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Pediatric Hip MCQs

Practice Set 46 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 901

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with severe left hip pain after tripping over a curb. He is completely unable to bear weight on the left leg, even with the assistance of crutches. Radiographs demonstrate a severe slipped capital femoral epiphysis (SCFE). Which of the following factors is the most significant predictor for the development of avascular necrosis in this patient?

. The radiographic chronicity of the slip
. The magnitude of epiphyseal displacement
. The inability to bear weight on the affected extremity
. The patient's body mass index (BMI)
. The method chosen for surgical fixation

Correct Answer & Explanation

. The radiographic chronicity of the slip

Explanation

According to the Loder classification, SCFE is categorized as stable or unstable based entirely on the clinical ability of the patient to bear weight (with or without crutches). Unstable SCFE (inability to bear weight) carries a high risk of avascular necrosis (ranging up to nearly 50%), compared to a minimal risk (<5%) in stable SCFE.

Question 902

Topic: Pediatric Hip

A 13-year-old boy weighing 95 kg presents with left groin pain and an obligatory external rotation of the hip with flexion. Radiographs confirm a left slipped capital femoral epiphysis (SCFE). Which of the following factors is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Age greater than 12 years
. Male sex
. Presentation with an acute slip
. Underlying endocrinopathy
. Obesity (>95th percentile)

Correct Answer & Explanation

. Age greater than 12 years

Explanation

The risk of a contralateral slip in patients with SCFE is approximately 25% to 60%. Absolute or strong relative indications for prophylactic pinning of the contralateral asymptomatic hip include underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), radiation therapy to the pelvis, open triradiate cartilage (young age, e.g., females <10 and males <12), and patients for whom reliable follow-up is unlikely. Age >12, male sex, and obesity alone are not universal indications for prophylactic pinning.

Question 903

Topic: Pediatric Hip
A 9-year-old boy presents with a painless limp and restricted hip internal rotation. Radiographs demonstrate fragmentation of the capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. Which of the following factors carries the worst prognosis for this patient?
. Male sex
. Age at presentation
. Presence of a limp
. Decreased internal rotation
. Unilateral involvement

Correct Answer & Explanation

. Age at presentation

Explanation

Age at the onset of symptoms is the most significant prognostic factor in Legg-Calvé-Perthes disease. Children who develop the disease after age 8 have a worse prognosis because they have less time for the femoral head to remodel before skeletal maturity, often leading to a residual aspherical femoral head and early osteoarthritis. The extent of lateral pillar involvement (Herring classification) is also a critical radiographic prognostic factor. Male sex is a risk factor for developing the disease, but older age carries the worst outcome.

Question 904

Topic: Pediatric Hip

A 4-month-old infant presents with a persistently dislocated left hip after a failed 6-week trial of Pavlik harness treatment. Ultrasound confirms the femoral head is dislocated but reducible with moderate force. The acetabulum appears dysplastic. What is the most appropriate next step in management?

. Observation and repeat ultrasound at 6 months of age
. Switch to an abduction orthosis
. Closed reduction and spica casting
. Open reduction and spica casting
. Femoral varus derotational osteotomy

Correct Answer & Explanation

. Observation and repeat ultrasound at 6 months of age

Explanation

After a failed trial of a Pavlik harness in an infant under 6 months of age with developmental dysplasia of the hip (DDH), the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. If closed reduction cannot be achieved or maintained within a safe zone, an open reduction is indicated. Continued observation or switching to another brace has a high failure rate once the Pavlik harness has definitively failed.

Question 905

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute on chronic left knee pain and an antalgic gait. Physical examination reveals obligate external rotation of the thigh during passive hip flexion. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning with a single cannulated screw. Which of the following is the most significant risk factor for the development of chondrolysis in this patient?

. Patient weight greater than the 95th percentile
. Acute symptom onset
. Unrecognized intra-articular pin penetration
. Delay in surgical intervention
. Use of a single rather than double screw construct

Correct Answer & Explanation

. Patient weight greater than the 95th percentile

Explanation

Chondrolysis is a devastating complication of SCFE characterized by rapid cartilage destruction and joint stiffness. The most significant recognized risk factor for chondrolysis is unrecognized intra-articular pin penetration during surgical fixation. Meticulous fluoroscopic evaluation (including the approach-withdraw technique) is essential to ensure the screw has not breached the articular surface.

Question 906

Topic: Pediatric Hip

An 8-year-old boy presents with a painless limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis. The treating orthopedic surgeon notes multiple 'head-at-risk' signs on the radiograph. According to Catterall, which of the following is considered a 'head-at-risk' sign in Legg-Calve-Perthes disease?

