Menu

Pediatric Lower Extremity MCQs

Practice Set 5 of 18

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

Question 81

Topic: Pediatric Lower Extremity

A 4-year-old boy presents with an asymmetric, painless swelling on the medial aspect of his ankle. Radiographs reveal an irregular, lobulated, ossified mass arising from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple epiphyseal dysplasia
. Chondroblastoma
. Dysplasia epiphysealis hemimelica (Trevor's disease)
. Osteochondritis dissecans
. Sinding-Larsen-Johansson syndrome

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica (Trevor's disease)

Explanation

Dysplasia epiphysealis hemimelica, or Trevor's disease, is characterized by an asymmetric overgrowth of cartilage (essentially an intra-articular osteochondroma) originating from an epiphysis. It most commonly affects the medial side of the knee or ankle in young children.

Question 82

Topic: Pediatric Lower Extremity

A 9-year-old boy with Duchenne Muscular Dystrophy presents with progressive tiptoe walking and frequent tripping. On examination, what is the most typical lower extremity contracture pattern driving this gait abnormality in ambulatory DMD patients?

. Calcaneovalgus
. Equinovarus
. Planovalgus
. Cavovarus
. Equinovalgus

Correct Answer & Explanation

. Equinovarus

Explanation

Equinovarus contractures are the most common deformity in ambulatory boys with DMD. This is due to the relative sparing and overpull of the posterior tibialis muscle and Achilles tendon compared to the weaker dorsiflexors and evertors.

Question 83

Topic: Pediatric Lower Extremity

In the Ponseti method for correcting idiopathic clubfoot, what is the correct sequence of deformity correction?

. Cavus, Adductus, Varus, Equinus
. Equinus, Varus, Adductus, Cavus
. Adductus, Cavus, Equinus, Varus
. Varus, Equinus, Cavus, Adductus
. Cavus, Varus, Equinus, Adductus

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method dictates sequential correction following the acronym CAVE: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus. Attempting to correct equinus before the other components often requires an Achilles tenotomy and risks causing a rocker-bottom deformity.

Question 84

Topic: Pediatric Lower Extremity

Patella alta is a known risk factor for recurrent patellar instability. Which of the following correctly describes the Caton-Deschamps index used to diagnose this condition?

. The ratio of the patellar tendon length to the greatest diagonal length of the patella.
. The ratio of the distance from the inferior articular margin of the patella to the anterior superior angle of the tibia, divided by the patellar articular surface length.
. The perpendicular distance from the inferior pole of the patella to the tibial plateau line, divided by the patellar articular surface length.
. The angle formed by the lines connecting the highest points of the medial and lateral femoral condyles to the deepest point of the trochlear groove.
. The distance between the tibial tubercle and the deepest portion of the trochlear groove.

Correct Answer & Explanation

. The ratio of the distance from the inferior articular margin of the patella to the anterior superior angle of the tibia, divided by the patellar articular surface length.

Explanation

The Caton-Deschamps index relies on articular margins rather than the inferior pole, making it useful even if a patient has had Osgood-Schlatter disease or previous distal pole excision. A value greater than 1.2 indicates patella alta.

Question 85

Topic: Pediatric Lower Extremity

A newborn is diagnosed with Proximal Focal Femoral Deficiency (PFFD). Radiographs demonstrate an absent femoral head, non-existent acetabulum, and a severely shortened, dysplastic femoral shaft. According to the Aitken classification, which class does this represent?

. Class A
. Class B
. Class C
. Class D
. Class E

Correct Answer & Explanation

. Class D

Explanation

In Aitken Class D PFFD, both the acetabulum and femoral head are completely absent, and the proximal femur is severely dysplastic or absent. This represents the most severe form in the Aitken classification.

Question 86

Topic: Pediatric Lower Extremity

A 6-year-old boy presents for evaluation of a leg length discrepancy. Radiographs reveal fibular hemimelia. Which of the following physical examination or radiographic findings is most classically associated with this condition?

. Polydactyly of the foot
. Anterior cruciate ligament (ACL) deficiency
. Vertical talus
. Medial ray deficiency
. Patella alta with quadriceps contracture

Correct Answer & Explanation

. Anterior cruciate ligament (ACL) deficiency

Explanation

Fibular hemimelia is a longitudinal deficiency commonly associated with anterior cruciate ligament (ACL) deficiency, ball-and-socket ankle deformities, tarsal coalition, and absent lateral (not medial) rays of the foot.

