An otherwise healthy 33-year-old man who works in construction reports a 3-month history of knee pain. Radiographs are shown in Figures 9a and 9b. An axial T 1 -weighted MRI scan with contrast, an angiogram, and histologies are shown in Figures 9c th

Dedifferentiated parosteal osteosarcoma

Figures A and B are radiographic images of an 85-year-old woman with isolated left hip pain. She describes a non-syncopal fall from standing 4 hours ago. Physical examination reveals pain with log-rolling the left thigh and the inability to bear weig

Stress view radiographs of the left hip

A 23-year-old male is involved in a motor vehicle accident and sustains a left open femur fracture, right open humeral shaft fracture, and an LC-II pelvic ring injury. Which of the following best describes the radiographic findings associated with th

Open-book injury with contralateral sacral compression fracture

An otherwise healthy 54-year-old man who underwent a successful multilevel lumbar decompression and fusion 4 years ago now reports increasingly severe bilateral thigh claudication with paresthesia and severe back pain for the past 12 months. Physical

Posterior decompression and instrumented fusion

A football player who injured his right lower extremity during a game could not get up and reported extreme pain. The initial sideline evaluation showed a probable anterior cruciate, posterior cruciate, and lateral collateral ligament rupture with a

Injury to the common peroneal nerve

Pediatric Orthopedics MCQ Quiz Review | Dr. Hutaif

Question 1

A 12-year-old obese male presents with left-sided Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most accepted indication for prophylactic pinning of the contralateral asymptomatic hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is indicated in patients with endocrinopathies (hypothyroidism, renal osteodystrophy, growth hormone deficiency), previous radiation therapy, and in some centers for very young age (<10 years for boys, <11 for girls) due to the exceedingly high risk of a subsequent contralateral slip.

Question 2

A 6-week-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During follow-up, she is noted to have decreased active extension of the knee on the treated side. What is the most likely cause?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hip which compresses the nerve against the inguinal ligament. It presents as decreased active extension of the knee. If this occurs, the harness should be adjusted or temporarily discontinued to prevent permanent nerve injury.

Question 3

According to the Ponseti method for treating congenital talipes equinovarus (clubfoot), what is the correct sequence of deformity correction?

Explanation

The Ponseti method corrects the clubfoot deformities in a specific sequence described by the acronym CAVE: Cavus (corrected first by elevating the first ray to align the forefoot with the hindfoot), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy as the final step).

Question 4

A 6-year-old boy falls on an outstretched hand and sustains a Gartland type III extension-type supracondylar humerus fracture. Upon examination, he is unable to make an 'OK' sign with his thumb and 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 and the flexor digitorum profundus to the index finger, both of which are required to form the 'OK' sign.

Question 5

What is the most common long-term complication associated with an un-united pediatric lateral condyle humerus fracture?

Explanation

Nonunion of a lateral condyle fracture typically leads to a progressive cubitus valgus deformity due to proximal migration of the lateral condyle. Over years or decades, this significant valgus alignment stretches the ulnar nerve behind the medial epicondyle, resulting in tardy ulnar nerve palsy.

Question 6

In a patient with Legg-Calve-Perthes disease, which of the following radiographic findings is considered a 'head-at-risk' sign according to Catterall?

Explanation

Catterall identified specific 'head-at-risk' radiographic signs that indicate a poorer prognosis in Perthes disease. These include the Gage sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), lateral calcification, lateral subluxation of the femoral head, and a horizontal growth plate.

Question 7

A 5-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated in the orthopedic clinic. Pelvic radiographs demonstrate a migration percentage of 45% bilaterally. What is the most appropriate management strategy?

Explanation

In cerebral palsy patients, a Reimer's migration percentage >40% typically indicates progressive hip subluxation that is past the point of responding to soft tissue releases alone (which are usually indicated for migration percentages between 25-40%). Bony reconstructive surgery, such as a VDRO often combined with a pelvic osteotomy, is required to achieve stable reduction.

Question 8

Proximal focal femoral deficiency (PFFD) is most frequently associated with which of the following congenital anomalies?

Explanation

PFFD is highly associated with fibular hemimelia, occurring in approximately 50-70% of cases. Evaluation of a patient with PFFD must include careful assessment of the entire limb to check for fibular deficiency, absence of cruciate ligaments, and foot deformities.

Question 9

A 13-year-old boy undergoes in situ pinning with a single cannulated screw for a stable SCFE. Three months postoperatively, he presents with severe hip pain, stiffness, and significantly restricted range of motion in all planes. Radiographs reveal a global joint space of 2 mm. What is the most likely diagnosis?

Explanation

Chondrolysis is a severe complication of SCFE, presenting with acute onset of pain, global restriction of hip motion, and joint space narrowing (<3mm) on radiographs. It is strongly associated with unrecognized intra-articular hardware penetration during pinning.

Question 10

Which of the following femoral fracture patterns in a non-ambulatory 8-month-old infant is most highly specific for non-accidental trauma (child abuse)?

