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Pediatric Hip MCQs

Practice Set 49 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 961

Topic: Pediatric Hip

When treating developmental dysplasia of the hip (DDH) with closed reduction and spica casting, maintaining the hip in forced, extreme abduction ('frog-leg' position) significantly increases the risk of which of the following complications?

. Recurrent posterior dislocation
. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Acetabular dysplasia
. Transient synovitis

Correct Answer & Explanation

. Recurrent posterior dislocation

Explanation

Forced abduction during spica casting compresses the cartilaginous femoral head against the acetabulum and compromises the medial circumflex femoral artery, leading to avascular necrosis. Hips should be immobilized in the 'human position' (hyperflexion, moderate abduction).

Question 962

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her right leg. Examination reveals decreased active extension of the right knee, but she withdraws to pain. What is the most likely cause, and what is the appropriate management?

. Femoral nerve palsy; discontinue harness
. Sciatic nerve palsy; discontinue harness
. Obturator nerve palsy; adjust harness
. Femoral nerve palsy; loosen anterior straps only
. Septic arthritis; immediate hip aspiration

Correct Answer & Explanation

. Femoral nerve palsy; discontinue harness

Explanation

Femoral nerve palsy is a known complication of Pavlik harness use, often due to hyperflexion. The appropriate management is temporary discontinuation of the harness until neurologic function returns.

Question 963

Topic: Pediatric Hip

A newborn girl with arthrogryposis multiplex congenita is found to have bilateral rigid, irreducible teratologic hip dislocations. What is the most appropriate management?

. Immediate application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction prior to walking age
. Bilateral proximal femoral osteotomies at age 5
. Observation and supportive care only

Correct Answer & Explanation

. Immediate application of a Pavlik harness

Explanation

Teratologic hip dislocations (e.g., in arthrogryposis or spina bifida) are rigid and fail conservative management like Pavlik harnesses. Open reduction is typically required and is usually performed prior to walking age.

Question 964

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in-situ pinning for a unilateral stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral hip?

. Male gender
. Obesity (>95th percentile BMI)
. Endocrine disorder (e.g., hypothyroidism)
. Age > 14 years
. African-American descent

Correct Answer & Explanation

. Male gender

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with SCFE associated with an underlying endocrine disorder (like hypothyroidism or renal osteodystrophy) due to the high risk of bilateral involvement.

Question 965

Topic: Pediatric Hip

A 4-week-old boy is fitted with a Pavlik harness for an Ortolani-positive right hip. To ensure proper positioning and minimize neurovascular or ischemic complications, how should the harness straps be adjusted?

. Anterior straps flex hips to 120 degrees; posterior straps allow adduction to neutral
. Anterior straps flex hips to 90-100 degrees; posterior straps limit adduction to neutral
. Anterior straps flex hips to 60 degrees; posterior straps force abduction to 80 degrees
. Anterior straps flex hips to 90 degrees; posterior straps force abduction to 90 degrees
. Anterior straps flex hips to 120 degrees; posterior straps force abduction to 60 degrees

Correct Answer & Explanation

. Anterior straps flex hips to 120 degrees; posterior straps allow adduction to neutral

Explanation

The Pavlik harness should flex the hips to approximately 90-100 degrees to prevent femoral nerve palsy (caused by hyperflexion). The posterior straps should limit adduction to neutral to prevent redislocation while avoiding forced abduction, which causes avascular necrosis.

Question 966

Topic: Pediatric Hip

A 4-month-old girl has been treated with a Pavlik harness for 4 weeks for an irreducible developmental dysplasia of the hip (DDH). Repeat ultrasound demonstrates a persistently dislocated left hip without significant improvement in the alpha angle. What is the most appropriate next step in management?

. Continue Pavlik harness for 4 more weeks
. Switch to a rigid abduction orthosis
. Closed reduction and spica casting under anesthesia
. Open reduction and femoral shortening osteotomy
. Observation until 1 year of age

Correct Answer & Explanation

. Continue Pavlik harness for 4 more weeks

Explanation

Prolonged use of a Pavlik harness in an irreducible hip beyond 3 to 4 weeks can cause 'Pavlik harness disease', damaging the posterior acetabulum. The appropriate next step is a closed reduction and spica casting under anesthesia.

