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Lower Extremity Trauma MCQs

Practice Set 30 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 581

Topic: Lower Extremity Trauma

A 55-year-old male sustains a high-energy varus impact to his knee. Radiographs reveal a medial tibial plateau fracture with significant depression and widening. What is the Schatzker classification for this injury, and what is the associated soft tissue injury most commonly seen?

. Schatzker I; medial meniscus tear
. Schatzker II; lateral collateral ligament tear
. Schatzker IV; lateral collateral ligament / posterolateral corner injury
. Schatzker V; patellar tendon rupture
. Schatzker VI; isolated medial meniscus tear

Correct Answer & Explanation

. Schatzker I; medial meniscus tear

Explanation

A medial tibial plateau fracture represents a Schatzker IV. This is typically a high-energy pattern resulting from severe varus stress, often leading to distraction or avulsion injuries to the lateral-sided structures, including the lateral collateral ligament (LCL) and the posterolateral corner (PLC).

Question 582

Topic: Lower Extremity Trauma

A 45-year-old male presents with a Schatzker Type IV tibial plateau fracture with a large posteromedial shear fragment. The surgeon plans a posteromedial approach with the patient in the prone position. The optimal internervous/intermuscular interval for this approach is between the:

. Medial head of the gastrocnemius and the soleus
. Medial head of the gastrocnemius and the pes anserinus
. Lateral head of the gastrocnemius and the biceps femoris
. Tibialis posterior and the flexor hallucis longus
. Semimembranosus and the semitendinosus

Correct Answer & Explanation

. Medial head of the gastrocnemius and the soleus

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted laterally, protecting the neurovascular bundle) and the pes anserinus/semimembranosus tendons (which are retracted medially). This provides excellent visualization for buttress plating of posteromedial shear fragments.

Question 583

Topic: Lower Extremity Trauma

A 22-year-old collegiate football player sustains a midfoot injury during a tackle. Weight-bearing radiographs demonstrate 3 mm of widening between the base of the first and second metatarsals, with a 'fleck sign' visible in the intercuneiform space. What is the most appropriate management for this athlete?

. Non-weight-bearing in a short leg cast for 6 weeks
. Immediate return to play with a rigid carbon-fiber orthotic
. Open reduction and internal fixation or primary arthrodesis of the Lisfranc complex
. Corticosteroid injection into the tarsometatarsal joints
. Closed reduction and percutaneous pinning with smooth Kirschner wires

Correct Answer & Explanation

. Non-weight-bearing in a short leg cast for 6 weeks

Explanation

The presentation describes a ligamentous Lisfranc injury with instability (diastasis > 2 mm and a positive 'fleck sign' representing avulsion of the Lisfranc ligament). Non-operative management is inadequate for unstable injuries. Stable anatomic fixation via Open Reduction Internal Fixation (ORIF) or primary arthrodesis is required to prevent debilitating post-traumatic midfoot arthrosis.

Question 584

Topic: Lower Extremity Trauma

A 9-year-old girl complains of a painful, snapping sensation in her lateral knee when walking. MRI confirms a Wrisberg variant discoid lateral meniscus. What is the defining anatomical characteristic of this variant?

. Absence of the anterior horn attachment
. Absence of the posterior meniscotibial attachment
. A continuous connection between the anterior and posterior horns
. Presence of a parameniscal cyst
. Complete coverage of the lateral tibial plateau

Correct Answer & Explanation

. Absence of the anterior horn attachment

Explanation

The Wrisberg variant of a discoid meniscus lacks the normal posterior meniscotibial (coronary ligament) attachment, being stabilized posteriorly only by the ligament of Wrisberg. This leads to hypermobility and the classic "snapping knee" syndrome.

Question 585

Topic: Lower Extremity Trauma

The menisci of the knee have distinct attachments that dictate their mobility and susceptibility to injury. Which of the following ligaments connects the anterior horn of the medial meniscus directly to the anterior horn of the lateral meniscus?

. Coronary ligament
. Transverse meniculate (meniscal) ligament
. Ligament of Wrisberg
. Ligament of Humphrey
. Oblique popliteal ligament

Correct Answer & Explanation

. Coronary ligament

Explanation

The transverse meniscal ligament (or transverse geniculate ligament) connects the anterior horns of the medial and lateral menisci. The ligaments of Wrisberg and Humphrey are the posterior meniscofemoral ligaments. Coronary ligaments connect the menisci to the tibial plateau.

