Pediatric Orthopaedic Self Ass Review | Dr Hutaif Pedia -...

Question 1

A 9-month-old girl undergoes an attempted closed reduction for developmental dysplasia of the hip (DDH). An intraoperative arthrogram reveals an 'hourglass' constriction preventing concentric reduction. Which of the following anatomic structures is responsible for this specific arthrographic appearance?

Explanation

In Developmental Dysplasia of the Hip (DDH), an 'hourglass' constriction seen on an intraoperative arthrogram is classically caused by the iliopsoas tendon tightly crossing and compressing the redundant capsule. While the pulvinar, ligamentum teres, transverse acetabular ligament, and inverted limbus can all act as physical blocks to concentric reduction, the iliopsoas tendon specifically produces the hourglass sign. A medial dye pool (>5mm) typically indicates intervening pulvinar or ligamentum teres.

Question 2

A 12-year-old boy presents with right knee pain and a limp. He walks with an externally rotated gait. Radiographs reveal a widened and irregular right proximal femoral physis, with Klein's line failing to intersect the lateral epiphysis. Which of the following represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

Explanation

Endocrine disorders (such as hypothyroidism, renal osteodystrophy, and growth hormone deficiency) represent a very strong risk factor for bilateral slipped capital femoral epiphysis (SCFE). Patients with these metabolic conditions, as well as those with prior pelvic radiation, typically warrant prophylactic prophylactic pinning of the contralateral hip due to the unusually high incidence of a subsequent slip. Chronologic age < 10 is also an indication.

Question 3

A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs show that the lateral pillar of the femoral head has maintained approximately 60% of its original height. According to the Herring lateral pillar classification, what is his grade, and what is the expected outcome of surgical containment compared to non-operative management?

Explanation

This patient has Herring Group B Perthes disease (lateral pillar height between 50% and 100%). Based on the multicenter prospective study by Herring et al., children over the age of 8 years at the onset of symptoms with Group B or B/C border disease have significantly better radiographic outcomes when treated with surgical containment (e.g., femoral or pelvic osteotomy) compared to non-operative treatment.

Question 4

In the treatment of congenital talipes equinovarus (clubfoot) using the Ponseti method, proper cast application must follow a specific sequence. What is the primary pathoanatomy that is addressed during the application of the very first cast?

Explanation

The Ponseti method addresses the deformities of clubfoot in a specific sequence: Cavus, Adductus, Varus, and Equinus (CAVE). The very first step is to correct the midfoot cavus. This is accomplished by elevating the first ray, which supinates the forefoot to align it with the hindfoot, effectively unlocking the midtarsal joint and allowing subsequent correction of the adductus and varus.

Question 5

A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Examination in the emergency department reveals a 'pink, pulseless' hand. He is immediately taken to the operating room for closed reduction and percutaneous pinning. Following stable fixation, the hand remains well-perfused and pink, with brisk capillary refill, but the radial pulse remains non-palpable by Doppler. What is the most appropriate next step in management?

Explanation

The management of a 'pink, pulseless' hand after reduction of a supracondylar fracture relies on tissue perfusion rather than pulse status. If the hand remains well-perfused (warm, pink, brisk capillary refill) following closed reduction and pinning, the standard of care is close observation and admission for 24-48 hours. Collateral circulation is typically sufficient to maintain hand viability, and the pulse often returns over days to weeks. Vascular exploration is indicated for a 'white, pulseless' hand or if perfusion is lost after reduction.

Question 6

A 10-year-old child with spastic diplegic cerebral palsy presents with progressive crouch gait. He underwent an isolated tendo-Achilles lengthening at age 5 for toe-walking. Physical examination reveals bilateral knee flexion contractures of 15 degrees and excessive ankle dorsiflexion during the stance phase of gait. What is the most likely primary underlying etiology of his current gait deterioration?

Explanation

Crouch gait in patients with cerebral palsy is characterized by excessive hip and knee flexion with excessive ankle dorsiflexion during the stance phase. A common iatrogenic cause is isolated lengthening of the Achilles tendon (without addressing concomitant hamstring spasticity). This leads to weakness of the gastrosoleus complex, removing the plantarflexion-knee extension couple. The tibia falls forward over the foot into excessive dorsiflexion, which secondarily increases knee and hip flexion, worsening the crouch.

Question 7

A 4-year-old girl is evaluated for a history of multiple low-energy fractures. Physical examination shows blue sclerae, normal stature, and normal dentition. Genetic analysis reveals a null mutation in the COL1A1 gene, resulting in a decreased total amount of structurally normal type I collagen. According to the Sillence classification, what is the diagnosis and its inheritance pattern?

Explanation

Type I Osteogenesis Imperfecta is the most common and mildest form. It is characterized by blue sclerae, recurrent childhood fractures that often decrease after puberty, normal stature, and usually normal teeth. Genetically, it is an autosomal dominant condition caused by a quantitative defect (a null mutation) leading to a decreased amount of structurally normal type I collagen. Types II, III, and IV involve qualitative defects (structurally abnormal collagen).

Question 8

A 12-year-old premenarchal girl presents with an adolescent idiopathic scoliosis. Her standing posteroanterior radiograph shows a right thoracic curve measuring 35 degrees. Her Risser stage is 0. What is the most appropriate evidence-based management for this patient?

Explanation

Based on the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST), bracing significantly decreases the progression of high-risk curves to the surgical threshold. The indication for bracing is a curve between 25 and 45 degrees in a skeletally immature patient (Risser 0-2, premenarchal or <1 year postmenarchal). A TLSO brace worn for a minimum of 18 hours per day demonstrates a dose-dependent success rate.