Question 87

Topic: Pediatric Lower Extremity

A 40-year-old patient presents with a severe bilateral Blount's disease deformity affecting both tibias and femurs. The surgeon is planning a proximal tibial osteotomy on the right leg. After performing the Malalignment Test (MAT), it is determined that both the ipsilateral (right) femoral mechanical axis and the contralateral (left) proximal tibial mechanical axis are abnormal. In this specific scenario, how should the Proximal Tibial Mechanical Axis (PMA) be accurately drawn?

. Extend the mechanical axis of the ipsilateral femur straight down through the center of the knee.
. Draw the PMA starting from the center of the deformed knee, angled distally at the contralateral MPTA relative to the proximal tibial joint line.
. Draw the PMA starting from the center of the knee, extending distally at exactly an 87° angle to the proximal tibial joint line.
. Draw the PMA parallel to the mid-diaphyseal line of the proximal tibia.
. Draw the PMA from the center of the hip to the center of the ankle.

Correct Answer & Explanation

. Draw the PMA starting from the center of the knee, extending distally at exactly an 87° angle to the proximal tibial joint line.

Explanation

Correct Answer: CThis question describes Scenario C for drawing the Proximal Tibial Mechanical Axis (PMA): "Abnormal Ipsilateral mLDFA and Abnormal Contralateral MPTA." The case states, "If the ipsilateral femur is deformed, AND the contralateral leg is also deformed... you have no patient-specific templates available. You must default to the population average normal MPTA, which is87°. Draw the PMA starting from the center of the knee, extending distally at exactly an 87° angle to the proximal tibial joint line."Option A is incorrectbecause this applies to Scenario A (Normal Ipsilateral mLDFA), which is not the case here.Option B is incorrectbecause this applies to Scenario B (Abnormal Ipsilateral mLDFA, but Normal Contralateral MPTA), which is also not the case here as the contralateral MPTA is abnormal.Option D is incorrect. While the anatomic axis uses mid-diaphyseal lines, the mechanical axis planning for the proximal tibia relies on the joint center and the MPTA, especially when the segment is short or deformed.Option E is incorrect. This describes the global mechanical axis of the entire lower limb, not the PMA of the tibia.

Question 88

Topic: Pediatric Lower Extremity

A patient requires a large angular correction of the proximal tibia for Blount's disease. During planning, the axis of correction (hinge) is placed on the convex (lateral) cortex. This placement of the hinge will mathematically result in:

. Pure angular correction without any length change.
. A closing wedge correction at the medial cortex.
. An opening wedge at the medial cortex, increasing overall bone length.
. A dome-shaped correction pathway.
. Immediate lateral collateral ligament laxity.

Correct Answer & Explanation

. An opening wedge at the medial cortex, increasing overall bone length.

Explanation

Placing the axis of correction on the convex (lateral) side of a deformity dictates that the correction will occur by opening a wedge on the concave (medial) side, which increases overall limb length.

Question 89

Topic: Pediatric Lower Extremity

A full-length standing radiograph shows a varus knee with a Mechanical Axis Deviation (MAD) of 30 mm medial to the knee center. The mLDFA is 88 degrees and the MPTA is 87 degrees. The Joint Line Convergence Angle (JLCA) is measured at 7 degrees. What is the primary cause of this patient's varus malalignment?

. Femoral diaphyseal bowing
. Tibial plateau depression
. Intra-articular deformity (e.g., cartilage loss or ligament laxity)
. Proximal focal femoral deficiency
. Metaphyseal fibrous defect

Correct Answer & Explanation

. Intra-articular deformity (e.g., cartilage loss or ligament laxity)

Explanation

The mLDFA and MPTA are within normal limits, ruling out extra-articular osseous deformities of the femur and tibia. An abnormally wide JLCA (>2 degrees) indicates that the varus deformity is intra-articular, such as from medial compartment arthritis.

Question 90

Topic: Pediatric Lower Extremity

A 30-year-old patient with a history of Blount's disease presents with progressive knee pain and a significant varus deformity. A full-length weight-bearing radiograph is shown below. Based on the Paley Method, if the mLDFA is measured at 87° and the MPTA is measured at 75°, where is the primary anatomical source of the bony deformity located?

. Distal femur
. Proximal tibia
. Mid-shaft femur
. Mid-shaft tibia
. Within the knee joint space (intra-articular)

Correct Answer & Explanation

. Proximal tibia

Explanation

Correct Answer: BThe text defines the normal values for joint orientation angles: 'mLDFA (Mechanical Lateral Distal Femoral Angle): Normal value is 87° (range 85-90°).' and 'MPTA (Mechanical Proximal Tibial Angle): Normal value is 87° (range 85-90°).' In this scenario, the mLDFA is 87°, which is within the normal range, indicating no significant deformity in the distal femur. However, the MPTA is 75°, which is significantly less than the normal 87°. A decreased MPTA indicates a varus deformity originating in the proximal tibia. While the image shows a varus deformity, the specific measurements provided pinpoint the proximal tibia as the primary bony source. Intra-articular deformity would be indicated by an abnormal JLCA, which is not directly given here, though it might be present secondarily.