Question 967

Topic: Pediatric Hip

An 18-month-old girl is newly diagnosed with developmental dysplasia of the right hip (DDH). The hip is completely dislocated but reducible on examination. Which of the following is the most appropriate initial treatment?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction and capsulorrhaphy
. Salter innominate osteotomy
. Observation until age 2

Correct Answer & Explanation

. Pavlik harness

Explanation

In a child older than 6 months of age who has begun to stand or walk, the Pavlik harness has an unacceptably high failure rate. Closed reduction and spica casting is the preferred initial treatment for typical DDH in children aged 6 to 18 months.

Question 968

Topic: Pediatric Hip

A 4-week-old female with a history of breech presentation is evaluated for hip instability. Ultrasound reveals an alpha angle of 45 degrees, a beta angle of 77 degrees, and 30% femoral head coverage bilaterally. What is the most appropriate initial management?

. Observation and repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction

Correct Answer & Explanation

. Observation and repeat ultrasound in 4 weeks

Explanation

An alpha angle < 60 degrees with subluxation or dislocation on ultrasound in a 4-week-old is diagnostic of DDH. The first-line treatment is a Pavlik harness to achieve reduction and promote acetabular development.

Question 969

Topic: Pediatric Hip

A 6-month-old girl has been treated with a Pavlik harness for 4 weeks for a dislocated left hip. A follow-up ultrasound confirms that the hip remains dislocated within the harness. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 2 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld brace)
. Closed reduction and spica casting
. Open reduction and spica casting
. Femoral varus derotational osteotomy

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 2 weeks

Explanation

Continued use of a Pavlik harness for a dislocated hip beyond 3 to 4 weeks without achieving reduction increases the risk of posterior acetabular wear ("Pavlik harness disease"). The next appropriate step is closed reduction and spica casting under anesthesia.

Question 970

Topic: Pediatric Hip

During the treatment of developmental dysplasia of the hip (DDH) with closed reduction and spica casting, which position places the hip at the greatest risk for avascular necrosis (AVN) of the femoral head?

. Hip flexion greater than 90 degrees
. Hip extension less than 0 degrees
. Hip abduction greater than 60 degrees
. Hip adduction greater than 10 degrees
. Internal rotation greater than 20 degrees

Correct Answer & Explanation

. Hip flexion greater than 90 degrees

Explanation

Extreme hip abduction (the "frog-leg" position) forces the cartilaginous femoral head tightly against the acetabulum, compressing the extracapsular epiphyseal vessels and significantly increasing the risk of avascular necrosis.

Question 971

Topic: Pediatric Hip

A 4-year-old girl is brought in for a painless limp. Pelvic radiographs show a unilaterally dislocated left hip with a false acetabulum and severe dysplasia of the true acetabulum. She has had no prior treatment. What is the recommended management?

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

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

In a child older than 3 years presenting with untreated DDH, soft tissue contractures and severe bony dysplasia require a comprehensive approach. This includes open reduction, a femoral shortening derotational osteotomy (to reduce AVN risk), and a pelvic osteotomy to provide adequate coverage.

Question 972

Topic: Pediatric Hip

An infant being treated in a Pavlik harness for developmental dysplasia of the hip (DDH) is noted by the parents to have stopped kicking the knee on the treated side. Physical examination confirms decreased active extension of the knee, though the foot and ankle move symmetrically. What is the most appropriate next step in management?

. Continue the harness and observe for 48 hours
. Discontinue the harness for 1 to 2 weeks
. Switch immediately to a rigid hip spica cast
. Perform immediate closed reduction under anesthesia
. Adjust the anterior straps to increase hip flexion

Correct Answer & Explanation

. Continue the harness and observe for 48 hours

Explanation

Femoral nerve palsy is a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued until quadriceps function returns, which usually occurs within 1 to 2 weeks.

Question 973

Topic: Pediatric Hip

A 2-year-old girl recently immigrated to the United States and is noted to have a painless limp. Examination reveals a positive Galeazzi sign and severely limited hip abduction. Radiographs show a dislocated left hip with a dysplastic acetabulum. What is the most appropriate treatment?

. Pavlik harness trial for 6 weeks
. Closed reduction and spica casting
. Open reduction, femoral shortening, and pelvic osteotomy
. Proximal femoral epiphysiodesis
. In situ shelf arthroplasty

Correct Answer & Explanation

. Pavlik harness trial for 6 weeks

Explanation

In a child older than 18-24 months presenting with untreated DDH, closed reduction carries a very high risk of AVN and is rarely successful. Treatment requires open reduction, often combined with femoral shortening to reduce joint tension and a pelvic osteotomy for acetabular coverage.

