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4. Pediatrics MCQs

Practice Set 86 of 334

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

Question 1701

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy presents with a displaced flexion-type supracondylar humerus fracture after falling directly onto a flexed elbow. Which of the following nerve injuries is most frequently associated with this specific fracture pattern?

. Anterior interosseous nerve
. Ulnar nerve
. Radial nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

While extension-type supracondylar humerus fractures most commonly injure the anterior interosseous nerve (AIN), flexion-type fractures have a higher association with ulnar nerve injuries due to posterior displacement of the proximal fragment.

Question 1702

Topic: 4. Pediatrics

A 48-year-old man presents with progressive numbness in his small and ring fingers, accompanied by intrinsic muscle wasting in his dominant hand. He reports having 'broken his elbow' as a young child. Radiographs reveal a severe cubitus valgus deformity. Nonunion of which of the following pediatric fractures is the most likely underlying cause?

. Supracondylar humerus fracture
. Medial epicondyle fracture
. Lateral condyle fracture
. Radial neck fracture
. Olecranon fracture

Correct Answer & Explanation

. Supracondylar humerus fracture

Explanation

Nonunion of a pediatric lateral condyle fracture typically leads to a progressive cubitus valgus deformity. Years later, this abnormal valgus angle causes stretching of the ulnar nerve, known as a tardy ulnar nerve palsy.

Question 1703

Topic: Pediatric Upper Extremity & Spine

A 7-year-old girl presents with a flexion-type supracondylar humerus fracture. Her hand is well-perfused, but she exhibits a specific neurologic deficit. Which nerve is most commonly injured in this specific fracture pattern?

. Anterior interosseous nerve
. Posterior interosseous nerve
. Ulnar nerve
. Superficial radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

Unlike extension-type supracondylar fractures where the anterior interosseous nerve is most commonly injured, flexion-type supracondylar fractures place the ulnar nerve at the greatest risk of injury.

Question 1704

Topic: Pediatric Upper Extremity & Spine

An 8-year-old boy presents to the emergency department with a flexion-type supracondylar humerus fracture. Which of the following nerve injuries is most frequently associated with this specific fracture configuration?

. Anterior interosseous nerve
. Posterior interosseous nerve
. Ulnar nerve
. Radial nerve proper
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

While extension-type supracondylar humerus fractures are most commonly associated with anterior interosseous nerve injuries, flexion-type fractures are classically and most frequently associated with ulnar nerve palsy.

Question 1705

Topic: 4. Pediatrics

In a 6-year-old child with late-onset infantile Blount's disease, radiographs show a severe depression of the medial tibial plateau and a medial physeal bar. What is the most appropriate surgical management?

. Guided growth (hemiepiphysiodesis) of the lateral proximal tibia
. High tibial osteotomy without physeal intervention
. Physeal bar resection with interposition grafting and a high tibial osteotomy
. Proximal tibial epiphysiodesis and distal femoral epiphysiodesis
. Derotational casting and brace treatment

Correct Answer & Explanation

. Physeal bar resection with interposition grafting and a high tibial osteotomy

Explanation

In advanced Blount's disease with a documented physeal bar (tether), simply performing an osteotomy or guided growth will fail because the tether prevents normal growth. The bar must be resected, and an osteotomy is usually required to correct the existing deformity.

Question 1706

Topic: Pediatric Hip

A 12-year-old obese male presents with left knee pain and a limp for 3 weeks. Examination reveals an antalgic gait. When the hip is passively flexed, it falls into obligatory external rotation.

What is the most appropriate definitive management for the left hip?

. Spica casting
. Core decompression
. In situ percutaneous screw fixation
. Open reduction and internal fixation with surgical dislocation
. Observation and protected weight bearing

Correct Answer & Explanation

. In situ percutaneous screw fixation

Explanation

The clinical presentation (obese adolescent, knee/thigh pain, obligatory external rotation with hip flexion) is classic for a Slipped Capital Femoral Epiphysis (SCFE). The standard of care for a stable or unstable SCFE is in situ percutaneous screw fixation (usually a single cannulated screw placed centrally in the epiphysis) to prevent further slippage and promote physeal closure.

Question 1707

Topic: Pediatric Hip

A 13-year-old obese male presents with insidious onset of left groin and knee pain. He walks with an externally rotated gait. When his left hip is passively flexed, it obligatory goes into external rotation. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). He undergoes in situ single-screw fixation. Which of the following is the most common long-term complication following successful fixation of this condition?

