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4. Pediatrics MCQs

Practice Set 54 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1061

Topic: 4. Pediatrics

A 6-year-old child undergoes plate fixation for a distal femoral fracture. The plate crosses the distal femoral physis. The fracture heals uneventfully. What is the most significant long-term concern unique to this pediatric patient that would necessitate consideration for hardware removal?

. Increased risk of infection due to the presence of foreign material.
. Development of stress shielding leading to disuse osteopenia of the femur.
. Hardware prominence causing pain and irritation, especially during sports.
. Potential for physeal growth arrest or angular deformity due to plate impingement.
. Difficulty with future imaging studies due to implant artifact.

Correct Answer & Explanation

. Potential for physeal growth arrest or angular deformity due to plate impingement.

Explanation

Correct Answer: DIn pediatric patients, the presence of open growth plates (physes) introduces a unique and critical consideration for internal fixation. A plate crossing or impinging upon a physis can cause damage to the growth plate, leading to premature physeal closure (growth arrest) or asymmetric growth, resulting in limb length discrepancy or angular deformity. Therefore, in children, plates near or across a physis are often removed once the fracture has healed to prevent or mitigate these growth disturbances. While other complications like infection, stress shielding, and hardware prominence can occur in both children and adults, physeal arrest is a concern unique to the growing skeleton.Option A is incorrect:Infection is a risk for any implant in any age group.Option B is incorrect:Stress shielding can occur, but physeal arrest is a more immediate and specific concern for children with plates crossing growth plates.Option C is incorrect:Hardware prominence is a common issue in both adults and children, but physeal arrest is a more severe and unique pediatric complication.Option E is incorrect:Imaging artifact is a general concern with metallic implants, not unique to children or the primary reason for removal.

Question 1062

Topic: 4. Pediatrics
A 2-year-old obese African American male presents to your clinic with bilateral bowing of the legs, which his parents report has been progressively worsening since he started walking at 10 months of age. Physical examination reveals significant varus deformity below the knees, with internal tibial torsion. Standing AP radiographs of the knees show a medial physeal beak and metaphyseal-epiphyseal irregularities, consistent with Langenskiöld Stage III changes in both tibias. The mechanical axis passes significantly medial to the center of both knees. Given this presentation, which of the following is the most appropriate initial surgical management?
. Observation with serial radiographs every 6 months, as physiologic bowing often resolves spontaneously.
. Bracing with a KAFO (Knee-Ankle-Foot Orthosis) to correct the deformity non-operatively.
. Lateral hemiepiphysiodesis of the proximal tibias using an eight-plate system.
. Acute proximal tibial varus-producing osteotomy with internal fixation.
. Medial hemiepiphysiodesis of the proximal tibias to stimulate growth on the affected side.

Correct Answer & Explanation

. Lateral hemiepiphysiodesis of the proximal tibias using an eight-plate system.

Explanation

The patient presents with classic features of infantile Blount disease: early onset (2 years old), progressive worsening, obesity, African American ethnicity, and radiographic findings of Langenskiöld Stage III changes. Infantile Blount disease, especially at Stage III, is unlikely to resolve spontaneously or with bracing alone, making observation and bracing inappropriate as primary surgical management options. Lateral hemiepiphysiodesis is indicated for progressive infantile Blount disease in Langenskiöld stages II-IV, typically in children aged 4-8 years, but can be considered earlier if progression is significant and there is sufficient remaining growth potential. The case describes a 2-year-old with progressive Stage III disease, making guided growth a suitable option to leverage the remaining growth. Acute proximal tibial varus-producing osteotomy is generally reserved for more severe deformities (Langenskiöld Stages V-VI), older children with less growth remaining, or failed guided growth. Medial hemiepiphysiodesis would further inhibit growth on the already pathologically suppressed medial side, exacerbating the varus deformity, and is therefore incorrect.