Question 91

Topic: Pediatric Lower Extremity

A 14-year-old male with Blount's disease undergoes deformity correction. During planning, a closing wedge osteotomy is desired to avoid lengthening the limb. Where must the hinge axis be located relative to the deformity to achieve a pure closing wedge correction without translation?

. On the concave cortex of the bone at the CORA level
. On the convex cortex of the bone at the CORA level
. In the center of the medullary canal at the CORA level
. On the bisector line outside the concave cortex
. On the bisector line outside the convex cortex

Correct Answer & Explanation

. On the convex cortex of the bone at the CORA level

Explanation

To achieve a closing wedge correction without length changes or translation, the hinge axis must be placed on the convex cortex of the bone exactly at the level of the CORA. Placing the hinge on the concave side would create an opening wedge.

Question 92

Topic: Pediatric Lower Extremity

A 16-year-old male with Blount's disease undergoes correction of a severe proximal tibial deformity.

Based on Paley's principles of oblique plane deformities, if a patient has both a coronal varus deformity and a sagittal apex posterior (procurvatum) deformity, what is the geometric relationship to the true plane of the deformity?

. The true deformity is a pure translational shift in the axial plane
. The true deformity lies in a single oblique plane located somewhere between the coronal and sagittal planes
. The true deformity is exclusively rotational and requires a transverse derotational osteotomy
. There are always two distinct CORAs that cannot be corrected by a single osteotomy
. The maximum angulation occurs at an orientation exactly 90 degrees to the oblique plane

Correct Answer & Explanation

. The true deformity lies in a single oblique plane located somewhere between the coronal and sagittal planes

Explanation

A combined angulation in orthogonal planes (e.g., coronal varus and sagittal procurvatum) actually represents a single angular deformity occurring in a single oblique plane. It can be corrected mathematically with a single appropriately aligned hinge or spatial frame.

Question 93

Topic: Pediatric Lower Extremity

A 10-year-old girl is noted to have a significant leg length discrepancy. Radiographs reveal anteromedial bowing of the shortened tibia, a deficient lateral malleolus, and an absent 5th ray of the foot. What is the most likely underlying diagnosis?

. Congenital pseudarthrosis of the tibia
. Proximal focal femoral deficiency
. Tibial hemimelia
. Fibular hemimelia
. Posteromedial bowing of the tibia

Correct Answer & Explanation

. Fibular hemimelia

Explanation

Fibular hemimelia is classically associated with an anteromedial tibial bow, an equinovalgus foot with absent lateral rays, and a deficient or absent fibula.

Question 94

Topic: Pediatric Lower Extremity

A patient presents with significant bowleg deformity due to late-onset Blount's disease. Based on the typical pathoanatomy of this condition, the multiplanar deformity of the proximal tibia primarily consists of which components?

. Varus, external rotation, and recurvatum
. Valgus, internal rotation, and procurvatum
. Varus, internal rotation, and procurvatum
. Valgus, external rotation, and recurvatum
. Varus, external rotation, and procurvatum

Correct Answer & Explanation

. Varus, internal rotation, and procurvatum

Explanation

Blount's disease typically presents with a three-dimensional deformity of the proximal tibia consisting of varus (coronal plane), internal rotation (axial plane), and procurvatum (sagittal plane, apex anterior).

Question 95

Topic: Pediatric Lower Extremity

A 28-year-old with Blount's disease sequelae has a complex proximal tibial deformity. When utilizing a hexapod external fixator, the software requires the identification of the "origin" and "corresponding point". These points fundamentally rely on defining which of the following?

. The anatomic axis of the femur
. The mechanical axis deviation
. The center of rotation of angulation (CORA)
. The joint line convergence angle
. The Paley multiplier

Correct Answer & Explanation

. The center of rotation of angulation (CORA)

Explanation

In 6-axis deformity correction systems, mounting parameters and deformity parameters must relate the rings to the bone segments and accurately locate the CORA for ideal correction.

Question 96

Topic: Pediatric Lower Extremity
A 5-year-old boy has had midfoot pain with activity for the past 3 months. He has no pain at rest. Radiographs are shown in Figures 29a and 29b. Management should consist of
. a vascularized pedicle bone graft.
. a short leg walking cast.
. a custom-molded orthotic.
. surgical debridement followed by antibiotics.
. a bone stimulator.