Explanation

Metaphyseal corner fractures (or classic metaphyseal lesions - CMLs) are highly specific for non-accidental trauma in infants. They result from violent pulling, twisting, or flailing of the extremity. While any fracture (including spiral) in a non-ambulatory infant is suspicious, the metaphyseal corner fracture carries the highest specificity for abuse.

Question 11

A 13-year-old girl sustains a juvenile Tillaux fracture of the ankle. This fracture pattern occurs due to avulsion by which ligament, and represents a failure of which part of the distal tibial physis to close first?

Explanation

A Tillaux fracture is a Salter-Harris III avulsion of the anterolateral distal tibial epiphysis caused by tension from the anterior inferior tibiofibular ligament (AITFL). It occurs in adolescents because the distal tibial physis closes asymmetrically (central, then anteromedial, then posteromedial), leaving the anterolateral portion open last and vulnerable to avulsion.

Question 12

A 4-year-old boy with Osteogenesis Imperfecta (OI) Type III is treated with intravenous pamidronate. What is the primary cellular mechanism of action of this medication in this patient population?

Explanation

Bisphosphonates, such as pamidronate, are structural analogs of pyrophosphate that bind to hydroxyapatite crystals in bone. They are ingested by osteoclasts and induce osteoclast apoptosis, thereby inhibiting osteoclast-mediated bone resorption. In OI, this increases bone mineral density and cortical thickness, reducing fracture frequency.

Question 13

A 9-year-old boy presents with a pathologic fracture through a centrally located, completely radiolucent lesion in the proximal humerus metaphysis. Radiographs show a 'fallen leaf' sign. What is the most appropriate initial management?

Explanation

The 'fallen leaf' (or fallen fragment) sign is pathognomonic for a Unicameral Bone Cyst (UBC). When a UBC presents with a pathologic fracture, the standard initial management is non-operative (sling immobilization) to allow the fracture to heal. Fracture hematoma can sometimes stimulate spontaneous resolution of the cyst.

Question 14

Which of the following features accurately differentiates infantile Blount's disease from adolescent Blount's disease?

Explanation

Infantile Blount's disease is often bilateral (up to 80%) and classically presents with a prominent lateral thrust during gait due to severe proximal medial tibial metaphyseal beaking and associated ligamentous laxity. Adolescent Blount's is usually unilateral, lacks the pronounced lateral thrust, and does not respond to orthotics.

Question 15

A 5-year-old boy with myelomeningocele at the L4 level is being evaluated for lower extremity deformities. Based strictly on his neurologic level, which deformity of the foot and ankle is he most likely to develop?

Explanation

In an L4 myelomeningocele, the anterior tibialis (L4) is functioning, leading to strong dorsiflexion. However, the triceps surae (S1-S2) is paralyzed, resulting in an absent plantarflexion counterforce. This classic muscle imbalance produces a calcaneus or calcaneovalgus foot deformity over time.

Question 16

An infant is diagnosed with congenital muscular torticollis of the right sternocleidomastoid (SCM) muscle. What is the typical resting posture of the infant's head and neck?

Explanation

The sternocleidomastoid muscle functions to laterally flex (tilt) the neck to the ipsilateral side and rotate the chin to the contralateral side. Therefore, a contracture of the right SCM results in the head tilting toward the right shoulder and the chin rotating toward the left shoulder.

Question 17

According to the Kocher criteria, what is the probability of septic arthritis in a pediatric hip if a patient presents with a fever >38.5 C, non-weight-bearing status, ESR >40 mm/hr, and a serum WBC >12,000/mm3?

Explanation

The Kocher criteria use four independent predictors to differentiate septic arthritis from transient synovitis: fever > 38.5 C, non-weight-bearing, ESR > 40, and WBC > 12,000. The probability of septic arthritis is approximately 3% for 1 predictor, 40% for 2, 93% for 3, and 99% when all 4 predictors are present.

Question 18

A 14-year-old boy presents with frequent ankle sprains and rigid, flat feet. On examination, he has restricted subtalar motion and peroneal spasticity. Radiographs show a 'C sign' on the lateral view. What is the most likely diagnosis?

Explanation

The 'C sign' on a lateral radiograph of the foot is a continuous C-shaped arc formed by the medial outline of the talar dome and the inferior outline of the sustentaculum tali. It is highly specific for a talocalcaneal (middle facet) coalition. A calcaneonavicular coalition typically shows the 'anteater sign' on an oblique radiograph.

Question 19

Which of the following cytogenetic abnormalities is most characteristically associated with primary Aneurysmal Bone Cysts (ABCs)?

Explanation

Primary Aneurysmal Bone Cysts are true neoplasms driven by recurrent translocations involving the USP6 (ubiquitin specific peptidase 6) gene on chromosome 17p13. Understanding this has shifted the paradigm of primary ABCs from reactive lesions to benign neoplasms. t(11;22) is seen in Ewing sarcoma; t(X;18) in synovial sarcoma; GNAS in fibrous dysplasia.

Question 20

When evaluating a lateral cervical spine radiograph of a 6-year-old child following minor trauma, apparent subluxation of C2 on C3 is noted. Which radiographic line or principle is most useful to distinguish physiologic pseudosubluxation from a true traumatic injury?

