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Lower Extremity Trauma MCQs

Practice Set 1 of 34

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

Question 1

Topic: Lower Extremity Trauma

The typical locations for bone contusions as viewed on magnetic resonance imaging after anterior cruciate ligament (AC L) injury are the:

. Medial femoral condyle and medial tibial plateau
. Anterior third of the lateral femoral condyle and posterolateral tibia
. Middle third of the lateral femoral condyle and posterolateral tibia
. Posterior third of the lateral femoral condyle and posterolateral tibia
. Patellofemoral compartment

Correct Answer & Explanation

. Middle third of the lateral femoral condyle and posterolateral tibia

Explanation

The typical locations for bone contusions after an AC L injury are the middle third of the lateral femoral condyle and the posterolateral tibia.

Question 2

Topic: Lower Extremity Trauma

Which of the following most accurately describes the location of the tibial attachment of the posterior cruciate ligament:

. At the level of the tibial plateau
. 0 mm to 5 mm inferior to the level of the tibial plateau
. 5 mm to 10 mm inferior to the level of the tibial plateau
. 10 mm to 15 mm inferior to the level of the tibial plateau
. 15 mm to 20 mm inferior to the level of the tibial plateau

Correct Answer & Explanation

. 10 mm to 15 mm inferior to the level of the tibial plateau

Explanation

The tibial attachment of the posterior cruciate ligament is usually 10 mm to 15 mm inferior to the joint line. Reconstructions of the posterior cruciate ligament should attempt to replicate this tibial attachment site.

Question 3

Topic: Lower Extremity Trauma

Which of the following radiographic parameters is considered the most reliable and reproducible for diagnosing a syndesmotic injury on standard AP and mortise ankle radiographs?

. Tibiofibular overlap less than 1 mm on the AP view
. Tibiofibular clear space greater than 5 mm on the AP view alone
. Medial clear space greater than 2 mm on the mortise view
. Tibiofibular clear space greater than 5 mm on both AP and mortise views
. Talar tilt greater than 5 degrees

Correct Answer & Explanation

. Tibiofibular clear space greater than 5 mm on both AP and mortise views

Explanation

A tibiofibular clear space greater than 5 mm, measured on both AP and mortise views, is the most reliable radiographic parameter for detecting syndesmotic diastasis. It is less dependent on rotation than tibiofibular overlap.

Question 4

Topic: Lower Extremity Trauma

In evaluating a patient with a suspected posterolateral corner injury, the reverse pivot shift test is performed. During the test, a clunk is felt as the knee is brought from flexion into extension. This clunk represents:

. Subluxation of the lateral tibial plateau anteriorly
. Reduction of the posteriorly subluxated lateral tibial plateau
. Subluxation of the medial tibial plateau posteriorly
. Reduction of the anteriorly subluxated medial tibial plateau
. Patellar reduction into the trochlear groove

Correct Answer & Explanation

. Reduction of the posteriorly subluxated lateral tibial plateau

Explanation

In a PLC injury, the lateral tibial plateau subluxates posteriorly during knee flexion. As the knee is extended during the reverse pivot shift test, the iliotibial band becomes an extensor and reduces the plateau at roughly 20 to 30 degrees of flexion.

Question 5

Topic: Lower Extremity Trauma
Sectioning the posterolateral structures alone affects lateral tibial plateau translation with:
. Increased anterior translation at 30° knee flexion
. Increased posterior translation at 90° knee flexion
. Increased posterior translation at 30° knee flexion
. Increased anterior translation at 90° knee flexion
. No change in translation of the knee

Correct Answer & Explanation

. Increased posterior translation at 30° knee flexion

Explanation

Biomechanical studies show that sectioning the posterolateral structures alone results in increases in posterior translation of the lateral tibial plateau primarily at 30° of knee flexion.

Question 6

Topic: Lower Extremity Trauma

Sectioning the posterolateral structures and posterior cruciate ligament results in:

. Increased posterior tibial translation at 30°
. Increased posterior tibial translation at 90
. Increased posterior tibial translation at 30° and 90°
. No increase in tibial translation
. Increased anterior tibial translation at 30° and 90

Correct Answer & Explanation

. Increased posterior tibial translation at 30° and 90°

Explanation

Biomechanical studies show that sectioning the posterolateral structures and posterior cruciate ligament results in increases in posterior translation of the medial and lateral tibial plateaus at 30° and 90° of knee flexion.

Question 7

Topic: Lower Extremity Trauma

The lateral meniscus differs from the medial meniscus in both morphology and mobility. Which of the following statements accurately describes the lateral meniscus?

. It is C-shaped and firmly attached to the lateral collateral ligament
. It is O-shaped and lacks direct attachment to the lateral collateral ligament
. It has a more extensive blood supply penetrating the central third
. It covers a smaller percentage of the tibial articular surface than the medial meniscus
. It is rigidly tethered posteriorly by the popliteus tendon

Correct Answer & Explanation

. It is C-shaped and firmly attached to the lateral collateral ligament

Explanation

The lateral meniscus is more circular (O-shaped) and covers a larger portion of the tibial plateau compared to the medial meniscus. It is highly mobile and is physically separated from the lateral collateral ligament by the popliteus tendon.

