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Lower Extremity Trauma MCQs

Practice Set 22 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 421

Topic: Lower Extremity Trauma



A 45-year-old male sustains a severe Schatzker VI tibial plateau fracture with a large posteromedial coronal shear fragment. The surgeon plans a dual-incision approach. Which of the following structures lies in closest proximity to the surgical interval utilized for the posteromedial approach to the tibia?

. Common peroneal nerve
. Saphenous nerve
. Anterior tibial artery
. Popliteal artery
. Sural nerve

Correct Answer & Explanation

. Saphenous nerve

Explanation

The posteromedial approach to the tibial plateau typically utilizes the internervous interval between the medial border of the tibia/pes anserinus and the medial head of the gastrocnemius. The saphenous nerve and the great saphenous vein run superficially along the medial aspect of the proximal tibia and must be identified and protected during the superficial dissection. The common peroneal nerve is lateral, and the popliteal artery is posterior, protected by the bulk of the gastrocnemius during this specific approach.

Question 422

Topic: Lower Extremity Trauma

During the flexion arc of a normal native human knee, the center of rotation of the femur relative to the tibia changes dynamically. Which of the following statements best describes the kinematic phenomenon known as 'femoral rollback'?

. The medial femoral condyle translates posteriorly more than the lateral femoral condyle during deep flexion.
. The lateral femoral condyle translates posteriorly significantly more than the medial femoral condyle during deep flexion.
. Both femoral condyles translate anteriorly symmetrically during deep flexion.
. The tibia internally rotates symmetrically relative to the femur during terminal extension.
. The patella tracks medially during early flexion and laterally during deep flexion.

Correct Answer & Explanation

. The lateral femoral condyle translates posteriorly significantly more than the medial femoral condyle during deep flexion.

Explanation

Femoral rollback is asymmetrical in the native knee. As the knee flexes, the lateral femoral condyle rolls back (translates posteriorly) significantly on the lateral tibial plateau, while the medial femoral condyle remains relatively stationary, acting as a pivot point. This differential rollback inherently couples knee flexion with internal rotation of the tibia relative to the femur.

Question 423

Topic: Lower Extremity Trauma
A 40-year-old pedestrian is struck by a motor vehicle, sustaining a severe valgus force to the knee. Computed tomography reveals a pure central depression fracture of the lateral tibial plateau, with the lateral cortical rim remaining intact. According to the Schatzker classification system, how is this fracture pattern classified?
. Schatzker I
. Schatzker II
. Schatzker III
. Schatzker IV
. Schatzker V

Correct Answer & Explanation

. Schatzker III

Explanation

Schatzker III fractures are pure central depressions of the lateral tibial plateau without an associated split of the lateral margin. Schatzker I is a pure wedge split of the lateral plateau. Schatzker II is a split-depression of the lateral plateau (most common). Schatzker IV involves the medial plateau. Schatzker V is a bicondylar fracture with intact metaphyseal-diaphyseal continuity. Schatzker VI involves metaphyseal-diaphyseal dissociation.

Question 424

Topic: Lower Extremity Trauma

A 45-year-old male feels a 'pop' in his posterior knee while squatting. MRI reveals a radial tear at the attachment site of the posterior horn of the medial meniscus.

Biomechanical studies indicate that a complete posterior root tear of the medial meniscus leads to which of the following?

. Decreased peak contact pressures in the medial compartment.
. A kinematic equivalent of a completely intact meniscus due to the intact meniscofemoral ligaments.
. Biomechanical equivalent of a total medial meniscectomy.
. Increased anterior translation of the tibia in extension.
. Subluxation of the lateral meniscus.

Correct Answer & Explanation

. Biomechanical equivalent of a total medial meniscectomy.

Explanation

The posterior root firmly anchors the medial meniscus to the tibial plateau, allowing it to convert axial loads into circumferential hoop stresses. A complete root tear severely disrupts these hoop stresses, leading to functional meniscal extrusion. Biomechanically, this failure is equivalent to a total medial meniscectomy, causing drastically increased peak contact pressures.

Question 425

Topic: Lower Extremity Trauma

A 45-year-old patient sustains a bicondylar tibial plateau fracture (Schatzker VI) with a displaced posteromedial fragment.

When utilizing a posteromedial approach to buttress this fragment, the surgical dissection typically exploits the internervous/intermuscular interval between which two structures?

. Tibialis anterior and extensor hallucis longus
. Popliteus and soleus
. Lateral head of the gastrocnemius and biceps femoris
. Medial head of the gastrocnemius and the pes anserinus
. Flexor digitorum longus and tibialis posterior

Correct Answer & Explanation

. Medial head of the gastrocnemius and the pes anserinus

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly along with the neurovascular bundle) and the pes anserinus (which is retracted anteriorly). This provides direct access to the posteromedial metaphysis to place an anti-glide buttress plate.

