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Pediatric Hip MCQs

Practice Set 45 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 881

Topic: Pediatric Hip

A 3-month-old girl with DDH is treated with a Pavlik harness. During a follow-up visit, she is noted to have decreased active knee extension on the affected side. What is the most appropriate next step in management?

. Continue the harness as prescribed
. Loosen the anterior straps
. Loosen the posterior straps
. Discontinue the harness entirely
. Change to a rigid hip abduction orthosis

Correct Answer & Explanation

. Continue the harness as prescribed

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness caused by excessive hip flexion. Loosening the anterior straps reduces hyperflexion and typically allows for full recovery of the nerve.

Question 882

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department with acute left groin pain and an inability to bear weight after a minor fall. Radiographs show a slipped capital femoral epiphysis. According to Loder's classification, what is the primary significance of his inability to bear weight?

. Increased risk of chondrolysis
. Increased risk of avascular necrosis (AVN)
. Indication for prophylactic pinning of the contralateral hip
. Need for an open reduction and internal fixation
. Increased likelihood of underlying endocrine abnormality

Correct Answer & Explanation

. Increased risk of chondrolysis

Explanation

Loder classified SCFE into stable (able to bear weight) and unstable (unable to bear weight). Unstable SCFE is associated with a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 883

Topic: Pediatric Hip

Prophylactic pinning of the contralateral, asymptomatic hip in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. 13-year-old boy with a BMI of 35
. 11-year-old girl with primary hyperparathyroidism
. 14-year-old boy with a traumatic unstable SCFE
. 12-year-old boy with a family history of SCFE
. 10-year-old girl with a stable, mild SCFE

Correct Answer & Explanation

. 13-year-old boy with a BMI of 35

Explanation

Patients with underlying endocrine disorders (e.g., hyperparathyroidism, hypothyroidism, renal osteodystrophy) have a very high rate of developing bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these patients.

Question 884

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp. Examination reveals a positive Galeazzi sign and limited abduction of the right hip. Radiographs confirm a dislocated right hip. Which of the following is the most appropriate definitive treatment?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Pavlik harness

Explanation

In a child older than 18 months with untreated DDH, closed methods generally fail. Open reduction is required, often combined with a pelvic osteotomy (e.g., Salter) to address the secondary acetabular dysplasia.

Question 885

Topic: Pediatric Hip

A 12-year-old boy presents with an unstable slipped capital femoral epiphysis (SCFE). The surgeon plans to perform a capsulotomy and percutaneous in situ pinning. What is the primary rationale for performing an anterior capsulotomy in this setting?

. To improve the radiographic visualization of the epiphysis
. To reduce intracapsular pressure and potentially decrease the risk of AVN
. To facilitate an anatomic open reduction of the slip
. To prevent post-operative chondrolysis
. To allow for easier placement of a second screw

Correct Answer & Explanation

. To improve the radiographic visualization of the epiphysis

Explanation

Unstable SCFE is associated with a hemarthrosis that increases intracapsular pressure, potentially compromising epiphyseal blood flow. An anterior capsulotomy decompresses the joint and is thought to reduce the high risk of AVN.

Question 886

Topic: Pediatric Hip
A 4-week-old female infant born in the breech presentation undergoes ultrasound screening for developmental dysplasia of the hip (DDH). The coronal image reveals an alpha angle of 40 degrees and a beta angle of 80 degrees. According to the Graf classification, what is the best initial management for this patient?
. Reassurance and clinical follow-up in 4 weeks
. Repeat ultrasound at 3 months of age
. Application of a Pavlik harness
. Immediate closed reduction and spica casting
. Open reduction with an adductor tenotomy

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

An alpha angle of less than 60 degrees indicates dysplasia, and an angle of 40 degrees falls into Graf Type III (dislocated but reducible). The standard of care for a newborn to 6-month-old with a dysplastic or dislocated hip is the application of a Pavlik harness.

Question 887

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department with acute severe right hip pain after a minor fall. He is completely unable to bear weight on the right leg, even with the use of crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Based on the Loder classification, this specific clinical presentation carries the highest risk for which of the following complications?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Premature physeal closure
. Contralateral SCFE within 6 months
. Cam-type femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

The Loder classification defines an unstable SCFE by the patient's inability to ambulate, with or without crutches. Unstable SCFE is associated with a markedly high rate of avascular necrosis (up to 50%), whereas stable SCFE rarely results in AVN.

Question 888

Topic: Pediatric Hip

A 12-year-old girl is diagnosed with a unilateral stable slipped capital femoral epiphysis (SCFE). She has a known medical history of panhypopituitarism and renal osteodystrophy. When counseling the parents about surgical management, what is the primary indication for recommending prophylactic in situ pinning of the contralateral hip?