Question 8

Topic: Lower Extremity Trauma

A 6-year-old boy presents with a painless "snapping" sensation in his lateral knee during extension. MRI reveals a thickened lateral meniscus covering the entire tibial plateau. The Wrisberg variant of this condition is unique due to the absence of which structure?

. Anterior horn attachment
. Posterior meniscofemoral ligament
. Coronary ligament (posterior capsular attachment)
. Popliteomeniscal fascicles
. Transverse meniscal ligament

Correct Answer & Explanation

. Coronary ligament (posterior capsular attachment)

Explanation

The Wrisberg variant of a discoid lateral meniscus lacks the normal posterior capsular attachments (coronary ligaments). It is tethered only by the ligament of Wrisberg, leading to hypermobility and the classic snapping knee syndrome.

Question 9

Topic: Lower Extremity Trauma

When performing a high tibial osteotomy (HTO) for isolated medial compartment osteoarthritis in a varus knee, the mechanical axis is typically corrected to pass through which specific point on the tibial plateau?

. Dead center (50% from medial to lateral)
. 62.5% from medial to lateral
. 30% from medial to lateral
. 80% from medial to lateral
. 40% from medial to lateral

Correct Answer & Explanation

. 62.5% from medial to lateral

Explanation

The goal of an HTO in medial compartment osteoarthritis is slight overcorrection to unload the medial compartment. The target mechanical axis is the Fujisawa point, located at 62-62.5% of the tibial plateau width from medial to lateral.

Question 10

Topic: Lower Extremity Trauma

An 11-year-old boy presents with a clicking and snapping knee. MRI reveals a symptomatic Wrisberg-variant discoid meniscus. What anatomical feature distinguishes this specific variant from other types of discoid menisci?

. Lack of an anterior horn attachment
. Absence of the posterior meniscofemoral ligament
. Lack of posterior coronary ligament attachments
. Complete meniscal coverage of the tibial plateau
. Presence of a parameniscal cyst

Correct Answer & Explanation

. Lack of posterior coronary ligament attachments

Explanation

The Wrisberg variant lacks normal posterior meniscotibial (coronary) ligament attachments. The meniscus relies solely on the ligament of Wrisberg, leading to hypermobility and the classic "snapping knee" presentation.

Question 11

Topic: Lower Extremity Trauma

A 6-year-old presents with torticollis following an upper respiratory infection. Radiographs reveal atlantoaxial rotatory subluxation. According to the Fielding and Hawkins classification, which describes a Type II injury?

. Rotatory displacement without anterior translation
. Rotatory displacement with anterior translation of 3 to 5 mm
. Rotatory displacement with anterior translation greater than 5 mm
. Posterior rotatory displacement
. Complete bilateral facet dislocation

Correct Answer & Explanation

. Rotatory displacement with anterior translation of 3 to 5 mm

Explanation

Fielding Type II is characterized by rotatory displacement with anterior translation of 3 to 5 mm. This indicates one lateral mass is displaced anteriorly with a deficient or ruptured transverse ligament.

Question 12

Topic: Lower Extremity Trauma
A 4-year-old child presents with a persistent head tilt to the right and chin rotation to the left following an upper respiratory infection. Imaging reveals anterior displacement of the atlas of 4 mm with one lateral mass acting as a pivot. According to the Fielding and Hawkins classification, what type of atlantoaxial rotatory subluxation is this?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

Fielding and Hawkins Type II involves anterior displacement of 3 to 5 mm with one lateral mass acting as the pivot point. It implies a deficiency of the transverse ligament.

Question 13

Topic: Lower Extremity Trauma
A 6-year-old child presents with new-onset torticollis following a recent upper respiratory infection. The head is tilted to the right and rotated to the left. Dynamic CT imaging confirms atlantoaxial rotatory subluxation (AARS). According to the Fielding and Hawkins classification, which type is characterized by anterior displacement of the atlas greater than 5 mm with both lateral masses displaced anteriorly?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type III

Explanation

Fielding and Hawkins Type III AARS involves anterior displacement of the atlas greater than 5 mm, indicating deficiency of both the transverse and alar ligaments. Type I has no anterior displacement, and Type II has 3 to 5 mm of anterior displacement.

Question 14

Topic: Lower Extremity Trauma

Which of the following statements describes the growth plate biomechanics of the distal femur:

. The collateral ligaments protect the distal femur.
. The posterior cruciate ligament protects the distal femur.
. The anterior cruciate ligaments protect the distal femur.
. The patellar ligament protects the distal femur.
. The distal femur is not protected by any ligaments.

Correct Answer & Explanation

. The distal femur is not protected by any ligaments.