Explanation

Swischuk's line is drawn from the anterior aspect of the posterior arch of C1 to the anterior aspect of the posterior arch of C3. In physiologic pseudosubluxation (a normal variant in children up to age 8), the anterior aspect of the posterior arch of C2 should pass within 1.5 to 2 mm of this line. Deviation greater than 2 mm suggests true subluxation or hangman's fracture.

Question 21

A 6-year-old child with spastic quadriplegic cerebral palsy undergoes radiographic screening of the pelvis. The Reimers' migration percentage is calculated to be 45% bilaterally. What is the most appropriate management for this patient?

Explanation

In children with cerebral palsy, hip displacement is common due to muscle imbalance. A Reimers' migration percentage (MP) greater than 40-50% in a spastic patient is generally an indication for reconstructive surgery to prevent a painful, dislocated hip. This is typically achieved with a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego) to improve acetabular coverage.

Question 22

Sillence Type I Osteogenesis Imperfecta (OI) typically presents with milder skeletal fragility and blue sclerae. Which of the following best describes the underlying genetic and molecular defect in this type of OI?

Explanation

Sillence Type I OI is the most common and mildest form. It is generally caused by a quantitative defect—specifically, decreased synthesis of structurally normal type I collagen, most often due to a premature stop codon (null allele) in the COL1A1 gene. Types II, III, and IV are typically caused by qualitative defects (abnormal collagen structure), usually from glycine substitutions in COL1A1 or COL1A2.

Question 23

A 5-year-old boy presents with an extension-type supracondylar humerus fracture. Radiographs show posterolateral displacement of the distal fragment. Based on this displacement pattern, which nerve is at the highest risk of injury?

Explanation

In extension-type supracondylar humerus fractures, the distal fragment dictates the direction of the proximal fragment. With posterolateral displacement of the distal fragment, the sharp proximal fragment displaces anteromedially. This places the structures in the anteromedial compartment—specifically the median nerve (AIN branch) and the brachial artery—at the greatest risk of injury. Posteromedial displacement endangers the radial nerve.

Question 24

A 10-year-old child presents with a progressive elbow deformity and numbness in the small finger. History reveals a conservatively managed lateral condyle fracture at age 4. What is the most likely structural deformity and the associated nerve palsy?

Explanation

Nonunion or premature lateral growth arrest following a lateral condyle fracture classically leads to a progressive cubitus valgus deformity. Over time, this valgus angulation stretches the ulnar nerve within the cubital tunnel, resulting in a tardy ulnar nerve palsy.

Question 25

A 14-year-old gymnast is diagnosed with a L5 isthmic spondylolysis. Which of the following factors is the strongest risk factor for the progression of spondylolysis to spondylolisthesis?

Explanation

Risk factors for the progression of spondylolysis to spondylolisthesis include a high slip angle, high pelvic incidence, dysplastic facet joints, and dome-shaped sacrum. The highest risk of progression occurs during the adolescent growth spurt.

Question 26

A 13-year-old boy presents with a painful, rigid flatfoot and peroneal spasticity. A lateral radiograph of the foot reveals the 'C-sign'. This radiographic finding is pathognomonic for which condition?

Explanation

The 'C-sign' on a lateral radiograph of the foot is highly indicative of a talocalcaneal (subtalar) coalition. It is formed by a continuous C-shaped arc representing the medial border of the talar dome and the posterior/inferior aspect of the sustentaculum tali. Calcaneonavicular coalitions classically demonstrate the 'anteater sign'.

Question 27

A 2.5-year-old girl is diagnosed with infantile Blount disease (tibia vara) with bilateral Langenskiöld stage II changes. What is the most appropriate initial management?

Explanation

For children under age 3 with infantile Blount disease exhibiting Langenskiöld stages I or II, bracing with KAFOs worn during weight-bearing is the standard initial treatment to correct the varus deformity. Surgery is indicated for children over 3-4 years old with progressive deformity or those with Langenskiöld stage III or higher.

Question 28

A newborn is evaluated for an absent right radius and an absent thumb (radial longitudinal deficiency). The consulting orthopedic surgeon recommends a thorough pediatric and genetics workup. Which of the following cardiac conditions is most classically associated with this musculoskeletal deformity?

Explanation

Radial longitudinal deficiency is associated with several syndromes, notably Holt-Oram syndrome (autosomal dominant, TBX5 mutation). Holt-Oram is classically characterized by radial-sided upper extremity anomalies and congenital heart defects, most commonly Atrial Septal Defects (ASDs) and Ventricular Septal Defects (VSDs).

Question 29

In a patient with spastic diplegic cerebral palsy, a 'crouch gait' can be severely exacerbated by isolated, iatrogenic surgical lengthening of which of the following structures?

Explanation

Crouch gait is characterized by excessive hip and knee flexion with increased ankle dorsiflexion during the stance phase. Isolated lengthening of the Achilles tendon (heel cords) in a child with spastic diplegia severely weakens the plantarflexion-knee extension couple, causing the tibia to advance too rapidly over the foot and forcing the knee into iatrogenic crouch.

Question 30

Achondroplasia is the most common form of short-limbed dwarfism. Which of the following accurately describes the molecular pathogenesis and inheritance pattern of this condition?

