Orthopedic Pediatrics Review | Dr Hutaif Pediatric Orth -...

Question 1

A 12-year-old boy with chronic renal failure presents with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. What is the most appropriate indication for prophylactic pinning of the contralateral right hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, chronic renal failure, growth hormone therapy) due to a significantly increased risk (approaching 100%) of bilateral involvement. Age less than 10, not older, is also considered a relative indication.

Question 2

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 3-week follow-up, the infant exhibits decreased spontaneous movement of the affected leg and absent knee extension. What is the most likely cause of this physical finding?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hip. It presents with decreased active knee extension and diminished spontaneous leg movements. The harness should be temporarily removed or adjusted, and the palsy typically resolves spontaneously.

Question 3

A 6-year-old girl sustains a severely displaced extension-type supracondylar humerus fracture. Upon examination in the emergency department, she is unable to flex the interphalangeal joint of her thumb and the distal interphalangeal joint of her index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) to the index and middle fingers. Injury results in the inability to make an 'A-OK' sign.

Question 4

According to the Herring lateral pillar classification for Legg-Calvé-Perthes disease, which of the following radiographic findings is the defining feature of a Group B hip?

Explanation

In the Herring lateral pillar classification, Group A has no involvement of the lateral pillar. Group B maintains >50% of the lateral pillar height. Group C maintains <50% of the lateral pillar height. Group B/C is a borderline category. This classification is highly prognostic for the final hip outcome.

Question 5

A 3-year-old boy treated successfully for idiopathic clubfoot with the Ponseti method presents with a relapse. He demonstrates dynamic supination during the swing phase of gait without a fixed bony deformity. What is the most appropriate surgical management?

Explanation

Relapse in clubfoot often presents with dynamic supination due to an overpowering anterior tibial tendon in the setting of a corrected, but functionally weak, evertor complex. Transfer of the entire anterior tibial tendon to the third (lateral) cuneiform (TATT) is the treatment of choice for dynamic supination in a relapsed Ponseti-treated clubfoot in a child over 30 months of age.

Question 6

A 12-year-old boy presents with frequent ankle sprains, peroneal spasticity, and a rigid, flat foot. Radiographs show a prominent 'C-sign' on the lateral view. Which of the following is the most likely diagnosis, and what is the best initial imaging modality to confirm the specific anatomic location and plan surgical intervention?

Explanation

The 'C-sign' on a lateral radiograph is formed by the medial outline of the talar dome and the posterior outline of the sustentaculum tali, which is a classic radiographic indicator of a talocalcaneal coalition (specifically involving the middle facet). CT scan is the gold standard imaging modality to delineate the bony anatomy and plan surgical resection.

Question 7

A newborn is diagnosed with congenital fibular hemimelia. Which of the following associated anomalies is most commonly found in the ipsilateral limb?

Explanation

Fibular hemimelia is a longitudinal deficiency associated with several ipsilateral limb anomalies, including absence of the lateral rays of the foot (not medial), anteromedial bowing of the tibia, limb length discrepancy, ball-and-socket ankle joint, and absence or hypoplasia of the anterior cruciate ligament (ACL).

Question 8

A newborn is noted to have severe radial deviation of the wrist with an absent thumb and shortened forearm. A screening echocardiogram reveals an atrial septal defect. Which of the following genetic conditions is most likely responsible?

Explanation

Holt-Oram syndrome is an autosomal dominant condition characterized by upper limb abnormalities (typically radial ray deficiencies, including an absent thumb) and congenital heart defects, most commonly an ASD or VSD. In TAR syndrome, the thumb is characteristically present despite an absent radius. Fanconi anemia is associated with aplastic anemia. VACTERL involves multiple organ systems but is less specific for this exact pairing without other findings.

Question 9

A 3-year-old child weighing 16 kg sustains an isolated, closed, diaphyseal femur fracture with 1 cm of shortening after a low-energy fall. What is the most appropriate initial management?

Explanation

For children aged 6 months to 5 years (and usually under 20 kg) with isolated diaphyseal femur fractures and less than 2 cm of shortening, early spica casting is the standard of care. Flexible nailing is generally reserved for older children (typically 5-11 years) or those over 50 lbs (22 kg).