. Avascular necrosis of the femoral head
. Chondrolysis
. Femoroacetabular impingement (FAI)
. Nonunion of the physis
. Implant failure

Correct Answer & Explanation

. Femoroacetabular impingement (FAI)

Explanation

The obligatory external rotation with hip flexion (Drehmann sign) is classic for SCFE. Following in situ fixation of a SCFE, the residual prominent anterior-superior femoral metaphysis frequently leads to Cam-type femoroacetabular impingement (FAI). While avascular necrosis (AVN) is the most devastating complication, it is far more common in unstable SCFE. Chondrolysis is less common today, historically associated with unrecognized intra-articular screw penetration. Thus, FAI is the most common long-term complication even after successful stable in situ pinning.

Question 1708

Topic: Pediatric Hip

In a patient with a typical slipped capital femoral epiphysis (SCFE), what is the true anatomic displacement of the femoral metaphysis (femoral neck) relative to the epiphysis?

. Posterior and inferior
. Posterior and superior
. Anterior and superior
. Anterior and inferior
. Medial and inferior

Correct Answer & Explanation

. Posterior and inferior

Explanation

In a SCFE, the clinical and radiographic appearance is often described as the epiphysis slipping "posterior and inferior." However, biomechanically and anatomically, the epiphysis remains relatively fixed in the acetabulum (tethered by the ligamentum teres). It is the femoral neck (metaphysis) that physically translates anteriorly and superiorly (and externally rotates). This anterior metaphyseal prominence is the classic source of Cam impingement post-SCFE.

Question 1709

Topic: Pediatric Hip

A 28-year-old male hockey player presents with groin pain exacerbated by hip flexion and internal rotation. An AP pelvis radiograph demonstrates a 'crossover sign' and a 'prominent ischial spine sign.' These radiographic findings are most indicative of which of the following pathologies?

. Cam-type femoroacetabular impingement
. Pincer-type femoroacetabular impingement secondary to acetabular retroversion
. Developmental dysplasia of the hip (DDH)
. Legg-Calve-Perthes disease
. Slipped capital femoral epiphysis (SCFE)

Correct Answer & Explanation

. Cam-type femoroacetabular impingement

Explanation

The crossover sign (anterior wall of the acetabulum crossing the posterior wall), prominent ischial spine sign, and posterior wall sign are radiographic markers of acetabular retroversion. This focal overcoverage leads to pincer-type femoroacetabular impingement (FAI).

Question 1710

Topic: Pediatric Hip

A 45-year-old female presents with severe end-stage osteoarthritis secondary to developmental dysplasia of the hip (DDH). Radiographs demonstrate complete dislocation of the femoral head with proximal migration greater than 100% of the femoral head height (Crowe IV).

During total hip arthroplasty, the acetabular component is placed at the level of the true acetabulum. Which of the following is the most appropriate technique to safely reduce the hip and minimize the risk of sciatic nerve palsy?

. Aggressive intraoperative stretching of the sciatic nerve
. Reaming the true acetabulum superiorly to accept a larger cup
. Placement of the acetabular cup in the false acetabulum (high hip center)
. Subtrochanteric shortening osteotomy of the femur
. Extensive release of the adductor and iliopsoas tendons without bone resection

Correct Answer & Explanation

. Aggressive intraoperative stretching of the sciatic nerve

Explanation

In Crowe IV DDH, restoring the anatomic center of rotation (true acetabulum) often requires distalizing the femur several centimeters. To accomplish this without causing catastrophic stretching of the sciatic nerve (lengthening > 4cm is high risk), a subtrochanteric shortening osteotomy is frequently required.

Question 1711

Topic: Pediatric Hip

A 12-year-old boy presents with left hip pain and an acutely worsening limp. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE) of the left hip. The right hip is radiographically normal and asymptomatic. Which of the following is the strongest universally accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Modified Southwick angle greater than 50 degrees on the affected side
. Patient age less than 10 years or open triradiate cartilage
. Male gender
. Body Mass Index greater than the 95th percentile
. Presence of an asymptomatic hip effusion on ultrasound

Correct Answer & Explanation

. Modified Southwick angle greater than 50 degrees on the affected side

Explanation

The primary indications for prophylactic pinning of a contralateral asymptomatic hip in a patient with SCFE include an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy), patient age less than 10 years, and open triradiate cartilage. These factors represent a high risk for subsequent contralateral slip.