Explanation

Achondroplasia is caused by a gain-of-function mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, which paradoxically inhibits chondrocyte proliferation in the proliferative zone of the physis. It is inherited in an autosomal dominant pattern, although ~80% of cases occur as spontaneous new mutations.

Question 31

A 9-year-old boy falls and fractures his proximal humerus. Radiographs reveal a central, purely lytic lesion in the metaphysis with a piece of cortical bone resting dependently within the cavity ('fallen leaf' sign). If aspirated, the fluid within this cyst is most likely to contain high levels of which substance?

Explanation

The clinical and radiographic presentation is classic for a Unicameral Bone Cyst (UBC) complicated by a pathologic fracture (fallen leaf sign). The serous fluid within a UBC is typically high in prostaglandins, interleukins, and other bone-resorbing factors, which contribute to the lytic expansion of the cyst.

Question 32

A 4-year-old boy sustains an isolated, closed spiral midshaft femur fracture after a fall from a slide. There is 1.5 cm of shortening. What is the gold standard treatment for this patient?

Explanation

For children between the ages of 6 months and 5 years with a diaphyseal femur fracture and less than 2 cm of shortening, early hip spica casting is the gold standard treatment. Flexible nailing is generally reserved for older children (ages 5-11 years).

Question 33

A 12-year-old boy with a BMI of 35 presents with acute-on-chronic hip pain. He is diagnosed with a slipped capital femoral epiphysis (SCFE). According to the Loder classification, which clinical finding classifies his SCFE as 'unstable'?

Explanation

The Loder classification divides SCFE into stable and unstable categories based entirely on the clinical ability to bear weight. An unstable SCFE is defined as the inability to bear weight, even with assistive devices. Unstable SCFEs carry a much higher risk of avascular necrosis (AVN), historically up to 47%.

Question 34

Congenital pseudarthrosis of the tibia (CPT) typically presents with anterolateral bowing of the tibia and subsequent fracture that fails to heal. This condition is most strongly associated with which of the following genetic syndromes?

Explanation

Congenital pseudarthrosis of the tibia (CPT) is strongly associated with Neurofibromatosis type 1 (NF1). Approximately 50% of patients with CPT have clinical stigmata of NF1, and the condition is notoriously difficult to treat, often requiring excision of the pseudarthrosis, bone grafting, and rigid internal fixation.

Question 35

When evaluating a patient with Adolescent Idiopathic Scoliosis (AIS), which of the following parameters is the strongest clinical predictor for the risk of curve progression?

Explanation

The risk of curve progression in AIS is highly dependent on the remaining growth potential. The period of highest risk for progression corresponds to the adolescent growth spurt, known as peak height velocity. Markers of skeletal immaturity (e.g., Risser 0, open triradiate cartilage) indicate that the child is entering or currently in this high-risk phase.

Question 36

A 13-year-old boy twists his ankle and sustains a Tillaux fracture (avulsion fracture of the anterolateral distal tibial epiphysis). This specific fracture pattern is dictated by the physiological closure sequence of the distal tibial physis. Which of the following describes the correct sequence of closure?

Explanation

The distal tibial physis closes asymmetrically over approximately 18 months. The closure begins centrally, proceeds anteromedially, then posteromedially, and finishes anterolaterally. Because the anterolateral physis remains open the longest, it is susceptible to avulsion by the anterior inferior tibiofibular ligament (AITFL), resulting in a Tillaux fracture.

Question 37

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Which of the following radiographic findings is one of Catterall's 'head-at-risk' signs, indicating a poorer prognosis and a higher likelihood of femoral head deformation?

Explanation

Catterall described five 'head-at-risk' signs that portend a poor prognosis in Perthes disease: 1) Gage sign (a V-shaped radiolucency in the lateral epiphysis and adjacent metaphysis), 2) Lateral calcification, 3) Lateral subluxation of the femoral head, 4) Metaphyseal cysts, and 5) A horizontal growth plate.

Question 38

A newborn is evaluated for congenital constriction rings around multiple digits, with an auto-amputation of the right index finger. This is diagnosed as Amniotic Band Syndrome. Which of the following congenital orthopedic anomalies is most commonly associated with this condition?

Explanation

Amniotic band syndrome is caused by the entrapment of fetal parts (usually limbs or digits) in fibrous amniotic bands. It is highly associated with clubfoot, occurring in up to 30% of these patients. It is also associated with cleft lip/palate and acrosyndactyly.

Question 39

A 5-year-old girl is brought to the ED after a motor vehicle collision. Neurological exam is normal. The lateral cervical spine radiograph shows 3 mm of anterior translation of C2 on C3. Which radiographic reference line is best used to differentiate physiologic pseudosubluxation from a true traumatic ligamentous injury?

Explanation

Swischuk's line (posterior cervical line) is drawn from the anterior aspect of the posterior arch of C1 to the anterior aspect of the posterior arch of C3. In physiologic pseudosubluxation of C2 on C3 (common in young children), the anterior aspect of the posterior arch of C2 should lie within 1-2 mm of this line. Deviation > 2 mm suggests a true structural or ligamentous injury.