Question 10

A 2-year-old girl is diagnosed with congenital scoliosis due to a fully segmented hemivertebra at T8. What is the most critical screening evaluation required before considering any spinal surgical intervention?

Explanation

Up to 40% of patients with congenital scoliosis have associated intraspinal anomalies, such as a tethered cord, syringomyelia, or diastematomyelia. An MRI of the entire spine is critical before surgical intervention to avoid neurologic injury during curve correction. Renal ultrasound and echocardiogram are also indicated due to associated VACTERL anomalies.

Question 11

A 13-year-old girl sustains a twisting ankle injury. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the physeal closure pattern of the distal tibia that directly predisposes her to this specific fracture pattern?

Explanation

The distal tibial physis closes over an 18-month period in a predictable sequence: it starts centrally, proceeds to the anteromedial portion, then posteromedial, and finally the lateral (anterolateral) portion closes last. Because the lateral physis remains open, the anterolateral epiphysis can be avulsed by the anterior inferior tibiofibular ligament, resulting in a Tillaux fracture.

Question 12

A 4-year-old boy presents with progressive bilateral genu varum and lateral thrust during gait. Standing radiographs show an acute downward turning of the medial metaphysis of the proximal tibia with a metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate treatment?

Explanation

This child has infantile Blount disease, indicated by a metaphyseal-diaphyseal angle > 16 degrees (Langenskiöld stage II or higher). Because the child is over the age of 3, bracing is generally ineffective and poorly tolerated. The definitive treatment for progressive infantile Blount disease in a child over age 3-4 is a proximal tibial valgus-derotation osteotomy.

Question 13

In a 7-year-old non-ambulatory child with spastic quadriplegic cerebral palsy (GMFCS Level V), routine radiographic surveillance reveals a Reimer's migration percentage of 45% in the right hip. There is no subchondral sclerosis or joint space narrowing. What is the most appropriate recommendation?

Explanation

In cerebral palsy, a Reimer's migration percentage > 40% typically indicates structural hip subluxation that will not respond reliably to soft tissue releases alone. Bony reconstruction with a Varus Derotational Osteotomy (VDRO), often combined with a pelvic osteotomy (e.g., Dega), is the standard of care to restore coverage and prevent painful dislocation.

Question 14

A 5-year-old boy presents with a 3-day history of right hip pain, refusal to bear weight, a temperature of 38.8°C, and an ESR of 55 mm/hr. Joint aspiration yields synovial fluid with a WBC count of 85,000/mm3 (>90% PMNs). After surgical irrigation and debridement, what is the most appropriate empirical intravenous antibiotic therapy pending culture results in an area with a 20% rate of community-acquired MRSA?

Explanation

Staphylococcus aureus is the most common cause of septic arthritis in children >3 months. Empirical therapy must target S. aureus. In areas where community-acquired MRSA prevalence exceeds 10-15%, anti-MRSA coverage such as Clindamycin or Vancomycin should be utilized as the first-line empiric agent pending culture sensitivities.

Question 15

A 10-year-old girl is found to have a post-traumatic physeal bar of the distal femur. A scanogram shows a 3 cm leg length discrepancy, and an MRI maps the bar as centrally located, occupying 30% of the cross-sectional area of the physis. She is expected to have 4 years of remaining growth. What is the most appropriate surgical management?

Explanation

Physeal bar resection is indicated if the bar occupies less than 50% of the cross-sectional area of the physis and the child has at least 2 years of remaining growth. Following resection, interposition with an inert material (such as autologous fat, Cranioplast, or bone wax) is critical to prevent the bar from reforming.

Question 16

Which of the following classifications of Osteogenesis Imperfecta (OI) according to the Sillence criteria is characterized as uniformly lethal in the perinatal period?

Explanation

Under the Sillence classification for Osteogenesis Imperfecta, Type II is the most severe form and is uniformly lethal in the perinatal period due to severe pulmonary hypoplasia and profound skeletal fragility resulting in multiple in utero fractures. Type I is mild, Type III is severe/progressive deforming, and Type IV is of moderate severity.