Question 586

Topic: Lower Extremity Trauma

The medial and lateral menisci of the knee exhibit distinct anatomical differences. Which of the following statements regarding meniscal anatomy is correct?

. The medial meniscus is more mobile than the lateral meniscus
. The lateral meniscus covers a smaller percentage of the tibial plateau than the medial meniscus
. The popliteus tendon hiatus disrupts the peripheral attachment of the medial meniscus
. The medial meniscus is C-shaped while the lateral meniscus is more circular (O-shaped)
. Both menisci receive a robust vascular supply extending to their inner third

Correct Answer & Explanation

. The medial meniscus is more mobile than the lateral meniscus

Explanation

The medial meniscus is C-shaped (semi-circular) with widely separated anterior and posterior horns. The lateral meniscus is more circular (O-shaped) and covers a larger portion of its respective tibial plateau. The lateral meniscus is also more mobile, partly due to the popliteus hiatus disrupting its peripheral attachment.

Question 587

Topic: Lower Extremity Trauma

When planning a medial opening wedge high tibial osteotomy (HTO) for isolated medial compartment osteoarthritis in a varus knee, the surgeon intends to shift the mechanical axis to the Fujisawa point. Where is the Fujisawa point located on the tibial plateau?

. At exactly 50% of the tibial width (center of the knee)
. At 62% of the tibial width, measured from the medial to lateral edge
. At 38% of the tibial width, measured from the medial to lateral edge
. At the lateral edge of the lateral meniscus
. At the medial tibial spine

Correct Answer & Explanation

. At exactly 50% of the tibial width (center of the knee)

Explanation

The Fujisawa point is traditionally targeted in HTO for medial compartment OA to slightly overcorrect the varus deformity and unload the medial compartment. It is located at 62% of the tibial plateau width from the medial edge (i.e., slightly lateral to the lateral tibial spine in the lateral compartment). This aligns the mechanical axis to pass through the lateral compartment, providing optimal unloading of the damaged medial cartilage while preventing excessive valgus overload.

Question 588

Topic: Lower Extremity Trauma

Popliteal artery injury is a rare but devastating complication of primary TKA. During which specific surgical maneuver is the artery at the highest risk of direct traumatic injury?

. Resection of the anterior femoral condyles
. Removal of medial osteophytes from the tibial plateau
. Release of the superficial medial collateral ligament (sMCL)
. Resection of the posterior tibial plateau and posterior femoral condyles
. Preparation and resurfacing of the patella

Correct Answer & Explanation

. Resection of the anterior femoral condyles

Explanation

The popliteal artery is situated directly posterior to the posterior capsule of the knee, at the level of the joint line. It is at greatest risk of direct laceration from the oscillating saw blade penetrating the posterior capsule during the proximal tibial cut or the posterior femoral condylar cuts.

Question 589

Topic: Lower Extremity Trauma

An asymptomatic 10-year-old boy undergoes a radiograph after a minor knee sprain. The plain film reveals an incidental finding: an eccentric, cortically based, multilocular radiolucency with a well-defined sclerotic border in the distal femur metaphysis.

Which of the following is the most appropriate management for this lesion?

. Observation and reassurance
. Curettage and bone grafting
. Wide en bloc resection
. Radiofrequency ablation
. Neoadjuvant chemotherapy followed by resection

Correct Answer & Explanation

. Observation and reassurance

Explanation

The radiograph describes a Non-Ossifying Fibroma (NOF) or Fibrous Cortical Defect. These are benign, asymptomatic, self-limiting developmental defects of bone rather than true neoplasms. They typically present as eccentric, cortically based, 'bubbly' metaphyseal lesions with sclerotic margins. The standard of care is observation and reassurance, as the vast majority will ossify and resolve spontaneously as the child reaches skeletal maturity.

Question 590

Topic: Lower Extremity Trauma

A 45-year-old male sustains a severe valgus stress injury to the knee, resulting in a Schatzker IV tibial plateau fracture with significant posteromedial depression. You plan a posteromedial surgical approach. The standard internervous/intermuscular plane for this approach is developed between which of the following structures?