Question 1063

Topic: 4. Pediatrics

A 7-year-old female with progressive right tibia vara is undergoing lateral hemiepiphysiodesis of the proximal tibia. The surgeon places an eight-plate across the lateral physis. Post-operatively, the limb gradually corrects into neutral alignment over 18 months. This correction is primarily achieved by which of the following biomechanical principles?

. Increased compressive forces on the medial physis stimulating growth, as per the Hueter-Volkmann law.
. Direct distraction of the lateral physis by the eight-plate, causing it to lengthen.
. Temporary arrest of growth on the lateral physis, allowing the medial physis to continue growing and correct the varus.
. Permanent fusion of the lateral physis, leading to a compensatory overgrowth of the medial physis.
. Remodeling of the metaphyseal bone due to altered stress distribution, independent of physeal growth.

Correct Answer & Explanation

. Temporary arrest of growth on the lateral physis, allowing the medial physis to continue growing and correct the varus.

Explanation

Correct Answer: CLateral hemiepiphysiodesis operates on the principle of guided growth, which leverages the Hueter-Volkmann law. In Blount disease, the medial physis is pathologically inhibited, leading to varus. By applying an eight-plate to the lateral aspect of the proximal tibial physis, growth on the lateral side is temporarily tethered or arrested (C). This allows the medial physis, which is no longer subjected to the concentrated compressive forces of varus and is allowed to express its natural growth potential, to 'catch up' and grow relatively faster. This differential growth gradually corrects the varus deformity. Option A is incorrect because increased compressive forces inhibit, not stimulate, growth according to Hueter-Volkmann. Option B is incorrect as the plate acts as a tether, not a distractor. Option D is incorrect because the eight-plate provides temporary, not permanent, arrest; permanent arrest would be achieved with transphyseal screws or physeal bar excision. Option E is incorrect as the primary mechanism is differential physeal growth, not metaphyseal remodeling independent of the physis.

Question 1064

Topic: 4. Pediatrics
A 6-year-old male presents with progressive bilateral tibia vara. Radiographic evaluation reveals Langenskiöld Stage V changes in the right proximal tibia, characterized by a significant physeal bar and epiphyseal wedging, and Stage III changes in the left proximal tibia. His skeletal age is 6 years. He has a Medial Proximal Tibial Angle (MPTA) of 68 degrees on the right and 78 degrees on the left. Which of the following is the most appropriate surgical plan for this patient?
. Bilateral lateral hemiepiphysiodesis of the proximal tibias.
. Right proximal tibial varus-producing osteotomy and left lateral hemiepiphysiodesis.
. Bilateral proximal tibial varus-producing osteotomies.
. Right medial physeal bar resection and left lateral hemiepiphysiodesis.
. Observation with bracing for both limbs, given his young age.

Correct Answer & Explanation

. Right proximal tibial varus-producing osteotomy and left lateral hemiepiphysiodesis.

Explanation

This patient presents with asymmetric Blount disease requiring different approaches for each limb. For the right tibia, Langenskiöld Stage V changes, an MPTA of 68 degrees (severe varus), and a significant physeal bar are contraindications for lateral hemiepiphysiodesis. Guided growth relies on the remaining growth potential of the medial physis, which is compromised by a significant physeal bar. Therefore, an acute correction via a proximal tibial varus-producing osteotomy is indicated for the right limb. For the left tibia, Langenskiöld Stage III changes and an MPTA of 78 degrees (mild-to-moderate varus) with open physes make it an ideal candidate for lateral hemiepiphysiodesis. Thus, option B, combining an osteotomy for the severe right side and guided growth for the moderate left side, is the most appropriate plan. Option A would likely fail on the right due to the physeal bar and severity. Option C is overly aggressive for the left side. Option D, while considering physeal bar resection, might not be sufficient for Stage V and severe angular deformity, and osteotomy is often preferred. Option E is inappropriate given the progressive nature and advanced stages of the disease.