Question 17

A 14-year-old female gymnast presents with insidious onset of low back pain exacerbated by extension. Plain radiographs are normal. An MRI shows marrow edema in the pars interarticularis of L5 bilaterally without a definitive fracture line. What is the most appropriate initial management?

Explanation

The patient has an acute stress reaction of the pars interarticularis (early spondylolysis), evidenced by MRI marrow edema without a radiographic defect. The mainstay of treatment is conservative: cessation of the offending activity (extension loading), rest, and physical therapy focused on antilordotic core strengthening. Surgery is not indicated for early stress reactions.

Question 18

A 2-year-old boy with achondroplasia presents with a thoracolumbar kyphosis of 35 degrees. He has no neurologic deficits and has just started walking independently. What is the most appropriate management?

Explanation

Thoracolumbar kyphosis in infants and toddlers with achondroplasia is very common. It typically resolves spontaneously in the majority of patients once they begin walking independently and develop compensatory lumbar lordosis and hip extension. Observation is the most appropriate initial management unless the curve is fixed, severe, or associated with neurologic compromise.

Question 19

A 4-year-old boy presents with congenital pseudarthrosis of the tibia (CPT). He has a known diagnosis of Neurofibromatosis type 1 (NF1). What is the primary histological characteristic of the pseudarthrosis tissue found at the fracture site in CPT?

Explanation

The tissue at the site of a congenital pseudarthrosis of the tibia is characterized as a 'fibrous hamartoma.' It consists of dense, highly cellular fibrous tissue that encases the bone and thickened periosteum, strangulating the local blood supply and inhibiting osteogenesis, which prevents normal fracture healing.

Question 20

A 13-year-old boy underwent in situ single-screw fixation for a stable right Slipped Capital Femoral Epiphysis (SCFE) two years ago. He now complains of progressive right hip stiffness and worsening pain. Radiographs reveal global joint space narrowing to 1.5 mm, periarticular osteopenia, and no signs of avascular necrosis. What is the most likely diagnosis?

Explanation

Chondrolysis is a devastating complication of SCFE, characterized by acute cartilage death and profound joint space narrowing (typically <3 mm). It presents with severe stiffness and pain. It has historically been associated with unrecognized screw penetration into the joint, severe slips, and prolonged spica casting. Radiographs classically show concentric joint space narrowing and periarticular osteopenia without collapse of the femoral head (which would indicate AVN).

Question 21

A 4-year-old obese boy presents with Langenskiöld stage III infantile Blount disease. Conservative management with bracing has failed, and he demonstrates a worsening lateral thrust during gait. What is the most appropriate next step in management?

Explanation

Children over age 3 or those with Langenskiöld stage III or higher who fail bracing require surgical intervention. A proximal tibial valgus osteotomy is the gold standard to correct alignment and prevent further physeal damage.

Question 22

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs demonstrate greater than 50% collapse of the lateral pillar of the femoral head. According to the Herring classification, what is his lateral pillar grade, and what is the expected outcome?

Explanation

Herring Group C is defined by greater than 50% loss of lateral pillar height. Patients in this group generally have a poor prognosis with a high likelihood of residual deformity, and surgical containment has limited benefit in older children.

Question 23

An infant with idiopathic clubfoot is undergoing Ponseti serial casting. After successfully correcting the cavus, adductus, and varus deformities, the foot remains in 15 degrees of rigid equinus. What is the next most appropriate step in management?

Explanation

The Ponseti method corrects deformities in the CAVE order: Cavus, Adductus, Varus, and Equinus. A percutaneous Achilles tenotomy is required in approximately 80% of cases to correct the residual rigid equinus.

Question 24

A 4-year-old child sustains a displaced lateral condyle fracture of the humerus that is left untreated. Years later, the patient develops a progressive deformity and neurological symptoms. What is the most likely late neurological complication?

Explanation

Nonunion of lateral condyle fractures leads to a progressive cubitus valgus deformity. Over time, this valgus angulation stretches the ulnar nerve, resulting in a tardy ulnar nerve palsy.

Question 25

A 2-week-old infant with arthrogryposis multiplex congenita presents with rigid, bilaterally dislocated hips. What is the most appropriate initial management strategy for the hip dysplasia in this patient?