. Semimembranosus and semitendinosus
. Medial head of the gastrocnemius and the pes anserinus
. Tibialis posterior and flexor digitorum longus
. Sartorius and gracilis
. Popliteus and soleus

Correct Answer & Explanation

. Semimembranosus and semitendinosus

Explanation

The posteromedial approach to the tibial plateau is critical for reducing and buttressing posteromedial shear fragments. The surgical interval is developed between the medial head of the gastrocnemius (retracted posteriorly/laterally) and the pes anserinus tendons (semitendinosus, gracilis, sartorius; retracted anteriorly/medially). Care must be taken to protect the saphenous nerve and great saphenous vein.

Question 591

Topic: Lower Extremity Trauma

A 50-year-old male falls off a ladder and sustains a bicondylar tibial plateau fracture with diaphyseal dissociation. What is the Schatzker classification, and what surgical approach is often required for the posteromedial fragment?

. Schatzker V; Anterolateral approach alone
. Schatzker VI; Dual approaches (Anterolateral and Posteromedial)
. Schatzker IV; Medial approach alone
. Schatzker VI; Single midline anterior approach
. Schatzker V; Dual approaches (Anterolateral and Posteromedial)

Correct Answer & Explanation

. Schatzker V; Anterolateral approach alone

Explanation

A bicondylar tibial plateau fracture with complete dissociation of the metaphysis from the diaphysis is a Schatzker VI fracture. Because of the common posteromedial shear fragment, dual incisions (anterolateral and posteromedial) are frequently required to achieve stable fixation and avoid extensive soft tissue stripping.

Question 592

Topic: Lower Extremity Trauma

A 28-year-old male sustains an acute distal tibiofibular syndesmotic injury. During surgical stabilization, the surgeon meticulously evaluates the individual syndesmotic ligaments. Which of the following ligaments provides the greatest resistance to lateral displacement of the fibula and is mechanically the strongest?

. Anterior inferior tibiofibular ligament (AITFL)
. Posterior inferior tibiofibular ligament (PITFL)
. Interosseous ligament
. Transverse tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

The posterior inferior tibiofibular ligament (PITFL) is the strongest component of the syndesmotic complex, contributing approximately 42% of the resistance to lateral fibular displacement. The AITFL contributes approximately 35%.

Question 593

Topic: Lower Extremity Trauma

A 25-year-old equestrian falls from a horse, sustaining a subtle Lisfranc injury with instability of the first, second, and third tarsometatarsal (TMT) joints. The surgeon opts for open reduction and internal fixation utilizing dorsal spanning plates rather than transarticular screws. What is the primary biomechanical and biologic advantage of using dorsal spanning plates in this scenario?

. Greater resistance to plantarflexion forces
. Prevention of iatrogenic damage to the TMT articular cartilage
. Elimination of the need for future hardware removal
. Decreased risk of superficial peroneal nerve injury
. Immediate full weight-bearing capabilities post-operatively

Correct Answer & Explanation

. Greater resistance to plantarflexion forces

Explanation

Dorsal spanning plates 'bridge' the tarsometatarsal joints without violating the joint surfaces, thereby preventing iatrogenic damage to the articular cartilage. This is thought to lower the incidence of secondary post-traumatic osteoarthritis compared to transarticular screws.

Question 594

Topic: Lower Extremity Trauma

A 22-year-old skier experiences a sudden 'popping' sensation behind his lateral malleolus after forced dorsiflexion and eversion of his ankle. Examination reveals tenderness and visible swelling over the peroneal tendons, which subluxate anteriorly with active eversion. Which of the following is the most common anatomic variant of the superior peroneal retinaculum (SPR) injury in this condition?

. Midsubstance transverse tear of the SPR
. Periosteal avulsion of the SPR from the lateral aspect of the distal fibula
. Avulsion of the SPR from its calcaneal insertion
. Concomitant tear of the inferior extensor retinaculum
. Intratendinous longitudinal split of the peroneus longus tendon

Correct Answer & Explanation

. Midsubstance transverse tear of the SPR

Explanation

Acute peroneal tendon dislocation is typically caused by failure of the superior peroneal retinaculum (SPR). The most common mechanism of SPR failure is a periosteal avulsion from its attachment on the posterolateral distal fibula, sometimes creating a 'fleck sign' on radiographs.

Question 595

Topic: Lower Extremity Trauma

A surgeon is performing a primary total knee arthroplasty. After making the initial bone cuts, trial components are placed. The knee is found to be tight in flexion but well-balanced in extension. Which of the following technical adjustments is the most appropriate to address this mismatch?