. Her age at presentation
. Her female gender
. Her underlying endocrine and metabolic disorder
. The stable classification of her current slip
. Her body mass index (BMI) over the 95th percentile

Correct Answer & Explanation

. Her age at presentation

Explanation

Patients with underlying endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism) have an exceedingly high risk (up to 100%) of developing bilateral SCFE. Prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in this population.

Question 889

Topic: Pediatric Hip

During a closed reduction for developmental dysplasia of the hip (DDH) under general anesthesia in a 9-month-old, the hip reduces at 100 degrees of flexion and 60 degrees of abduction. However, it redislocates when abduction is reduced to 40 degrees. The safe zone of Ramsey is determined to be narrow. Which of the following is the best next step to safely enlarge this zone?

. Perform a percutaneous Achilles tendon lengthening
. Perform a percutaneous adductor longus tenotomy
. Proceed immediately to a femoral shortening osteotomy
. Cast the child in 80 degrees of abduction
. Perform an iliopsoas tenotomy

Correct Answer & Explanation

. Perform a percutaneous Achilles tendon lengthening

Explanation

A narrow safe zone of Ramsey (< 20 degrees between reduction and redislocation) increases the risk of avascular necrosis if the hip is forced into hyperabduction. A percutaneous adductor longus tenotomy safely increases the maximal abduction, widening the safe zone for a safer spica cast position.

Question 890

Topic: Pediatric Hip

A 13-year-old girl was treated 8 months ago with a single cannulated screw for a SCFE. She now presents with progressive hip stiffness, worsening pain, and a significant loss of hip range of motion. Radiographs demonstrate diffuse joint space narrowing of the affected hip without focal collapse. What is the most likely etiology of this late complication?

. Avascular necrosis
. Unrecognized intra-articular screw penetration leading to chondrolysis
. Septic arthritis
. Hardware failure resulting in loss of fixation
. Secondary osteoarthritis due to femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is characterized by acute loss of articular cartilage and joint space narrowing, presenting with severe stiffness. In the setting of SCFE treatment, it is most strongly associated with unrecognized intra-articular hardware penetration.

Question 891

Topic: Pediatric Hip

A 2-year-old girl is brought to the clinic for a newly noticed painless limp. Radiographs demonstrate a completely dislocated right hip with a false acetabulum and a dysplastic true acetabulum. Based on her age and presentation, what is the most appropriate initial management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction, pelvic osteotomy, and potential femoral shortening
. Wait until skeletal maturity for a total hip arthroplasty
. Observation as the false acetabulum will remodel

Correct Answer & Explanation

. Pavlik harness application

Explanation

Children presenting with DDH after 18-24 months of age typically have significant secondary adaptive changes (acetabular dysplasia and capsular constriction). Successful treatment usually requires an open reduction combined with a pelvic osteotomy and often a femoral shortening osteotomy.

Question 892

Topic: Pediatric Hip

A 12-year-old, overweight boy complains of vague left knee pain for the past 3 months. His knee examination is completely unremarkable. When the examiner passively flexes his left hip to 90 degrees, the leg obligately deviates into external rotation. What is the most likely underlying diagnosis?

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

Correct Answer & Explanation

. Legg-Calve-Perthes disease

Explanation

Obligate external rotation of the hip during passive flexion is a pathognomonic physical exam finding for a slipped capital femoral epiphysis (SCFE). Furthermore, SCFE frequently presents as referred knee or thigh pain, leading to potential misdiagnosis if the hip is not examined.

Question 893

Topic: Pediatric Hip

A 10-year-old boy is diagnosed with a unilateral stable slipped capital femoral epiphysis. Which of the following radiographic parameters is considered the most reliable predictor for the development of a subsequent contralateral slip?

. Initial slip angle > 50 degrees
. Southwick slip angle on the lateral radiograph
. Modified Oxford bone age score
. Klein's line intersection on the anteroposterior radiograph
. Femoral neck-shaft angle

Correct Answer & Explanation

. Initial slip angle > 50 degrees

Explanation

The Modified Oxford bone age score relies on pelvic radiographs to determine skeletal maturity and is the most reliable predictor of a contralateral slip. Patients with a lower score (greater skeletal immaturity) are at the highest risk for sequential SCFE.

Question 894

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip. At a follow-up visit, the parents report the infant is no longer kicking her right leg. Examination reveals an inability to actively extend the knee on the affected side. This complication is most directly caused by which of the following?

