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Pediatric Hip MCQs

Practice Set 80 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 1581

Topic: Pediatric Hip
A 45-year-old female with adult developmental dysplasia of the hip (DDH) is planned for a primary THA. Preoperative radiographs demonstrate that her femoral head is proximally migrated, equating to 85% subluxation relative to the true acetabulum. According to the Crowe classification, what is her stage, and what surgical complexity is most likely anticipated to achieve reduction into the true acetabulum?
. Crowe I; use of an extra-large 'jumbo' cup without femoral shortening.
. Crowe II; routine primary stem insertion.
. Crowe III; high likelihood of requiring a subtrochanteric shortening osteotomy or accepting a high hip center.
. Crowe IV; standard reduction easily achievable by complete capsular release.
. Crowe I; varus derotational osteotomy alone.

Correct Answer & Explanation

. Crowe III; high likelihood of requiring a subtrochanteric shortening osteotomy or accepting a high hip center.

Explanation

The Crowe classification stages DDH based on the percentage of proximal subluxation (proximal migration divided by vertical head height). Crowe I: <50%, Crowe II: 50-74%, Crowe III: 75-100%, Crowe IV: >100% (complete dislocation). At 85% subluxation, she is Crowe III. Bringing the femoral head down to the true acetabulum in Crowe III and IV hips often stretches the sciatic nerve beyond its physical tolerance (typically a limit of 3-4 cm of lengthening). Therefore, a subtrochanteric shortening osteotomy is frequently required to reduce the joint safely without catastrophic nerve palsy.

Question 1582

Topic: Pediatric Hip

An overweight 13-year-old boy presents with right thigh pain and an obligatory external rotation of the hip during active hip flexion. Radiographs confirm a mild stable slipped capital femoral epiphysis (SCFE). During in situ single-screw fixation, where should the screw ideally be placed within the epiphysis?

. Anterior-superior quadrant
. Anterior-inferior quadrant
. Posterior-superior quadrant
. Posterior-inferior quadrant
. Directly central in both AP and lateral planes

Correct Answer & Explanation

. Anterior-superior quadrant

Explanation

The ideal starting point for in situ pinning of a SCFE is on the anterior neck, aiming for the center-center position of the epiphysis on both the anteroposterior and lateral radiographic views. This central placement minimizes the risk of joint penetration and avoids the lateral epiphyseal vessels, reducing the risk of avascular necrosis.

Question 1583

Topic: Pediatric Hip

A 6-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after failing Pavlik harness treatment. A closed reduction and spica casting are planned. To minimize the risk of avascular necrosis (AVN) of the femoral head during casting, what is the safest position for the hip?

. 90-100 degrees of flexion and less than 60 degrees of abduction
. 120 degrees of flexion and 90 degrees of abduction
. Neutral flexion and maximal internal rotation
. Extension and maximal abduction
. 110 degrees of flexion and maximal external rotation

Correct Answer & Explanation

. 90-100 degrees of flexion and less than 60 degrees of abduction

Explanation

Immobilizing the hip in extreme abduction (the classic 'frog-leg' position) dramatically increases the risk of AVN, particularly of the posterosuperior aspect of the femoral head, due to compression of the medial circumflex femoral artery branches. The 'safe zone' of Ramsey requires casting the hip in 90-100 degrees of flexion and moderate abduction (typically <60 degrees).

Question 1584

Topic: Pediatric Hip

A 6-year-old boy presents with a painless limp. Radiographs reveal sclerosis and fragmentation of the proximal femoral epiphysis. According to the Herring lateral pillar classification, which of the following describes a Group B hip?

. No involvement of the lateral pillar
. >50% maintenance of lateral pillar height
. <50% maintenance of lateral pillar height
. Complete collapse of the lateral pillar
. Involvement of only the medial pillar

Correct Answer & Explanation

. No involvement of the lateral pillar

Explanation

The Herring lateral pillar classification for Legg-Calve-Perthes disease evaluates the height of the lateral portion of the capital femoral epiphysis on an AP radiograph. Group A has 100% height maintained, Group B maintains >50% height, and Group C has <50% height maintained.

Question 1585

Topic: Pediatric Hip

A 13-year-old obese boy presents with right groin pain and an antalgic gait. Radiographs reveal a slipped capital femoral epiphysis (SCFE) of the right hip. The left hip is radiographically normal. Which of the following is the most widely accepted absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Patient age older than 15 years at presentation
. Presence of a diagnosed endocrine disorder (e.g., hypothyroidism)
. A severe slip angle (>60 degrees) on the affected side
. Body Mass Index (BMI) greater than 35
. African American ethnicity

Correct Answer & Explanation

. Patient age older than 15 years at presentation

Explanation

Prophylactic pinning of the contralateral hip in SCFE is debated for idiopathic cases but is highly recommended (considered an absolute indication by most authorities) in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism), previous radiation therapy, or very young age at presentation (<10 years), as these patients have an exceptionally high risk of a contralateral slip.