Question 9

A 14-year-old female gymnast complains of insidious onset, mechanical low back pain that is sharply exacerbated by lumbar extension. Her neurological examination is unremarkable. Standard AP, lateral, and oblique radiographs of the lumbar spine show no abnormalities. What is the most appropriate next imaging study to evaluate for an acute pars interarticularis stress reaction while minimizing ionizing radiation?

Explanation

In a pediatric or adolescent athlete with suspected acute spondylolysis (pars stress reaction) and normal radiographs, MRI of the lumbar spine (specifically utilizing STIR or T2 fat-suppressed sequences) is the diagnostic modality of choice. It is highly sensitive for detecting bone marrow edema indicative of an early stress reaction, without exposing the young patient to the significant ionizing radiation associated with CT scans or SPECT.

Question 10

A 13-year-old boy presents with a painful, rigid flatfoot and a history of recurrent ankle sprains. Physical examination reveals severely restricted subtalar motion and palpable spasm of the peroneal tendons. A lateral radiograph demonstrates an elongation of the anterior process of the calcaneus, known as the 'anteater sign'.

What is the most likely diagnosis?

Explanation

The 'anteater sign' on a lateral radiograph is pathognomonic for a calcaneonavicular coalition. This is a common cause of rigid flatfoot and peroneal spasticity in adolescents (typically becoming symptomatic between ages 8 and 12). In contrast, a talocalcaneal coalition typically becomes symptomatic slightly later (ages 12-16) and is associated with the 'C-sign' on a lateral radiograph.

Question 11

A 3-year-old boy weighing 14 kg is brought to the emergency department after falling from a low bed. Radiographs demonstrate an isolated, closed, spiral midshaft fracture of the right femur with 1.5 cm of shortening. The child is otherwise healthy and the history is consistent with the injury. What is the most appropriate definitive management?

Explanation

For young children (typically ages 6 months to 4-5 years) weighing less than 20 kg (44 lbs) with an isolated diaphyseal femur fracture and less than 2-3 cm of initial shortening, early hip spica casting is the gold standard treatment. Flexible nailing is indicated for older children (ages 5-11) or those weighing over 20 kg. A Pavlik harness is used for infants younger than 6 months.

Question 12

A 5-year-old boy is evaluated for an acute onset of right hip pain and a limp. He is afebrile but refuses to bear any weight on the right leg. Laboratory tests show a WBC count of 11,000/mm³, an ESR of 25 mm/hr, and a CRP of 0.8 mg/dL. Radiographs of the pelvis are unremarkable. According to the Kocher criteria, what is the approximate statistical probability that this patient has septic arthritis of the hip?

Explanation

The Kocher criteria differentiate septic arthritis from transient synovitis in children. The four criteria are: non-weight-bearing on the affected side, fever > 38.5°C (101.3°F), ESR > 40 mm/hr, and WBC > 12,000/mm³. This patient meets only ONE criterion (non-weight-bearing). The probability of septic arthritis based on the number of criteria met is: 0 criteria = <1%, 1 criterion = 3%, 2 criteria = 40%, 3 criteria = 71%, and 4 criteria = 93%.

Question 13

A 3-year-old girl is evaluated for persistent bowing of her lower extremities. A standing AP radiograph reveals bilateral genu varum. Which of the following radiographic parameters is most predictive of progression to infantile Blount disease rather than representing physiologic bowing?

Explanation

The metaphyseal-diaphyseal angle (Drennan angle) is a critical radiographic measurement used to distinguish physiologic bowing from infantile Blount disease. An angle greater than 16 degrees is highly predictive of progression to Blount disease, whereas an angle less than 10 degrees suggests physiologic bowing that will likely resolve spontaneously. Angles between 10 and 16 degrees warrant close radiographic observation.

Question 14

A 9-year-old boy presents with arm pain after throwing a baseball. Radiographs reveal a minimally displaced pathologic fracture through a centrally located, geographic, purely radiolucent lesion in the proximal humerus metaphysis. A small fragment of cortical bone is seen resting at the dependent portion of the radiolucent cavity.

What is the most likely diagnosis?

Explanation

The scenario describes the classic 'fallen leaf' (or 'fallen fragment') sign, which is pathognomonic for a unicameral bone cyst (UBC), also known as a simple bone cyst. It occurs when a piece of the thin cortical wall fractures and falls into the fluid-filled cavity. Aneurysmal bone cysts (ABCs) are typically eccentrically located and expansile, and do not demonstrate this sign.

Question 15

A 6-year-old boy is brought to the clinic due to torticollis that has been present for two weeks. His mother reports the symptoms began a few days after he recovered from a severe streptococcal pharyngitis. He holds his head tilted to the right and rotated to the left. Neurologic examination is entirely normal. A dynamic CT scan demonstrates a fixed C1-C2 rotation. What is the most likely diagnosis?

Explanation

Grisel syndrome is a non-traumatic atlantoaxial rotatory subluxation (AARS) that occurs secondary to an inflammatory process in the upper respiratory tract or neck, such as pharyngitis, tonsillitis, or retropharyngeal abscess. The inflammation causes hyperemia and laxity of the transverse ligament and adjacent capsular structures, leading to subluxation.

Question 16

An infant is born with prominent anterolateral bowing of the left tibia. Radiographs demonstrate cortical thickening, obliteration of the medullary canal, and sclerosis at the apex of the curve. Which of the following systemic conditions is most strongly associated with this orthopaedic manifestation?

Explanation

Anterolateral bowing of the tibia is the classic precursor to congenital pseudarthrosis of the tibia (CPT). Over 50% of patients with CPT have an underlying diagnosis of Neurofibromatosis type 1 (NF-1). In contrast, posteromedial bowing is typically a benign condition associated with calcaneovalgus foot posture and resolves spontaneously, though it can leave a leg length discrepancy.

