This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 5601
Topic: Pelvic & Acetabular Trauma
In a hemodynamically unstable patient with an anteroposterior compression (APC) type III pelvic ring injury, what is the anatomical target for the optimal placement of a circumferential pelvic sheet or binder?
Correct Answer & Explanation
. Greater trochanters
Explanation
Optimal placement of a pelvic binder is centered directly over the greater trochanters. Placing the binder too high (e.g., iliac crests or ASIS) reduces its biomechanical efficacy in closing the pelvic volume and can paradoxically open the true pelvis further.
Question 5602
Topic: 2. Trauma
Which of the following injury patterns classically defines a 'floating shoulder'?
Correct Answer & Explanation
. Glenoid neck fracture and ipsilateral clavicle shaft fracture
Explanation
A 'floating shoulder' refers to a double disruption of the superior shoulder suspensory complex, most classically represented by an ipsilateral fracture of the glenoid neck and a fracture of the clavicle shaft, thereby functionally isolating the glenohumeral joint from the axial skeleton.
Question 5603
Topic: 2. Trauma
A 45-year-old trauma patient sustains an intra-articular distal femur fracture. Advanced imaging identifies a coronal plane fracture of the lateral femoral condyle (Hoffa fragment).
Biomechanical studies suggest which of the following screw orientations provides the most rigid fixation for this specific fracture pattern?
Correct Answer & Explanation
. Posteroanterior oriented lag screws
Explanation
A Hoffa fracture is a coronal plane fracture of the femoral condyle, more commonly affecting the lateral condyle. Biomechanical studies have demonstrated that posteroanterior (PA) directed lag screws provide superior stability and higher load to failure compared to anteroposterior (AP) directed screws. While AP screws are often used clinically due to ease of placement via an anterior approach, PA screws are biomechanically advantageous because they enter through thicker cortical bone posteriorly and are directed perpendicular to the fracture plane.
Question 5604
Topic: 2. Trauma
A 35-year-old farmer sustains an open midshaft tibia fracture when a tractor rolls over his leg. The wound is 12 cm long with significant contamination, including soil and manure. According to standard orthopedic trauma guidelines, what is the most appropriate prophylactic intravenous antibiotic regimen?
Correct Answer & Explanation
. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin
Explanation
This is a Gustilo-Anderson Type III open fracture occurring in a farming environment. The standard antibiotic protocol for a Type III open fracture includes a first-generation cephalosporin (for Gram-positive coverage) and an aminoglycoside (for Gram-negative coverage). However, when the wound is heavily contaminated with soil, manure, or standing water (e.g., farm injuries), the addition of high-dose penicillin is indicated to provide coverage against anaerobic organisms, particularly Clostridium species, to prevent gas gangrene.
Question 5605
Topic: 2. Trauma
A 35-year-old man sustains a high-energy Pauwels Type III (vertical shear) femoral neck fracture. To maximize biomechanical stability and minimize the risk of varus collapse during internal fixation, current biomechanical literature suggests which of the following constructs provides the highest resistance to shear forces?
Correct Answer & Explanation
. A sliding hip screw (SHS) construct combined with a partially threaded derotational cancellous screw
Explanation
Pauwels Type III femoral neck fractures have a fracture line greater than 50 degrees from the horizontal, subjecting the fracture to extreme shear forces and a high risk of varus collapse, nonunion, and AVN. Biomechanical studies consistently show that a fixed-angle device, such as a sliding hip screw (SHS), combined with a derotational screw, provides superior resistance to vertical shear and varus collapse compared to multiple cancellous screws alone in young adults.
Question 5606
Topic: 2. Trauma
The Lower Extremity Assessment Project (LEAP) study investigated outcomes in patients with severe lower extremity trauma, including high-grade open tibial shaft fractures. The study compared limb salvage versus early amputation. Which of the following factors was found to be the most significant predictor of poor long-term clinical and functional outcomes in these patients?
Correct Answer & Explanation
. Low socioeconomic status and lack of continuous health insurance
Explanation
A hallmark finding of the landmark LEAP study was that socioeconomic and psychosocial factors, rather than the initial injury severity or the surgical decision (limb salvage vs. amputation), were the strongest predictors of long-term functional outcome. Factors such as low socioeconomic status, lack of continuous health insurance, poor social support, smoking, and lower educational levels correlated highly with poor outcomes and failure to return to work.
Question 5607
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?
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 5608
Topic: 2. Trauma
In the surgical management of a vertically oriented, displaced femoral neck fracture (Pauwels Type III) in a 30-year-old patient, which of the following internal fixation constructs provides the highest resistance to vertical shear forces and minimizes the risk of varus collapse?