Question 426

Topic: Lower Extremity Trauma

A 42-year-old active male presents with medial knee pain and a varus deformity. Standing full-length radiographs confirm genu varum with mechanical axis deviation of 10mm into the medial compartment. There is isolated medial compartment osteoarthritis. The surgeon plans a medial opening wedge high tibial osteotomy (HTO). During the planning, what is the primary radiographic parameter used to achieve optimal load transfer through the lateral compartment?

. Weight-bearing line passing through the lateral third of the tibial plateau.
. Restoration of the anatomical femorotibial angle to 175 degrees.
. Achieving a HKA (Hip-Knee-Ankle) angle of 183 degrees.
. Correction of the medial proximal tibial angle (MPTA) to 90 degrees.
. Targeting an overcorrection to 5 degrees of valgus.

Correct Answer & Explanation

. Weight-bearing line passing through the lateral third of the tibial plateau.

Explanation

The goal of a medial opening wedge high tibial osteotomy (HTO) for isolated medial compartment osteoarthritis and genu varum is to shift the mechanical load from the diseased medial compartment to the healthier lateral compartment. This is achieved by creating a slight valgus alignment of the limb.Option A (Weight-bearing line passing through the lateral third of the tibial plateau) is the correct target. The weight-bearing line (or mechanical axis) connects the center of the femoral head to the center of the ankle. For HTO, the aim is to shift this line laterally. Passing it through the lateral third of the tibial plateau (typically 62-65% of the tibial width from medial) ensures sufficient unloading of the medial compartment and optimal load transfer through the healthier lateral compartment, maximizing the longevity of the osteotomy.Option B (Restoration of the anatomical femorotibial angle to 175 degrees) refers to the anatomical axis, not the mechanical axis, and doesn't directly dictate load transfer.Option C (Achieving a HKA (Hip-Knee-Ankle) angle of 183 degrees) describes a valgus alignment, but the specific target is more precisely defined by the weight-bearing line's position on the tibial plateau rather than a generic HKA angle. While 183 degrees indicates 3 degrees of mechanical valgus, the target zone for the weight-bearing line is more refined.Option D (Correction of the medial proximal tibial angle (MPTA) to 90 degrees) is an angle used in planning but is not the primary measure for final load distribution. A specific MPTA is targeted to achieve the desired mechanical axis shift, but the ultimate goal is where the weight-bearing line falls.Option E (Targeting an overcorrection to 5 degrees of valgus) is a general statement about valgus correction. While overcorrection into valgus is intended, the specific endpoint is defined by the weight-bearing line's position, not just a degree of valgus, and 5 degrees might be too much or too little for an individual patient, depending on their specific anatomy and desired load shift.

Question 427

Topic: Lower Extremity Trauma

A surgeon is performing a posteromedial approach to the tibia to fix a Schatzker IV tibial plateau fracture involving a posteromedial shear fragment. Between which two anatomical structures is the primary surgical interval developed?

. Tibialis posterior and Flexor digitorum longus
. Medial head of the gastrocnemius and the pes anserinus
. Popliteus and Soleus
. Semimembranosus and Semitendinosus
. Medial collateral ligament and medial meniscus

Correct Answer & Explanation

. Medial head of the gastrocnemius and the pes anserinus

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly) and the pes anserinus (which is retracted anteriorly). This provides excellent exposure to the posteromedial corner of the tibial plateau, allowing for buttress plating of posteromedial shear fragments often seen in Schatzker IV and bicondylar tibial plateau fractures.

Question 428

Topic: Lower Extremity Trauma

A 45-year-old male sustains a Schatzker Type VI tibial plateau fracture. During surgical approach, the surgeon utilizes a dual-incision technique (anterolateral and posteromedial). Which structure is at greatest risk of iatrogenic injury during the superficial dissection of the posteromedial approach?

. Common peroneal nerve
. Anterior tibial artery
. Saphenous nerve
. Medial superior genicular artery
. Popliteal artery

Correct Answer & Explanation

. Saphenous nerve

Explanation

The posteromedial approach to the tibial plateau requires careful dissection through the superficial tissues, where the saphenous nerve and great saphenous vein reside and are at highest risk of iatrogenic injury. Deep dissection retracts the pes anserinus tendons and protects the MCL.

Question 429

Topic: Lower Extremity Trauma

A 35-year-old male sustains a severe Schatzker IV tibial plateau fracture with a large, displaced posteromedial fragment. The surgeon elects to perform a direct posteromedial approach for optimal buttress plating. This surgical approach utilizes an internervous/intermuscular interval primarily between which two structures?