Question 974

Topic: Pediatric Hip

A 3-week-old female infant is evaluated for a suspected hip abnormality. Examination reveals a palpable clunk when her hips are abducted with anteriorly directed pressure on the greater trochanter. What is the most appropriate initial management?

. Pavlik harness
. Observation and repeat examination in 3 weeks
. Rigid abduction orthosis
. Closed reduction and spica cast
. Hip ultrasound

Correct Answer & Explanation

. Pavlik harness

Explanation

The palpable clunk on abduction describes a positive Ortolani test, indicating a dislocated but reducible hip. Immediate treatment with a Pavlik harness is the gold standard for reducible DDH in infants younger than 6 months.

Question 975

Topic: Pediatric Hip

A 7-month-old infant is referred for evaluation of a developmental dysplasia of the hip (DDH) that was missed at birth. Ultrasound confirms a completely dislocated right hip. What is the most appropriate initial management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction via an anterior approach
. Femoral shortening osteotomy
. Observation until walking age

Correct Answer & Explanation

. Pavlik harness application

Explanation

The Pavlik harness is most effective in infants under 6 months of age. For an infant 6 to 18 months old, closed reduction and spica casting is the preferred initial treatment for DDH.

Question 976

Topic: Pediatric Hip

A 13-year-old boy presents with right knee pain and a noticeable limp for 3 weeks. Radiographs reveal an unstable slipped capital femoral epiphysis (SCFE) of the right hip. He is unable to bear weight, even with crutches. What is the most severe potential complication associated with this condition and its surgical fixation?

. Avascular necrosis of the femoral head
. Chondrolysis
. Coxa vara
. Early osteoarthritis
. Femoral neck fracture

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Avascular necrosis (AVN) is the most devastating complication following SCFE and occurs at a much higher rate in unstable slips (up to 47%) compared to stable slips.

Question 977

Topic: Pediatric Hip

A newborn girl with a positive Ortolani sign on the left hip is fitted with a Pavlik harness. Which of the following complications is most likely to occur if the anterior straps of the harness are adjusted to place the hips in excessive flexion (>120 degrees)?

. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Obturator nerve palsy
. Inferior dislocation of the hip
. Knee flexion contracture

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive flexion in a Pavlik harness causes compression of the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. Excessive abduction (tight posterior straps) increases the risk of avascular necrosis.

Question 978

Topic: Pediatric Hip

A 2-year-old boy undergoes open reduction for a late-presenting DDH. During a medial approach, which structure must be carefully protected as it passes posterior to the iliopsoas tendon to avoid vascular compromise to the femoral head?

. Iliopsoas tendon
. Transverse acetabular ligament
. Medial femoral circumflex artery (MFCA)
. Lateral femoral circumflex artery (LFCA)
. Obturator artery

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head in this age group. It is at significant risk during a medial approach for DDH as it courses posterior to the iliopsoas tendon.

Question 979

Topic: Pediatric Hip

A 6-week-old female infant born breech presents for evaluation. Ultrasound demonstrates an alpha angle of 43 degrees and a beta angle of 78 degrees on the left hip. The right hip is normal. What is the most appropriate initial management?

. Observation with repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Closed reduction and spica casting
. Open reduction and spica casting
. Application of a rigid abduction orthosis

Correct Answer & Explanation

. Observation with repeat ultrasound in 4 weeks

Explanation

An alpha angle less than 60 degrees and a beta angle greater than 55 degrees (Graf Type III/IV) indicates developmental dysplasia of the hip (DDH). The Pavlik harness is the gold standard initial treatment for DDH in infants under 6 months of age.

Question 980

Topic: Pediatric Hip

A 12-year-old obese boy presents with sudden inability to bear weight on his left leg. He reports a 2-month history of vague left knee pain. Radiographs reveal a severe, posterior translation of the proximal femoral epiphysis. He cannot bear weight even with crutches. What intervention best minimizes the risk of osteonecrosis?

. Closed reduction via forceful internal rotation prior to pinning
. Urgent capsulotomy and in situ single-screw fixation
. Skeletal traction for 2 weeks followed by pinning
. Prophylactic pinning of the contralateral hip only
. Subtrochanteric valgus osteotomy

Correct Answer & Explanation

. Closed reduction via forceful internal rotation prior to pinning

Explanation

This is an unstable slipped capital femoral epiphysis (SCFE), defined by the inability to bear weight. Urgent/emergent capsulotomy to decompress the intracapsular hematoma combined with in situ single-screw fixation is recommended to reduce the high risk of osteonecrosis associated with unstable SCFE.

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