Question 1586

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking the treated leg. Examination reveals an inability to actively extend the knee, while foot and ankle movements are intact. Which nerve is most likely compressed, and what aspect of the harness positioning is responsible?

. Sciatic nerve; excessive hip flexion
. Femoral nerve; excessive hip flexion
. Obturator nerve; excessive hip abduction
. Femoral nerve; excessive hip abduction
. Sciatic nerve; inadequate hip flexion

Correct Answer & Explanation

. Sciatic nerve; excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by hyperflexion of the hip (anterior straps pulled too tightly). It presents as an inability to actively extend the knee due to transient loss of quadriceps function. The appropriate management is to loosen the anterior straps or temporarily discontinue the harness to allow nerve recovery.

Question 1587

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin and knee pain, and is diagnosed with a slipped capital femoral epiphysis (SCFE). The right hip is completely asymptomatic with normal radiographs. Which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

. Patient age less than 10 years at presentation
. Male sex
. Concomitant endocrine disorder (e.g., hypothyroidism)
. Severe obesity (BMI > 99th percentile)
. Radiographic evidence of a severe slip angle on the affected side

Correct Answer & Explanation

. Patient age less than 10 years at presentation

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) are absolute indications for prophylactic contralateral pinning in SCFE due to the extraordinarily high risk (often >50-100%) of developing a bilateral slip. Other relative indications include young age at presentation (<10 years for girls, <12 years for boys) and poor reliability for follow-up, but endocrine etiology remains the classic absolute indication.

Question 1588

Topic: Pediatric Hip

A 4-month-old female is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up examination, the orthopedist notes that the harness straps are excessively tightened in the anterior aspect, placing the hips in extreme hyperflexion. This specific positioning error puts the child at highest risk for which of the following complications?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In Pavlik harness treatment for DDH, hyperflexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as loss of active knee extension). Conversely, excessive forced abduction places the patient at highest risk for avascular necrosis (AVN) of the femoral head due to compression of the medial circumflex femoral artery.

Question 1589

Topic: Pediatric Hip

A 6-week-old female infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes the infant has stopped kicking her left leg. Examination reveals decreased active knee extension on the left. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness immediately and switch to rigid spica casting
. Discontinue the harness and observe for neurologic recovery
. Obtain an emergent MRI of the lumbar spine

Correct Answer & Explanation

. Adjust the anterior straps to increase hip flexion

Explanation

The infant has developed a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The most appropriate management is to temporarily discontinue the harness until neurologic function returns.

Question 1590

Topic: Pediatric Hip

A 13-year-old boy presents with a limp and obligate external rotation of his right hip when flexed. He is diagnosed with a severe, stable slipped capital femoral epiphysis (SCFE). Which of the following is the most common serious complication of in situ single-screw fixation for this condition?

. Chondrolysis
. Avascular necrosis
. Osteoarthritis
. Femoral neck fracture
. Screw cutout

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a major complication of SCFE treatment, often associated with unrecognized joint penetration by the hardware during in situ pinning. Avascular necrosis is more commonly associated with unstable SCFE.

Question 1591

Topic: Pediatric Hip

A 6-week-old female infant is brought to the clinic. The Ortolani maneuver is positive on the left hip. Ultrasound demonstrates an alpha angle of 45 degrees. Which of the following is the most appropriate initial treatment?

. Observation and repeat ultrasound in 4 weeks
. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and spica casting
. Denis Browne splint

Correct Answer & Explanation

. Observation and repeat ultrasound in 4 weeks

Explanation

A positive Ortolani sign indicates a dislocated but reducible hip, confirming DDH, and an alpha angle <60 degrees is abnormal. The Pavlik harness is the gold standard initial treatment for infants under 6 months of age.

Question 1592

Topic: Pediatric Hip

An 11-year-old obese male complains of left knee and groin pain for 3 weeks. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). During physical examination, when the affected hip is passively flexed, which obligate motion is classically observed?

. Internal rotation
. External rotation
. Adduction
. Abduction
. Extension

Correct Answer & Explanation

. Internal rotation

Explanation

In patients with SCFE, the femoral neck typically displaces anteriorly and superiorly relative to the epiphysis. This anatomical change causes obligate external rotation of the hip during passive hip flexion.

Question 1593

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The mother notes that the child is no longer extending her knee actively on the treated side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Excessive abduction causing obturator nerve palsy
. Excessive flexion causing femoral nerve palsy
. Ischemic contracture of the quadriceps
. Development of a septic hip

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness if the hip is positioned in excessive flexion. It is typically reversible upon releasing or adjusting the harness to reduce the flexion angle.

Question 1594

Topic: Pediatric Hip

A 25-year-old hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. AP pelvis and Dunn lateral radiographs demonstrate an alpha angle of 68 degrees and a positive crossover sign. Which of the following morphologic abnormalities is most likely present?