Explanation

Whereas the the proximal tibial physis is protected by the collateral ligaments and tibial tubercle epiphysis, the distal femoral physis is vulnerable to injury because it is not protected by any ligaments.

Question 15

Topic: Lower Extremity Trauma

Which of the following is the best starting point for inserting a rigid femoral intramedullary nail in a 13-year-old boy:

. Piriformis fossa
. Medial to the tip of the greater trochanter
. Apex of the greater trochanter
. Between the tip and the growth plate of the greater trochanter
. Below the growth plate of the greater trochanter

Correct Answer & Explanation

. Medial to the tip of the greater trochanter

Explanation

Avascular necrosis is a risk if a nail is inserted near the piriformis fossa in a patient younger than 15 years old with open physes. The best way to avoid this risk is to insert the intramedullary nail just lateral to the tip of the greater trochanter.

Question 16

Topic: Lower Extremity Trauma

A 12-year-old girl has genu valgum and requests correction. Radiographs reveal 12° valgus of the mechanical axis, with 2° arising in the distal femur and 3° arising in the proximal tibia. No evidence of other disorders are present. Recommended treatment includes:

. Observation
. Knee-ankle-foot orthosis worn at night
. Medial distal femur staple hemiepiphysiodesis
. Lateral opening wedge osteotomy of the distal femur
. Medial closing wedge osteotomy of the proximal tibia

Correct Answer & Explanation

. Medial distal femur staple hemiepiphysiodesis

Explanation

This patient has a significant amount of valgus. Valgus at the knee is evident when signaled by even a low number of degrees. The patient is at an age when medial distal femur staple hemiepiphysiodesis would be the best treatment for genu valgum. Medial distal femur staple hemiepiphysiodesis is a safe and effective procedure and is performed using small incisions, which allow for immediate ambulation.

Question 17

Topic: Lower Extremity Trauma

A 10-year-old girl has a leg length discrepancy. Using the multiplier method, her projected discrepancy at skeletal maturity is calculated to be 3.5 cm. Assuming a normal, stable hip and knee, what is the most appropriate surgical management?

. Contralateral distal femoral epiphysiodesis
. Ipsilateral acute lengthening with an external fixator
. Ipsilateral gradual lengthening with an intramedullary nail at age 10
. Contralateral proximal tibial acute shortening
. Observation and a 3.5 cm shoe lift for life

Correct Answer & Explanation

. Contralateral distal femoral epiphysiodesis

Explanation

Projected leg length discrepancies between 2.0 and 5.0 cm at maturity are typically best managed with a properly timed contralateral epiphysiodesis to halt growth on the longer leg.

Question 18

Topic: Lower Extremity Trauma
A 4-year-old obese girl presents with severe, progressive bilateral genu varum. Radiographs show marked depression of the medial tibial plateau and a prominent medial metaphyseal beak. Given her age and progressive deformity (Langenskiöld stage III), what is the most appropriate surgical intervention?
. Medial distal femoral hemiepiphysiodesis
. Proximal tibial valgus osteotomy
. Observation with physical therapy
. Unilateral hinged knee brace
. Lateral tibial hemiepiphysiodesis

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

Infantile Blount disease in children older than 3 years with severe or progressive deformity (Langenskiöld stage III or higher) generally requires surgical correction. A proximal tibial valgus osteotomy is the gold standard to restore normal mechanical axis and relieve pressure on the medial physis.

Question 19

Topic: Lower Extremity Trauma

A 12-year-old boy of Ashkenazi Jewish descent presents with hepatosplenomegaly, anemia, and bone pain. Radiographs of his distal femora demonstrate an 'Erlenmeyer flask' deformity. Bone marrow aspirate reveals large macrophages with a 'wrinkled tissue paper' appearance. What is the deficient enzyme?

. Sphingomyelinase
. Hexosaminidase A
. Alpha-L-iduronidase
. Glucocerebrosidase
. Arylsulfatase A

Correct Answer & Explanation

. Glucocerebrosidase

Explanation

Gaucher disease is a lysosomal storage disorder caused by a deficiency of glucocerebrosidase. The accumulation of glucocerebroside in macrophages leads to bone marrow expansion, causing osteopenia, bone crises, and the classic Erlenmeyer flask deformity of the distal femur.

Question 20

Topic: Lower Extremity Trauma

A 45-year-old man sustains a Schatzker IV tibial plateau fracture featuring a displaced posteromedial fragment. Which surgical approach provides the most direct access for the application of a buttress plate to this specific fragment?

. Anterolateral approach
. Direct anterior approach
. Posteromedial approach between the medial gastrocnemius and pes anserinus
. Posterolateral approach with fibular osteotomy
. Medial parapatellar approach

Correct Answer & Explanation

. Posteromedial approach between the medial gastrocnemius and pes anserinus

Explanation

A posteromedial approach utilizing the interval between the medial head of the gastrocnemius and the pes anserinus allows for direct visualization and the application of an anti-glide buttress plate to the posteromedial fragment.

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