Question 17

A 7-year-old boy is evaluated for a painless, audible 'clunking' in his lateral knee during walking. Physical examination reveals a palpable snapping over the lateral joint line during active knee extension. MRI confirms a thick, block-like lateral meniscus. Which specific ligamentous attachments are uniquely deficient in the Wrisberg variant of this condition?

Explanation

The patient has a snapping discoid lateral meniscus. The Wrisberg variant is a specific type of discoid meniscus characterized by a lack of normal posterior meniscotibial (coronary) ligament attachments. Its only posterior attachment is to the posterior meniscofemoral ligament of Wrisberg. This lack of peripheral fixation causes hypermobility, leading the meniscus to subluxate anteriorly into the joint during extension, causing the classic 'snap' or 'clunk'.

Question 18

A 4-year-old boy is referred for progressive lower extremity bowing and short stature. He has a waddling gait. Laboratory analysis reveals normal serum calcium, significantly low serum phosphate, normal parathyroid hormone (PTH) levels, and elevated alkaline phosphatase. Which of the following is the most likely underlying genetic mechanism for his disorder?

Explanation

The clinical and laboratory picture (normal calcium, normal PTH, low phosphate) is classic for X-linked hypophosphatemic rickets (XLHR), the most common form of heritable rickets. It is caused by a mutation in the PHEX gene, which leads to overactivity of FGF23, resulting in profound renal phosphate wasting and impaired bone mineralization. Nutritional rickets would typically present with low/normal calcium and elevated PTH.

Question 19

A 13-year-old girl twists her ankle while playing soccer and is unable to bear weight. Radiographs demonstrate a displaced Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis.

This specific fracture pattern occurs because of the asymmetric closure of the distal tibial physis. Which portion of the distal tibial physis is typically the LAST to close?

Explanation

The injury described is a juvenile Tillaux fracture. It occurs because the distal tibial physis closes in an asymmetric, characteristic pattern over approximately an 18-month period. Closure begins centrally, progresses medially, then posteriorly, and the anterolateral portion is the last to close. During this vulnerable period, an external rotation force causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis.

Question 20

A 5-year-old boy sustains a minimally displaced lateral condyle fracture of the humerus (Milch Type II) that is treated with long-arm cast immobilization. The patient is lost to follow-up and returns 12 years later as a teenager. He has developed a progressive, prominent deformity of the elbow. Which of the following is the most likely long-term neurologic complication associated with nonunion of this specific fracture?

Explanation

Nonunion of a lateral condyle fracture typically results in progressive cubitus valgus due to continued growth of the medial side while the lateral side fails to grow or shifts proximally. Over time, the increasing valgus deformity stretches the ulnar nerve behind the medial epicondyle, classically leading to a tardy ulnar nerve palsy.

Question 21

A 5-year-old girl presents with a high-riding left scapula and restricted shoulder abduction. Imaging reveals an omovertebral bone bridging the cervical spine and the scapula. If a Woodward procedure is planned, which of the following structures is most at risk during the release of the superior medial angle of the scapula?

Explanation

During a Woodward procedure for Sprengel deformity, the spinal accessory nerve is at risk when detaching the trapezius from the scapula, especially at the superomedial angle where the omovertebral bone typically attaches.

Question 22

A newborn is noted to have a shortened right lower extremity with a valgus ankle and absent lateral rays of the foot.

Which of the following knee ligament anomalies is most consistently associated with this condition?

Explanation

Fibular hemimelia is the most common congenital long bone deficiency. It is highly associated with an absent or hypoplastic anterior cruciate ligament (ACL), a ball-and-socket ankle joint, absent lateral rays, and tarsal coalitions.

Question 23

A 3-year-old child with Proximal Focal Femoral Deficiency (PFFD) has a severely shortened femur, an absent femoral head, and no true acetabulum evident on radiographs. According to the Aitken classification, which class does this represent?

Explanation

In the Aitken classification of PFFD: Class A has a femoral head and normal acetabulum with a subtrochanteric defect that eventually ossifies. Class B has a femoral head and normal acetabulum, but the subtrochanteric pseudoarthrosis does not ossify. Class C lacks a femoral head and has severe acetabular dysplasia, but a small tuft of proximal femur exists. Class D is the most severe, with an absent femoral head, absent acetabulum, and a severely shortened femoral shaft with no proximal tuft.

Question 24

A 2-year-old boy presents with an anterolateral bow of the tibia and an impending fracture.

You suspect a systemic condition. Which of the following is the most appropriate initial screening measure for the presumed diagnosis?

Explanation

Anterolateral bowing of the tibia is pathognomonic for congenital pseudoarthrosis of the tibia (CPT), which is strongly associated with Neurofibromatosis type 1 (NF1) in up to 50% of cases. Screening for NF1 includes assessing clinical criteria such as Lisch nodules (iris hamartomas) via a slit-lamp examination.

Question 25

Which type of Osteogenesis Imperfecta (OI) is considered the most severe form compatible with survival past the neonatal period, typically characterized by severe progressive deformity, extremely short stature, and dentinogenesis imperfecta?

Explanation

According to the Sillence classification for OI: Type I is mild (blue sclera, normal height, rare deformity). Type II is perinatal lethal. Type III is the most severe non-lethal form, characterized by progressive deformity, very short stature, dentinogenesis imperfecta, and normal to grayish sclerae. Type IV is intermediate in severity.

Question 26

A 2-year-old child with achondroplasia presents with hypotonia, motor delay, and newly diagnosed central sleep apnea.

What is the most likely etiology of these neurological findings?