. Isolated Cam impingement
. Isolated Pincer impingement
. Mixed Cam and Pincer impingement
. Developmental dysplasia of the hip (DDH)
. Slipped capital femoral epiphysis (SCFE)

Correct Answer & Explanation

. Isolated Cam impingement

Explanation

The patient has imaging signs of both Cam (alpha angle greater than 50-55 degrees on a Dunn lateral) and Pincer (positive crossover sign on an AP pelvis, indicating focal or global acetabular retroversion) impingement. Most cases of femoroacetabular impingement (FAI) represent a mixed morphology rather than isolated Cam or Pincer impingement.

Question 1595

Topic: Pediatric Hip

A 25-year-old ice hockey goalie complains of deep, activity-related groin pain. An AP pelvis radiograph demonstrates a "crossover sign" and prominent ischial spines. Which of the following diagnoses best explains these radiographic findings?

. Cam impingement due to a decreased alpha angle
. Pincer impingement due to acetabular retroversion
. Cam impingement secondary to an old slipped capital femoral epiphysis
. Pincer impingement due to excessive acetabular anteversion
. Ischiofemoral impingement

Correct Answer & Explanation

. Cam impingement due to a decreased alpha angle

Explanation

A crossover sign (anterior rim crossing the posterior rim) and prominent ischial spines on an AP pelvis radiograph are classic indicators of focal or global acetabular retroversion, a primary cause of Pincer-type FAI.

Question 1596

Topic: Pediatric Hip

A 13-year-old obese boy presents with left thigh pain and a limp for 3 weeks. Examination reveals an obligate external rotation of the left hip with passive flexion. Radiographs show a mild slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate definitive management for the affected hip?

. Spica casting in internal rotation
. Open reduction and internal fixation to restore anatomic alignment
. In situ fixation with a single cannulated screw
. Observation and non-weight bearing with crutches
. Proximal femoral corrective osteotomy

Correct Answer & Explanation

. Spica casting in internal rotation

Explanation

The standard of care for a stable, mild to moderate SCFE is in situ fixation using a single cannulated screw placed in the center of the epiphysis. Open reduction increases the risk of avascular necrosis and is generally reserved for severe, unstable slips in specialized centers using specific surgical exposures (e.g., modified Dunn approach).

Question 1597

Topic: Pediatric Hip

A 4-month-old female infant is being evaluated for developmental dysplasia of the hip (DDH). She has been treated with a properly applied Pavlik harness for 4 weeks; however, follow-up clinical examination and ultrasound show no improvement, and the hip remains dislocated. What is the next most appropriate step in management?

. Continue Pavlik harness treatment for an additional 4 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting under anesthesia
. Open reduction through an anterior approach
. Varus derotational osteotomy of the proximal femur

Correct Answer & Explanation

. Continue Pavlik harness treatment for an additional 4 weeks

Explanation

Failure of Pavlik harness treatment for DDH is typically defined if the hip remains dislocated after 3-4 weeks of proper wear. Continuing the harness in a persistently dislocated hip places the infant at high risk for 'Pavlik harness disease' (erosion of the posterior acetabular wall). The next most appropriate step for an infant of this age is a closed reduction and spica casting under general anesthesia, usually confirmed with an intraoperative arthrogram.

Question 1598

Topic: Pediatric Hip

When utilizing a Pavlik harness for the treatment of Developmental Dysplasia of the Hip (DDH), hyperflexion of the hips most commonly places the infant at risk for which complication?

. Femoral nerve palsy
. Sciatic nerve palsy
. Avascular necrosis of the femoral head
. Inferior dislocation of the hip
. Transient synovitis

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is the most common nerve injury associated with the Pavlik harness and is typically caused by excessive hip flexion. Avascular necrosis is a devastating complication usually associated with extreme hyperabduction rather than hyperflexion.

Question 1599

Topic: Pediatric Hip

In the treatment of severe Slipped Capital Femoral Epiphysis (SCFE), an intracapsular cuneiform osteotomy of the femoral neck is performed. This aggressive over-correction most significantly increases the risk of which devastating complication?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoral nerve palsy
. Premature physeal closure
. Nonunion of the greater trochanter

Correct Answer & Explanation

. Chondrolysis

Explanation

Avascular necrosis (AVN) is the most severe and devastating complication of SCFE treatment. Intracapsular base-of-neck or cuneiform osteotomies aggressively stretch or transect the retinacular vessels (branches of the MFCA), leading to a high rate of AVN compared to in-situ pinning or extracapsular osteotomies.

Question 1600

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up visit, the parents report she has stopped spontaneously kicking her affected leg. Physical examination reveals an absence of active knee extension. Which of the following is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to decrease hip abduction
. Discontinue the harness temporarily until neurologic function returns
. Transition immediately to a rigid hip spica cast
. Obtain an emergent ultrasound to evaluate for a septic hip

Correct Answer & Explanation

. Adjust the anterior straps to increase hip flexion

Explanation

The patient has developed a femoral nerve palsy, a known complication of the Pavlik harness typically caused by excessive hip flexion. The standard management is to remove the harness or significantly relax the straps until spontaneous active knee extension returns, after which the harness can often be carefully reapplied or an alternative brace considered.

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