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Pediatric Hip MCQs

Practice Set 79 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 1561

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with acute severe hip pain and inability to bear weight after a minor fall. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant prognostic implication of his inability to bear weight?

. Increased risk of contralateral SCFE
. Increased risk of chondrolysis
. Increased risk of avascular necrosis (AVN)
. Decreased need for surgical fixation
. Guaranteed premature physeal closure

Correct Answer & Explanation

. Increased risk of contralateral SCFE

Explanation

The Loder classification defines a SCFE as unstable if the patient is unable to bear weight with or without crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 50%) compared to stable SCFE.

Question 1562

Topic: Pediatric Hip

In the management of Legg-Calve-Perthes disease, the Herring lateral pillar classification is widely used to determine prognosis. A hip where the lateral pillar of the femoral head maintains greater than 50% but less than 100% of its original height is classified as:

. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group A

Explanation

In the Herring classification, Group B indicates >50% lateral pillar height maintained. Group A has no loss of height, and Group C has <50% of the original lateral pillar height maintained.

Question 1563

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the parents report the infant has stopped kicking the affected leg. Examination reveals weakness in knee extension. This complication is most likely due to excessive positioning in which direction?

. Excessive hip extension
. Excessive hip adduction
. Excessive hip flexion
. Excessive knee flexion
. Excessive hip internal rotation

Correct Answer & Explanation

. Excessive hip extension

Explanation

Femoral nerve palsy is the most common neurologic complication associated with the Pavlik harness and is caused by excessive hip flexion compressing the nerve against the inguinal ligament. It usually resolves completely after adjusting or temporarily discontinuing the harness.

Question 1564

Topic: Pediatric Hip

A 12-year-old obese boy is diagnosed with a unilateral left-sided slipped capital femoral epiphysis (SCFE). In which of the following scenarios is prophylactic percutaneous in situ pinning of the contralateral right hip most strongly indicated?

. If the patient has a skeletal age of 14 years
. If the left SCFE is classified as acute and unstable
. If the patient has an underlying diagnosis of renal osteodystrophy or hypothyroidism
. If the patient demonstrates a mild restriction of internal rotation on the asymptomatic side
. If the patient has a body mass index (BMI) at the 85th percentile

Correct Answer & Explanation

. If the patient has a skeletal age of 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial for idiopathic cases but is strongly recommended for patients with endocrine disorders (such as hypothyroidism, panhypopituitarism) or metabolic bone diseases (like renal osteodystrophy), as well as those undergoing prior radiation therapy to the pelvis. These patients have a significantly higher risk (up to 100% in some metabolic conditions) of developing a subsequent contralateral slip compared to the general idiopathic SCFE population. Other factors favoring prophylactic pinning include younger age (open triradiate cartilage) and follow-up unreliability.

Question 1565

Topic: Pediatric Hip

A 3-month-old female is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report that the child has stopped actively extending her right knee. On examination, the infant lacks active knee extension, and the patellar reflex is absent on the right. What positioning error in the Pavlik harness is the most likely cause of this complication?

. Inadequate hip abduction
. Excessive hip abduction
. Inadequate hip flexion
. Excessive hip flexion
. Excessive internal rotation of the hip

Correct Answer & Explanation

. Inadequate hip abduction

Explanation

The patient is presenting with a femoral nerve palsy, which is the most common nerve injury associated with Pavlik harness use. Femoral nerve palsy occurs secondary to excessive hip flexion, which causes compression or stretch of the femoral nerve against the inguinal ligament or the brim of the pelvis. The hallmark sign is decreased or absent active knee extension. Treatment is to loosen or temporarily remove the anterior straps to decrease hip flexion, which usually leads to spontaneous recovery. Excessive hip abduction is the risk factor for avascular necrosis (AVN) of the femoral head.

Question 1566

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of his left hip. In which of the following clinical scenarios is prophylactic percutaneous pinning of the contralateral right hip most strongly indicated?

