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Lower Extremity Trauma MCQs

Practice Set 19 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 361

Topic: Lower Extremity Trauma

A patient with an apex anterior (procurvatum) deformity of the distal femur is planned for correction. Which of the following radiographic angles is utilized to assess the sagittal plane alignment of the distal femur?

. Posterior proximal femoral angle (PPFA)
. Posterior distal femoral angle (PDFA)
. Anterior distal tibial angle (ADTA)
. Proximal posterior tibial angle (PPTA)
. Mechanical lateral distal femoral angle (mLDFA)

Correct Answer & Explanation

. Posterior distal femoral angle (PDFA)

Explanation

Sagittal alignment of the distal femur is assessed using the posterior distal femoral angle (PDFA), which normally averages 83 degrees.

Question 362

Topic: Lower Extremity Trauma

A patient undergoes radiographic analysis for genu valgum. The mechanical lateral distal femoral angle (mLDFA) is calculated. Which of the following values definitively indicates a femoral valgus deformity?

. 95 degrees
. 87 degrees
. 81 degrees
. 100 degrees
. 89 degrees

Correct Answer & Explanation

. 87 degrees

Explanation

The normal mLDFA is approximately 87 degrees (range 85-90 degrees). An angle less than 85 degrees indicates a valgus deformity of the distal femur, whereas an angle greater than 90 indicates varus.

Question 363

Topic: Lower Extremity Trauma

A patient requires a multiplanar deformity correction of the tibia. A lateral radiograph is obtained to measure the posterior proximal tibial angle (PPTA). What is the normal average PPTA used as a reference in Paley's analysis?

. 81 degrees
. 87 degrees
. 90 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal posterior proximal tibial angle (PPTA) is approximately 81 degrees. This reflects the normal posterior slope of the tibial plateau, which is roughly 9 degrees relative to the perpendicular of the anatomic axis.

Question 364

Topic: Lower Extremity Trauma
  • Which of the following is considered an advantage of an unreamed intramedullary nail over a reamed intramedullary nail?
. Avoids the risk of marrow emboli
. Avoids injury to the intramedullary nutrient vessels
. Results in faster healing of fractures
. Results in more secure fixation
. Results in faster regeneration of the endosteal blood supply

Correct Answer & Explanation

. Results in faster regeneration of the endosteal blood supply

Explanation

The advantage of an unreamed intramedullary nail is a loose-fitting intramedullary rod. Placed in the medullary canal, it allows the endosteal circulation to regenerate rapidly and completely where space has been left between the nail and the endosteal surface. The endosteal blood vessels are destroyed during introduction of reamed intramedullary nail.

Question 365

Topic: Lower Extremity Trauma
Which of the following statements best describes the anatomic considerations of the popliteal artery posterior to the knee joint?
. It lies posterior to the popliteal vein and 9 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.
. It lies anterior to the popliteal vein and 9 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.
. It lies lateral to the popliteal vein and 15 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.
. It lies medial to the popliteal vein and 9 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.
. It lies anterior to the popliteal vein and 15 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.

Correct Answer & Explanation

. It lies anterior to the popliteal vein and 9 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.

Explanation

Popliteal artery injury during total knee arthroplasty is relatively rare. Knee flexion, the position that occurs during most of the arthroplasty procedure, allows the popliteal vessels to fall posteriorly, further away from harm. Anatomically, the popliteal artery lies anterior to the popliteal vein and 9 mm posterior to the posterior aspect of the tibial plateau in 90 degrees of flexion.

Question 366

Topic: Lower Extremity Trauma

-If a physician elects to shorten a femur by 4 cm for traumatic bone loss treatment and places an intramedullary nail for fixation, which deformity will be created in the lower extremity?

. Patella alta
. Medial mechanical axis deviation
. Lateral mechanical axis deviation
. Increased anatomic tibiofemoral angle
. Translation of the anatomical axis of the femur

Correct Answer & Explanation

. Patella alta

Explanation

Question 367

Topic: Lower Extremity Trauma

A 45-year-old male sustains a Schatzker IV tibial plateau fracture involving a large, displaced posteromedial shear fragment. The surgeon plans a posteromedial approach in the supine position. The optimal inter-nervous and inter-muscular interval for exposing the posteromedial tibial plateau is bounded by which of the following structures?