Question 1065

Topic: 4. Pediatrics

A 10-year-old male with adolescent Blount disease undergoes lateral hemiepiphysiodesis of the proximal tibia. During the procedure, after drilling the pilot holes for the eight-plate screws, the surgeon performs fluoroscopic checks. Which of the following findings on fluoroscopy would necessitate immediate repositioning or re-drilling of a screw?

. The screw provides bicortical purchase in the metaphysis.
. The screw is parallel to the physis but only unicortical in the epiphysis.
. The screw threads are seen crossing the physis on both AP and lateral views.
. The plate is centered over the physis with screws in the epiphysis and metaphysis.
. The screw length is appropriate, avoiding posterior neurovascular structures.

Correct Answer & Explanation

. The screw threads are seen crossing the physis on both AP and lateral views.

Explanation

Correct Answer: CThe most critical aspect of eight-plate placement for guided growth is to ensure that the screws do not cross or compress the physis. If the screw threads are seen crossing the physis (C), it indicates direct damage to the growth plate, which can lead to premature physeal arrest, growth disturbance, or failure of the guided growth mechanism. This finding necessitates immediate repositioning or re-drilling of the screw. Options A, B, D, and E describe correct or acceptable findings. Bicortical purchase in the metaphysis (A) is desirable for stability. Unicortical purchase in the epiphysis (B) is often acceptable to avoid articular violation. Centered plate placement (D) and appropriate screw length (E) are also crucial for successful surgery.

Question 1066

Topic: 4. Pediatrics

A 12-year-old female underwent lateral hemiepiphysiodesis for progressive adolescent Blount disease. She is now 18 months post-surgery and presents for a follow-up. Standing full-length AP radiographs show a mechanical axis that passes 6 mm lateral to the center of the knee, indicating a mild valgus alignment. Her skeletal age is 13 years, with approximately 2 years of remaining growth. What is the most appropriate next step in her management?

. Continue observation with the eight-plate in situ, with follow-up in 6 months.
. Perform a medial hemiepiphysiodesis of the proximal tibia to correct the valgus.
. Remove the eight-plate now to prevent further overcorrection and allow for potential rebound into neutral.
. Perform a varus-producing osteotomy of the proximal tibia to acutely correct the valgus.
. Advise the patient to increase weight-bearing on the affected limb to stimulate medial growth.

Correct Answer & Explanation

. Remove the eight-plate now to prevent further overcorrection and allow for potential rebound into neutral.

Explanation

Correct Answer: CThe goal of guided growth is to achieve a slight overcorrection into valgus (typically 5-7 degrees of mechanical valgus) before hardware removal. This strategy accounts for the potential rebound phenomenon and allows the limb to settle into a neutral mechanical axis by skeletal maturity. The patient's current alignment of 6 mm lateral to the center of the knee (mild valgus) falls within this target range. Therefore, removing the eight-plate now (C) is the most appropriate next step to prevent further overcorrection and allow the limb to normalize. Continuing observation (A) risks significant overcorrection into genu valgum. Performing a medial hemiepiphysiodesis (B) would be an intervention for established, significant valgus, not for a planned slight overcorrection. A varus-producing osteotomy (D) is an acute, invasive procedure for severe, fixed valgus, not for this scenario. Advising increased weight-bearing (E) is not a recognized method to influence physeal growth in this context and would not address the overcorrection.

Question 1067

Topic: 4. Pediatrics

A 15-year-old male presents with severe, progressive adolescent Blount disease. Radiographs show an MPTA of 65 degrees, a significant medial physeal bar spanning 60% of the physis, and a skeletal age of 15 years, indicating limited remaining growth. He has significant pain and functional limitations. Given these findings, which of the following is the most appropriate definitive surgical intervention?

. Lateral hemiepiphysiodesis with an eight-plate.
. Medial physeal bar resection with fat interposition.
. Proximal tibial varus-producing osteotomy.
. Observation with continued weight management and bracing.
. Distal femoral medial hemiepiphysiodesis.

Correct Answer & Explanation

. Proximal tibial varus-producing osteotomy.