. Presence of an open triradiate cartilage
. Age greater than 14 years at presentation
. Underlying hypothyroidism or renal osteodystrophy
. Body mass index > 95th percentile
. A slip angle > 50 degrees on the affected side

Correct Answer & Explanation

. Presence of an open triradiate cartilage

Explanation

While prophylactic pinning of the contralateral hip in SCFE remains controversial in idiopathic cases, it is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). These patients have an exceedingly high risk (often approaching 100%) of bilateral involvement.

Question 1567

Topic: Pediatric Hip

A 6-week-old infant is diagnosed with Developmental Dysplasia of the Hip (DDH) and is subsequently placed in a Pavlik harness for treatment. The treating physician must carefully adjust the straps to maintain the hips in approximately 100 degrees of flexion and safe abduction. If the anterior straps are pulled too tight, causing hyperflexion of the hips beyond 120 degrees, which of the following complications is most likely to occur?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Inferior hip dislocation
. Acetabular dysplasia
. Sciatic nerve palsy

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In the application of a Pavlik harness, hyperflexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to an iatrogenic femoral nerve palsy (presenting as decreased quadriceps function/loss of active knee extension). Conversely, excessive forced abduction is classically associated with avascular necrosis (AVN) of the femoral head.

Question 1568

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents note she has stopped kicking her left leg. Examination reveals decreased active extension of the left knee but normal ankle movements. What is the most likely iatrogenic cause of this presentation?

. Hyperflexion of the hip in the harness
. Excessive abduction of the hip in the harness
. Ischemic necrosis of the femoral head
. Excessive adduction of the hip in the harness
. Traction injury to the sciatic nerve

Correct Answer & Explanation

. Hyperflexion of the hip in the harness

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy. This manifests clinically as decreased active knee extension. It is generally treated by adjusting the harness to reduce the degree of hip flexion. Excessive abduction is notoriously associated with avascular necrosis (AVN) of the femoral head, not isolated femoral nerve palsy.

Question 1569

Topic: Pediatric Hip

Which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) has the strongest clinical indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

. A 13-year-old boy with a BMI in the 99th percentile
. A 12-year-old girl with primary hypothyroidism
. A 14-year-old boy with a prior contralateral SCFE
. An 11-year-old boy with a positive family history of SCFE
. A 10-year-old girl with isolated precocious puberty

Correct Answer & Explanation

. A 13-year-old boy with a BMI in the 99th percentile

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients presenting with an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation). These atypical patients have an extraordinarily high risk (approaching 100% in some series) of developing bilateral disease compared to the idiopathic adolescent population.

Question 1570

Topic: Pediatric Hip

In a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Male sex
. Obesity (> 95th percentile BMI)
. Underlying endocrine disorder
. Moderate-to-severe slip angle (> 50 degrees) on the affected side

Correct Answer & Explanation

. Age greater than 14 years

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, renal osteodystrophy), patients previously treated with radiation therapy, and typically in children presenting at a young age (< 10 years). These patients have an exceptionally high risk of developing a contralateral slip.

Question 1571

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents note that the infant is no longer actively extending her left knee, though she moves her ankle and toes normally. Which of the following is the most likely cause of this finding?

. Sciatic nerve palsy from excessive hip abduction
. Femoral nerve palsy from excessive hip flexion
. Obturator nerve palsy from excessive hip external rotation
. Superior gluteal nerve palsy from harness strap pressure
. Tibial nerve palsy from foot strap tightness

Correct Answer & Explanation

. Sciatic nerve palsy from excessive hip abduction

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment and is typically caused by excessive hip hyperflexion compressing the nerve against the inguinal ligament. It manifests as decreased active quadriceps function (lack of active knee extension) and resolves with adjustment of the flexion straps.

Question 1572

Topic: Pediatric Hip

A 4-month-old female infant is undergoing radiographic evaluation for suspected developmental dysplasia of the hip (DDH). An AP pelvis radiograph is obtained. Which of the following specific radiographic parameters definitively indicates abnormal acetabular development at this age?