Explanation

In achondroplasia, foramen magnum stenosis is a critical and potentially life-threatening complication in infants and toddlers. It causes cervicomedullary compression leading to central sleep apnea, hypotonia, quadriparesis, sudden death, and motor delays.

Question 27

A 7-year-old boy with Morquio syndrome (Mucopolysaccharidosis type IV) is evaluated prior to undergoing a corrective osteotomy for severe genu valgum. Which of the following preoperative evaluations is most critical for avoiding a catastrophic perioperative complication?

Explanation

Morquio syndrome is characterized by odontoid hypoplasia and severe ligamentous laxity, which frequently leads to profound atlantoaxial instability (C1-C2). Preoperative flexion-extension cervical spine radiographs (and often an MRI) are critical before any surgery requiring intubation or positioning to prevent cervical spinal cord injury.

Question 28

A 12-year-old gymnast presents with lower back pain and is diagnosed with an L5-S1 isthmic spondylolisthesis. Her slip is currently measured at 30% (Grade II). Which of the following radiographic parameters indicates the highest risk for progression of the slip?

Explanation

Risk factors for the progression of a pediatric spondylolisthesis include young age, female sex, high slip grade (>50%), high slip angle (kyphotic L5-S1 angle), a high pelvic incidence, and dysplastic features such as doming of the sacrum or a trapezoidal L5. A dysplastic sacral dome directly decreases the bony restraint to anterior translation.

Question 29

A 13-year-old boy presents with frequent lateral ankle sprains and rigid, flat feet. On examination, subtalar motion is markedly restricted. Which of the following radiographic findings is most characteristic of a calcaneonavicular coalition?

Explanation

The 'anteater nose sign' represents an elongation of the anterior process of the calcaneus, which is the classic radiographic finding for a calcaneonavicular coalition, best visualized on a 45-degree internal oblique radiograph of the foot. The 'C-sign' is seen on lateral radiographs in talocalcaneal coalitions.

Question 30

Which of the following best describes the fundamental pathoanatomy of congenital vertical talus?

Explanation

Congenital vertical talus is characterized by a fixed, rigid plantarflexed talus with an irreducible dorsal dislocation of the navicular on the talar neck. The calcaneus is in fixed equinus and valgus, distinguishing it from oblique talus, where the navicular dislocation is reducible.

Question 31

An 8-year-old boy with Legg-Calve-Perthes disease is evaluated.

Radiographs obtained during the fragmentation phase demonstrate that only 40% of the lateral pillar of the femoral head has maintained its normal radiolucent height. According to the Herring Lateral Pillar Classification, what is the assigned grade, and what is the expected prognosis?

Explanation

Herring Lateral Pillar Group C indicates that less than 50% of the lateral pillar height is maintained during the fragmentation phase. These hips have a poor prognosis for spherical congruency (often developing Stulberg IV or V outcomes) and generally perform poorly regardless of the chosen treatment modality, especially in children older than 8 years.

Question 32

A 12-year-old boy weighing 95 kg presents with a unilateral stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in-situ pinning of the asymptomatic, normal contralateral hip?

Explanation

While young age (boys <12, girls <10) and open triradiate cartilage increase the risk for contralateral SCFE, the strongest absolute indication for prophylactic pinning is an underlying endocrinopathy (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or prior pelvic radiation therapy, as the risk of a contralateral slip approaches 50-100% in these populations.

Question 33

A 2-year-old girl is brought in by her parents for significant bowing of both legs.

You are trying to differentiate between physiologic genu varum and infantile Blount disease. Which of the following radiographic parameters is most diagnostic of infantile Blount disease?

Explanation

Drennan's metaphyseal-diaphyseal angle (MDA) is critical in differentiating physiologic bowing from infantile Blount disease. An angle >16 degrees has a very high positive predictive value for Blount disease. An angle <10 degrees strongly suggests physiologic bowing.

Question 34

A 6-month-old infant presents with complete, simple syndactyly of the long and ring fingers of the right hand. When discussing surgical release, what is the ideal timing and the most critical technical consideration to prevent web creep?

Explanation

Simple syndactyly release is typically performed between 12 and 18 months of age, before the development of fine motor pinch skills. Border digits (thumb-index or ring-small) are released earlier (around 6 months) to prevent angular deformity. To reconstruct the web space and prevent distal migration (web creep), a dorsal rectangular or triangular flap is typically utilized, along with full-thickness skin grafts for the exposed sides of the digits.

Question 35

A newborn is noted to have severe bilateral radial deviation of the wrists, absent thumbs, and an absent radius on radiographs. An echocardiogram reveals an atrial septal defect (ASD). Which of the following syndromes is most likely?

Explanation

Holt-Oram syndrome is an autosomal dominant condition characterized by radial longitudinal deficiency (often bilateral with absent thumbs) and congenital heart defects, most commonly an ASD or VSD. TAR syndrome typically features an absent radius but importantly has present thumbs, distinguishing it from other causes of radial clubhand.

Question 36

A 6-year-old child with spastic quadriplegic cerebral palsy (GMFCS Level V) undergoes routine hip surveillance.

The AP pelvic radiograph shows a Reimers Migration Percentage of 45% on the right hip. The hip is reducible, and there is no pain. Which of the following is the most appropriate management?

Explanation

In children with CP, a Reimers Migration Percentage (RMP) >40-50% indicates significant hip subluxation with bony dysplasia. While soft tissue releases are indicated for early subluxation (RMP 30-40%) in younger children, an RMP >40% typically requires bony reconstruction with a Varus Derotational Osteotomy (VDRO) and a pelvic osteotomy (e.g., Dega or San Diego) to prevent painful chronic dislocation.