Explanation

Correct Answer: CThis patient presents with several factors that contraindicate guided growth and indicate the need for an acute correction. The MPTA of 65 degrees signifies severe varus deformity. The presence of a significant medial physeal bar (60%) will mechanically impede any 'catch-up' growth from the medial physis, rendering hemiepiphysiodesis ineffective. Furthermore, a skeletal age of 15 years indicates limited remaining growth potential, which is a prerequisite for successful guided growth. Therefore, a proximal tibial varus-producing osteotomy (C) is the most appropriate definitive surgical intervention for severe deformities, significant physeal bars, or in patients with limited growth potential. Lateral hemiepiphysiodesis (A) would fail due to the physeal bar and limited growth. Medial physeal bar resection (B) might be considered for smaller bars and less severe deformities, but for a 60% bar and severe angular deformity, osteotomy is more reliable. Observation and bracing (D) are inappropriate for severe, progressive disease in an older adolescent. Distal femoral medial hemiepiphysiodesis (E) would address femoral varus, which is not the primary pathology described here, and would not correct the severe tibial deformity.

Question 1068

Topic: 4. Pediatrics
The shift in surgical management of Blount disease from acute osteotomies to guided growth techniques, particularly using tension band plates, has been significantly influenced by the work of which orthopedic surgeon, who extensively documented the efficacy and safety of these methods?
. Walter Blount
. Peter Stevens
. Ignacio Ponseti
. Robert Salter
. M. E. Müller

Correct Answer & Explanation

. Peter Stevens

Explanation

Peter Stevens has been a leading proponent and researcher in guided growth, extensively documenting the efficacy and safety of temporary hemiepiphysiodesis using eight-plates for various angular deformities, including Blount disease. His work has been instrumental in popularizing this less invasive approach. Walter Blount originally described the disease. Ignacio Ponseti is renowned for his non-operative method for clubfoot correction. Robert Salter is known for his work on physeal injuries (Salter-Harris classification) and innominate osteotomy for hip dysplasia. M. E. Müller was a pioneer in internal fixation and total hip arthroplasty, and a founder of the AO Foundation.

Question 1069

Topic: 4. Pediatrics

A 2-year-old child presents with progressive bilateral genu varum. Standing radiographs reveal a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees. According to current evidence, what is the most appropriate initial management?

. Observation and reassurance
. Ankle-foot orthosis (AFO)
. Knee-ankle-foot orthosis (KAFO)
. Guided growth (lateral 8-plate)
. High tibial osteotomy

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO)

Explanation

A metaphyseal-diaphyseal angle (Drennan's angle) > 16 degrees is highly predictive of infantile Blount disease. The standard initial treatment for a child under age 3 with confirmed infantile Blount disease is bracing with a KAFO worn during weight-bearing activities.

Question 1070

Topic: 4. Pediatrics
According to the Langenskiöld classification of infantile Blount disease, which of the following radiographic findings distinguishes Stage VI from earlier stages?
. Initial beaking of the medial metaphysis
. Saucer-shaped defect of the medial metaphysis
. A cleft forming in the medial epiphysis
. Closure of the medial physis with formation of a bony bridge
. Subluxation of the lateral tibial plateau

Correct Answer & Explanation

. Closure of the medial physis with formation of a bony bridge

Explanation

Langenskiöld Stage VI is characterized by the formation of a true bony bridge (physeal bar) across the medial aspect of the proximal tibial physis. This irreversible arrest requires more complex surgical management, such as physeal bar excision or contralateral epiphysiodesis.

Question 1071

Topic: 4. Pediatrics

Which biomechanical principle best explains the primary pathophysiology of medial physeal suppression and subsequent varus progression in infantile Blount disease?

. Wolff's law
. Hueter-Volkmann principle
. Pauwels' principle
. Tension-stress effect
. Poisson effect

Correct Answer & Explanation

. Hueter-Volkmann principle

Explanation

The Hueter-Volkmann principle states that increased mechanical compression across a physis slows its growth. In Blount disease, excessive compressive forces on the medial proximal tibial physis, often worsened by early walking and obesity, retard medial growth and exacerbate the varus deformity.

