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Pediatric Hip MCQs

Practice Set 81 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 1601

Topic: Pediatric Hip

A 12-year-old obese male presents with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. Which of the following patient profiles is a strongly accepted indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

. All male patients presenting with unilateral SCFE
. Patients with an underlying endocrine disorder or metabolic bone disease
. Patients presenting with a chronic, stable SCFE
. Patients older than 14 years of age
. Patients with a slip angle greater than 50 degrees on the affected side

Correct Answer & Explanation

. All male patients presenting with unilateral SCFE

Explanation

Prophylactic pinning of the contralateral hip in SCFE is generally indicated for patients at high risk for a future contralateral slip. These include patients with underlying endocrinopathies (e.g., hypothyroidism, growth hormone deficiency), metabolic bone disease, prior pelvic radiation, and very young age (typically < 10 years).

Question 1602

Topic: Pediatric Hip

A 4-month-old infant has been treated with a Pavlik harness for 4 weeks for a completely dislocated left hip. Ultrasound evaluation today shows the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue Pavlik harness for an additional 4 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Observation and re-evaluation at age 6 months

Correct Answer & Explanation

. Continue Pavlik harness for an additional 4 weeks

Explanation

Failure to achieve reduction after 3-4 weeks of Pavlik harness treatment requires cessation of the harness to prevent "Pavlik harness disease" (posterior acetabular wear). The next appropriate step is typically a closed reduction and spica casting under general anesthesia.

Question 1603

Topic: Pediatric Hip
A 12-year-old boy with chronic renal failure presents with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. What is the most appropriate indication for prophylactic pinning of the contralateral right hip?
. Age greater than 14 years at presentation
. Presence of an underlying endocrine or metabolic disorder
. Grade III slip on the primarily affected left side
. Presence of a lateral slip angle greater than 50 degrees
. Male gender

Correct Answer & Explanation

. Presence of an underlying endocrine or metabolic disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, chronic renal failure, growth hormone therapy) due to a significantly increased risk (approaching 100%) of bilateral involvement. Age less than 10, not older, is also considered a relative indication.

Question 1604

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 3-week follow-up, the infant exhibits decreased spontaneous movement of the affected leg and absent knee extension. What is the most likely cause of this physical finding?

. Avascular necrosis of the femoral head
. Obturator nerve palsy due to excessive abduction
. Femoral nerve palsy due to excessive hyperflexion
. Sciatic nerve palsy due to excessive adduction
. Transient synovitis secondary to brace wear

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hip. It presents with decreased active knee extension and diminished spontaneous leg movements. The harness should be temporarily removed or adjusted, and the palsy typically resolves spontaneously.

Question 1605

Topic: Pediatric Hip
According to the Herring lateral pillar classification for Legg-Calvé-Perthes disease, which of the following radiographic findings is the defining feature of a Group B hip?
. No involvement or collapse of the lateral pillar
. Greater than 50% maintenance of lateral pillar height
. Less than 50% maintenance of lateral pillar height
. Complete collapse of the lateral pillar
. Involvement of the medial pillar exclusively

Correct Answer & Explanation

. Greater than 50% maintenance of lateral pillar height

Explanation

In the Herring lateral pillar classification, Group A has no involvement of the lateral pillar. Group B maintains >50% of the lateral pillar height. Group C maintains <50% of the lateral pillar height. Group B/C is a borderline category. This classification is highly prognostic for the final hip outcome.

Question 1606

Topic: Pediatric Hip

A 13-year-old boy underwent in situ single-screw fixation for a stable right Slipped Capital Femoral Epiphysis (SCFE) two years ago. He now complains of progressive right hip stiffness and worsening pain. Radiographs reveal global joint space narrowing to 1.5 mm, periarticular osteopenia, and no signs of avascular necrosis. What is the most likely diagnosis?

. Implant failure
. Chondrolysis
. Avascular necrosis (AVN)
. Septic arthritis
. Femoroacetabular impingement (FAI)

Correct Answer & Explanation

. Implant failure

Explanation

Chondrolysis is a devastating complication of SCFE, characterized by acute cartilage death and profound joint space narrowing (typically <3 mm). It presents with severe stiffness and pain. It has historically been associated with unrecognized screw penetration into the joint, severe slips, and prolonged spica casting. Radiographs classically show concentric joint space narrowing and periarticular osteopenia without collapse of the femoral head (which would indicate AVN).