Correct Answer & Explanation

. a short leg walking cast.

Explanation

DISCUSSION: The radiographs show classic findings for Koehler’s disease (osteochondrosis of the navicular). The patient’s age and clinical history are typical for this self-limiting condition. Patients will improve with time, but the duration of symptoms is much shorter if the patient is placed in a cast. There is no role for surgery in this disease.

Question 97

Topic: Pediatric Lower Extremity

The CT scan shows the involvement area is approximately 30% of the posterior facet. What is the most appropriate treatment?

. Surgical resection
. Lateral column lengthening
. Coalition resection and lateral column lengthening
. Triple arthrodesis

Correct Answer & Explanation

. Surgical resection

Explanation

DISCUSSIONRadiographs reveal a talocalcaneal coalition. The incidence of tarsal coalition in the general population ranges between 2% and 13%. The incidence of tarsal coalition among patients with FGFR-related craniosynostosis syndromes is much higher than among the general population. Tarsal coalitions have been noted in FGFR-1-, FGFR-2-, and FGFR-3-related craniosynostosis syndromes of Apert, Pfeiffer, Crouzon, Jackson-Weiss, and Muenke, but not in Beare-Stevenson or Crouzonodermoskeletal syndromes. The FGFR genes are involved in cell proliferation, differentiation, migration, apoptosis, and pattern formation.Additionally, nonsyndromic familial coalitions have been described with autosomal-dominant patterns of inheritance.Cross-sectional imaging should always be obtained prior to resection of a radiographically evident coalition to define the extent of the coalition and determine the coexistence of an additional coalition. CT scan is the gold standard test; however, MRI can be helpful to define a suspected fibrous coalition if a CT scan is nondiagnostic. A bone scan may be useful if pain or history is atypical for a symptomatic coalition. Laboratory tests such as CBC, ESR, CRP, ANA, and RF may be indicated if the imaging evaluation does not confirm a tarsal coalition and if there is concern for malignancy, infection, or inflammatory arthritis.Investigators have suggested that larger talocalcaneal coalitions with surface areas larger than 33% to 50% of the size of the posterior facet are unsuitable for resection and primary arthrodesis should be considered. However, a study by Koshbin and associates found that with long-term follow-up, favorable functional outcomes were seen even with resections of large talocalcaneal coalitions occupying more than 50% of surface area.

Question 98

Topic: Pediatric Lower Extremity
Figure 16 shows the clinical photograph of a 3-month-old infant with a foot deformity that has been nonprogressive since birth. Examination reveals that the deformity corrects actively and with passive manipulation. There is no associated equinus. Management should consist of
. serial casting.
. UCBL orthotics.
. abductor hallucis lengthening.
. observation and parental reassurance.
. corrective shoes.

Correct Answer & Explanation

. observation and parental reassurance.

Explanation

The patient has bilateral metatarsus adductus deformities. Deformities that are passively correctable spontaneously resolve and no treatment is required. Therefore, observation is the management of choice for passively correctable deformities.

Question 99

Topic: Pediatric Lower Extremity

In the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequence of deformity correction?

. Equinus, Varus, Adduction, Cavus
. Cavus, Adduction, Varus, Equinus
. Adduction, Varus, Cavus, Equinus
. Cavus, Varus, Adduction, Equinus
. Equinus, Cavus, Adduction, Varus

Correct Answer & Explanation

. Cavus, Adduction, Varus, Equinus

Explanation

The Ponseti method follows the CAVE mnemonic: Cavus (corrected by elevating the first ray), Adduction, Varus, and finally Equinus. Correcting the equinus last typically requires a percutaneous Achilles tenotomy.

Question 100

Topic: Pediatric Lower Extremity
A 25-year-old man has ankle instability and a lateral foot callosity. Radiographs are shown. Management options are best determined by the
. patient’s response to physical therapy.
. patient’s response to casting.
. patient’s response to selective injections.
. results of Coleman block testing.
. results of Semmes-Weinstein monofilament testing.

Correct Answer & Explanation

. results of Coleman block testing.

Explanation

DISCUSSION: The patient has a cavovarus deformity that has resulted in lateral foot overload and stressing of the lateral ligaments. Further treatment depends on the ability to correct the deformity. The Coleman block test indicates whether a deformity is fixed or supple. A supple deformity will respond to orthotic management or soft-tissue procedures, while a fixed deformity requires corrective osteotomy or fusion.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page