Question 37

A 6-year-old boy presents with severe neck pain and torticollis 10 days after a tonsillectomy. He holds his head tilted to the right and rotated to the left. Neurological examination is normal. Radiographs reveal an increased atlantodental interval (ADI) of 4.5 mm. Which of the following is the most likely diagnosis?

Explanation

Grisel syndrome is a non-traumatic atlantoaxial rotatory subluxation (AARS) associated with inflammation of the adjacent head and neck tissues (such as after pharyngitis, tonsillectomy, or upper respiratory tract infections). The inflammatory hyperemia causes laxity of the transverse ligament, leading to subluxation.

Question 38

A 10-year-old boy sustains a minor twisting injury to his proximal humerus. Radiographs show a centrally located, expansile, purely lytic lesion in the metadiaphysis with a 'fallen leaf' sign.

Which of the following describes the most appropriate initial management for this lesion after the fracture heals?

Explanation

The scenario and 'fallen leaf' sign describe a simple (unicameral) bone cyst (UBC), classic for a proximal humerus lesion. After the pathologic fracture heals, initial management typically involves cyst aspiration (yielding serous fluid) followed by an injection of corticosteroids (methylprednisolone) or bone marrow aspirate to stimulate healing.

Question 39

A newborn is examined in the nursery and noted to have severe genu recurvatum with the tibia dislocated anteriorly on the femur. Which of the following conditions is most commonly associated with this presentation, and what is the primary initial treatment?

Explanation

Congenital dislocation of the knee (CDK) presents as a hyperextension deformity. It is strongly associated with developmental dysplasia of the hip (DDH) and clubfoot. Initial treatment for idiopathic CDK involves gentle manipulation and serial casting to gradually bring the knee into a flexed position.

Question 40

A 3-month-old infant presents with irritability, fever, and massive swelling of the mandible and bilateral clavicles. Radiographs reveal marked periosteal new bone formation. Laboratory studies show an elevated ESR and alkaline phosphatase. What is the most appropriate management?

Explanation

The clinical picture is classic for Infantile Cortical Hyperostosis (Caffey disease). It typically presents before 6 months of age with a triad of irritability, soft tissue swelling, and cortical thickening/hyperostosis of the underlying bones (most commonly the mandible, clavicles, and ulnae). It is a self-limiting inflammatory condition that resolves spontaneously, and treatment is symptomatic with NSAIDs.

Question 41

A 6-year-old boy falls on an outstretched hand and sustains an extension-type supracondylar humerus fracture. Upon neurologic examination, he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which of the following nerves is most likely injured?

Explanation

Anterior interosseous nerve (AIN) injury is the most common neurologic complication in extension-type supracondylar humerus fractures. It presents clinically as an inability to form the "OK" sign due to weakness of the flexor pollicis longus and flexor digitorum profundus.

Question 42

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her one-week follow-up, the parents report she is not moving her right leg as much. Exam reveals decreased active knee extension on the affected side. What is the most appropriate next step in management?

Explanation

Transient femoral nerve palsy is a known complication of excessive hip flexion in a Pavlik harness, presenting as decreased active knee extension. The harness must be discontinued temporarily to allow for nerve recovery before resuming or altering treatment.

Question 43

A 3-year-old boy treated successfully with the Ponseti method for idiopathic clubfoot presents with an early relapse. He walks with a dynamic supination deformity of the foot during the swing phase of gait. Passive dorsiflexion is 15 degrees. After correcting any residual fixed deformities with a brief period of serial casting, what is the most appropriate surgical intervention?

Explanation

Relapsed clubfoot presenting with dynamic supination in a child over 2.5 years of age is best treated with a tibialis anterior tendon transfer (TATT) to the lateral cuneiform. This eliminates the deforming supination force and balances the foot.

Question 44

A 14-year-old boy presents with acute ankle pain after an external rotation injury. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. Avulsion by which of the following structures is responsible for this fracture pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is caused by an avulsion force from the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury as the physis begins to close asymmetrically.

Question 45

A 4-year-old boy presents with an acute onset limp, severe right hip pain, and a temperature of 38.6°C. He refuses to bear weight on the right leg. Laboratory evaluation reveals an ESR of 45 mm/hr and a WBC count of 13,500/mm³. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?

Explanation

The Kocher criteria for differentiating septic arthritis from transient synovitis include non-weight-bearing, temperature >38.5°C, ESR >40 mm/hr, and WBC >12,000/mm³. The presence of all four criteria yields a 99% predicted probability of septic arthritis.

Question 46

A 5-year-old girl with spastic quadriplegic cerebral palsy is undergoing routine hip surveillance. Which of the following radiographic parameters is the most critical to monitor for predicting the risk of progressive hip subluxation and the need for reconstructive surgery?

Explanation

Reimers migration percentage is the standard and most reliable radiographic measurement for monitoring hip displacement in children with cerebral palsy. A migration percentage exceeding 30% typically prompts consideration for soft tissue or bony reconstructive surgery.

Question 47

A 13-year-old premenarchal female presents for evaluation of a spinal deformity. Radiographs reveal a right thoracic curve with a Cobb angle of 32 degrees. Her Risser stage is 0. What is the most appropriate management?

Explanation

TLSO bracing is indicated in skeletally immature patients (Risser 0-2, premenarchal) with adolescent idiopathic scoliosis who have a curve magnitude between 25 and 45 degrees. Bracing has been shown to significantly decrease the risk of curve progression to surgical magnitude.

Question 48

A 12-year-old boy presents with a history of recurrent ankle sprains and a painful, rigid flatfoot. A lateral radiograph of the foot demonstrates an elongated anterior process of the calcaneus, known as the "anteater nose" sign. Which of the following conditions is the most likely diagnosis?