. An acetabular index of 22 degrees
. The ossific nucleus of the femoral head located in the lower inner quadrant of Perkin and Hilgenreiner lines
. A continuous and intact Shenton's line
. An acetabular index of 35 degrees
. A center-edge angle of Wiberg of 30 degrees

Correct Answer & Explanation

. An acetabular index of 22 degrees

Explanation

The acetabular index (AI) measures the slope of the cartilaginous acetabular roof. At birth, a normal AI is less than 30 degrees, and by 6 months, it should typically be less than 25 degrees. An AI of 35 degrees at 4 months is abnormally steep and highly indicative of acetabular dysplasia. The other options describe normal findings: the femoral head normally sits in the lower inner quadrant, Shenton's line should be intact, and an AI of 22 is normal for this age.

Question 1573

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department after a minor trip and fall. Radiographs demonstrate a displaced right slipped capital femoral epiphysis (SCFE). On examination, he is completely unable to bear weight on the right leg, even with the assistance of crutches. Which of the following factors is most strongly associated with the high risk of developing osteonecrosis of the femoral head in this specific patient?

. The patient's elevated body mass index (BMI)
. The chronicity of prodromal symptoms prior to the acute slip
. The inability to bear weight on the affected extremity
. The degree of posterior slip angle on the lateral radiograph
. The exact direction of the epiphyseal displacement

Correct Answer & Explanation

. The patient's elevated body mass index (BMI)

Explanation

The inability to bear weight on the affected extremity, even with crutches, defines an 'unstable' SCFE according to the Loder classification. Unstable SCFE is a true orthopedic emergency and carries a high risk of developing avascular necrosis (AVN), reported to be between 20% and 50%. Stable slips (able to bear weight) have an AVN risk approaching 0%.

Question 1574

Topic: Pediatric Hip

In the pathophysiology of a Slipped Capital Femoral Epiphysis (SCFE), the proximal femoral epiphysis typically remains seated within the acetabulum while the femoral neck displaces. What is the characteristic anatomic direction of the displacement of the femoral metaphysis relative to the epiphysis?

. Posterior and inferior
. Anterior and superior
. Anterior and inferior
. Posterior and superior
. Directly medial

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the name is somewhat of a misnomer. The epiphysis does not truly 'slip' out of the acetabulum; rather, it remains seated posteriorly and inferiorly due to the tethering of the ligamentum teres. It is the femoral metaphysis (neck) that displaces anteriorly and superiorly relative to the epiphysis, driven by the mechanical forces of weight-bearing and external rotation acting on a weakened physis.

Question 1575

Topic: Pediatric Hip
A 45-year-old female with developmental dysplasia of the hip (DDH) is planning to undergo a THA. Preoperative radiographs show that her femoral head is subluxated superiorly by 85% of the normal vertical height of the corresponding normal femoral head. Based on the Crowe classification, what type of DDH does she have?
. Crowe I
. Crowe II
. Crowe III
. Crowe IV
. Crowe V

Correct Answer & Explanation

. Crowe III

Explanation

The Crowe classification assesses the degree of proximal subluxation of the femoral head in DDH. Crowe I is <50% subluxation; Crowe II is 50-74% subluxation; Crowe III is 75-99% subluxation; and Crowe IV is 100% or greater subluxation (complete dislocation). An 85% subluxation falls into the Crowe III category.

Question 1576

Topic: Pediatric Hip
A 40-year-old female with bilateral developmental dysplasia of the hip (DDH) presents for THA. Radiographs reveal that the femoral head is subluxated proximally by 80% of the height of the normal acetabulum. According to the Crowe classification, what is her grade?
. Crowe I
. Crowe II
. Crowe III
. Crowe IV
. Crowe V

Correct Answer & Explanation

. Crowe III

Explanation

The Crowe classification for adult DDH measures the amount of proximal subluxation relative to the height of the normal acetabulum. Crowe I: <50%; Crowe II: 50-74%; Crowe III: 75-100%; Crowe IV: >100% (complete dislocation). An 80% subluxation falls into Crowe III.

