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Pediatric Hip MCQs

Practice Set 75 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 1481

Topic: Pediatric Hip

A 14-year-old boy presents with an unstable slipped capital femoral epiphysis (SCFE) and undergoes open reduction and internal fixation via a surgical hip dislocation approach. To minimize the risk of osteonecrosis, preserving the blood supply to the epiphysis is critical. Which vessel provides the primary blood supply to the femoral head in this patient?

. Obturator artery via the ligamentum teres
. Deep branch of the medial femoral circumflex artery
. Descending branch of the lateral femoral circumflex artery
. Inferior gluteal artery

Correct Answer & Explanation

. Obturator artery via the ligamentum teres

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head in adolescents. Protection of this retinacular vessel is critical during surgical hip dislocation for SCFE.

Question 1482

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents note the child is no longer actively kicking the knee into extension on the affected side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Sciatic nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hip flexion
. Obturator nerve stretch injury

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy in a Pavlik harness is caused by hyperflexion of the hip. Management involves adjusting the anterior strap to reduce flexion or temporarily discontinuing the harness until function returns.

Question 1483

Topic: Pediatric Hip

When evaluating a patient with Legg-Calve-Perthes (LCP) disease, several demographic and radiographic factors guide prognosis. Which of the following is associated with a POOR clinical outcome?

. Age of onset at 4 years
. Male gender
. Female gender
. Herring Lateral Pillar Group A classification

Correct Answer & Explanation

. Age of onset at 4 years

Explanation

Female patients with LCP disease generally have a worse prognosis than age-matched males because they reach skeletal maturity earlier, allowing less time for the femoral head to remodel.

Question 1484

Topic: Pediatric Hip

According to the Loder classification, which clinical finding strictly defines a slipped capital femoral epiphysis (SCFE) as 'unstable'?

. Slip angle greater than 50 degrees
. Presence of an effusion on ultrasound
. Inability to ambulate with or without crutches
. Duration of symptoms less than 3 weeks

Correct Answer & Explanation

. Slip angle greater than 50 degrees

Explanation

The Loder classification defines a SCFE as unstable if the patient is unable to ambulate even with crutches. Unstable slips carry a significantly higher risk of avascular necrosis (up to 47%).

Question 1485

Topic: Pediatric Hip

A 13-year-old boy undergoes an urgent in situ pinning for an unstable slipped capital femoral epiphysis (SCFE) of the right hip.

Which of the following complications is he at the highest risk for developing compared to a patient with a stable SCFE?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Slip progression
. Infection

Correct Answer & Explanation

. Chondrolysis

Explanation

Unstable SCFE is defined by the inability to bear weight and is associated with a significantly higher risk of avascular necrosis (AVN), up to 50%, compared to almost 0% in stable SCFE. Urgent decompression and pinning are required to mitigate this risk.

Question 1486

Topic: Pediatric Hip

A 10-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up appointment, the mother notes that the child is no longer kicking her right leg actively. On examination, there is decreased spontaneous active knee extension on the right. What is the most likely cause?

. Excessive hip flexion in the harness
. Excessive hip abduction in the harness
. Septic arthritis of the hip
. Avascular necrosis of the femoral head
. Excessive hip adduction in the harness

Correct Answer & Explanation

. Excessive hip flexion in the harness

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of the Pavlik harness caused by excessive hip flexion. If this occurs, the harness is typically removed or adjusted to reduce flexion until nerve function recovers.

Question 1487

Topic: Pediatric Hip

In evaluating a child with Legg-Calve-Perthes disease (LCPD),

which of the following is considered the single most significant prognostic factor for the final outcome of the hip?

. Gender of the patient
. Duration of symptoms prior to diagnosis
. Age of the patient at the onset of the disease
. Degree of initial hip pain
. Presence of a limp

Correct Answer & Explanation

. Gender of the patient

Explanation

Age at disease onset is the most critical prognostic factor in LCPD. Children diagnosed before the age of 6 to 8 years have significantly better remodeling potential and superior long-term clinical outcomes compared to older children.

Question 1488

Topic: Pediatric Hip

A 28-year-old professional hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a prominent bony bump at the anterosuperior femoral head-neck junction with an alpha angle of 65 degrees. He is diagnosed with Femoroacetabular Impingement (FAI). Which of the following conditions is a known risk factor for the development of this specific type of lesion?

. Developmental Dysplasia of the Hip (DDH)
. Slipped Capital Femoral Epiphysis (SCFE)
. Legg-Calve-Perthes Disease
. Acetabular retroversion
. Coxa profunda

Correct Answer & Explanation

. Developmental Dysplasia of the Hip (DDH)

Explanation

The patient has a Cam lesion, characterized by an abnormal femoral head-neck offset (alpha angle >50-55 degrees). A mild or subclinical Slipped Capital Femoral Epiphysis (SCFE) leads to an anterior and superior metaphyseal prominence, a well-known cause of secondary Cam-type FAI. Acetabular retroversion and coxa profunda are associated with Pincer-type FAI (acetabular overcoverage).