Explanation

Teratologic hip dislocations, such as those in arthrogryposis, are notoriously rigid and typically do not respond to a Pavlik harness. They usually require delay until the infant is older for a definitive open reduction, often with simultaneous femoral shortening.

Question 26

During the Ponseti method of serial casting for idiopathic clubfoot, the deformities must be corrected in a specific sequential order to avoid iatrogenic complications. Which deformity must be corrected first?

Explanation

The Ponseti method corrects deformities using the 'CAVE' sequence: Cavus, Adduction, Varus, and Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot.

Question 27

The Herring Lateral Pillar classification is used to determine the prognosis in Legg-Calve-Perthes disease. Which of the following radiographic parameters defines a Lateral Pillar Group C?

Explanation

The Lateral Pillar classification evaluates the height of the lateral third of the femoral head on an AP radiograph during the fragmentation stage. Group C is defined as having less than 50% of the normal lateral pillar height maintained, which portends a poor prognosis.

Question 28

A 12-year-old boy undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). During the procedure, the surgeon fails to recognize intra-articular pin penetration. What is the most likely long-term complication?

Explanation

Unrecognized intra-articular pin penetration is the primary cause of iatrogenic chondrolysis after SCFE fixation. Surgeons must utilize the 'approach-withdraw' principle on live fluoroscopy to ensure hardware does not breach the joint.

Question 29

An adolescent sustains a triplane fracture of the distal tibia. Which combination of radiographic appearances classically characterizes this injury?

Explanation

A triplane fracture occurs during the asymmetric closure of the distal tibial physis. It classically appears as a Salter-Harris III fracture on the AP radiograph and a Salter-Harris II on the lateral radiograph.

Question 30

A 4-year-old boy presents with dynamic supination of the foot during the swing phase of gait. He was successfully treated for clubfoot as an infant using the Ponseti method. What is the treatment of choice for this specific relapse?

Explanation

Dynamic supination during gait in a relapsed clubfoot is driven by an overactive tibialis anterior muscle. Transferring the tibialis anterior tendon to the lateral cuneiform redirects its force to assist in dorsiflexion without supinating the foot.

Question 31

An 8-month-old infant with achondroplasia presents with profound hypotonia, feeding difficulties, and episodes of central apnea. What is the most likely orthopedic cause of these symptoms?

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, which can compress the cervicomedullary junction. This life-threatening complication can manifest as central apnea, hypotonia, and sudden infant death.

Question 32

A 14-year-old boy presents with a rigid flatfoot, recurrent ankle sprains, and peroneal spasm. An oblique radiograph of the foot reveals an "anteater nose" sign. Which pathology does this finding represent?

Explanation

The 'anteater nose' sign is seen on 45-degree oblique foot radiographs and represents an elongated anterior process of the calcaneus. It is pathognomonic for a calcaneonavicular coalition.

Question 33

Osteogenesis imperfecta is characterized by recurrent fractures, blue sclera, and dentinogenesis imperfecta. This condition is primarily caused by an autosomal dominant genetic mutation affecting which of the following?

Explanation

Osteogenesis imperfecta is primarily caused by mutations in the COL1A1 or COL1A2 genes, which encode for Type I collagen. Type I collagen is the predominant structural protein found in bone, sclera, and dentin.

Question 34

A newborn is diagnosed with congenital scoliosis due to a unilateral unsegmented bar and a contralateral hemivertebra. Which of the following routine screening investigations is mandatory for this patient?

Explanation

Up to 30% of patients with congenital scoliosis have associated genitourinary anomalies due to shared embryological timing. A renal ultrasound is mandatory to rule out life-threatening anomalies like unilateral renal agenesis.

Question 35

According to hip surveillance guidelines for children with Cerebral Palsy, what is the approximate risk of hip displacement (migration percentage > 30%) in a child functioning at GMFCS Level V?

Explanation

The risk of progressive hip displacement in cerebral palsy is directly correlated with the Gross Motor Function Classification System (GMFCS) level. Children at GMFCS level V (non-ambulatory) have a 90% risk of hip displacement requiring rigorous radiographic surveillance.

