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Pediatric Hip MCQs

Practice Set 9 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 161

Topic: Pediatric Hip

A 6-week-old female infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, she is noted to have an inability to actively extend the knee on the treated side. This complication is most likely due to excessive positioning in which direction?

. Excessive hip extension
. Excessive hip adduction
. Excessive hip flexion
. Excessive hip abduction
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and is typically caused by excessive hip flexion. The harness should be adjusted or temporarily discontinued until quadriceps function returns.

Question 162

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of strict Pavlik harness treatment. What is the next best step in management?

. Continue Pavlik harness for an additional 6 weeks
. Closed reduction and spica casting under anesthesia
. Open reduction and Pemberton pelvic osteotomy
. Botulinum toxin injection into the adductors
. Observation until 1 year of age followed by a Salter osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia

Explanation

In an infant (typically under 18 months) who fails Pavlik harness treatment, the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. Open reduction is reserved for failure of closed reduction.

Question 163

Topic: Pediatric Hip

A 13-year-old overweight boy presents with left knee pain and a limp for 3 weeks. Examination reveals limited internal rotation of the left hip. What obligatory motion of the hip during passive flexion is classic for this condition?

. Obligatory adduction
. Obligatory internal rotation
. Obligatory external rotation
. Obligatory abduction
. Obligatory extension

Correct Answer & Explanation

. Obligatory external rotation

Explanation

Slipped capital femoral epiphysis (SCFE) typically presents with an obligatory external rotation of the thigh as the hip is passively flexed, due to the posterior and inferior displacement of the femoral head.

Question 164

Topic: Pediatric Hip

A 4-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. To avoid iatrogenic avascular necrosis (AVN) of the femoral head, which position must be strictly avoided during harness application?

. Excessive flexion
. Excessive adduction
. Excessive external rotation
. Excessive abduction
. Excessive extension

Correct Answer & Explanation

. Excessive abduction

Explanation

Excessive abduction in a Pavlik harness places extreme pressure on the vascular supply to the femoral head, drastically increasing the risk of iatrogenic avascular necrosis. Care must be taken to keep the hips in a safe zone of abduction.

Question 165

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of left thigh pain and a limp. On examination, he has an obligate external rotation of the left hip during flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following is the most devastating long-term complication of in-situ pinning of this condition?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Leg length discrepancy
. Hardware failure

Correct Answer & Explanation

. Avascular necrosis

Explanation

While chondrolysis and impingement can occur, avascular necrosis (AVN) of the femoral head is the most devastating complication following SCFE and its surgical treatment. Unstable SCFEs carry a much higher risk of AVN than stable ones, but poor pin placement can also precipitate it.

Question 166

Topic: Pediatric Hip

A 13-year-old obese male presents with progressively worsening right knee pain for 3 weeks and an inability to bear weight on the right leg for the past 24 hours. Radiographs demonstrate a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following best describes the primary rationale for performing an anterior capsulotomy prior to surgical pinning of this condition?

. To allow for direct visualization and anatomical reduction of the displaced epiphysis.
. To decrease intracapsular pressure and reduce the subsequent risk of osteonecrosis.
. To facilitate the removal of loose intra-articular cartilage fragments.
. To improve the trajectory and accuracy of percutaneous screw placement.
. To prevent the future development of cam-type femoroacetabular impingement (FAI).

Correct Answer & Explanation

. To decrease intracapsular pressure and reduce the subsequent risk of osteonecrosis.

Explanation

In an unstable SCFE, a massive intracapsular hematoma increases pressure, which can tamponade retinacular blood flow and lead to osteonecrosis (avascular necrosis). An anterior capsulotomy effectively decompresses the joint, thereby mitigating this critical complication.

Question 167

Topic: Pediatric Hip

A 6-week-old female infant is noted to have an asymmetric thigh crease and a positive Ortolani test on the left side. Ultrasound confirms an unstable left hip. What is the first-line treatment?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction
. Observation and repeat ultrasound in 6 weeks
. Bilateral hip abduction orthosis (Ilfeld splint)

Correct Answer & Explanation

. Pavlik harness application

Explanation

The Pavlik harness is the gold standard first-line treatment for reducible developmental dysplasia of the hip (DDH) in infants younger than 6 months. It dynamically maintains the hip in flexion and abduction, promoting normal acetabular development.