Question 1712

Topic: Pediatric Hip

A 12-year-old boy presents with right-sided groin pain and an externally rotated leg. Radiographs confirm a unilateral slipped capital femoral epiphysis (SCFE). Which of the following conditions constitutes the strongest absolute indication for prophylactic in situ pinning of the asymptomatic contralateral hip?

. Age of 14 years
. Body Mass Index > 95th percentile
. Hypothyroidism
. Bilateral knee pain
. A primary SCFE slip angle of 15 degrees

Correct Answer & Explanation

. Age of 14 years

Explanation

Patients with an underlying endocrinopathy (such as hypothyroidism) or renal osteodystrophy have an exceptionally high risk of developing contralateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these systemic conditions.

Question 1713

Topic: 4. Pediatrics
Posttraumatic physeal arrest is most common at which of the following locations?
. Proximal tibia
. Proximal humerus
. Distal radius
. Distal humerus
. Distal tibia

Correct Answer & Explanation

. Distal tibia

Explanation

DISCUSSION: Posttraumatic physeal arrest occurs most commonly in the distal medial tibia. Using MRI, Ecklund and associates confirmed this finding. Arrest of the distal radius and proximal humerus are rare after trauma. Traumatic injuries of the distal femoral and distal ulnar physis have a high incidence of growth arrest as well. REFERENCES: Ecklund K, Jaramillo D: Patterns of premature physeal arrest: MR imaging of 111 children. AJR Am J Roentgenol 2002; 178:967-972.

Question 1714

Topic: 4. Pediatrics

A 22-year-old competitive skier presents with lateral ankle pain and an audible 'snapping' sensation behind the lateral malleolus during forced dorsiflexion and eversion. Clinical examination is notable for visible subluxation of the peroneal tendons over the fibula. Which primary anatomical restraint is most likely incompetent in this condition?

. Inferior extensor retinaculum
. Superior peroneal retinaculum
. Calcaneofibular ligament
. Anterior talofibular ligament
. Superior extensor retinaculum

Correct Answer & Explanation

. Inferior extensor retinaculum

Explanation

Peroneal tendon subluxation or dislocation is primarily caused by injury, attenuation, or congenital incompetence of the superior peroneal retinaculum (SPR). The SPR is the primary static restraint that holds the peroneus longus and brevis tendons within the retromalleolar groove of the distal fibula. Surgical management typically involves repair or reconstruction of the SPR, often combined with fibular groove deepening.

Question 1715

Topic: 4. Pediatrics
A 12-year-old girl has bilateral developmentally dislocated hips. History reveals no previous treatment, and she reports no discomfort. Good long-term clinical results are most likely to occur with
. Surgical reduction of both hips and stabilization with a pelvic procedure.
. No development of false acetabula.
. Performance of surface replacements.
. Abductor strengthening exercises.
. Chiari osteotomy.

Correct Answer & Explanation

. No development of false acetabula.

Explanation

The natural history of complete developmental dislocation of the hip is dependent on two factors: bilaterality and the presence or absence of a false acetabulum. Patients with bilateral dislocations may have low back pain because of hyperlordosis, but they tend to have less disability than patients with unilateral dislocations who have secondary problems related to limb-length inequality. Degenerative joint disease and clinical disability are most likely to develop in patients with completely dislocated hips and well-developed false acetabula. In a 12-year-old child who has bilateral developmental hip dislocations, it would be difficult to obtain surgical treatment results that are better than the natural history of the disorder. Abductor strengthening exercises are unlikely to influence the long-term outcome in this disorder. Surface replacements are not indicated in young asymptomatic patients.

Question 1716

Topic: 4. Pediatrics
A 10-year-old boy falls while skiing and sustains a Type III tibial eminence fracture. He undergoes successful arthroscopic reduction and internal fixation. During his postoperative course, which of the following is the most common complication associated with this injury and its surgical treatment?
. Premature closure of the proximal tibial physis
. Recurrent anterior knee instability due to ligamentous stretch
. Arthrofibrosis resulting in restricted range of motion
. Nonunion of the bony avulsion fragment
. Patellofemoral pain syndrome

Correct Answer & Explanation

. Arthrofibrosis resulting in restricted range of motion

Explanation

Arthrofibrosis (post-operative stiffness) is the most frequent complication following both non-operative and operative management of tibial eminence fractures in pediatric patients. While minor residual laxity may be detectable on objective testing (such as KT-1000 measurements), clinical instability is rare. Early physical therapy emphasizing range of motion is crucial to prevent stiffness. Physeal arrest is a rare complication if proper surgical technique (avoiding fixation across the physis) is utilized.