Explanation

The "anteater nose" sign on a lateral foot radiograph is pathognomonic for a calcaneonavicular coalition. This condition typically presents between 8 and 12 years of age as the cartilaginous bar begins to ossify, causing a rigid, painful flatfoot.

Question 49

A 13-year-old obese boy with left hip pain after a minor fall is unable to bear weight, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Compared to a patient with a stable SCFE, this patient is at significantly higher risk for which of the following complications?

Explanation

An unstable SCFE is defined clinically by the inability to bear weight. It carries a markedly higher risk of avascular necrosis (AVN), reaching up to nearly 50%, due to the acute disruption of the epiphyseal blood supply.

Question 50

A newborn is evaluated for a shortened right lower extremity and an absent lateral foot ray. Radiographs confirm fibular hemimelia. Which of the following is the most common associated ligamentous anomaly in the ipsilateral knee?

Explanation

Fibular hemimelia is a longitudinal limb deficiency characterized by a shortened tibia, absent fibula, and absent lateral rays. It is highly associated with knee instability, most commonly due to an absent or severely hypoplastic anterior cruciate ligament (ACL).

Question 51

A neonate is born with blue sclerae, significant limb deformities, and multiple healing intrauterine fractures. The infant develops severe respiratory distress and succumbs to respiratory failure shortly after birth. According to the Sillence classification for Osteogenesis Imperfecta (OI), which type does this presentation represent?

Explanation

Sillence Type II is the perinatal lethal form of Osteogenesis Imperfecta. It is characterized by severe bone fragility, multiple in utero fractures, profound deformities, and early death typically due to pulmonary hypoplasia and respiratory insufficiency.

Question 52

A 2-year-old child weighing in the 99th percentile presents with bilateral severe genu varum. Radiographs reveal a sharp varus angulation at the proximal tibial metaphysis, consistent with Langenskiöld stage II infantile Blount's disease. What is the most appropriate initial management?

Explanation

Infantile Blount's disease in a child under 3 years of age with early Langenskiöld stages (I or II) is initially managed non-operatively with knee-ankle-foot orthoses (KAFOs). Surgery is reserved for older children or cases that fail bracing.

Question 53

A 4-year-old girl is evaluated for anterolateral bowing of her left tibia that recently progressed to a fracture after a minor stumble. This specific condition is most strongly associated with which of the following genetic disorders?

Explanation

Congenital pseudarthrosis of the tibia presents with anterolateral bowing and typically fractures early in childhood. It is highly associated with Neurofibromatosis type 1 (NF-1), which is present in approximately 50% of these patients.

Question 54

A 14-year-old boy presents with vague, activity-related knee pain. MRI reveals a 1.5 cm osteochondritis dissecans (OCD) lesion on the lateral aspect of the medial femoral condyle. The physes are open, and the lesion shows no fluid signal behind the fragment. What is the most appropriate initial treatment?

Explanation

Juvenile osteochondritis dissecans (jOCD) occurring in patients with open physes and stable lesions (no fluid behind the fragment on MRI) has a high rate of spontaneous healing. A trial of non-operative management, including activity modification and brief immobilization, is the initial standard of care.

Question 55

A 6-year-old boy presents with a displaced extension-type supracondylar humerus fracture. His hand is pink and well-perfused, but he cannot flex the interphalangeal joint of his thumb or the distal interphalangeal joint of his index finger. Which of the following nerve structures is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index and middle fingers.

Question 56

A 3-year-old boy with a history of idiopathic clubfoot treated with the Ponseti method presents with a relapsed deformity. Examination reveals dynamic supination of the foot during the swing phase of gait. He has a plantigrade foot with passive correctability. Which of the following is the most appropriate surgical intervention?

Explanation

Dynamic supination in a relapsed Ponseti-treated clubfoot is best managed with a full tibialis anterior tendon transfer (TATT) to the lateral cuneiform. A SPLATT is typically reserved for spastic conditions like cerebral palsy.

Question 57

A 4-week-old female infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her leg on the affected side. On examination, there is an absence of active knee extension, but ankle and toe movements are normal. What is the most appropriate next step in management?

Explanation

The infant has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness must be removed temporarily until nerve function recovers to prevent permanent injury or 'Pavlik disease'.

Question 58

An 8-year-old girl with cerebral palsy (GMFCS Level V) presents for routine follow-up. Her AP pelvis radiograph demonstrates a Reimers' migration percentage of 55% in the right hip. There is no evidence of advanced degenerative changes. What is the most appropriate management?

Explanation

A migration percentage over 50% in a spastic CP hip is highly unlikely to resolve with soft tissue releases alone. Bony reconstruction with a VDRO and concomitant pelvic osteotomy is the standard of care to achieve stable coverage.

Question 59

A 13-year-old boy with a BMI in the 95th percentile presents with 3 weeks of knee pain and a limp. Radiographs demonstrate a stable slipped capital femoral epiphysis (SCFE) of the left hip. He is treated with single in-situ cannulated screw fixation. Two months later, he complains of global restriction of hip motion and severe pain. Radiographs reveal diffuse joint space narrowing. Which of the following factors most significantly increases the risk of this specific complication?

Explanation

Chondrolysis is characterized by diffuse joint space narrowing and stiffness after SCFE fixation. Unrecognized intra-articular hardware penetration is the most significant preventable risk factor.

Question 60

A 4-year-old boy presents with a 3-day history of right hip pain and refusal to bear weight. His temperature is 38.6°C (101.5°F). Labs reveal a WBC count of 14,000/mm³, ESR of 45 mm/hr, and a CRP of 3.5 mg/dL. According to the Kocher criteria, what is the probability that this child has septic arthritis?

Explanation

The child has 3 of the 4 classic Kocher criteria (fever, inability to bear weight, ESR >40). The probability of septic arthritis with 3 criteria is approximately 93%.