Question 40

A 4-year-old boy is brought to the ED with right hip pain. He is refusing to bear weight on the right leg. His temperature is 38.6°C (101.5°F). Labs reveal an ESR of 45 mm/hr and a serum WBC of 10,000 cells/mm³. According to the Kocher criteria, what is the probability that this child has septic arthritis of the hip?

Explanation

The Kocher criteria for differentiating septic arthritis from transient synovitis include: 1) Non-weight-bearing, 2) Temperature > 38.5°C, 3) ESR > 40 mm/hr, and 4) Serum WBC > 12,000 cells/mm³. This patient meets 3 criteria (NWB, Temp > 38.5, ESR > 40). According to Kocher's original study, the probability of septic arthritis is approximately 3% for 1 criterion, 40% for 2, 93% for 3, and 99% for 4 criteria.

Question 41

A 13-year-old boy presents with right hip pain and inability to bear weight for 2 days. X-rays confirm a slipped capital femoral epiphysis. According to the Loder classification, what is the primary prognostic significance of his inability to bear weight?

Explanation

According to the Loder classification, an unstable SCFE is defined by the inability to bear weight even with crutches. Unstable slips carry a significantly higher risk of avascular necrosis (up to nearly 50%) compared to stable slips.

Question 42

In a 6-year-old child with spastic quadriplegic cerebral palsy, the Reimers migration percentage of the right hip is measured at 55%. What is the most appropriate surgical management?

Explanation

A Reimers Migration Percentage greater than 50% in a spastic CP patient indicates severe subluxation progressing to dislocation. Concurrent varus derotational osteotomy (VDRO) and pelvic osteotomy are required to restore joint congruency and stability.

Question 43

A 2-year-old girl is diagnosed with late-presenting unilateral Developmental Dysplasia of the Hip (DDH). During open reduction, a Salter osteotomy is performed. Through which structural hinge does the distal fragment rotate to improve anterior and lateral coverage?

Explanation

The Salter innominate osteotomy is an incomplete, directional transiliac osteotomy that hinges on a flexible pubic symphysis. It redirects the entire acetabulum to improve anterolateral coverage of the femoral head without changing acetabular volume.

Question 44

A 4-year-old boy previously treated for clubfoot with the Ponseti method presents with a relapsed deformity. He exhibits dynamic supination of the foot during the swing phase of gait. What is the most appropriate definitive management?

Explanation

Dynamic supination during the swing phase of gait is a common sign of a relapsed clubfoot treated with the Ponseti method. It is best managed by transferring the whole tibialis anterior tendon to the lateral cuneiform to balance eversion and inversion forces.

Question 45

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, his hand remains pink but pulseless. What is the next best step in management?

Explanation

A well-perfused (pink) but pulseless hand after adequate reduction and pinning of a supracondylar fracture indicates collateral circulation is intact. Close clinical observation is the standard of care, as the palpable pulse typically returns within a few days.

Question 46

An 8-year-old boy with Legg-Calvé-Perthes disease is evaluated radiographically. According to the modified lateral pillar (Herring) classification, which finding portends the worst prognosis?

Explanation

The Herring (lateral pillar) classification is highly prognostic in Legg-Calvé-Perthes disease. Group C, defined as having less than 50% of the lateral pillar height maintained, predicts a poor radiographic and clinical outcome, particularly in children over 8 years old.

Question 47

A 13-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis (Tillaux fracture). Which ligament is responsible for the avulsion of this fracture fragment?

Explanation

A Tillaux fracture is a Salter-Harris III avulsion fracture of the anterolateral distal tibial epiphysis. The mechanism involves external rotation of the foot, causing the anterior inferior tibiofibular ligament (AITFL) to avulse the unfused lateral fragment.

Question 48

A 14-year-old girl undergoes reduction and instrumented fusion for a high-grade isthmic spondylolisthesis at L5-S1. Postoperatively, she develops new-onset weakness in ankle dorsiflexion and great toe extension. Which nerve root was most likely stretched during the reduction?

Explanation

Reduction of a high-grade L5-S1 spondylolisthesis stretches the L5 nerve root as the L5 vertebra is translated backward and superiorly. This commonly presents postoperatively as a traction injury causing weakness in ankle dorsiflexion and great toe extension.

Question 49

A 6-year-old boy presents with a supracondylar humerus fracture that is posterolaterally displaced. On clinical examination, he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is a branch of the median nerve and is the most commonly injured nerve in extension-type, posterolaterally displaced supracondylar fractures. It provides motor innervation to the flexor pollicis longus and flexor digitorum profundus to the index and middle fingers.

Question 50

A 3-year-old girl is diagnosed with untreated developmental dysplasia of the hip (DDH). Radiographs reveal a completely dislocated left hip with a false acetabulum. What is the most appropriate surgical management at this age?

Explanation

In children over 2 to 3 years of age, soft tissue contractures and acetabular dysplasia require an open reduction combined with a femoral shortening osteotomy (to reduce joint pressure and AVN risk) and a pelvic osteotomy (to improve acetabular coverage).

Question 51

A 13-year-old girl sustains an ankle injury while playing soccer. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism of injury for this specific fracture pattern?