Question 1072

Topic: 4. Pediatrics
A 9-year-old female presents with recurrent infantile Blount disease. Radiographs reveal a Langenskiöld stage VI deformity with a complete medial physeal bony bar and severe medial joint depression. The mechanical axis is severely deviated medially. What is the most appropriate surgical intervention?
. Lateral proximal tibial hemiepiphysiodesis alone
. Proximal tibial closing wedge osteotomy with fibular osteotomy
. Medial physeal bar resection with interpositional graft and valgus-producing osteotomy
. Total knee arthroplasty
. Medial collateral ligament reefing and pes anserinus transfer

Correct Answer & Explanation

. Medial physeal bar resection with interpositional graft and valgus-producing osteotomy

Explanation

Langenskiöld stage VI is defined by a medial physeal bony bridge (bar). In a growing child, simply realigning the limb is insufficient; successful management requires excision of the bony bar with interposition material (e.g., fat) combined with a corrective osteotomy.

Question 1073

Topic: 4. Pediatrics

When evaluating an obese 13-year-old male with progressive genu varum to differentiate adolescent Blount disease from severe physiologic bowing, which of the following radiographic findings isolated to the proximal tibia is most specific for Blount disease?

. Symmetrical lateral bowing of the femur and tibia
. A metaphyseal-diaphyseal angle (MDA) of exactly 10 degrees
. Widening of the medial physis with a prominent medial metaphyseal beak
. Lateral mechanical axis deviation passing through the lateral compartment
. Anterior wedging of the distal femoral epiphysis

Correct Answer & Explanation

. Widening of the medial physis with a prominent medial metaphyseal beak

Explanation

Adolescent Blount disease typically presents with pathological changes strictly at the proximal tibia, including widening of the medial proximal tibial physis and a characteristic medial metaphyseal beak. Physiologic bowing generally presents as a diffuse, symmetric curvature.

Question 1074

Topic: 4. Pediatrics
An 8-year-old obese male with untreated infantile Blount disease presents with severe left knee varus. Radiographs demonstrate a complete medial physeal bridge with severe medial articular depression, consistent with Langenskiöld Stage VI. Which of the following is the most appropriate surgical intervention?
. Observation and full-time KAFO bracing
. Proximal tibial valgus osteotomy alone
. Lateral hemiepiphysiodesis
. Medial physeal bar excision, hemi-plateau elevation, and proximal tibial valgus osteotomy
. Distal femoral varus osteotomy

Correct Answer & Explanation

. Medial physeal bar excision, hemi-plateau elevation, and proximal tibial valgus osteotomy

Explanation

Langenskiöld Stage VI is characterized by a complete osseous bar across the medial physis and severe joint line depression. Successful treatment requires resection of the physeal bar to allow growth, elevation of the depressed medial plateau to restore joint congruity, and a metaphyseal valgus osteotomy.

Question 1075

Topic: 4. Pediatrics
A 2.5-year-old girl with a BMI in the 99th percentile presents with unilateral varus bowing of her right leg. Radiographs demonstrate a prominent medial metaphyseal beak and a metaphyseal-diaphyseal angle of 18 degrees, consistent with Langenskiöld Stage II Blount disease. What is the most appropriate initial management?
. Observation with repeat radiographs in 1 year
. Daytime use of a Knee-Ankle-Foot Orthosis (KAFO)
. Proximal tibial valgus osteotomy
. Lateral hemiepiphysiodesis
. Medial physeal bar excision

Correct Answer & Explanation

. Daytime use of a Knee-Ankle-Foot Orthosis (KAFO)

Explanation

Infantile Blount disease in a patient under 3 years old with Langenskiöld Stage I or II is initially managed non-operatively. The standard treatment is dynamic bracing, typically with a KAFO worn during weight-bearing hours to unload the medial physis.