. Between the medial gastrocnemius and semimembranosus
. Between the pes anserinus and the medial head of the gastrocnemius
. Between the soleus and the popliteus
. Between the medial collateral ligament and the posterior oblique ligament
. Between the flexor hallucis longus and the Achilles tendon

Correct Answer & Explanation

. Between the pes anserinus and the medial head of the gastrocnemius

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the pes anserinus tendons anteriorly and the medial head of the gastrocnemius posteriorly. Retracting the pes anteriorly and the gastrocnemius (and soleus) posteriorly exposes the posteromedial metaphysis of the proximal tibia safely.

Question 430

Topic: Lower Extremity Trauma
A 45-year-old male sustains a high-energy traumatic injury to his knee. Radiographs and CT show a bicondylar fracture of the tibial plateau with extension of the fracture line into the tibial diaphysis. This injury is best classified as which Schatzker type?
. Schatzker III
. Schatzker IV
. Schatzker V
. Schatzker VI
. Schatzker VII

Correct Answer & Explanation

. Schatzker VI

Explanation

Schatzker VI is a bicondylar tibial plateau fracture with dissociation of the metaphysis from the diaphysis. Schatzker V is a bicondylar fracture with intact metaphyseal-diaphyseal continuity.

Question 431

Topic: Lower Extremity Trauma

A 60-year-old patient with long-standing, poorly controlled diabetes presents with a unilaterally swollen, warm, and erythematous foot. Radiographs demonstrate dramatic tarsometatarsal joint subluxation, extensive bony fragmentation, and periarticular debris. Which classification system is strictly used to stage the radiographic progression of this specific neuroarthropathic condition?

. Brodsky classification
. Eichenholtz classification
. Hawkins classification
. Wagner classification
. Sanders classification

Correct Answer & Explanation

. Eichenholtz classification

Explanation

The Eichenholtz classification describes the natural history and radiographic staging of Charcot neuroarthropathy. Stage 0 is clinical inflammation with normal x-rays. Stage 1 is the developmental/fragmentation phase (debris, dislocation). Stage 2 is the coalescence phase (absorption of debris, early fusion). Stage 3 is the consolidation/reconstruction phase. Brodsky classifies the anatomic location of Charcot joints, while Wagner is used for diabetic foot ulcers.

Question 432

Topic: Lower Extremity Trauma
A 7-year-old boy presents with torticollis following an upper respiratory tract infection. Radiographs and CT show anterior displacement of the atlas on the axis of 4 mm, with one lateral mass acting as the pivot point. 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 AARS involves anterior displacement of the atlas by 3-5 mm, with one lateral mass acting as the pivot point, indicating a deficiency of the transverse ligament. Type I has no anterior displacement (pivot on the dens). Type III has >5mm anterior displacement (deficiency of transverse and alar ligaments). Type IV involves posterior displacement.

Question 433

Topic: Lower Extremity Trauma

The mechanical axis of the lower extremity is defined as a line drawn from the center of the femoral head to the center of the ankle joint. In a normal, well-aligned lower limb, where does this mechanical axis pass relative to the knee joint center?

. Exactly through the center of the knee joint
. 10 mm lateral to the center of the knee joint
. 8-10 mm medial to the center of the knee joint
. 25 mm medial to the center of the knee joint
. Through the lateral collateral ligament

Correct Answer & Explanation

. 8-10 mm medial to the center of the knee joint

Explanation

In a normally aligned human leg, the mechanical axis passes slightly medial to the geometric center of the knee joint (typically about 8 to 10 mm medial to the midpoint of the tibial plateau). This slight medial offset is why the medial compartment of the normal knee bears a larger percentage (approximately 60%) of the physiological weight-bearing load compared to the lateral compartment.

Question 434

Topic: Lower Extremity Trauma

A 40-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. Which of the following findings makes the utilization of a dual-incision (anterolateral and posteromedial) approach mandatory rather than a single lateral approach?

. Severe lateral articular depression
. Comminution of the anterior tibial tuberosity
. A displaced posteromedial coronal split fragment
. Involvement of the fibular head
. An associated meniscal tear

Correct Answer & Explanation

. A displaced posteromedial coronal split fragment

Explanation

A displaced posteromedial fragment is a classic indication for a posteromedial approach because it cannot be adequately reduced or buttressed from an anterolateral approach. A posteromedial buttress plate is typically required to resist the deforming shear forces during weight-bearing.

Question 435

Topic: Lower Extremity Trauma

A trauma surgeon decides to ream a tibial shaft and change the planned solid intramedullary nail from a 10 mm diameter to a 12 mm diameter. By approximately what factor does this change increase the torsional rigidity of the implant?