Question 61

An 18-month-old male infant presents with bilateral bowing of the lower extremities. Radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees bilaterally, with lateral thrust during gait. Which of the following is the most appropriate initial management for this condition?

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees strongly indicates infantile Blount's disease rather than physiologic bowing. Initial management for children under age 3 involves bracing (KAFOs) to offload the medial physis.

Question 62

A 14-year-old girl sustains an isolated, closed, midshaft femur fracture. She weighs 45 kg (99 lbs). Which of the following stabilization methods is associated with the lowest risk of osteonecrosis of the femoral head while providing optimal stability?

Explanation

For pediatric patients weighing less than 50 kg, ESIN provides excellent stability and allows early mobilization. Rigid antegrade nailing through the piriformis fossa carries an unacceptably high risk of avascular necrosis in children.

Question 63

A neonate is diagnosed with achondroplasia. Which of the following routine screening evaluations is most critical in the first year of life to prevent sudden death?

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, which can cause cervicomedullary compression and central sleep apnea. Early screening with a polysomnogram and MRI is critical to identify those needing suboccipital decompression.

Question 64

A 4-year-old boy, initially treated for idiopathic clubfoot with the Ponseti method, presents with recurrent deformity. During gait analysis, he demonstrates dynamic supination of the foot during the swing phase. Passive range of motion is full and symmetric to the contralateral side. Which of the following is the most appropriate surgical management?

Explanation

Dynamic supination during the swing phase in a recurrent clubfoot with supple passive ROM is a classic indication for a whole anterior tibial tendon transfer to the lateral cuneiform (or cuboid). This rebalances the foot without tethering the dynamic inversion forces.

Question 65

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. On initial presentation, his hand is pulseless but pink, warm, and has a capillary refill time of 1.5 seconds. After successful closed reduction and percutaneous pinning, the radial pulse remains unpalpable, but the hand remains pink and warm with excellent capillary refill. What is the most appropriate next step in management?

Explanation

A 'pulseless but pink' hand after anatomic closed reduction and pinning of a supracondylar humerus fracture is an indication for observation. As long as perfusion is clinically adequate, collateral circulation is sufficient, and the pulse often returns within a few days.

Question 66

A 13-year-old boy undergoes in situ single-screw fixation for a stable, moderate Slipped Capital Femoral Epiphysis (SCFE). Six months later, he complains of increasing hip pain and profound global stiffness. Radiographs demonstrate concentric joint space narrowing of the affected hip without segmental collapse. What is the most likely etiology of this complication?

Explanation

Chondrolysis in the setting of SCFE is strongly associated with unrecognized pin penetration into the joint space. It presents with progressive global stiffness, pain, and concentric joint space narrowing on radiographs.

Question 67

A 13-year-old boy presents with a painful, rigid flatfoot and a history of recurrent ankle sprains. Lateral radiographs of the foot demonstrate a continuous bony outline connecting the talar dome and the sustentaculum tali (the 'C-sign'). What is the most likely diagnosis, and which anatomical structure is primarily involved?

Explanation

The 'C-sign' on a lateral foot radiograph is indicative of a talocalcaneal coalition. This coalition most commonly involves the middle facet of the subtalar joint.

Question 68

A 6-week-old female infant is currently being treated in a Pavlik harness for Developmental Dysplasia of the Hip (DDH). Her mother notes that the infant has stopped kicking her right leg over the past 24 hours. Physical examination reveals an absence of active knee extension on the right, but withdrawal to a needle prick remains intact. What is the most appropriate next step in management?

Explanation

The patient is presenting with a femoral nerve palsy, the most common nerve injury associated with the Pavlik harness (often due to hyperflexion). The harness should be discontinued or modified significantly until active quadriceps function returns.

Question 69

A 6-year-old girl with spastic diplegic cerebral palsy (GMFCS Level IV) is evaluated during routine hip surveillance. Her radiographs reveal a Reimers' migration percentage of 55% in the left hip with associated acetabular dysplasia. Under general anesthesia, the hip is easily reducible and abducts to 45 degrees. What is the most appropriate surgical intervention?

Explanation

In children with CP and a migration percentage > 50% with associated acetabular dysplasia, soft tissue release alone is insufficient. Comprehensive reconstruction with both a proximal femoral VDRO and a volume-reducing pelvic osteotomy is indicated.

Question 70

A 12-year-old premenarchal female presents with Adolescent Idiopathic Scoliosis (AIS). Her standing PA spine radiograph reveals a right thoracic curve of 34 degrees. Her Risser stage is 0. According to the standard guidelines, what is the most appropriate management?

Explanation

Bracing is indicated for a growing child (Risser 0-2, premenarchal) with a scoliotic curve between 25 and 45 degrees. A TLSO worn for at least 16-18 hours per day is the standard of care to halt progression.

Question 71

A 4-year-old boy presents to the emergency department with a 2-day history of right hip pain, a severe limp, and a temperature of 38.9°C. He refuses to bear weight on the right leg. Laboratory evaluation reveals a WBC count of 14,000/mm³ and an ESR of 55 mm/hr. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?

Explanation

The patient meets all 4 Kocher criteria (non-weight-bearing, temperature > 38.5°C, WBC > 12,000/mm³, ESR > 40 mm/hr). The presence of all four criteria carries a 93% to 99% predictive probability for septic arthritis.

Question 72

An infant is evaluated for short stature. Examination reveals rhizomelic shortening of the limbs, frontal bossing, midface hypoplasia, and a normal trunk length. Both parents are of average height. What is the genetic basis of this child's condition?

Explanation

The child has classic features of achondroplasia. While achondroplasia is autosomal dominant, roughly 80% of cases occur via a de novo (spontaneous) mutation in the FGFR3 gene, explaining why both parents are of normal height.