. Medial head of the gastrocnemius and the pes anserinus tendons
. Lateral head of the gastrocnemius and the popliteus muscle
. Tibialis anterior and extensor hallucis longus
. Soleus and the flexor digitorum longus
. Semimembranosus and semitendinosus muscles

Correct Answer & Explanation

. Medial head of the gastrocnemius and the pes anserinus tendons

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted laterally and posteriorly to protect the neurovascular bundle) and the pes anserinus tendons (which are retracted medially and anteriorly). This provides direct, safe access to the posteromedial shear fragment for buttress plating.

Question 368

Topic: Lower Extremity Trauma
A 25-year-old male sustains a Hawkins Type III talar neck fracture following a fall from height. Radiographs taken at 8 weeks post-ORIF reveal a subchondral radiolucent band in the dome of the talus on the AP view (Hawkins sign). What is the physiological significance and expected clinical outcome based on this radiographic finding?
. It represents subchondral osteopenia secondary to hyperemia, indicating intact vascularity and a highly favorable prognosis against AVN
. It indicates the onset of aggressive avascular necrosis and predicts imminent talar body collapse
. It is a classic sign of early non-union at the talar neck, necessitating prompt bone grafting
. It indicates an undiagnosed concurrent subtalar dislocation requiring revision surgery
. It represents a post-traumatic cartilaginous defect requiring osteochondral autograft transfer

Correct Answer & Explanation

. It represents subchondral osteopenia secondary to hyperemia, indicating intact vascularity and a highly favorable prognosis against AVN

Explanation

The Hawkins sign is a subchondral radiolucent band seen in the dome of the talus, typically appearing 6 to 8 weeks after injury. It represents subchondral osteopenia (bone resorption) which can only occur in the presence of an intact blood supply causing localized hyperemia. Therefore, a positive Hawkins sign is a highly reliable indicator that the talar body remains vascularized, predicting a very low risk of avascular necrosis (AVN).

Question 369

Topic: Lower Extremity Trauma

Figure 1 is the MR image of a high school soccer player who sustained a right knee injury during a game while making a cut toward the ball. He felt a pop and his leg gave way. During physical examination, as the knee is moved from full extension into flexion with an internal rotation and valgus force, you notice a "clunk" within the knee. What is the most likely biomechanical basis for the "clunk"?

. In extension with internal rotation/valgus force, the medial tibial plateau is subluxated; with flexion, the medial tibial plateau reduces.
. In extension with internal rotation/valgus force, the medial tibial plateau is reduced; with flexion, the medial tibial plateau subluxates.
. In extension with internal rotation/valgus force, the lateral tibial plateau is reduced; with flexion, the lateral plateau subluxates.
. In extension with internal rotation/valgus force, the lateral tibial plateau is subluxated; with flexion, the lateral plateau reduces.

Correct Answer & Explanation

. In extension with internal rotation/valgus force, the medial tibial plateau is subluxated; with flexion, the medial tibial plateau reduces.

Explanation

This patient sustained an isolated anterior cruciate ligament (ACL) injury based upon the mechanism described and examination findings. The finding that produces the “clunk” is the pivot-shift maneuver, which is positive in a knee with an incompetent ACL. With an ACL-deficient knee in full extension and internal rotation, the lateral tibial plateau subluxates anteriorly. As the knee is flexed, the lateral tibial plateau slides posteriorly into a reduced position, causing an audible clunk. Response D correctly describes the pathomechanics that result in the audible clunk heard during the pivot-shift maneuver. Responses A and B are incorrect because they describe the medial tibial plateau, which is not part of the pathomechanics of the pivot shift. Response C is incorrect because in extension, the lateral tibial plateauis subluxated, not reduced.