Question 1076

Topic: 4. Pediatrics

A 3-year-old child presents with bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees on the right and 19 degrees on the left. Which of the following is the most appropriate next step in management?

. Observation and reassurance
. Bilateral knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomies
. Eight-plate hemiepiphysiodesis
. Measurement of serum 25-OH vitamin D

Correct Answer & Explanation

. Bilateral knee-ankle-foot orthoses (KAFOs)

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees is highly predictive of infantile Blount disease. Bracing with KAFOs is indicated for children under age 3-4 with early-stage disease to unload the medial compartment and prevent further physeal suppression.

Question 1077

Topic: 4. Pediatrics
A 5-year-old boy with infantile Blount disease presents for evaluation. Radiographs demonstrate an osseous bridge across the medial proximal tibial physis with a cleft in the medial metaphysis. According to the Langenskiöld classification, what stage does this represent, and what is the typical treatment?
. Stage II; bracing
. Stage III; guided growth
. Stage IV; valgus-producing osteotomy
. Stage V; physeal bar excision and osteotomy
. Stage VI; physeal bar excision and osteotomy

Correct Answer & Explanation

. Stage VI; physeal bar excision and osteotomy

Explanation

Langenskiöld Stage VI is characterized by a true bony bridge (bar) across the medial physis. Treatment requires physeal bar excision with interposition material, usually combined with a corrective proximal tibial osteotomy to realign the mechanical axis.

Question 1078

Topic: 4. Pediatrics

Which of the following radiographic findings is most characteristic of adolescent Blount disease when compared to infantile Blount disease?

. Severe depression of the medial tibial plateau with a prominent beak
. Pronounced varus primarily located at the distal femur
. Widening and radiolucency of the medial proximal tibial physis without a severe metaphyseal beak
. Spontaneous resolution of the deformity by skeletal maturity
. A well-defined osseous physeal bar early in the disease course

Correct Answer & Explanation

. Widening and radiolucency of the medial proximal tibial physis without a severe metaphyseal beak

Explanation

Adolescent Blount disease typically presents with widening and radiolucency of the medial aspect of the proximal tibial physis due to chronic stress. It generally lacks the severe medial plateau depression and prominent 'beaking' that is pathognomonic for late-stage infantile Blount disease.

Question 1079

Topic: 4. Pediatrics

Which of the following biomechanical principles most directly explains the pathophysiology of progressive varus deformity in early-onset Blount disease?

. Hueter-Volkmann principle
. Wolff's Law
. Relative medial tibial ischemia from aberrant vascularity
. Excessive lateral compartment loading inducing compensatory varus
. Overactivity of the pes anserinus

Correct Answer & Explanation

. Hueter-Volkmann principle

Explanation

The Hueter-Volkmann principle states that increased compressive forces inhibit physeal growth. In Blount disease, early walking in heavy children increases medial compressive forces, leading to suppression of medial proximal tibial physeal growth and subsequent progressive varus.

Question 1080

Topic: 4. Pediatrics



When evaluating a radiograph of a child with suspected Blount disease, the metaphyseal-diaphyseal angle (Drennan angle) is a critical measurement. Which anatomical landmarks define the lines used for this measurement?

. Mechanical axis of the tibia and the articular surface of the knee
. Anatomical axis of the tibia and a line parallel to the proximal tibial metaphysis
. Mechanical axis of the femur and the anatomical axis of the tibia
. A line drawn through the distal femoral condyles and the proximal tibial plateau
. A line perpendicular to the anatomical axis of the tibia and a line through the proximal tibial physis

Correct Answer & Explanation

. Anatomical axis of the tibia and a line parallel to the proximal tibial metaphysis

Explanation

The metaphyseal-diaphyseal angle (Drennan angle) is the angle formed by the anatomical axis of the tibia intersecting a line drawn through the two most prominent points of the proximal tibial metaphysis (medial and lateral metaphyseal beaks).

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