Explanation

This describes a juvenile Tillaux fracture, which occurs due to an external rotation force. The anterior inferior tibiofibular ligament (AITFL) pulls and avulses the anterolateral epiphysis, which is the last portion of the distal tibial physis to close.

Question 52

A 4-year-old boy presents with right hip pain, fever (38.8 C), and inability to bear weight. His ESR is 55 mm/hr, CRP is 35 mg/L, and WBC count is 14,000/mm3. According to the Kocher criteria, what is the probability that this child has septic arthritis rather than transient synovitis?

Explanation

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

Question 53

A 14-year-old boy undergoes percutaneous in situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE). Six months later, he presents with severe hip stiffness, pain, and a significant loss of internal rotation and abduction. Radiographs show concentric joint space narrowing of the affected hip. What is the most likely diagnosis?

Explanation

Concentric joint space narrowing and stiffness following SCFE, especially if a pin penetrated the joint space during surgery, is the hallmark of chondrolysis. Avascular necrosis typically presents with subchondral collapse rather than diffuse joint space loss.

Question 54

A 12-year-old boy presents with a rigid, painful flatfoot and peroneal muscle spasm. A lateral radiograph of the foot demonstrates the 'C-sign'. Which of the following is the most likely anatomical location of his pathology?

Explanation

The 'C-sign' on a lateral radiograph is indicative of a talocalcaneal coalition, which most commonly occurs at the middle facet. A calcaneonavicular coalition would instead show the 'anteater nose' sign on a 45-degree oblique view.

Question 55

A 6-year-old boy with spastic quadriplegic cerebral palsy has a hip migration percentage of 60% on anteroposterior pelvis radiography. The hip is subluxated but reducible. What is the most appropriate surgical intervention?

Explanation

A migration percentage greater than 50% in a child with spastic CP indicates severe hip subluxation. Bony reconstruction with a proximal femoral varus derotation osteotomy (VDRO) and a concurrent pelvic osteotomy is the gold standard to achieve a stable, congruent hip.

Question 56

Which of the following is the primary basis for the Herring Lateral Pillar classification used in Legg-Calve-Perthes disease?

Explanation

The Herring Lateral Pillar classification is based on the height of the lateral pillar of the capital femoral epiphysis on an AP radiograph during the early fragmentation phase. It is the most reliable prognostic indicator for late outcomes.

Question 57

A 9-year-old boy weighing 65 kg (143 lbs) sustains a length-unstable, comminuted midshaft femur fracture. Which of the following fixation methods is associated with the highest risk of loss of reduction and poor outcomes in this specific patient?

Explanation

Titanium elastic nails (TENs) are contraindicated in children weighing more than 50 kg (110 lbs) or for length-unstable (comminuted) fractures due to a high risk of implant failure, malunion, and loss of reduction.

Question 58

A 13-year-old girl is diagnosed with adolescent idiopathic scoliosis (AIS). She is pre-menarchal, Risser 0, with a right thoracic curve of 35 degrees. What is the most appropriate management?

Explanation

TLSO bracing is indicated for growing children (Risser 0-2, pre-menarchal) with an AIS curve between 25 and 45 degrees. Her high risk of progression makes immediate full-time bracing the standard of care.

Question 59

During the Ponseti casting technique for a rigid congenital clubfoot, what is the most likely complication if forceful dorsiflexion is attempted before the heel varus and forefoot supination are fully corrected?

Explanation

Attempting to correct equinus by dorsiflexing the foot before correcting the cavus, adductus, and heel varus causes a midfoot break, clinically presenting as a rocker-bottom foot deformity.

Question 60

An 8-year-old boy presents with a symptomatic unicameral bone cyst (UBC) in the proximal humerus. Radiographs show a 'fallen leaf' sign. What is the most widely accepted initial invasive treatment for an active, symptomatic UBC?

Explanation

The standard first-line surgical/invasive treatment for a symptomatic or fracture-prone unicameral bone cyst is aspiration followed by injection of methylprednisolone, demineralized bone matrix, or bone marrow aspirate. Curettage and grafting are reserved for refractory cases.

Question 61

An infant with achondroplasia presents with central apnea, profound hypotonia, and hyperreflexia. What is the most critical anatomical abnormality responsible for these symptoms?

Explanation

Infants with achondroplasia have a small skull base, predisposing them to foramen magnum stenosis. This can cause cervicomedullary compression, leading to central apnea, hypotonia, quadriparesis, and even sudden death if unrecognized.

Question 62

A 10-year-old boy is evaluated for a suspected limb length discrepancy. Bone age is calculated, and the multiplier method is used. On average, how much longitudinal growth is contributed per year by the distal femoral and proximal tibial physes, respectively?

Explanation

The distal femur contributes approximately 9 mm per year, and the proximal tibia contributes approximately 6 mm per year to longitudinal growth. This rule of thumb is critical for timing epiphysiodesis procedures.

Question 63

A 6-year-old girl complains of a snapping sensation and pain on the lateral side of her knee. MRI reveals a thickened meniscus that covers the entire lateral tibial plateau. During arthroscopy, the meniscus lacks posterior capsular attachments. What is the name of this specific variant?