Question 370

Topic: Lower Extremity Trauma
A surgeon is preparing a medial gastrocnemius rotational flap to cover a medial proximal tibia defect at the time of revision knee replacement surgery. To optimize coverage, the surgeon must optimally mobilize which artery?
. Profundus femoris
. Middle genicular
. Medial sural
. Inferior medial genicular

Correct Answer & Explanation

. Medial sural

Explanation

The medial sural arteries vascularize the gastrocnemius, plantaris, and soleus muscles proximally. They arise from the popliteal artery. If not adequately mobilized, a gastrocnemius-soleus flap can be devascularized.

Question 371

Topic: Lower Extremity Trauma
Figure 34 shows the standing AP radiograph of a 2-year-old girl who has a left bowleg deformity. Her mother states that she first noticed the problem when the child began walking at age 10 months, and the deformity has worsened over the past 6 months. Examination reveals a definite lateral thrust of the knee during the stance phase of gait. Management should consist of
. observation.
. a proximal tibial and fibular osteotomy.
. daytime ambulatory bracing.
. elevation of the medial tibial plateau.
. an MRI scan of the knee.

Correct Answer & Explanation

. daytime ambulatory bracing.

Explanation

DISCUSSION: Infantile tibia vara is a developmental condition characterized by a varus angulation of the proximal end of the tibia that is caused by a growth disturbance of the proximal medial physis. In a study of 42 affected extremities in 24 children younger than age 3 years, it was found that daytime ambulatory brace treatment favorably altered the natural history of tibia vara.

Question 372

Topic: Lower Extremity Trauma

A 19-year-old woman sustained a displaced talar neck fracture while cliff jumping. The fracture is managed with open reduction and internal fixation. Which of the following best describes the findings in the 2-months postoperative radiographs shown in Figures 67a and 67b, and subsequent treatment plan? Review Topic

. There is a positive Hawkins sign, indicating the patient is unlikely to develop osteonecrosis.
. There is a positive Hawkins sign, indicating the patient has developed osteonecrosis.
. Hawkins sign cannot be determined on radiographs; therefore, MRI is required.
. No Hawkins sign is visible, and therefore the patient is not likely to develop osteonecrosis.
. No Hawkins sign is visible; therefore, the patient should be kept non-weight-bearing until a Hawkins sign appears

Correct Answer & Explanation

. There is a positive Hawkins sign, indicating the patient is unlikely to develop osteonecrosis.

Explanation

The radiographs reveal a positive Hawkins sign, a subchondral lucency in the talar dome best seen on a mortise radiograph indicating viability of the talar body. Once a Hawkins sign appears, it is unlikely that that the patient will develop osteonecrosis.Osteonecrosis is best diagnosed with radiographs. Although MRI can be helpful in assessing the extent of osteonecrosis, it is unnecessary for purely diagnostic purposes. A Hawkins sign typically will appear at 6 to 8 weeks after fracture; however, the absence of a Hawkins sign at that time does not necessarily indicate osteonecrosis. Most authors agree that even in the absence of a Hawkins sign, weight bearing can commence at 10 to 12 weeks after surgery.

Question 373

Topic: Lower Extremity Trauma
At the time of arthroscopy, a 9-year-old boy was found to have a Watanabe type II discoid lateral meniscus. What is the most appropriate treatment?
. Saucerization of the meniscus only
. Saucerization and stabilization of the meniscus
. Stabilization of the meniscus only
. Complete meniscectomy

Correct Answer & Explanation

. Saucerization of the meniscus only

Explanation

The Watanabe type II meniscus should only require saucerization for treatment because it is not unstable. The Watanabe classification defines 3 types of discoid menisci. In type I (stable, complete), the block-shaped lateral meniscus covers the entire lateral tibial plateau, whereas in type II (stable, partial), the lateral meniscus covers less than or equal to 80% of the tibial plateau. Type III discoid menisci (unstable, ligament of Wrisberg) appear to be normal except for a thickened posterior horn, but they lack posterior meniscal attachments, including the meniscotibial (ie, coronary) ligament. The type III discoid meniscus is stabilized only by the meniscofemoral ligament of Wrisberg. This results in hypermobility of the lateral meniscus at the posterior horn, which pulls into the intercondylar notch with knee extension, resulting in snapping knee syndrome. Complete meniscectomy should be avoided if possible.