. Resect more distal femur
. Upsize the femoral component
. Recut the tibia with increased posterior slope
. Release the posterior capsule
. Recut the distal femur in more valgus

Correct Answer & Explanation

. Resect more distal femur

Explanation

A knee that is tight in flexion but balanced in extension has an isolated tight flexion gap. Increasing the posterior slope of the tibial cut resects more posterior tibial bone, effectively increasing the flexion gap without significantly altering the extension gap. Resecting more distal femur or releasing the posterior capsule would affect the extension gap.

Question 596

Topic: Lower Extremity Trauma

A 10-year-old girl is evaluated for an idiopathic limb length discrepancy (LLD). Radiographs indicate her right lower extremity is 20 mm longer than her left. Her bone age matches her chronological age. Utilizing the Menelaus rule of thumb for growth remaining, at what age should an isolated right distal femoral epiphysiodesis be performed to equalize her leg lengths at maturity?

. 10.5 years
. 11.8 years
. 12.5 years
. 13.2 years
. 14.0 years

Correct Answer & Explanation

. 10.5 years

Explanation

According to the Menelaus method (Rule of Thumb), girls complete longitudinal growth at age 14 (boys at 16). The distal femur grows at a rate of approximately 3/8 inch (9 mm or ~1 cm) per year. The proximal tibia grows at 1/4 inch (6 mm) per year. To correct a 20 mm (2 cm) discrepancy using ONLY the distal femur, 20 mm / 9 mm/year = 2.22 years of growth are required. Therefore, the epiphysiodesis should be performed 2.22 years before growth ceases: 14 - 2.2 = 11.8 years of age.

Question 597

Topic: Lower Extremity Trauma

A 21-year-old football player sustains a syndesmotic ankle injury. Which of the following radiographic measurements is the most reliable indicator of a syndesmotic injury on a standard AP and mortise radiograph?

. Tibiofibular clear space > 5 mm on AP view
. Tibiofibular overlap > 1 mm on mortise view
. Tibiofibular clear space > 5 mm on both AP and mortise views
. Medial clear space > 4 mm on AP view
. Talar tilt angle > 10 degrees

Correct Answer & Explanation

. Tibiofibular clear space > 5 mm on AP view

Explanation

The tibiofibular clear space is measured 1 cm proximal to the plafond. A distance > 5 mm on BOTH the AP and Mortise views is the most reliable indicator of syndesmotic widening, as it is relatively unaffected by rotational variations during image acquisition, unlike tibiofibular overlap.

Question 598

Topic: Lower Extremity Trauma
When comparing two solid cylindrical titanium rods used for intramedullary nailing, Rod A has a radius of 'r' and Rod B has a radius of '2r'. By what factor does the area moment of inertia (and therefore the bending stiffness) increase in Rod B compared to Rod A?
. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 16

Explanation

The area moment of inertia (I) for a solid cylinder is calculated as I = (π × r^4) / 4. Therefore, bending stiffness is proportional to the radius to the fourth power (r^4). If the radius is doubled (2r), the bending stiffness increases by a factor of 2^4, which equals 16.

Question 599

Topic: Lower Extremity Trauma

An orthopedic surgeon reams the medullary canal to accommodate a larger diameter intramedullary nail for a tibial shaft fracture. Increasing the radius of a solid cylindrical intramedullary nail increases its torsional rigidity by a factor proportional to which power of the radius?

. r^2
. r^3
. r^4
. r^5
. r^6

Correct Answer & Explanation

. r^2

Explanation

The torsional rigidity of a solid cylindrical implant is proportional to the polar moment of inertia, which varies with the radius to the fourth power (r^4). Therefore, small increases in nail diameter drastically increase resistance to torsional forces.

Question 600

Topic: Lower Extremity Trauma

Review the basic principles of intramedullary nail biomechanics.

The torsional rigidity of a solid cylindrical intramedullary nail is proportional to its radius raised to which power?

. Radius squared (r^2)
. Radius cubed (r^3)
. Radius to the fourth power (r^4)
. Radius to the fifth power (r^5)
. Inversely proportional to radius squared

Correct Answer & Explanation

. Radius squared (r^2)

Explanation

The torsional rigidity of a solid cylinder is directly proportional to the polar area moment of inertia, which mathematically correlates to the radius raised to the fourth power (r^4). Thus, a small increase in nail diameter massively increases torsional stiffness.

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