. 1.2
. 1.4
. 1.7
. 2.1
. 2.5

Correct Answer & Explanation

. 2.1

Explanation

The torsional rigidity of a solid cylinder is proportional to the radius (or diameter) raised to the fourth power (r^4). Therefore, increasing the diameter from 10 mm to 12 mm increases the rigidity by a factor of (12/10)^4 = 1.2^4 = 2.0736, which is approximately 2.1.

Question 436

Topic: Lower Extremity Trauma

During the surgical approach to the posteromedial aspect of the tibial plateau for internal fixation of a Schatzker IV fracture, the primary internervous/intermuscular plane is utilized. Which structures define the borders of this interval?

. Semimembranosus and the medial head of the gastrocnemius
. Pes anserinus and the medial head of the gastrocnemius
. Tibialis posterior and flexor digitorum longus
. Medial head of the gastrocnemius and the soleus
. Semitendinosus and semimembranosus

Correct Answer & Explanation

. Pes anserinus and the medial head of the gastrocnemius

Explanation

The posteromedial approach to the tibial plateau utilizes an interval between the medial head of the gastrocnemius (innervated by the tibial nerve) posteriorly, and the pes anserinus (innervated by the femoral and sciatic nerves) anteriorly. Retracting the gastrocnemius posteriorly and laterally protects the popliteal neurovascular bundle.

Question 437

Topic: Lower Extremity Trauma

A 24-year-old elite skier presents with lateral ankle pain and a snapping sensation behind the lateral malleolus. Physical examination confirms subluxation of the peroneal tendons with resisted eversion and dorsiflexion. Which anatomical structure is primarily responsible for preventing this condition, and is likely deficient or torn?

. Calcaneofibular ligament
. Superior peroneal retinaculum
. Inferior peroneal retinaculum
. Anterior talofibular ligament
. Peroneus brevis tendon sheath

Correct Answer & Explanation

. Superior peroneal retinaculum

Explanation

The superior peroneal retinaculum (SPR) is the primary static restraint to subluxation and dislocation of the peroneal tendons out of the retromalleolar groove. Disruption, stripping, or avulsion (e.g., 'fleck sign') of the SPR is the hallmark of peroneal tendon instability.

Question 438

Topic: Lower Extremity Trauma

A 42-year-old male sustains a high-energy Schatzker Type IV tibial plateau fracture with a significant posteromedial shear fragment. Surgical fixation requires a posteromedial approach to the knee. The optimal intermuscular interval for this approach is developed between the medial head of the gastrocnemius posteriorly and which of the following structures anteriorly?

. Soleus muscle
. Semimembranosus tendon
. Pes anserinus tendons (Sartorius, Gracilis, Semitendinosus)
. Popliteus muscle
. Flexor hallucis longus muscle

Correct Answer & Explanation

. Pes anserinus tendons (Sartorius, Gracilis, Semitendinosus)

Explanation

The classic posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly/laterally to protect the neurovascular bundle) and the pes anserinus tendons (Sartorius, Gracilis, Semitendinosus), which are retracted anteriorly. This safely exposes the posteromedial metaphysis of the proximal tibia for anti-glide plating.

Question 439

Topic: Lower Extremity Trauma

A 40-year-old male sustains a high-energy complex tibial plateau fracture involving a large, displaced posteromedial fragment (Schatzker IV). The surgeon plans a direct posteromedial approach for buttress plating. Which of the following describes the correct inter-nervous or muscular interval for this specific approach?

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

Correct Answer & Explanation

. Between the semimembranosus and the medial head of the gastrocnemius

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted laterally/posteriorly along with the neurovascular bundle) and the pes anserinus / semimembranosus (which are retracted medially/anteriorly). This provides excellent direct access to the posteromedial corner of the tibia for buttress plate application.

Question 440

Topic: Lower Extremity Trauma

A 28-year-old soccer player sustains a twisting ankle injury. Radiographs show a widened medial clear space on the gravity stress view, consistent with a syndesmotic injury. During operative fixation, what is the most important factor in achieving a good long-term clinical outcome?

. Use of suture-button fixation instead of metallic screw fixation
. Placement of the fixation exactly 2 cm above the joint line
. Anatomic reduction of the distal tibiofibular joint within the incisura
. Routine removal of the syndesmotic screws at exactly 8 weeks postoperatively
. Fixing the fibula in relative internal rotation to tighten the complex

Correct Answer & Explanation

. Anatomic reduction of the distal tibiofibular joint within the incisura

Explanation

The most critical factor determining clinical outcomes in syndesmotic injuries is the anatomic reduction of the fibula within the incisura. Malreduction is highly associated with poor functional outcomes and early post-traumatic ankle arthritis.

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