Question 168

Topic: Pediatric Hip

A 7-year-old boy presents with a painless limp that has worsened over the past few months. He has limited internal rotation and abduction of his left hip. Radiographs reveal fragmentation and sclerosis of the proximal femoral epiphysis. What is the most likely diagnosis?

. Slipped capital femoral epiphysis
. Transient synovitis
. Septic arthritis
. Legg-Calve-Perthes disease
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Legg-Calve-Perthes disease

Explanation

Legg-Calve-Perthes disease is an idiopathic avascular necrosis of the proximal femoral epiphysis, typically occurring in boys aged 4-8 years. Radiographic progression follows stages of initial sclerosis, fragmentation, reossification, and finally healing or remodeling.

Question 169

Topic: Pediatric Hip

In the surgical management of an unstable slipped capital femoral epiphysis (SCFE) using a single cannulated screw, which complication is most directly related to unrecognized intra-articular hardware penetration?

. Avascular necrosis
. Chondrolysis
. Femoral neck fracture
. Slipped progression
. Cam impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis (rapid cartilage destruction) is strongly associated with unrecognized intra-articular hardware penetration during SCFE pinning. Careful fluoroscopic evaluation using the approach-withdraw technique helps prevent this.

Question 170

Topic: Pediatric Hip

A 4-month-old female infant is evaluated for asymmetric thigh folds. Ultrasound reveals a dysplastic left hip with an alpha angle of 50 degrees and a beta angle of 80 degrees. What is the most appropriate initial management?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction and capsulorrhaphy
. Observation with repeat ultrasound in 3 months
. Pelvic osteotomy

Correct Answer & Explanation

. Pavlik harness

Explanation

For developmental dysplasia of the hip (DDH) in an infant under 6 months of age, the Pavlik harness is the gold standard initial treatment. It maintains the hip in flexion and abduction to safely promote acetabular remodeling.

Question 171

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp. Radiographs show sclerosis and flattening of the capital femoral epiphysis. According to the Herring lateral pillar classification, greater than 50% loss of lateral pillar height categorizes the hip into which group?
. Group A
. Group B
. Group C
. Group B/C
. Group D

Correct Answer & Explanation

. Group C

Explanation

In the Herring classification for Legg-Calvรฉ-Perthes disease, a loss of more than 50% of the lateral pillar height defines Group C. This group carries the poorest prognosis regarding long-term hip joint congruity and function.

Question 172

Topic: Pediatric Hip

A 6-month-old infant is diagnosed with developmental dysplasia of the hip (DDH) after failing 6 weeks of treatment in a Pavlik harness. Ultrasound confirms persistent dislocation. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 6 weeks
. Closed reduction and spica casting under general anesthesia
. Immediate open reduction and femoral shortening osteotomy
. Application of a Denis Browne bar
. Observation until walking age

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia

Explanation

If a Pavlik harness fails to achieve reduction in an infant with DDH after 3 to 4 weeks, continuing it is contraindicated due to the risk of 'Pavlik harness disease'. The next step is typically closed reduction and application of a hip spica cast under anesthesia.

Question 173

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of right groin pain and a limp. On examination, he walks with an antalgic gait, and his right hip goes into obligate external rotation when flexed. Radiographs confirm a slipped capital femoral epiphysis (SCFE). What is the standard surgical treatment?

. Closed reduction and spica casting
. In situ single screw fixation
. Proximal femoral derotational osteotomy
. Core decompression
. Open reduction and internal fixation with a dynamic hip screw

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The classic presentation of SCFE includes obligate external rotation with hip flexion. The gold standard of treatment is in situ fixation across the physis, typically utilizing a single partially threaded cannulated screw, to prevent further slippage.

Question 174

Topic: Pediatric Hip

An obese 12-year-old boy presents with a 3-week history of right groin and knee pain, walking with an externally rotated limp. Radiographs demonstrate widening of the capital femoral physis with the epiphysis displaced posteriorly and inferiorly. Which of the following is the most feared complication directly associated with attempted forceful closed reduction of this condition?