Question 1607

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs demonstrate greater than 50% collapse of the lateral pillar of the femoral head. According to the Herring classification, what is his lateral pillar grade, and what is the expected outcome?
. Group A, with an excellent prognosis
. Group B, with a fair prognosis
. Group C, with a poor prognosis regardless of treatment
. Group B/C border, requiring immediate containment
. Group C, with an excellent prognosis following spica casting

Correct Answer & Explanation

. Group C, with a poor prognosis regardless of treatment

Explanation

Herring Group C is defined by greater than 50% loss of lateral pillar height. Patients in this group generally have a poor prognosis with a high likelihood of residual deformity, and surgical containment has limited benefit in older children.

Question 1608

Topic: Pediatric Hip

The Herring Lateral Pillar classification is used to determine the prognosis in Legg-Calve-Perthes disease. Which of the following radiographic parameters defines a Lateral Pillar Group C?

. > 50% maintenance of lateral pillar height on AP pelvis
. < 50% maintenance of lateral pillar height on AP pelvis
. Complete collapse of the central pillar on frog-leg lateral
. Epiphyseal extrusion > 20% on AP pelvis
. Subchondral fracture (Crescent sign) on frog-leg lateral

Correct Answer & Explanation

. > 50% maintenance of lateral pillar height on AP pelvis

Explanation

The Lateral Pillar classification evaluates the height of the lateral third of the femoral head on an AP radiograph during the fragmentation stage. Group C is defined as having less than 50% of the normal lateral pillar height maintained, which portends a poor prognosis.

Question 1609

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). During the procedure, the surgeon fails to recognize intra-articular pin penetration. What is the most likely long-term complication?

. Avascular necrosis
. Coxa vara deformity
. Chondrolysis
. Femoroacetabular impingement
. Osteomyelitis

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized intra-articular pin penetration is the primary cause of iatrogenic chondrolysis after SCFE fixation. Surgeons must utilize the 'approach-withdraw' principle on live fluoroscopy to ensure hardware does not breach the joint.

Question 1610

Topic: Pediatric Hip

According to the Loder classification, which clinical finding strictly defines an "unstable" slipped capital femoral epiphysis (SCFE)?

. Slip angle > 50 degrees
. Symptom duration less than 3 weeks
. Inability to bear weight, even with crutches
. Presence of a hip effusion on ultrasound
. Radiographic evidence of epiphyseal sclerosis

Correct Answer & Explanation

. Slip angle > 50 degrees

Explanation

The Loder classification defines an unstable SCFE solely by the patient's inability to walk or bear weight on the affected limb, regardless of crutch use. Unstable slips carry a substantially higher risk of avascular necrosis compared to stable slips.

Question 1611

Topic: Pediatric Hip

An 8-year-old boy presents with a limp and hip pain. Radiographs reveal Legg-Calve-Perthes disease with greater than 50% loss of lateral pillar height. According to the Herring classification, what group does this represent and what is the associated prognosis?

. Herring Lateral Pillar A; excellent prognosis
. Herring Lateral Pillar B; fair prognosis
. Herring Lateral Pillar C; poor prognosis
. Catterall Group I; excellent prognosis
. Salter-Thompson B; poor prognosis

Correct Answer & Explanation

. Herring Lateral Pillar A; excellent prognosis

Explanation

The Herring Lateral Pillar classification strongly correlates with outcome in Perthes disease. Group C is defined by >50% collapse of the lateral pillar of the femoral head and consistently carries the worst prognosis for joint congruity.

Question 1612

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department unable to bear weight on his left leg even with crutches after a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most likely severe complication associated with this specific presentation?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoroacetabular impingement
. Contralateral slip progression
. Septic arthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

The inability to bear weight even with crutches defines an unstable SCFE. Unstable slips are associated with a high rate of avascular necrosis, with reported risks ranging from 20% to 50% due to acute vascular disruption.

Question 1613

Topic: Pediatric Hip

A 3-year-old girl presents with a painless limp. She has never been treated for developmental dysplasia of the hip (DDH). Radiographs show a chronically dislocated left hip with a false acetabulum. What is the most appropriate surgical intervention?

. Closed reduction and spica casting
. Open reduction alone
. Open reduction, femoral shortening derotational osteotomy, and pelvic osteotomy
. Application of a Pavlik harness
. Shelf arthroplasty

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In a child older than 2 to 3 years with a neglected DDH dislocation, open reduction alone is insufficient and carries a high risk of AVN and redislocation. Femoral shortening (to decompress the joint) and a pelvic osteotomy (to correct acetabular dysplasia) are concurrently required.