. Medial epiphyseal cyst
. Gage sign
. Widening of the medial joint space
. Acetabular dysplasia
. Coxa magna

Correct Answer & Explanation

. Medial epiphyseal cyst

Explanation

Catterall described five 'head-at-risk' clinical and radiographic signs indicating a poorer prognosis in Legg-Calve-Perthes disease. The radiographic signs include: Gage sign (a V-shaped radiolucent defect in the lateral portion of the epiphysis and adjacent metaphysis), calcification lateral to the epiphysis, lateral subluxation of the femoral head, a horizontal growth plate, and metaphyseal cysts.

Question 907

Topic: Pediatric Hip

A 9-month-old girl presents for an initial orthopedic evaluation. She has asymmetric thigh folds and limited abduction of the left hip. Ultrasound at 6 weeks of age was reportedly abnormal but the parents did not follow up. Current radiographs demonstrate a dislocated left hip with a dysplastic acetabulum. What is the most appropriate next step in management?

. Trial of Pavlik harness for 3 weeks
. Closed reduction and hip spica casting
. Open reduction and femoral shortening osteotomy
. Open reduction and pelvic osteotomy
. Observation until age 2, followed by open reduction

Correct Answer & Explanation

. Trial of Pavlik harness for 3 weeks

Explanation

The patient has late-presenting developmental dysplasia of the hip (DDH). The Pavlik harness is generally indicated for infants under 6 months of age; its success rate drops significantly and the risk of complications rises in older infants. For children aged 6 to 18 months, the gold standard initial treatment is closed reduction and application of a hip spica cast, often preceded by or performed concurrently with an adductor tenotomy. Open reduction with or without pelvic/femoral osteotomies is typically reserved for failures of closed reduction or primary treatment in children older than 18 months.

Question 908

Topic: Pediatric Hip

An 11-year-old boy with a BMI in the 99th percentile presents with left knee pain and a limp for 4 weeks. Radiographs show a mild, stable slipped capital femoral epiphysis (SCFE) of the left hip. The parents ask about the risk to the other hip. Which of the following is the strongest indication for prophylactic pinning of the contralateral, asymptomatic right hip?

. Age of 11 years
. Obesity
. Male sex
. Underlying endocrine disorder
. Presence of knee pain rather than hip pain

Correct Answer & Explanation

. Age of 11 years

Explanation

The decision to perform prophylactic pinning of the contralateral hip in a unilateral SCFE patient requires balancing the risks of surgery against the risk of a subsequent slip. Patients with underlying endocrine disorders (such as hypothyroidism, growth hormone deficiency, or panhypopituitarism) or renal osteodystrophy have an extremely high risk (up to 100%) of bilateral involvement, making an underlying endocrine disorder a strong, widely accepted indication for prophylactic pinning. Other relative indications may include young age (<10 for girls, <11 for boys) or inability to follow up.

Question 909

Topic: Pediatric Hip

An 8-year-old boy presents with a 2-month history of a painless limp. Radiographs demonstrate sclerosis and fragmentation of the proximal femoral epiphysis consistent with Legg-Calve-Perthes disease. Which of the following is considered the most important radiographic prognostic factor for determining the final outcome of the hip?

. Degree of metaphyseal cyst formation
. Extent of lateral pillar involvement
. Presence of a subchondral fracture line (Crescent sign)
. Degree of medial joint space widening
. Premature physeal closure

Correct Answer & Explanation

. Degree of metaphyseal cyst formation

Explanation

The Herring lateral pillar classification system evaluates the height of the lateral portion of the capital femoral epiphysis on an AP pelvis radiograph during the fragmentation stage of Legg-Calve-Perthes disease. It is widely recognized as the most reliable radiographic prognostic indicator for final hip outcome. Hips in Group A (no lateral pillar involvement) have the best prognosis, while Group C (<50% lateral pillar height maintained) have the poorest outcome. Age of onset (especially >8 years) is the most significant clinical prognostic factor.

Question 910

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 35 presents with an acute on chronic slipped capital femoral epiphysis (SCFE) of the left hip. He undergoes uneventful in situ pinning. When considering prophylactic pinning of the contralateral right hip, which of the following is the most important risk factor for developing a subsequent SCFE?

. Male sex
. Age > 10 years at the time of presentation
. Initial slip angle > 50 degrees
. Endocrine disorder
. Family history of SCFE

Correct Answer & Explanation

. Male sex

Explanation

Prophylactic pinning of the contralateral hip in patients with a unilateral SCFE is indicated in patients with endocrine disorders (e.g., hypothyroidism, growth hormone supplementation, renal osteodystrophy), prior radiation therapy, and an age of presentation less than 10 years in boys or 11 years in girls. Male sex and family history alone do not mandate prophylactic pinning. Slip angle determines severity but not automatically contralateral risk in the absence of other specific factors.