. Chondrolysis
. Avascular necrosis (AVN)
. Slipped capital femoral epiphysis of the contralateral hip
. Femoroacetabular impingement (FAI)
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Forceful closed reduction of a slipped capital femoral epiphysis (SCFE) significantly increases the risk of avascular necrosis due to stretching or tearing of the tenuous retinacular vessels. In situ pinning is the standard of care to avoid this catastrophic complication.

Question 175

Topic: Pediatric Hip

An obese 12-year-old boy presents with an inability to bear weight on his left leg and severe left hip pain. Radiographs show a posterior and inferior slip of the proximal femoral epiphysis. He is diagnosed with an unstable slipped capital femoral epiphysis (SCFE). Which complication is most highly associated with this specific presentation?

. Chondrolysis
. Leg length discrepancy
. Femoroacetabular impingement
. Avascular necrosis of the femoral head
. Nonunion

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Unstable SCFE (defined as the inability to bear weight even with crutches) has a high risk of avascular necrosis, with rates up to 50%. Prompt diagnosis and careful surgical management are required to minimize this risk.

Question 176

Topic: Pediatric Hip

An 18-month-old child is diagnosed with untreated developmental dysplasia of the hip (DDH) on the right side. Which of the following is the most appropriate initial surgical management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction with or without pelvic/femoral osteotomy
. Shelf acetabuloplasty
. Total hip arthroplasty

Correct Answer & Explanation

. Open reduction with or without pelvic/femoral osteotomy

Explanation

After 18 months of age, closed reduction is rarely successful due to severe soft tissue contractures and acetabular dysplasia. Open reduction, often combined with a pelvic or femoral osteotomy, is the standard of care to achieve stable concentric reduction.

Question 177

Topic: Pediatric Hip

A 13-year-old obese male presents with right thigh pain and a limp. Examination reveals obligate external rotation of the right hip during passive flexion. Radiographs confirm a severe, stable slipped capital femoral epiphysis (SCFE). What is the most appropriate definitive management?

. Spica casting
. In situ pinning with a single cannulated screw
. Open reduction and internal fixation with multiple screws
. Immediate subtrochanteric osteotomy
. Observation and non-weight bearing

Correct Answer & Explanation

. In situ pinning with a single cannulated screw

Explanation

In situ percutaneous pinning with a single central cannulated screw is the gold standard for a stable SCFE. This prevents further slippage while minimizing the risk of avascular necrosis and chondrolysis.

Question 178

Topic: Pediatric Hip

A 9-year-old boy presents with a 3-week history of right groin pain and an antalgic limp. His BMI is in the 25th percentile for his age. Radiographs confirm a mild stable slipped capital femoral epiphysis (SCFE). Given the patient's age and weight, which of the following is the most appropriate initial laboratory workup?

. Complete blood count and inflammatory markers
. Rheumatoid factor and antinuclear antibodies
. Thyroid-stimulating hormone (TSH) and free T4
. Serum calcium, phosphate, and alkaline phosphatase
. Parathyroid hormone (PTH) and vitamin D levels

Correct Answer & Explanation

. Thyroid-stimulating hormone (TSH) and free T4

Explanation

SCFE in children under 10 years of age, or in those whose weight is less than the 50th percentile, is highly associated with underlying endocrine disorders. Hypothyroidism is the most common endocrine etiology, making TSH and free T4 essential in the initial screening.

Question 179

Topic: Pediatric Hip

An obese 13-year-old boy presents with an obligatory external rotation of his right hip when it is passively flexed. Radiographs reveal a slipped capital femoral epiphysis (SCFE). Which of the following is the most likely direction of epiphyseal displacement relative to the femoral neck?

. Anterior and superior
. Anterior and inferior
. Posterior and inferior
. Posterior and superior
. Strictly medial

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the femoral epiphysis typically displaces posteriorly and inferiorly relative to the femoral neck. The clinical sign is obligate external rotation during hip flexion.

Question 180

Topic: Pediatric Hip

A 6-month-old infant is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Two weeks later, the baby exhibits decreased active extension of the left knee. What is the most likely complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Obturator nerve palsy
. Sciatic nerve palsy
. Septic arthritis

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hip flexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament. This leads to femoral nerve palsy, manifesting as decreased active knee extension.

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