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 1201
Topic: 2. Trauma
A 45-year-old roofer falls from a height and sustains an intra-articular calcaneus fracture. The Sanders classification is commonly used for surgical planning. On which specific radiographic view and anatomical landmark is the Sanders classification based?
Correct Answer & Explanation
. Coronal CT image showing fracture lines through the posterior facet
Explanation
The Sanders classification for intra-articular calcaneus fractures is based on the number and location of primary fracture lines through the posterior facet. It is specifically determined using the coronal plane on computed tomography (CT).
Question 1202
Topic: 2. Trauma
A 21-year-old collegiate basketball player sustains an acute diaphyseal-metaphyseal junction fracture of the fifth metatarsal. He wishes to return to play as safely and quickly as possible. What is the most appropriate management?
Correct Answer & Explanation
. Intramedullary screw fixation
Explanation
Zone 2 fifth metatarsal fractures (Jones fractures) have a high rate of nonunion due to a watershed blood supply at this level. Intramedullary screw fixation is highly recommended in elite athletes to minimize nonunion risk and expedite return to sport.
Question 1203
Topic: 2. Trauma
A 35-year-old male presents after a high-energy motor vehicle collision with hemodynamic instability, a palpable hematoma in the left groin, and a pelvic ring injury classified as Young-Burgess LC-III. What is the most appropriate initial management step after fluid resuscitation and basic life support?
Correct Answer & Explanation
. Application of a pelvic binder
Explanation
In hemodynamically unstable patients with pelvic ring injuries, the priority after fluid resuscitation and basic life support is to mechanically stabilize the pelvis to tamponade hemorrhage. A pelvic binder (or sheet) provides rapid temporary mechanical stabilization, reducing the volume of the pelvic cavity and potentially controlling venous bleeding. While angiography is often needed for arterial bleeds, mechanical stabilization is typically the immediate first step. External fixation is a more definitive form of stabilization but may not be as rapid to apply as a binder. Laparotomy is indicated for suspected intra-abdominal hemorrhage, which is a separate consideration from direct pelvic bleeding in LC-III injuries.
Question 1204
Topic: 2. Trauma
A 48-year-old male sustains a comminuted, intra-articular fracture of the distal radius (AO type C3) with significant metaphyseal comminution and displacement. He is an active manual labourer. What is the most appropriate surgical treatment to optimize functional outcomes in this patient?
Correct Answer & Explanation
. Volar locking plate fixation
Explanation
Correct Answer: DFor unstable, comminuted, intra-articular distal radius fractures (AO type C3), especially in active individuals requiring optimal functional outcomes and early return to work, volar locking plate fixation has become the preferred surgical treatment. It provides strong, stable fixation that allows for accurate anatomical reduction (particularly of the articular surface) and facilitates early range of motion, which is crucial for preventing stiffness and achieving the best possible functional recovery. Other methods like K-wires or external fixation are typically less stable for such complex fractures or may not allow for immediate mobilization.
Question 1205
Topic: 2. Trauma
An examiner asks a very open-ended question, such as 'Tell me about fractures around the knee.' How should you initiate your response to provide structure and depth?
Correct Answer & Explanation
. Providing a structured overview by categorizing fractures (e.g., distal femur, patella, tibial plateau, proximal fibula), briefly discussing general principles of assessment and management, and then offering to delve deeper into a specific area if desired by the examiner.
Explanation
Correct Answer: COpen-ended questions test your ability to structure a broad topic. Initiating with a categorized overview demonstrates organized thinking and control of the subject matter. It shows you can distill a vast topic into manageable sections, and then offers the examiner the opportunity to guide you to a specific area of interest, making your answer relevant and tailored. Avoiding structure or immediately narrowing the topic is less effective.
Question 1206
Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels III) femoral neck fracture. Which of the following biomechanical factors best explains the high rate of nonunion and hardware failure in this fracture pattern?
Correct Answer & Explanation
. High shear forces disrupting the fracture hematoma and stability
Explanation
Pauwels III fractures have a vertical orientation (angle greater than 50 degrees), which translates weight-bearing loads into high shear forces rather than compressive forces. This leads to instability, varus collapse, and an increased risk of nonunion.