Explanation

The Wrisberg variant of a discoid lateral meniscus lacks normal posterior coronary ligament attachments. It is solely tethered by the meniscofemoral ligament of Wrisberg, making it highly hypermobile and responsible for the classic 'snapping knee' syndrome.

Question 64

A 4-year-old boy sustains a lateral condyle fracture of the humerus. Radiographs show 3 mm of displacement. The fracture is treated with closed reduction and percutaneous pinning. What is the most common long-term complication if this fracture fails to unite (non-union)?

Explanation

Lateral condyle non-unions characteristically lead to progressive cubitus valgus deformity. Over time, the valgus angulation stretches the ulnar nerve, resulting in a tardy ulnar nerve palsy.

Question 65

In a newborn with Erb's palsy (C5-C6 root injury), the arm is classically held in internal rotation, shoulder adduction, elbow extension, and forearm pronation (waiter's tip posture). Which muscle's paralysis primarily contributes to the inability to externally rotate the shoulder?

Explanation

Erb's palsy affects the upper trunk (C5-C6), paralyzing the suprascapular nerve, which innervates the infraspinatus (the primary external rotator). The intact internal rotators (subscapularis, pectoralis major) overpower the shoulder, forcing it into internal rotation.

Question 66

A 5-year-old girl presents with torticollis following a mild upper respiratory infection. Radiographs show rotatory subluxation of the atlantoaxial joint. What is the most common underlying mechanism for this specific condition (Grisel's syndrome)?

Explanation

Grisel's syndrome is a non-traumatic atlantoaxial subluxation caused by inflammatory hyperemia of the retropharyngeal space (often post-URI or ENT surgery). The inflammation leads to laxity of the transverse ligament and subsequent subluxation.

Question 67

A 12-year-old baseball pitcher presents with chronic lateral elbow pain. Radiographs demonstrate focal radiolucency and fragmentation of the capitellum. What is the most likely diagnosis?

Explanation

OCD of the capitellum typically occurs in overhead athletes aged 11 to 15 years, presenting with lateral elbow pain and focal fragmentation. Panner's disease is an osteochondrosis of the entire capitellum but occurs in a younger age group (typically 7-10 years) and heals without fragmentation.

Question 68

A 5-year-old child presents to the emergency department after a high-speed motor vehicle collision. Lateral cervical spine radiographs show 3 mm of anterior translation of C2 on C3. Swischuk's line is drawn and passes 1 mm anterior to the posterior arch of C3. What is the correct interpretation?

Explanation

Pseudosubluxation of C2 on C3 is a normal variant in children up to 8 years old. Swischuk's line (spinolaminar line from C1 to C3) should pass within 2 mm of the anterior cortex of the posterior arch of C2; if it does, the subluxation is physiological rather than traumatic.

Question 69

A 6-year-old child sustains a minimally displaced lateral condyle fracture of the humerus. Which of the following is the most common long-term complication if this injury goes unrecognized and untreated?

Explanation

Untreated lateral condyle fractures often lead to nonunion and progressive cubitus valgus. This valgus deformity progressively stretches the ulnar nerve, leading to tardy ulnar nerve palsy years later.

Question 70

In a 7-year-old boy diagnosed with Legg-Calve-Perthes disease, which of the following radiographic findings is considered the most reliable indicator of a poor prognosis according to the Herring classification?

Explanation

The Herring Lateral Pillar classification is the most reliable prognostic indicator for Legg-Calve-Perthes disease. Group C, which involves greater than 50% collapse of the lateral pillar, portends a poor clinical outcome.

Question 71

A 5-year-old boy presents with an extension-type Gartland III supracondylar humerus fracture. Examination reveals a "pink, pulseless" hand. Following closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the most appropriate next step in management?

Explanation

A well-perfused (pink) but pulseless hand after adequate reduction of a supracondylar fracture typically has adequate collateral circulation and can be observed closely. Open exploration is indicated if the hand is persistently white, cold, and pulseless after reduction.

Question 72

A 3-year-old girl is undergoing surgical treatment for developmental dysplasia of the hip (DDH). The surgeon plans a pelvic osteotomy that involves an incomplete osteotomy of the ilium leaving the sciatic notch intact, hinging on the triradiate cartilage to improve anterolateral coverage. Which osteotomy is being described?

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage. It primarily improves anterolateral acetabular coverage without disrupting the sciatic notch and decreases acetabular volume.

Question 73

A 13-year-old girl sustains an isolated fracture of the anterolateral distal tibial epiphysis. What is the pathomechanics of this specific injury pattern?

Explanation

A juvenile Tillaux fracture occurs due to external rotation forces avulsing the anterolateral distal tibial epiphysis via the AITFL. This happens because the distal tibial physis closes asymmetrically from central to anteromedial, leaving the anterolateral portion open and vulnerable.

Question 74

A 14-year-old boy presents with rigid, painful flatfeet and a history of recurrent ankle sprains. Radiographs reveal an "anteater nose" sign on the lateral view. Which of the following is the most appropriate initial management for this condition?