. Excessive flexion of the anterior straps
. Inadequate flexion of the anterior straps
. Excessive abduction of the posterior straps
. Inadequate abduction of the posterior straps
. Excessive internal rotation of the lower leg

Correct Answer & Explanation

. Excessive flexion of the anterior straps

Explanation

Femoral nerve palsy in a Pavlik harness is caused by hyperflexion of the hips, typically resulting from overly tight anterior straps. Management consists of loosening the straps to reduce flexion and monitoring for spontaneous recovery.

Question 895

Topic: Pediatric Hip

According to the Loder classification, an unstable slipped capital femoral epiphysis (SCFE) is associated with a significantly higher rate of which of the following complications when compared to a stable SCFE?

. Chondrolysis
. Avascular necrosis of the femoral head
. Premature physeal closure
. Femoroacetabular impingement
. Development of a contralateral slip

Correct Answer & Explanation

. Chondrolysis

Explanation

The Loder classification defines an unstable SCFE by the patient's inability to ambulate even with crutches. Unstable slips carry a nearly 50% risk of avascular necrosis, whereas the rate in stable slips is close to zero.

Question 896

Topic: Pediatric Hip

A 3-year-old girl is diagnosed with a neglected, completely dislocated unilateral developmental dysplasia of the hip. She is scheduled for an open reduction and pelvic osteotomy. What is the primary biomechanical rationale for performing a concurrent femoral shortening osteotomy in this patient?

. To correct excessive femoral anteversion
. To stimulate rapid acetabular remodeling
. To reduce tension on the soft tissues and minimize the risk of avascular necrosis
. To overcorrect leg lengths postoperatively
. To redirect the femoral head posteriorly into the true acetabulum

Correct Answer & Explanation

. To correct excessive femoral anteversion

Explanation

In older children (typically over 2-3 years) with untreated DDH, a femoral shortening osteotomy is often necessary during open reduction. Shortening the femur relieves soft-tissue tension across the joint, significantly reducing the risk of avascular necrosis.

Question 897

Topic: Pediatric Hip

A 14-year-old girl presents with progressive groin pain and marked stiffness 8 months after undergoing an uncomplicated in situ pinning for a stable slipped capital femoral epiphysis. Radiographs reveal diffuse narrowing of the hip joint space with preservation of femoral head sphericity. What is the most likely diagnosis?

. Avascular necrosis
. Septic arthritis
. Chondrolysis
. Implant prominence into the joint
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is characterized by diffuse joint space narrowing and severe stiffness following SCFE treatment, with the femoral head typically remaining spherical. Risk factors include severe slips, spica casting, and unrecognized intra-articular hardware penetration.

Question 898

Topic: Pediatric Hip

An ultrasound is performed on a 4-week-old female infant to evaluate for developmental dysplasia of the hip. According to the Graf classification, a normal, mature hip (Type 1) is defined by which of the following sonographic measurements?

. Alpha angle greater than 60 degrees
. Alpha angle less than 50 degrees
. Beta angle greater than 77 degrees
. Alpha angle between 50 and 59 degrees
. Beta angle less than 43 degrees

Correct Answer & Explanation

. Alpha angle greater than 60 degrees

Explanation

In the Graf ultrasound classification, the alpha angle measures the concavity of the bony acetabular roof. An alpha angle greater than 60 degrees indicates a normal, mature hip (Type 1).

Question 899

Topic: Pediatric Hip

A 3-month-old girl with Developmental Dysplasia of the Hip (DDH) is treated with a Pavlik harness. At her two-week follow-up, the mother reports that the infant is no longer kicking her right leg as much. On examination, the infant demonstrates decreased active knee extension on the right side. What is the most likely cause of this finding?

. Femoral nerve palsy due to excessive hip flexion
. Sciatic nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive hip abduction
. Femoral nerve palsy due to excessive hip abduction
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Hyperflexion of the hips in a Pavlik harness can cause compression of the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy. This presents as decreased active extension of the knee (quadriceps weakness). The treatment is to decrease the amount of flexion or temporarily discontinue the harness until nerve function returns. Avascular necrosis is typically caused by excessive abduction.

Question 900

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in situ single screw fixation for a stable mild slipped capital femoral epiphysis (SCFE) of the left hip. Nine months later, he returns complaining of progressive left hip pain, severe stiffness, and an inability to participate in sports. Radiographs reveal diffuse joint space narrowing of the left hip and subchondral irregularities, with the screw threads completely within the femoral head. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Implant failure
. Septic arthritis
. Contralateral SCFE

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute or insidious onset of pain, marked stiffness, and diffuse joint space narrowing on radiographs. Although hardware penetration into the joint is a known risk factor, chondrolysis can occur even with properly placed implants or unoperated cases. Avascular necrosis typically presents with subchondral collapse, sclerosis, or segmental changes rather than global joint space narrowing.

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