Correct Answer & Explanation
. A dynamic hip screw (DHS) with an anti-rotation screw
Explanation
Pauwels Type III femoral neck fractures have a high vertical angle (>50 degrees), creating extreme shear forces across the fracture site. Multiple biomechanical studies have demonstrated that a fixed-angle construct, such as a Dynamic Hip Screw (DHS) combined with an anti-rotation screw, provides superior biomechanical stability and higher resistance to shear forces and varus collapse compared to multiple cancellous screws in young adults with vertically oriented femoral neck fractures.
Question 5609
Topic: 2. Trauma
A 28-year-old male is treated with intramedullary nailing for a closed, comminuted midshaft tibial fracture. Twelve hours post-operatively, he complains of severe leg pain out of proportion to the injury, unrelieved by intravenous opioids. Passive stretch of the toes elicits excruciating pain. Compartment pressure monitoring reveals an absolute compartment pressure of 35 mmHg, and his blood pressure is 110/60 mmHg. What is the most appropriate next step in management?
Correct Answer & Explanation
. Immediate four-compartment fasciotomy of the leg
Explanation
The diagnosis is acute compartment syndrome. The critical threshold for intervention is the delta pressure (Diastolic Blood Pressure - Absolute Compartment Pressure). In this patient, the delta pressure is 60 - 35 = 25 mmHg. A delta pressure of less than 30 mmHg represents inadequate tissue perfusion pressure and is a strict indication for emergent fasciotomy (four-compartment in the leg). Elevating the leg above the level of the heart is contraindicated as it further decreases arterial inflow and worsens tissue ischemia.
Question 5610
Topic: 2. Trauma
A 35-year-old male is brought to the trauma bay after a motorcycle collision. He is hemodynamically unstable (BP 75/40 mmHg, HR 130 bpm). Pelvic radiographs reveal an Anteroposterior Compression Type III (APC-III) open-book pelvic ring injury with severe symphyseal diastasis. Following the initiation of a massive transfusion protocol, which of the following is the most effective initial mechanical intervention to reduce pelvic volume and control venous hemorrhage?
Correct Answer & Explanation
. Placement of a pelvic circumferential compression device (binder) centered over the greater trochanters
Explanation
In a hemodynamically unstable patient with an 'open-book' (APC) pelvic ring injury, the initial and most rapid mechanical intervention is the application of a pelvic circumferential compression device (pelvic binder or sheet). It must be centered over the greater trochanters (not the iliac crests) to effectively close the pelvic ring, reduce pelvic volume, and create a tamponade effect for venous bleeding (the most common source of hemorrhage). External fixation, preperitoneal packing, and angioembolization are subsequent steps if the binder and resuscitation fail to stabilize the patient.
Question 5611
Topic: 2. Trauma
A 72-year-old female falls and sustains a displaced, intracapsular femoral neck fracture. Due to the high risk of avascular necrosis and nonunion associated with this injury pattern, a hemiarthroplasty is planned. The profound vascular vulnerability of the adult femoral head is due to its heavy reliance on the ascending cervical branches. Which artery is the primary source of these critical ascending branches?
Correct Answer & Explanation
. Medial femoral circumflex artery
Explanation
In the adult, the principal blood supply to the femoral head is derived from the medial femoral circumflex artery (MFCA). The MFCA gives rise to the lateral epiphyseal artery system (ascending cervical branches) that penetrate the joint capsule at the base of the femoral neck and course along the retinaculum to perfuse the femoral head. Displaced intracapsular fractures disrupt these vessels, leading to a high rate of osteonecrosis. The artery of the ligamentum teres provides a negligible supply in adults.
Question 5612
Topic: 2. Trauma
A 28-year-old male is brought to the trauma center unconscious following a motorcycle crash. He has a closed, highly comminuted midshaft tibia fracture. The extremity is swollen and tense. Due to his altered mental status, continuous intracompartmental pressure monitoring is initiated. An emergent four-compartment fasciotomy is universally indicated when the difference between the patient's diastolic blood pressure and the absolute compartmental pressure (Delta P) falls below what critical threshold?
Correct Answer & Explanation
. 30 mm Hg
Explanation
The diagnosis of acute compartment syndrome in an obtunded patient relies on objective pressure measurements. The 'Delta P' concept states that a fasciotomy is indicated when the tissue pressure rises to within 30 mm Hg of the diastolic blood pressure (Delta P < 30 mm Hg). Absolute compartment pressure values alone are less reliable than the Delta P because muscle perfusion depends on the arteriolar pressure gradient, which is directly related to the systemic diastolic pressure.
Question 5613
Topic: 2. Trauma
A 40-year-old male sustains a high-energy motor vehicle collision resulting in a severe bicondylar tibial plateau fracture (Schatzker VI).
On examination, the soft tissues are grossly swollen and tense, but there is no compartment syndrome. The initial management is application of a knee-spanning external fixator. What is the most reliable clinical indicator that the soft tissues are ready for definitive open reduction and internal fixation?