Question 1614

Topic: Pediatric Hip

A 13-year-old obese boy presents with left hip pain and inability to ambulate, even with crutches, following a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk associated with this specific presentation?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Contralateral slip
. Premature osteoarthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

The inability to ambulate with or without crutches defines an unstable SCFE. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN) of the femoral head, with rates historically reported between 20% and 50%.

Question 1615

Topic: Pediatric Hip

An 18-month-old girl presents with untreated developmental dysplasia of the left hip (DDH). Radiographs show a completely dislocated femoral head. Which of the following is the most appropriate initial management?

. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction, possible pelvic/femoral osteotomy, and spica casting
. Observation until age 3, then varus derotational osteotomy
. Skeletal traction for 6 weeks followed by bracing

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

In children older than 18 months with a dislocated hip, closed reduction is rarely successful or stable. Open reduction, often combined with a pelvic or femoral shortening osteotomy, is the treatment of choice to safely reduce the joint.

Question 1616

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the parents report the infant is no longer kicking the right leg. On clinical examination, the infant demonstrates an absence of active knee extension on the right side but has normal ankle movements. What is the most likely cause of this complication?

. Excessive hip flexion in the harness
. Excessive hip abduction in the harness
. Inadequate hip flexion in the harness
. Inadequate hip abduction in the harness
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness resulting from excessive hip flexion, which compresses the femoral nerve against the rim of the pelvis or inguinal ligament. Excessive hip abduction, in contrast, increases the risk of avascular necrosis (AVN) of the femoral head.

Question 1617

Topic: Pediatric Hip

A 13-year-old obese male presents with an acute inability to bear weight on the left leg. Radiographs reveal a slipped capital femoral epiphysis (SCFE). Which of the following factors at presentation is the most statistically significant predictor for the future development of avascular necrosis (AVN) of the femoral head?

. Severity of the slip angle greater than 50 degrees
. The patient's body mass index (BMI)
. Inability to ambulate with or without crutches (unstable SCFE)
. Duration of preceding chronic groin pain symptoms
. The use of a double-screw construct for fixation

Correct Answer & Explanation

. Severity of the slip angle greater than 50 degrees

Explanation

According to the Loder classification, SCFE is classified into stable (able to bear weight) and unstable (unable to bear weight, even with crutches). Unstable SCFE has a substantially higher risk of developing avascular necrosis (approaching 47% in some series), making weight-bearing status the most important clinical prognostic factor for AVN.

Question 1618

Topic: Pediatric Hip

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. When assessing the prognosis using the Herring lateral pillar classification on the AP radiograph of the pelvis during the fragmentation phase, which of the following parameters defines a Type B classification?

. No radiolucency in the lateral pillar
. Greater than 50% of the lateral pillar height is maintained
. Less than 50% of the lateral pillar height is maintained
. Complete collapse of the entire epiphysis with subluxation
. Extrusion of the lateral aspect of the femoral head (Gage sign)

Correct Answer & Explanation

. No radiolucency in the lateral pillar

Explanation

The Herring lateral pillar classification relies on the height of the lateral third of the femoral epiphysis (the lateral pillar) on an AP radiograph during the fragmentation stage. Type A: no involvement. Type B: >50% of lateral pillar height is maintained. Type C: <50% of lateral pillar height is maintained. The classification is highly prognostic for final hip sphericity.

Question 1619

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 32 presents with left-sided slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic right hip?

. Patient's chronological age of 12 years
. Initial left slip angle of 30 degrees
. Underlying endocrine disorder (e.g., hypothyroidism)
. Presence of referred knee pain on the left
. BMI greater than 30

Correct Answer & Explanation

. Patient's chronological age of 12 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrinopathies (like hypothyroidism, panhypopituitarism, or renal osteodystrophy), as they have a significantly higher rate of bilateral involvement (up to 100% in some series) compared to idiopathic cases.

Question 1620

Topic: Pediatric Hip

In the treatment of developmental dysplasia of the hip (DDH) using a Pavlik harness, allowing excessive flexion of the hip beyond 120 degrees places the infant at increased risk for which complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Inferior dislocation of the hip
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In a Pavlik harness, excessive hyperflexion (greater than 120 degrees) risks compressing the femoral nerve, leading to a transient femoral nerve palsy. Excessive abduction is famously associated with avascular necrosis (AVN) of the femoral head.

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