of chondrolysis
. To reduce the risk of avascular necrosis (AVN)
. To prevent contralateral slip
. To restore limb length
. To avoid hardware failure

Correct Answer & Explanation

. To reduce the risk of avascular necrosis (AVN)

Explanation

Unstable SCFE has a high risk of AVN. Open reduction with capsulotomy decompresses the joint hematoma and anatomically aligns the epiphysis without forceful manipulation, theoretically lowering AVN risk.

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