Correct Answer & Explanation
. Appearance of skin wrinkles on the anterior knee/leg
Explanation
In high-energy tibial plateau fractures, definitive internal fixation is delayed until the soft tissue envelope recovers to minimize wound complications. The most reliable clinical sign that swelling has adequately subsided and surgery can safely proceed is the appearance of skin wrinkles (the 'wrinkle sign'), which typically occurs 10 to 14 days post-injury.
Question 5614
Topic: Pelvic & Acetabular Trauma
A 35-year-old male is involved in a severe crush injury at a construction site. Imaging reveals a widely displaced Anteroposterior Compression (APC) pelvic ring injury. According to the Young-Burgess classification, what specific ligamentous disruption differentiates an APC-III injury from an APC-II injury?
Correct Answer & Explanation
. Complete disruption of both anterior and posterior sacroiliac ligaments
Explanation
In the Young-Burgess classification, an APC-II injury is characterized by symphyseal diastasis and disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but the posterior sacroiliac ligaments remain intact (rotationally unstable, vertically stable). An APC-III injury involves complete disruption of both the anterior AND posterior sacroiliac ligaments, rendering the hemipelvis both rotationally and vertically unstable.
Question 5615
Topic: 2. Trauma
A 28-year-old male sustains a high-energy Pauwels type III (vertical) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability and resistance against the specific deforming forces characteristic of this fracture pattern?
Correct Answer & Explanation
. A sliding hip screw combined with an anti-rotation cancellous screw
Explanation
Pauwels III fractures are vertically oriented (>50 degrees to the horizontal) and experience massive vertical shear forces, leading to a high rate of varus collapse, nonunion, and failure when fixed with multiple cancellous screws alone. Biomechanical studies have shown that a fixed-angle construct, such as a sliding hip screw (which acts as a strong buttress against vertical shear) combined with an anti-rotation screw, provides superior stability for vertical femoral neck fractures in young adults.
Question 5616
Topic: Pelvic & Acetabular Trauma
A 32-year-old male is brought to the trauma bay in hemorrhagic shock after a motorcycle crash. An anteroposterior radiograph of the pelvis demonstrates an APC-III injury. A pelvic binder is applied. To maximize reduction of the pelvic volume, at what anatomical landmark should the binder be centered?
Correct Answer & Explanation
. Greater trochanters
Explanation
Pelvic binders should be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests or ASIS can paradoxically widen the true pelvis or fail to achieve adequate reduction in an open-book pelvic injury.
Question 5617
Topic: Upper Extremity Trauma
According to recent quantitative anatomical studies utilizing MRI and gadolinium, which of the following vessels provides the principal intraosseous blood supply to the humeral head, challenging historical teachings regarding proximal humerus vascularity?
Correct Answer & Explanation
. Posterior humeral circumflex artery
Explanation
Historically, the anterior humeral circumflex artery (via its arcuate branch) was thought to be the primary blood supply to the humeral head. However, modern quantitative studies (e.g., Hettrich et al.) have demonstrated that the posterior humeral circumflex artery provides the vast majority (approximately 64%) of the intraosseous blood supply to the humeral head.
Question 5618
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'?
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 5619
Topic: 2. Trauma
A 28-year-old male undergoes reamed intramedullary nailing for a closed comminuted tibial shaft fracture.
In the recovery room, he complains of severe leg pain out of proportion to the injury, unremitting despite high-dose intravenous opioids. Passive stretch of his toes elicits excruciating pain. Intracompartmental pressure testing yields an anterior compartment pressure of 45 mmHg, and his diastolic blood pressure is 65 mmHg. What is the most appropriate next step in management?
Correct Answer & Explanation
. Perform an emergent four-compartment fasciotomy of the leg
Explanation
The patient exhibits classic clinical signs of acute compartment syndrome. The objective threshold for emergent fasciotomy is a delta P (diastolic blood pressure minus compartment pressure) of less than 30 mmHg. In this case, delta P is 20 mmHg (65 - 45 = 20), which is an absolute indication for emergent four-compartment fasciotomy. Elevating the leg above the heart is contraindicated as it reduces arterial perfusion pressure and exacerbates ischemia.
Question 5620
Topic: 2. Trauma
A 45-year-old male is struck by a vehicle and sustains a complex tibial plateau fracture.
The injury is classified as a Schatzker Type IV fracture. What is the classic mechanism of injury, and which surgical approach is most commonly required for anatomic reduction and buttressing of this specific pattern?
Correct Answer & Explanation
. Varus force with axial loading; Posteromedial approach
Explanation
Schatzker Type IV represents a medial tibial plateau fracture, classically caused by a high-energy varus force combined with axial loading. Because the medial plateau is dense and strong, this fracture implies high energy and often subluxation/dislocation of the knee joint. The optimal surgical approach involves buttressing the medial fragment, which is best achieved via a posteromedial approach to place an anti-glide or buttress plate.
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