Question 36

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

Explanation

The Loder classification defines an unstable SCFE solely by the patient's inability to walk or bear weight on the affected limb, regardless of crutch use. Unstable slips carry a substantially higher risk of avascular necrosis compared to stable slips.

Question 37

The Kocher criteria are used to differentiate pediatric septic arthritis from transient synovitis. Which additional laboratory marker was later added by Caird et al. to increase the predictive value of the original criteria?

Explanation

Caird et al. added CRP > 2.0 mg/dL to the original four Kocher criteria (fever, non-weight-bearing, ESR > 40, WBC > 12,000). The presence of all five parameters predicts a >97% probability of septic arthritis.

Question 38

A 4-year-old child previously treated for idiopathic clubfoot with the Ponseti method presents with a recurrent dynamic supination deformity during the swing phase of gait. Passive range of motion is full and the foot is plantigrade. Which of the following is the most appropriate surgical management?

Explanation

Dynamic supination in a relapsed clubfoot treated by the Ponseti method is usually caused by the overpull of a strong tibialis anterior against weak evertors. The standard treatment is transferring the entire tibialis anterior tendon to the third (lateral) cuneiform to balance foot biomechanics.

Question 39

An 8-year-old boy presents with a limp and hip pain. Radiographs reveal Legg-Calve-Perthes disease with greater than 50% loss of lateral pillar height. According to the Herring classification, what group does this represent and what is the associated prognosis?

Explanation

The Herring Lateral Pillar classification strongly correlates with outcome in Perthes disease. Group C is defined by >50% collapse of the lateral pillar of the femoral head and consistently carries the worst prognosis for joint congruity.

Question 40

A 13-year-old boy presents to the emergency department unable to bear weight on his left leg even with crutches after a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most likely severe complication associated with this specific presentation?

Explanation

The inability to bear weight even with crutches defines an unstable SCFE. Unstable slips are associated with a high rate of avascular necrosis, with reported risks ranging from 20% to 50% due to acute vascular disruption.

Question 41

A 14-year-old patient with spastic diplegic cerebral palsy presents with progressive crouch gait. Physical examination reveals hamstring tightness and evidence of a prior iatrogenic over-lengthening of the Achilles tendon. What is the primary kinematic driver of this gait pattern?

Explanation

Crouch gait in cerebral palsy is frequently precipitated by over-lengthening the Achilles tendon, which leads to iatrogenic plantarflexor weakness. Without strong plantarflexors to control tibial advancement, the knee and hip collapse into flexion during the stance phase.

Question 42

A 2-year-old child presents with a history of multiple low-energy fractures and blue sclerae. A diagnosis of osteogenesis imperfecta is made. This condition is most commonly caused by a mutation affecting which of the following genes?

Explanation

Osteogenesis imperfecta is most commonly an autosomal dominant disorder caused by mutations in the COL1A1 or COL1A2 genes. This results in defective type 1 collagen production, leading to bone fragility and classic blue sclerae.

Question 43

A newborn is diagnosed with fibular hemimelia characterized by anteromedial bowing of the tibia and absent lateral rays of the foot. Which of the following ligamentous anomalies of the knee is most likely present?

Explanation

Fibular hemimelia is a longitudinal deficiency spectrum that is strongly associated with an absent or hypoplastic anterior cruciate ligament (ACL). Other common associations include a ball-and-socket ankle joint and tarsal coalition.

Question 44

A 14-year-old boy sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis while playing soccer. What is the most common mechanism of injury for this specific fracture pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia caused by an external rotation force. The anterior inferior tibiofibular ligament (AITFL) avulses the anterolateral epiphysis, which is the last portion of the physis to fuse.

Question 45

A 12-year-old boy presents with recurrent ankle sprains and a rigid, painful flatfoot. Oblique radiographs of the foot demonstrate an "anteater nose" sign. What is the most likely diagnosis?

Explanation

The "anteater nose" sign on a 45-degree oblique foot radiograph is pathognomonic for a calcaneonavicular coalition. In contrast, a talocalcaneal coalition is best visualized on a lateral radiograph displaying the "C-sign" or on coronal CT.