Question 1577

Topic: Pediatric Hip

A 22-year-old professional hockey player presents with chronic groin pain exacerbated by flexion and internal rotation. AP pelvis radiographs demonstrate a prominent alpha angle of 65 degrees and a positive crossover sign. Which of the following combinations correctly identifies the morphologic deformities present?

. Cam impingement and acetabular retroversion
. Pincer impingement and acetabular anteversion
. Cam impingement and acetabular anteversion
. Pincer impingement and coxa valga
. Cam impingement and coxa vara

Correct Answer & Explanation

. Cam impingement and acetabular retroversion

Explanation

An alpha angle > 55 degrees indicates a lack of femoral head-neck offset, defining a Cam-type femoroacetabular impingement. A positive crossover sign (where the anterior rim of the acetabulum crosses lateral to the posterior rim on an AP pelvis radiograph) is indicative of acetabular retroversion, which causes focal anterior Pincer impingement.

Question 1578

Topic: Pediatric Hip

In the evaluation of Legg-Calve-Perthes Disease (LCPD), Catterall described several 'head at risk' signs that portend a poorer prognosis. Which of the following is one of these classic radiographic signs?

. Gage sign
. Klein's line intersection
. Southwick angle > 30 degrees
. Trethowan sign
. Drehmann sign

Correct Answer & Explanation

. Gage sign

Explanation

Catterall's 'head at risk' signs for Legg-Calve-Perthes Disease include the Gage sign (a V-shaped radiolucent defect in the lateral aspect of the epiphysis/physis), calcification lateral to the epiphysis, lateral subluxation of the femoral head, a horizontal growth plate, and metaphyseal cysts. Klein's line and Trethowan sign are associated with SCFE.

Question 1579

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and a total inability to bear weight on the left leg. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent single-screw in situ fixation. Postoperatively, he develops avascular necrosis (AVN) of the femoral head. Which of the following initial presentation factors is the most significant independent predictor for the development of AVN in this patient?

. Severity of the slip angle (greater than 50 degrees)
. Age of the patient at the time of presentation
. Inability to bear weight prior to surgery (unstable slip)
. Patient obesity (BMI >95th percentile)
. Use of a single screw rather than two screws for fixation

Correct Answer & Explanation

. Severity of the slip angle (greater than 50 degrees)

Explanation

According to Loder's classification, a SCFE is categorized as 'unstable' if the patient is entirely unable to bear weight, even with crutches. Unstable slips have an extremely high rate of avascular necrosis (up to 47-50%), regardless of the treatment method, due to the acute disruption of the retinacular vessels supplying the femoral head. Stable slips have a much lower rate of AVN (<10%). While slip severity increases the risk of osteoarthritis, instability is the paramount risk factor for AVN.

Question 1580

Topic: Pediatric Hip
A 42-year-old female with untreated developmental dysplasia of the hip (DDH) presents for a primary total hip arthroplasty. Preoperative radiographs show a completely dislocated femoral head articulating with a false acetabulum. The proximal migration of the femoral head is measured to be 35% of the vertical height of the normal hemipelvis. According to the Crowe classification, what is her specific grade, and what adjunctive surgical procedure is most routinely required during her THA?
. Crowe II; Femoral head structural autograft for the acetabular roof
. Crowe III; Greater trochanteric advancement
. Crowe IV; Subtrochanteric shortening osteotomy
. Crowe IV; Periacetabular osteotomy
. Crowe III; Distal femoral extension osteotomy

Correct Answer & Explanation

. Crowe IV; Subtrochanteric shortening osteotomy

Explanation

The Crowe classification for DDH evaluates the degree of proximal migration of the femoral head relative to the true acetabulum. A migration of greater than 20% of the pelvic height (or >100% of the femoral head height) defines a Crowe IV dysplasia. Bringing the hip down from this high dislocated position into the true acetabulum places massive tension on the sciatic nerve. To prevent catastrophic sciatic nerve palsy and allow reduction, a subtrochanteric shortening osteotomy of the femur is frequently required.

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