Question 73

A 14-year-old boy sustains an ankle injury while sliding into second base. Radiographs reveal a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis (Tillaux fracture). Which of the following best describes the physeal closure pattern that predisposes to this specific fracture pattern?

Explanation

The distal tibial physis closes in an asymmetric pattern: central first, then anteromedial, then posteromedial, and finally the anterolateral portion. The open anterolateral physis is avulsed by the anterior inferior tibiofibular ligament (AITFL).

Question 74

A 2-year-old girl is diagnosed with complete congenital absence of the fibula (Fibular Hemimelia). In addition to an equinovalgus foot deformity and significant limb length discrepancy, what is the most common associated anomaly within her ipsilateral knee?

Explanation

Fibular hemimelia is highly associated with a hypoplastic or absent anterior cruciate ligament (ACL), resulting in anteroposterior instability of the knee, as well as tarsal coalition and ball-and-socket ankle joints.

Question 75

A 4-year-old girl presents with severe bilateral genu varum and an observable lateral thrust during gait. Radiographs show a sharply downsloping medial tibial metaphysis with an apparent bony bridge crossing the medial physis. According to the Langenskiöld classification, this corresponds to Stage IV Blount's disease. What is the most appropriate surgical intervention?

Explanation

In Langenskiöld Stage IV (or higher) infantile Blount's disease, a medial physeal bar has formed. Successful treatment requires both excision of the tethering bony bar (epiphyseolysis) and a corrective proximal tibial osteotomy.

Question 76

A healthy 3-year-old boy weighing 16 kg sustains an isolated, closed spiral fracture of the midshaft left femur during a playground fall. Radiographs show 1.5 cm of shortening. Which of the following is the most appropriate definitive management?

Explanation

For children under the age of 5 (and typically <20 kg) with an isolated diaphyseal femur fracture and acceptable shortening (<2 cm), closed reduction and hip spica casting is the standard of care with excellent outcomes.

Question 77

An 8-year-old boy with a BMI in the 50th percentile (normal weight) presents with a 2-month history of a left-sided limp and obligatory external rotation when the left hip is flexed. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Given the patient's presentation, which of the following laboratory evaluations is most critical?

Explanation

SCFE occurring in a child under the age of 10 or outside the typical demographic (non-obese) should raise high clinical suspicion for an underlying endocrine disorder, most commonly hypothyroidism or renal osteodystrophy.

Question 78

A 3-year-old boy presents with marked anterolateral bowing of the right tibia. Radiographs demonstrate diaphyseal narrowing and an impending fracture at the apex of the deformity. Physical examination reveals six large café-au-lait macules on his trunk. What is the inheritance pattern of the most likely underlying syndrome?

Explanation

The clinical picture is classic for congenital pseudarthrosis of the tibia (CPT) associated with Neurofibromatosis Type 1 (NF1). NF1 is inherited in an autosomal dominant pattern.

Question 79

An 11-year-old boy sustains a completely displaced Salter-Harris II fracture of the distal femur. He is treated with anatomic closed reduction and percutaneous crossed pinning. Despite achieving an anatomic reduction, what is the most significant and frequent long-term complication associated with this specific injury?

Explanation

Distal femoral physeal fractures have a notoriously high rate of growth arrest (up to 50%), largely due to the undulating, highly complex anatomy of the physis, which sustains significant trauma even in Salter-Harris I and II patterns.

Question 80

A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). His radiographs demonstrate that the lateral pillar of the femoral head has maintained approximately 60% of its original height. When determining his long-term prognosis and likelihood of developing early osteoarthritis, which of the following is considered the most critical independent prognostic factor?

Explanation

In Legg-Calvé-Perthes disease, age at clinical onset is the most significant independent prognostic factor. Children diagnosed after the age of 8 typically have much poorer remodeling potential and clinical outcomes compared to younger children.

Question 81

A 14-year-old elite baseball pitcher complains of vague, progressive right shoulder pain over the past 3 months. The pain is exacerbated by throwing. AP external rotation radiographs reveal a widened proximal humerus physis compared to the contralateral side. What is the primary pathophysiology underlying this condition?

Explanation

The patient has 'Little League Shoulder', which is essentially a chronic stress fracture (epiphysiolysis) through the hypertrophic zone of the proximal humeral physis due to repetitive rotational and distraction forces.

Question 82

A 5-year-old girl is referred for evaluation of a high-riding, hypoplastic left scapula that restricts her shoulder abduction. Imaging reveals an omovertebral bone connecting the superior angle of the scapula to the cervical spine. Which of the following conditions is most strongly associated with this deformity?

Explanation

Sprengel deformity (congenital elevation of the scapula) is frequently associated with an omovertebral bone/band and is most commonly syndromically linked to Klippel-Feil syndrome (cervical spine fusion anomalies).

Question 83

A 2-month-old infant presents to the emergency department with a fresh femur fracture following a routine diaper change. Examination reveals blue sclerae, generalized osteopenia, and evidence of multiple healing rib fractures on radiographs. A diagnosis of Osteogenesis Imperfecta (OI) Type I is suspected. At the molecular level, this condition is primarily caused by a defect in which of the following?

Explanation

Osteogenesis Imperfecta is a genetic disorder of connective tissue caused primarily by qualitative or quantitative defects in Type I collagen, coded by the COL1A1 and COL1A2 genes.

Pediatric Orthopaedics: Comprehensive MCQ Question Bank & Exam Prep

Pediatric Orthopaedic Self Ass Review | Dr Hutaif Pedia -...

Key Takeaway

Pediatric Orthopaedic Self Ass Review | Dr Hutaif Pedia -...

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