Question 46

A 3-year-old boy presents with severe, progressive tibia vara. Radiographs demonstrate Langenskiold stage III infantile Blount's disease. What is the primary pathoanatomical mechanism driving this deformity?

Explanation

Infantile Blount's disease results from mechanical overloading of the posteromedial proximal tibial physis, consistent with the Heuter-Volkmann principle. This excessive compression disrupts normal endochondral ossification, leading to growth suppression and progressive varus.

Question 47

A 6-year-old non-ambulatory child with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated in the hip surveillance clinic. Radiographs reveal a Reimers migration percentage of 45% bilaterally. What is the recommended definitive management?

Explanation

In a child with CP and a hip migration percentage approaching or exceeding 40-50%, soft tissue releases alone are inadequate and carry a high failure rate. Bony reconstruction with a proximal femoral VDRO and a pelvic osteotomy (e.g., Dega) is indicated to restore concentric reduction.

Question 48

A 14-year-old girl is evaluated for Adolescent Idiopathic Scoliosis (AIS). Her main thoracic curve measures 55 degrees, and her thoracolumbar curve measures 20 degrees but bends out to 5 degrees on side-bending films. The center sacral vertical line (CSVL) falls between the pedicles of the apical lumbar vertebra. What is her Lenke classification?

Explanation

A main thoracic curve >40 degrees with a flexible thoracolumbar curve that bends out to <25 degrees defines a Lenke Type 1 (Main Thoracic) pattern. Because the CSVL bisects the apical lumbar vertebra, she is assigned a lumbar modifier A.

Question 49

An 8-year-old boy weighing 35 kg sustains a closed, length-stable midshaft femur fracture after falling off a bicycle. What is the most widely accepted standard of care for definitive fixation?

Explanation

Flexible intramedullary nails are the standard of care for length-stable femoral shaft fractures in children aged 5 to 11 years weighing less than 50 kg (110 lbs). Rigid antegrade nailing is contraindicated in this age group due to the risk of avascular necrosis from piriformis fossa entry.

Question 50

A 6-year-old boy presents with painless snapping and popping in the lateral aspect of his knee. MRI reveals a discoid lateral meniscus that lacks normal posterior capsular attachments (coronary ligaments) and is attached only by the meniscofemoral ligament. What is this variant called?

Explanation

The Wrisberg variant of a discoid meniscus completely lacks posterior capsular attachments, relying solely on the meniscofemoral ligament of Wrisberg. This hypermobility leads to an unstable meniscus that subluxates into the joint, causing symptomatic snapping even without a formal tear.

Question 51

A 5-year-old girl is treated non-operatively for a lateral condyle fracture of the humerus that was displaced 3 mm. She subsequently develops a symptomatic nonunion. Which of the following long-term complications is most directly associated with this condition?

Explanation

Nonunion of a pediatric lateral condyle fracture typically results in a progressive cubitus valgus deformity. Over several years, this valgus angulation stretches the ulnar nerve, leading to tardy ulnar nerve palsy.

Question 52

A 3-year-old girl presents with a painless limp. She has never been treated for developmental dysplasia of the hip (DDH). Radiographs show a chronically dislocated left hip with a false acetabulum. What is the most appropriate surgical intervention?

Explanation

In a child older than 2 to 3 years with a neglected DDH dislocation, open reduction alone is insufficient and carries a high risk of AVN and redislocation. Femoral shortening (to decompress the joint) and a pelvic osteotomy (to correct acetabular dysplasia) are concurrently required.

Question 53

A 4-month-old infant with achondroplasia presents with hypotonia, hyperreflexia, and episodes of central apnea. What is the most critical next step in diagnostic evaluation?

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, which can cause severe cervicomedullary compression manifesting as central apnea, myelopathy, and hypotonia. Urgent MRI of the craniocervical junction is vital to determine if suboccipital decompression is necessary.

Question 54

An 8-year-old boy presents with a limp and hip pain. Radiographs reveal fragmentation of the capital femoral epiphysis. According to the Herring classification, which radiographic feature is the most important prognostic factor in this disease process?

Explanation

The Herring Lateral Pillar classification is the most reliable prognostic indicator in Legg-Calve-Perthes disease. It assesses the height of the lateral pillar on the AP radiograph during the fragmentation stage.