Question 374

Topic: Lower Extremity Trauma

A 45-year-old male sustains a Schatzker IV tibial plateau fracture with a large, displaced posteromedial fragment. The surgeon elects to buttress this fragment using a standard posteromedial approach with the patient prone. Which anatomic interval is utilized to access the posteromedial tibial plateau?

. Between the medial head of the gastrocnemius and the semimembranosus
. Between the medial head of the gastrocnemius and the pes anserinus
. Between the popliteus and the soleus
. Between the semitendinosus and the medial collateral ligament
. Between the tibialis posterior and the flexor digitorum longus

Correct Answer & Explanation

. Between the medial head of the gastrocnemius and the semimembranosus

Explanation

The standard posteromedial approach to the tibial plateau uses the interval between the medial head of the gastrocnemius (which is retracted laterally along with the neurovascular bundle to protect it) and the pes anserinus tendons (which are retracted medially). This safely exposes the posteromedial cortex of the proximal tibia.

Question 375

Topic: Lower Extremity Trauma

When performing a posteromedial approach to the knee for open reduction and internal fixation of a Schatzker IV tibial plateau fracture, the dissection is typically carried out between the medial head of the gastrocnemius and which of the following structures?

. Popliteus
. Pes anserinus tendons
. Semitendinosus alone
. Soleus
. Iliotibial band

Correct Answer & Explanation

. Popliteus

Explanation

The classic posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (retracted laterally with the neurovascular bundle) and the pes anserinus tendons (retracted medially).

Question 376

Topic: Lower Extremity Trauma

During retrograde intramedullary nailing of a distal femur fracture, the ideal starting point in the intercondylar notch is located in line with the anatomic axis of the femoral shaft and specifically:

. Anterior to Blumensaat's line
. Just anterior to the PCL origin
. Just posterior to the ACL origin
. Centered exactly between the ACL and PCL origins
. Anterior to the intercondylar roof

Correct Answer & Explanation

. Anterior to Blumensaat's line

Explanation

The optimal starting point for a retrograde femoral nail is perfectly centered in the intercondylar notch in the coronal plane, and just anterior to the origin of the posterior cruciate ligament (PCL) in the sagittal plane.

Question 377

Topic: Lower Extremity Trauma

A 26-year-old male underwent statically locked intramedullary nail fixation for a comminuted left femur fracture. An early post-operative computed tomography (CT) scanogram was taken to check rotational alignment, as shown in Figure A. What would be the next best step in the management of this patient?

. Observation and close follow-up
. Dynamization of the intramedullary nail
. Revision surgery, internally rotate distal fragment by 19 degrees
. Revision surgery, externally rotate distal fragment by 8 degrees
. Revision surgery, internally rotate proximal fragment by 11 degrees