Question 911

Topic: Pediatric Hip

An infant is placed in a Pavlik harness for treatment of developmental dysplasia of the hip (DDH). During a follow-up visit, the parents report that the child has stopped kicking the leg. Examination reveals an absence of active knee extension on the affected side, but intact ankle dorsiflexion and plantar flexion. What is the most appropriate next step in management?

. Adjust the posterior straps to decrease hip abduction
. Adjust the anterior straps to decrease hip flexion
. Immediate surgical exploration
. Switch to a rigid abduction orthosis
. Continue harness as this is a transient normal finding

Correct Answer & Explanation

. Adjust the posterior straps to decrease hip abduction

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment for DDH. It is caused by excessive hip flexion, which can compress the femoral nerve against the rim of the pelvis. The diagnosis is made clinically by a loss of active knee extension (decreased quadriceps function) while ankle motion remains intact. Management consists of either adjusting the anterior straps to reduce hip flexion or removing the harness entirely until nerve function returns. Continuing the harness without adjustment risks permanent nerve injury.

Question 912

Topic: Pediatric Hip
Which of the following is the most important prognostic factor for long-term outcome in a child with Legg-Calvé-Perthes disease?
. Age at onset of symptoms
. Degree of medial pillar collapse
. Catterall classification
. Gender of the patient
. Presence of an effusion on MRI

Correct Answer & Explanation

. Age at onset of symptoms

Explanation

In Legg-Calvé-Perthes disease, the age at the onset of symptoms is the most consistently reliable prognostic factor for final hip outcome. Children who present at less than 6 years of age have a better prognosis because they have greater potential for remodeling of the femoral head. Children presenting after 8 years of age have a worse prognosis. The other most important prognostic factor is the degree of lateral (not medial) pillar involvement according to the Herring classification.

Question 913

Topic: Pediatric Hip

An 11-year-old girl with a history of renal osteodystrophy presents with a 3-week history of left groin and knee pain. She is diagnosed with a moderate slipped capital femoral epiphysis (SCFE) on the left side. Her right hip is completely asymptomatic, and radiographs of the right hip are normal. What is the most appropriate management regarding the contralateral right hip?

. Observation until symptoms develop
. Prophylactic in situ pinning
. Application of a hip spica cast
. Magnetic resonance imaging to assess for a pre-slip
. Bilateral proximal femoral osteotomies

Correct Answer & Explanation

. Observation until symptoms develop

Explanation

Prophylactic in situ pinning of the contralateral hip is highly recommended in patients with SCFE associated with an underlying endocrinopathy or metabolic bone disease (such as renal osteodystrophy, hypothyroidism, or growth hormone deficiency). These patients have an extremely high rate of bilateral involvement (up to 100% in some metabolic conditions) compared to idiopathic cases. Observation is generally reserved for idiopathic cases with a reliable follow-up.

Question 914

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring classification system, which of the following radiographic parameters evaluated during the fragmentation stage is the most reliable predictor of long-term outcome?
. The degree of metaphyseal cyst formation
. The maintenance of the height of the lateral pillar of the capital femoral epiphysis
. The presence of a subchondral fracture (crescent sign)
. The extent of lateral epiphyseal extrusion
. The early closure of the capital femoral physis

Correct Answer & Explanation

. The maintenance of the height of the lateral pillar of the capital femoral epiphysis

Explanation

The Herring Lateral Pillar Classification is based on AP radiographs during the fragmentation stage of Legg-Calvé-Perthes disease. It divides the femoral head into three pillars (medial, central, and lateral). The height of the lateral pillar is the most reliable prognostic indicator. Group A (>100% height maintained) has the best outcome, Group B (>50% maintained) has an intermediate outcome, and Group C (<50% maintained) has the worst outcome regarding future joint congruency and arthritis risk.

Question 915

Topic: Pediatric Hip

An obese 12-year-old boy presents with acute-on-chronic left thigh pain and is unable to bear weight on the left leg, even with crutches. Radiographs demonstrate a posterior and medial displacement of the proximal femoral epiphysis. According to the Loder classification, what is the most significant complication directly associated with his specific presentation type?

. Chondrolysis
. Avascular necrosis
. Slip progression
. Femoroacetabular impingement
. Leg length discrepancy

Correct Answer & Explanation

. Chondrolysis

Explanation

The Loder classification divides Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable slips based on the patient's ability to bear weight (with or without crutches). This patient cannot bear weight, indicating an unstable SCFE. Unstable SCFE has a notoriously high rate of avascular necrosis (AVN), reported to be as high as 47-50%, compared to nearly 0% in stable SCFE. Chondrolysis is more commonly associated with unrecognized pin penetration into the joint space.