Question 55

During the Ponseti method for treating idiopathic clubfoot, what is the first step in the manipulative correction process?

Explanation

The first step in the Ponseti method is correcting the cavus by elevating the first ray and supinating the forefoot to align it with the hindfoot. Further corrections follow the CAVE sequence: Cavus, Adductus, Varus, and Equinus.

Question 56

A 2-year-old girl is evaluated for bilateral genu varum. Which radiographic finding is most predictive of progression to infantile Blount disease rather than physiologic bowing?

Explanation

A metaphyseal-diaphyseal angle (MDA) of Drennan greater than 16 degrees has a high positive predictive value for progression to infantile Blount disease. Angles less than 10 degrees typically resolve spontaneously as physiologic bowing.

Question 57

A 6-year-old boy with spastic quadriplegic cerebral palsy is undergoing hip surveillance. Which muscle group's spasticity is the primary driver of the posterosuperior hip subluxation commonly seen in these patients?

Explanation

Hip displacement in cerebral palsy is primarily driven by the overactivity and contracture of the hip adductors and flexors (iliopsoas). This creates a posterosuperior vector of force, leading to subluxation and eventually dislocation.

Question 58

A 13-year-old girl sustains an ankle injury. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibia. Which ligament's avulsion force is responsible for this specific fracture pattern?

Explanation

The juvenile Tillaux fracture is a Salter-Harris III avulsion fracture of the anterolateral distal tibial epiphysis. It is caused by an external rotation force with tension transmitted through the anterior inferior tibiofibular ligament (AITFL).

Question 59

According to the Kocher criteria, which combination of clinical findings yields a 99% predictive probability for septic arthritis of the hip in a pediatric patient?

Explanation

The Kocher criteria include non-weight-bearing status, temperature >38.5 C, ESR >40 mm/hr, and WBC >12,000 cells/mm3. The presence of all four criteria indicates a 99% probability of septic arthritis over transient synovitis.

Question 60

A 4-year-old boy with blue sclerae and a history of multiple fractures is diagnosed with Osteogenesis Imperfecta. What is the fundamental genetic defect associated with the most common forms of this condition?

Explanation

Osteogenesis Imperfecta is predominantly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes. This leads to quantitative or qualitative defects in Type I collagen, the major structural protein in bone.

Question 61

A 5-year-old boy sustains a minimally displaced lateral condyle fracture of the humerus. Which of the following is the most likely long-term complication if this fracture goes on to nonunion?

Explanation

Nonunion of a lateral condyle fracture typically results in progressive cubitus valgus deformity. This valgus angulation stretches the ulnar nerve, often leading to a tardy ulnar nerve palsy years later.

Question 62

A 13-year-old obese boy presents with left hip pain and inability to ambulate, even with crutches, following a minor fall. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk associated with this specific presentation?

Explanation

The inability to ambulate with or without crutches defines an unstable SCFE. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN) of the femoral head, with rates historically reported between 20% and 50%.

Question 63

A 6-year-old girl undergoes closed reduction and percutaneous pinning for a Gartland type III supracondylar humerus fracture. Postoperatively, her hand is warm, pink, and has brisk capillary refill, but the radial pulse remains unpalpable. What is the most appropriate next step in management?

Explanation

A pink, pulseless hand following reduction and pinning of a supracondylar fracture indicates adequate collateral perfusion. The standard of care is close clinical observation rather than immediate surgical exploration, as the pulse often returns over time.

Question 64

An 18-month-old girl presents with untreated developmental dysplasia of the left hip (DDH). Radiographs show a completely dislocated femoral head. Which of the following is the most appropriate initial management?

Explanation

In children older than 18 months with a dislocated hip, closed reduction is rarely successful or stable. Open reduction, often combined with a pelvic or femoral shortening osteotomy, is the treatment of choice to safely reduce the joint.

Pediatric Orthopaedics: Comprehensive MCQ Question Bank & Exam Prep

Orthopedic Pediatrics Review | Dr Hutaif Pediatric Orth -...

Key Takeaway

Orthopedic Pediatrics Review | Dr Hutaif Pediatric Orth -...

Chapter Index