Correct Answer & Explanation

. Observation and close follow-up

Explanation

The CT scanogram shows the operative left femur is 8 degrees externally rotated compared to the native right femur. No correction is required unless malalignment is>15 degrees and symptomatic. Therefore, the most appropriate next step would be to continue with postoperative observation and close follow-up.The primary purpose of CT scanogram is to measure the angle of rotation of the femoral neck relative to the femoral condyle. To do this, the right and left femurs must be scanned together using a 5mm helical slice scanner at the hip and knee. The first slice should reveal the alignment of the femoral neck, so as to allow for measurement of the femoral neck-to-horizontal (FNH) angle. The second slice should reveal the alignment of the posterior femoral condyles. This allows measurement of the posterior condyle-to-horizontal (PCH) angle. Finally, to calculate the rotational alignment (RA), the FNH angle and PCH angles are subtracted (e.g., RA = FNH -PCH). Normal RA is usually +5 to +20 degrees, which is also referred to as 5 to 20 degrees of femoral anteversion.Lindsey et al. reviewed femoral malrotation following intramedullary nail fixation. They showed the incidence of rotational malalignment was ~28%. Normal femoral neck anteversion (angle of the femoral neck relative to the transverse axis through the femoral condyles) is ~11-13°. However, they noted that some patients have up to 15° difference in rotation in native limbs. Therefore <15 degrees of rotational difference after fixation is considered acceptable.Gugala et al. examined the long-term functional implications for patients with iatrogenic femoral malrotation following femoral intramedullary nail fixation. Theyshowed that patients can compensate for even significant femoral malrotation (up to 30 degrees) and tolerate it well. However, external femoral malrotation (more common) appears to be better compensated/tolerated than internal malrotation.Figure A shows that the left femoral neck is externally rotated (ER) by 15° to the horizontal (ER15). The right femoral neck is externally rotated (ER) by 4° to the horizontal (ER4). The left distal fragment is ER10. The right distal fragment is internally rotated (IR) by 9°. Thus, left femur has a total (ER15)-(ER10)= (+15)-(+10)=(+5), and right femur has (ER4)-(IR9)= (+4)-(-9)=(+13) to the horizontal. Therefore, the difference is 8 degrees.Incorrect Answers:>15 degrees and symptomatic.

Question 378

Topic: Lower Extremity Trauma

Figure 1 is the MRI scan of a 35-year-old female soccer player who injured her knee during a game. Given the findings of the scan, physical examination is most likely to reveal

. grade 2 pivot shift.
. positive Thessaly test.
. positive quadriceps active test.
. positive dial test at 30°.

Correct Answer & Explanation

. grade 2 pivot shift.

Explanation

The MRI scan clearly reveals bone bruises in the mid lateral femoral condyle and posterior tibial plateau. These MRI findings are commonly associated with acute anterior cruciate ligament injuries. Therefore, the preferred answer would be a positive pivot shift examination. A positive posterior drawer and positive quad active test are associated with posterior cruciate ligament injuries. A positive dial test would be suggestive of a posterolateral instability of the knee.

Question 379

Topic: Lower Extremity Trauma
A 7-year-old girl presents with snapping and lateral joint line pain in her right knee. MRI demonstrates a Wrisberg variant discoid lateral meniscus. According to the Watanabe classification, what anatomical feature defines this specific variant?
. Complete coverage of the lateral tibial plateau with normal posterior attachments
. Incomplete coverage of the lateral tibial plateau with normal posterior attachments
. Absence of the posterior meniscotibial (coronary) ligaments, with the meniscofemoral ligament of Wrisberg serving as the only posterior attachment
. A hypermobile medial meniscus
. An anteriorly displaced meniscus with intact posterior attachments

Correct Answer & Explanation

. Absence of the posterior meniscotibial (coronary) ligaments, with the meniscofemoral ligament of Wrisberg serving as the only posterior attachment

Explanation

The Watanabe classification describes three types of discoid meniscus: Complete (Type I), Incomplete (Type II), and Wrisberg variant (Type III). The Wrisberg variant lacks the normal posterior meniscotibial (coronary) attachments; its only posterior tether is the meniscofemoral ligament of Wrisberg, leading to hypermobility and the classic 'snapping knee' presentation.

Question 380

Topic: Lower Extremity Trauma

A 19-year-old female hears a "pop" while pivoting during basketball. Based on the classic MRI findings of a noncontact ACL rupture, what associated bone bruise pattern is most commonly seen?

. Medial femoral condyle and medial tibial plateau
. Lateral femoral condyle and posterolateral tibial plateau
. Anterior lateral femoral condyle and anterior medial tibial plateau
. Trochlear groove and patella
. Posterior medial femoral condyle and anterior lateral tibial plateau

Correct Answer & Explanation

. Medial femoral condyle and medial tibial plateau

Explanation

Noncontact ACL injuries (pivot-shift mechanism) characteristically produce bone bruises involving the lateral femoral condyle (terminal sulcus) and the posterolateral tibial plateau due to anterior subluxation and impaction.

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