Explanation

The "anteater nose" sign is pathognomonic for a calcaneonavicular tarsal coalition. Initial management of symptomatic tarsal coalition is conservative, typically involving cast immobilization or orthotics before considering surgical resection.

Question 75

A 2.5-year-old obese girl presents with bilateral severe genu varum. Radiographs show medial metaphyseal beaking and an abnormal metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate initial treatment?

Explanation

Infantile Blount disease (Langenskiold stages I-II in children < 3 years old with a metaphyseal-diaphyseal angle > 16 degrees) is initially treated with KAFOs. Surgery is reserved for failure of brace treatment or in older children.

Question 76

A 4-year-old boy presents with an acute onset of a right-sided limp. He has a temperature of 38.6 C (101.5 F), an ESR of 45 mm/hr, a WBC count of 13,000/mm3, and refuses to bear weight. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?

Explanation

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

Question 77

A 6-year-old child with spastic quadriplegic cerebral palsy has a Gross Motor Function Classification System (GMFCS) level of V. What is the recommended frequency for radiographic hip surveillance in this patient?

Explanation

Patients with GMFCS level V are at the highest risk for hip displacement (up to 90%). Surveillance guidelines recommend clinical exams and AP pelvis radiographs every 6 months until age 7, and then annually until skeletal maturity.

Question 78

A 4-year-old boy previously treated for bilateral idiopathic clubfeet with the Ponseti method presents with dynamic supination of the feet during the swing phase of gait. Passive range of motion is full, and there is no fixed deformity. What is the most appropriate surgical intervention?

Explanation

Dynamic supination in a previously treated clubfoot with flexible joints is best treated with a complete tibialis anterior tendon transfer to the third (lateral) cuneiform. A split transfer (SPLATT) is typically reserved for spastic conditions like cerebral palsy.

Question 79

A 2-year-old child presents with multiple fractures, blue sclerae, and dentinogenesis imperfecta. Genetic testing reveals a mutation in the COL1A1 gene. Which of the following is the primary mechanism of action of the most commonly prescribed medical therapy for this condition?

Explanation

Bisphosphonates are the medical treatment of choice for Osteogenesis Imperfecta. They work by inhibiting osteoclast-mediated bone resorption, which increases bone density and decreases fracture rates.

Question 80

A 14-year-old female gymnast complains of lower back pain that worsens with extension. Oblique radiographs of the lumbar spine demonstrate a "Scotty dog with a collar" sign. If conservative treatment with rest and bracing fails after 6 months, what is the most appropriate surgical option for a persistent L5 pars defect without spondylolisthesis?

Explanation

In a young athlete with symptomatic spondylolysis (pars defect) that fails conservative management and has no significant spondylolisthesis or disc degeneration, direct pars repair is the surgical treatment of choice to preserve motion.

Question 81

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Which intraoperative technical error is most strongly associated with the development of chondrolysis?

Explanation

Unrecognized intraoperative joint penetration by the guidewire or screw is the most common iatrogenic cause of chondrolysis in SCFE treatment. An intraoperative "approach-withdraw" fluoroscopic technique is used to prevent this complication.

Question 82

A 4-year-old child sustains a closed, isolated midshaft femur fracture. The fracture has 1.5 cm of shortening and is angulated 10 degrees. What is the most appropriate definitive management?

Explanation

For children aged 6 months to 5 years with a femur fracture having acceptable alignment (<2 cm shortening), early spica casting is the gold standard treatment. Flexible nailing is generally indicated for older children (ages 5-11).

Question 83

A 13-year-old premenarchal female with Risser stage 0 presents with adolescent idiopathic scoliosis. Her right thoracic curve measures 32 degrees on standing PA radiographs. What is the most appropriate management?

Explanation

Bracing is indicated in skeletally immature patients (Risser 0-2, premenarchal) with curves between 25 and 40 degrees. A TLSO worn >18 hours/day significantly decreases the risk of curve progression to surgical thresholds.

Question 84

A macrosomic newborn presents with an adducted, internally rotated shoulder, extended elbow, and pronated forearm ("waiter's tip" posture). Grasp reflex is intact. Which nerve roots are primarily involved in this injury?

Explanation

Erb-Duchenne palsy is an upper trunk brachial plexus injury involving the C5 and C6 nerve roots. It presents with the classic "waiter's tip" posture due to paralysis of the shoulder abductors, elbow flexors, and forearm supinators, while preserving hand function.

Question 85

A 10-year-old boy sustains an injury to his distal radius. Radiographs demonstrate a fracture line propagating through the physis and exiting through the metaphysis, leaving a triangular metaphyseal fragment attached to the epiphysis. What Salter-Harris classification represents this injury?

Explanation

A Salter-Harris Type II fracture goes through the physis and exits through the metaphysis, carrying a metaphyseal fragment (Thurston-Holland fragment). It is the most common type of pediatric physeal fracture.

Updated Orthopedic Review | Dr Hutaif General Orthopedi -...

Orthopedic With Answer Peds Review | Dr Hutaif Pediatri -...

Key Takeaway

Orthopedic With Answer Peds Review | Dr Hutaif Pediatri -...

Chapter Index