Question 1717

Topic: 4. Pediatrics

Figures 53a through 53d show the clinical photographs and radiographs of the lower extremity of a newborn male. Examination reveals this to be an isolated finding. The child otherwise has a normal neurologic examination. The hips are stable and there are no spinal defects. What is the most appropriate treatment at this time? Review Topic

. Symes amputation once ambulatory
. Observation as the deformity will slowly resolve and the child will be left with a limb-length discrepancy
. Immediate osteotomy for correction of the deformity
. Casting for correction of the deformity
. Genetic testing for neurofibromatosis

Correct Answer & Explanation

. Observation as the deformity will slowly resolve and the child will be left with a limb-length discrepancy

Explanation

The radiographs and clinical photographs reveal a child with posteromedial bowing of the tibia. This is a congenital anomaly that is associated with a calcaneal valgus foot. It is a relatively benign condition. The severity of the bow diminishes with time; however, the child will be left with a limb-length discrepancy, usually in the range of4 cm. The residual limb-length discrepancy presents the greatest challenge for orthopaedic management. This, however, can usually be handled with limb-lengthening techniques. Casting can be used for severe cases with unresolving significant contracture; however, gradual spontaneous correction is usually the norm. This condition is quite different from anterior lateral bowing that can be associated with neurofibromatosis and pathologic fracture or pseudoarthrosis of the tibia.

Question 1718

Topic: Pediatric Hip

A 12-year-old overweight male presents with an atraumatic limp and left knee pain. An AP radiograph of the pelvis reveals a positive Trethowan sign. Which of the following defines a positive Trethowan sign in this context?

. A subchondral crescent sign in the anterosuperior aspect of the femoral epiphysis
. A line drawn along the superior border of the femoral neck intersecting less than half of the epiphysis
. A line drawn along the superior border of the femoral neck failing to intersect the lateral portion of the femoral epiphysis
. Widening and irregularity of the proximal femoral physis compared to the contralateral side
. A metaphyseal blanch sign denoting overlapping of the femoral neck and head

Correct Answer & Explanation

. A line drawn along the superior border of the femoral neck failing to intersect the lateral portion of the femoral epiphysis

Explanation

The Trethowan sign is defined by Klein's line. Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In a normal hip, this line intersects the lateral portion of the capital femoral epiphysis. A positive Trethowan sign occurs when Klein's line does not intersect the epiphysis, highly indicative of a Slipped Capital Femoral Epiphysis (SCFE).

Question 1719

Topic: Pediatric Hip

A 12-year-old obese male presents with a stable, mild slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following circumstances is prophylactic in situ pinning of the contralateral, asymptomatic right hip most strongly indicated?

. Presentation with an acute-on-chronic SCFE on the symptomatic left side
. Patient age greater than 14 years at presentation
. An open triradiate cartilage on AP pelvis radiograph
. Southwick slip angle greater than 50 degrees on the left side
. Presence of a diagnosed underlying endocrine disorder such as hypothyroidism

Correct Answer & Explanation

. Presence of a diagnosed underlying endocrine disorder such as hypothyroidism

Explanation

While prophylactic pinning of the contralateral hip in SCFE remains controversial for idiopathic cases, it is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). These patients have an extremely high risk (often >50-80%) of developing bilateral SCFE. Other relative indications for prophylactic pinning include younger age (e.g., girls <10, boys <12) and open triradiate cartilage (modified Oxford bone age).

Question 1720

Topic: Pediatric Upper Extremity & Spine

Which bundle of the ulnar collateral ligament (UCL) of the elbow is the primary restraint to valgus stress during the late cocking phase of throwing, and where is its isometric origin?

. Anterior bundle, originating from the anteroinferior medial epicondyle
. Posterior bundle, originating from the posteroinferior medial epicondyle
. Transverse bundle, originating from the olecranon
. Anterior bundle, originating from the sublime tubercle
. Posterior bundle, originating from the medial supracondylar ridge

Correct Answer & Explanation

. Anterior bundle, originating from the anteroinferior medial epicondyle

Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress between 30 and 120 degrees of flexion. Its isometric origin is located on the anteroinferior surface of the medial epicondyle.

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