Question 1489

Topic: Pediatric Hip
A 45-year-old female with developmental dysplasia of the hip (DDH) presents for THA. Preoperative radiographs show the femoral head is subluxated, with 80% proximal migration relative to the height of the normal true acetabulum. Based on the Crowe classification, what type of dysplasia does she have?
. Crowe Type I
. Crowe Type II
. Crowe Type III
. Crowe Type IV
. Crowe Type V

Correct Answer & Explanation

. Crowe Type III

Explanation

The Crowe classification of DDH evaluates the degree of proximal migration of the femoral head: Type I: <50% subluxation; Type II: 50-75% subluxation; Type III: 75-100% subluxation; Type IV: >100% subluxation (complete dislocation). With 80% proximal migration, the patient falls into the Crowe Type III category.

Question 1490

Topic: Pediatric Hip
A 35-year-old female with developmental dysplasia of the hip (DDH) Crowe Type IV is undergoing THA. The surgeon plans to place the acetabular component in the true anatomic hip center. If the leg is lengthened >4 cm without a subtrochanteric shortening osteotomy, which nerve division is most susceptible to traction injury?
. Femoral nerve
. Obturator nerve
. Superior gluteal nerve
. Sciatic nerve (peroneal division)
. Sciatic nerve (tibial division)

Correct Answer & Explanation

. Sciatic nerve (peroneal division)

Explanation

Bringing the hip center down to the true anatomic acetabulum in Crowe IV DDH can cause significant limb lengthening. Lengthening >4 cm puts the sciatic nerve at high risk for a traction palsy. The peroneal division of the sciatic nerve is tethered at the fibular head and has less connective tissue support, making it much more susceptible to injury than the tibial division.

Question 1491

Topic: Pediatric Hip

A 13-year-old boy presents with an inability to bear weight on his right leg after a minor fall. Radiographs show a slipped capital femoral epiphysis (SCFE). He is unable to walk even with the assistance of crutches. What is the most significant prognostic factor for the subsequent development of avascular necrosis (AVN) in this patient?

. Degree of the slip angle on the lateral radiograph
. Patient age at the time of presentation
. Stability of the slip
. Delay to surgical intervention greater than 24 hours
. The specific method of surgical fixation utilized

Correct Answer & Explanation

. Degree of the slip angle on the lateral radiograph

Explanation

According to the Loder classification, an unstable SCFE is defined strictly by the patient's inability to bear weight, even with crutches. Unstable slips have a drastically higher rate of AVN (up to 47-50%) compared to stable slips, where the AVN rate approaches zero. While time to surgery is debated, stability is the most definitively proven prognostic factor for AVN.

Question 1492

Topic: Pediatric Hip

A 4-month-old girl is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. At her 2-week follow-up, the parents note that she is no longer actively kicking her left leg. On examination, the infant lacks active knee extension on the left side, though distal perfusion and other movements are intact. What is the most appropriate next step in management?

. Continue the harness unchanged and order an MRI of the lumbar spine
. Adjust the harness straps to increase hip flexion beyond 120 degrees
. Discontinue the harness immediately to allow for spontaneous neurological recovery
. Transition the patient immediately to a rigid bilateral hip spica cast
. Perform an immediate closed reduction under general anesthesia

Correct Answer & Explanation

. Continue the harness unchanged and order an MRI of the lumbar spine

Explanation

The infant has developed a femoral nerve palsy, a known complication of Pavlik harness treatment, usually caused by excessive hip hyperflexion compressing the femoral nerve against the inguinal ligament. The standard of care is to immediately discontinue the harness to allow the nerve to recover, which usually occurs within days to weeks, before reassessing treatment options.

Question 1493

Topic: Pediatric Hip

In a severe, stable slipped capital femoral epiphysis (SCFE) treated with in situ single screw fixation, what is the most significant consequence of unrecognized pin penetration into the anterior-superior quadrant of the joint?

. Avascular necrosis of the femoral head
. Chondrolysis
. Cam-type femoroacetabular impingement
. Femoral neck fracture
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Unrecognized intra-articular hardware penetration during SCFE pinning is the leading iatrogenic cause of chondrolysis. While avascular necrosis (AVN) is a devastating complication, it is more often associated with the initial severity/instability of the slip or aggressive attempted reduction rather than isolated pin penetration.