Question 916

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) has been managed with a Pavlik harness for 4 weeks. Repeat dynamic ultrasound demonstrates that the affected hip remains completely dislocated and cannot be reduced in the harness. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Add a second diaper to maximize abduction
. Discontinue the Pavlik harness and plan for closed reduction and spica casting
. Perform an immediate open reduction
. Perform an isolated adductor tenotomy and reapply the Pavlik harness

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 4 weeks

Explanation

If a dislocated hip fails to reduce after 3 to 4 weeks of Pavlik harness treatment, the harness must be discontinued. Prolonged use of the harness in an unreduced hip can lead to 'Pavlik harness disease' (erosion and damage to the posterior acetabular cartilage) and increases the risk of avascular necrosis. The next step is a transition to an alternative rigid abduction orthosis or, more definitively, a closed reduction with spica casting under general anesthesia (with or without an arthrogram and adductor tenotomy).

Question 917

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. The lateral pillar maintains 60% of its normal height. According to the prospective multicenter study by Herring et al., what is the most appropriate management for this specific presentation?
. Observation and activity modification only
. Surgical containment (e.g., proximal femoral or pelvic osteotomy)
. Total hip arthroplasty
. Core decompression of the femoral head
. Prophylactic epiphysiodesis of the contralateral hip

Correct Answer & Explanation

. Surgical containment (e.g., proximal femoral or pelvic osteotomy)

Explanation

The patient has Legg-Calvé-Perthes disease. Maintaining 60% of the lateral pillar height places him in Herring Lateral Pillar Group B. The multicenter prospective study by Herring et al. demonstrated that children aged 8 years or older at the time of disease onset who have Group B (or B/C border) lateral pillar involvement have significantly better long-term radiographic and clinical outcomes when treated with surgical containment (such as a proximal femoral varus osteotomy or pelvic osteotomy) compared to non-operative management.

Question 918

Topic: Pediatric Hip

A 7-month-old girl presents for evaluation of a persistent limp and asymmetric thigh folds. She has had no prior orthopedic treatment. Ultrasound and plain radiographs confirm a completely dislocated left hip consistent with developmental dysplasia of the hip (DDH). Clinical examination demonstrates limited abduction of the left hip and a positive Galeazzi sign. What is the most appropriate initial management for this patient?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and spica casting
. Varus derotational osteotomy of the proximal femur
. Salter innominate osteotomy

Correct Answer & Explanation

. Pavlik harness application

Explanation

For children 6 to 18 months of age with previously untreated developmental dysplasia of the hip (DDH), closed reduction with hip spica casting is generally the initial treatment of choice. The Pavlik harness is highly successful in infants under 6 months of age but has a significantly higher failure rate in older, larger, and more active infants. Open reduction is indicated if closed reduction fails to achieve a stable, concentric reduction within a safe zone, or as a primary option in children presenting over 18 months of age. Pelvic or femoral osteotomies are typically reserved for children older than 18 months or those with residual dysplasia following successful reduction.

Question 919

Topic: Pediatric Hip

A 12-year-old obese boy with a history of end-stage renal disease presents with a 3-week history of left thigh pain and a noticeable limp. He denies trauma. Examination reveals obligate external rotation of the left hip upon passive flexion. Radiographs demonstrate a mild left slipped capital femoral epiphysis (SCFE). Radiographs of the right hip appear normal. What is the most appropriate definitive management?

. In situ pinning of the left hip only
. In situ pinning of the left hip and prophylactic pinning of the right hip
. Closed reduction and pinning of the left hip
. Spica cast immobilization of the left hip
. Proximal femoral osteotomy of the left hip

Correct Answer & Explanation

. In situ pinning of the left hip only

Explanation

This patient presents with a stable slipped capital femoral epiphysis (SCFE) and underlying chronic renal failure (renal osteodystrophy). The standard treatment for a stable SCFE is in situ single-screw fixation. Prophylactic pinning of the contralateral asymptomatic hip remains controversial in purely idiopathic SCFE but is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, chronic renal failure, prior radiation, growth hormone therapy). These patients have an exceptionally high risk (up to 50-100%) of developing a bilateral slip. Closed reduction of a SCFE is contraindicated as it significantly increases the risk of avascular necrosis (AVN).

Question 920

Topic: Pediatric Hip

Following a complex total hip arthroplasty via a posterior approach for developmental dysplasia of the hip (DDH), the patient is noted to have a foot drop. They cannot dorsiflex the great toe but have preserved plantar flexion. Which nerve division is most likely injured, and what is the typical mechanism?

. Tibial division of the sciatic nerve from direct transection
. Peroneal division of the sciatic nerve from excessive lengthening
. Femoral nerve from anterior retractor placement
. Superior gluteal nerve from proximal extension of the split
. Obturator nerve from extruded cement

Correct Answer & Explanation

. Tibial division of the sciatic nerve from direct transection

Explanation

The peroneal division of the sciatic nerve is the most commonly injured nerve during THA, particularly in cases involving significant limb lengthening (e.g., DDH). It is more susceptible to stretch injury than the tibial division because it is tethered at the fibular head and has less supportive connective tissue.

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