Question 1494

Topic: Pediatric Hip

A 13-year-old boy who underwent in-situ pinning for a stable, severe slipped capital femoral epiphysis (SCFE) 6 months ago now presents with severe hip stiffness and a painful limp. Radiographs demonstrate a concentric loss of joint space in the affected hip of greater than 50% accompanied by periarticular osteopenia. What is the most likely diagnosis?

. Avascular necrosis (AVN) of the femoral head
. Chondrolysis
. Septic arthritis
. Hardware penetration into the joint
. Cam-type femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

Chondrolysis is a severe complication of SCFE, characterized clinically by progressive stiffness and pain, and radiographically by a concentric loss of joint space (greater than 50% compared to the contralateral side) and regional osteopenia. Risk factors include severe slips, unrecognised pin penetration, and spica cast immobilization. AVN typically presents with subchondral collapse and sclerosis rather than concentric joint space narrowing.

Question 1495

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notices that the infant is no longer kicking her right leg, and the quadriceps muscle appears flaccid. Which of the following harness positioning errors is the most likely cause of this complication?

. Excessive abduction of the hips
. Insufficient abduction of the hips
. Excessive flexion of the hips
. Insufficient flexion of the hips
. Excessive extension of the hips

Correct Answer & Explanation

. Excessive abduction of the hips

Explanation

A femoral nerve palsy in an infant treated with a Pavlik harness is typically caused by excessive flexion of the hips (hyperflexion), which compresses the femoral nerve against the inguinal ligament. Excessive abduction is associated with a different severe complication: avascular necrosis (AVN) of the femoral head.

Question 1496

Topic: Pediatric Hip

An infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During follow-up, the physician notices that the hips have been placed in approximately 130 degrees of flexion. Which of the following complications is most likely to result directly from this specific positioning error?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In a Pavlik harness, extreme or excessive hyperflexion (greater than 120 degrees) risks compressing the femoral nerve against the edge of the inguinal ligament, leading to transient femoral nerve palsy (manifesting as decreased active knee extension). Conversely, excessive abduction (not flexion) is the primary risk factor for avascular necrosis of the femoral head. Note: Inferior dislocation can also occur with extreme flexion, but femoral nerve palsy is a highly tested direct neurological consequence of hyperflexion.

Question 1497

Topic: Pediatric Hip

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

. Age greater than 14 years in males
. Presence of an underlying endocrine disorder
. Grade I slip on the symptomatic side
. BMI greater than the 95th percentile
. Male gender

Correct Answer & Explanation

. Age greater than 14 years in males

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior pelvic radiation therapy, as these patients have a much higher risk of bilateral involvement (up to 100% in some endocrine cohorts) compared to idiopathic cases.

Question 1498

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. If the anterior straps are adjusted too tightly, placing the hips in extreme hyperflexion, the infant is at highest risk for which complication?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Hyperflexion of the hips in a Pavlik harness (anterior straps too tight) can compress the femoral nerve against the inguinal ligament, leading to femoral nerve palsy. Excessive abduction (posterior straps too tight) increases the risk of avascular necrosis (AVN) of the femoral head.

Question 1499

Topic: Pediatric Hip

In the management of Slipped Capital Femoral Epiphysis (SCFE), prophylactic in situ fixation of the asymptomatic contralateral hip is widely debated. However, it is most strongly indicated and universally recommended in which of the following clinical scenarios?

. An 11-year-old boy with idiopathic SCFE
. A 10-year-old girl with primary hypothyroidism
. A 14-year-old boy with Down syndrome
. A 13-year-old girl with skeletal maturity (Risser 4)
. A 12-year-old boy with a BMI greater than the 95th percentile

Correct Answer & Explanation

. An 11-year-old boy with idiopathic SCFE

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients with an underlying metabolic or endocrine disorder (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation) due to the exceedingly high risk (up to 100%) of contralateral slip. Idiopathic obesity alone (Option E) increases risk but prophylactic pinning remains controversial and is evaluated on a case-by-case basis based on bone age and follow-up reliability.

Question 1500

Topic: Pediatric Hip

During ultrasonographic evaluation of an infant for Developmental Dysplasia of the Hip (DDH) using the Graf classification, the alpha angle is measured. This angle represents:

. The angle between the ilium and the osseous roof of the acetabulum
. The angle between the ilium and the cartilaginous roof of the acetabulum
. The angle between the femoral neck and the femoral shaft
. The percentage of femoral head coverage by the acetabulum
. The angle between the labrum and the joint capsule

Correct Answer & Explanation

. The angle between the ilium and the osseous roof of the acetabulum

Explanation

In the Graf ultrasound classification for DDH, the alpha angle represents the osseous roof of the acetabulum. It is formed by the intersection of the baseline (drawn along the ilium) and the osseous roof line. A normal alpha angle is greater than 60 degrees. The beta angle measures the cartilaginous roof of the acetabulum.

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