Question 1207
Topic: Pelvic & Acetabular Trauma
A 45-year-old hemodynamically unstable male presents after a motorcycle accident with an APC-III pelvic ring injury. A pelvic binder is applied, and he receives 2 units of packed RBCs, but his systolic blood pressure remains 70 mmHg. A FAST exam is negative. What is the most appropriate next step in management?
In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST, the source of bleeding is presumed to be the pelvis. Preperitoneal packing or angiography (depending on institutional protocol and immediate availability) is the next definitive step to control hemorrhage.
Question 1208
Topic: 2. Trauma
A 25-year-old male presents with a 6-month-old scaphoid proximal pole nonunion. MRI demonstrates avascular necrosis of the proximal pole, but there are no signs of radiocarpal arthritis. What is the most appropriate surgical treatment?
Correct Answer & Explanation
. Vascularized bone grafting (e.g., medial femoral condyle) and rigid fixation
Explanation
For a scaphoid nonunion with AVN of the proximal pole and no arthritic changes, vascularized bone grafting (such as a pedicled distal radius graft or free medial femoral condyle graft) provides the best union rates. Salvage procedures (four-corner fusion, PRC) are reserved for cases with arthritis.
Question 1209
Topic: 2. Trauma
A 30-year-old male is admitted with a comminuted midshaft tibia fracture. Overnight, he develops pain out of proportion to the injury. His blood pressure is 110/70 mmHg. Direct measurement of the anterior compartment pressure is 45 mmHg. What is the "delta pressure" and what is the next step in management?
Correct Answer & Explanation
. 25 mmHg; urgent four-compartment fasciotomy
Explanation
The delta pressure is calculated as Diastolic BP minus Compartment Pressure (70 - 45 = 25 mmHg). A delta pressure less than 30 mmHg is highly sensitive for acute compartment syndrome, necessitating urgent four-compartment fasciotomies.
Question 1210
Topic: 2. Trauma
A 30-year-old male sustains a high-energy vertical femoral neck fracture (Pauwels Type III). What biomechanical challenge is most critical to overcome when selecting a fixation construct for this specific fracture pattern?
Correct Answer & Explanation
. High vertical shear forces leading to varus collapse
Explanation
Pauwels Type III femoral neck fractures have a vertically oriented fracture line (>50 degrees), which subjects the fracture site to high vertical shear forces rather than compression. Fixation constructs must be robust enough to resist these shear forces to prevent varus collapse and nonunion.
Question 1211
Topic: 2. Trauma
In the ABOS Part II structured oral examination, candidates are frequently asked to defend their surgical indications. If a candidate presents a complex intra-articular fracture that resulted in early hardware failure, what is the primary competency the examiner is assessing by probing the initial choice of fixation?
Correct Answer & Explanation
. The candidate's practice-based learning and objective evaluation of their own complications
Explanation
The structured oral exam evaluates not just medical knowledge, but also practice-based learning. Examiners probe complications to see if the candidate can honestly self-reflect, identify technical or cognitive errors, and articulate how they would improve future practice.
Question 1212
Topic: Pelvic & Acetabular Trauma
A 35-year-old male involved in a high-speed MVC presents with a hemodynamically unstable APC-III pelvic ring injury. Following pelvic binder application and initial fluid resuscitation, his blood pressure remains 70/40 mmHg. The FAST exam is negative. What is the next best step in management?
For a hemodynamically unstable pelvic fracture with a negative FAST exam (ruling out major intra-abdominal hemorrhage), preperitoneal pelvic packing and/or angiography with embolization is the appropriate emergent intervention.
Question 1213
Topic: 2. Trauma
A 28-year-old male presents with radial-sided wrist pain 8 months after a fall. Radiographs demonstrate a scaphoid waist fracture nonunion with a "humpback" deformity. MRI confirms the proximal pole is well-vascularized. What is the recommended treatment?
Correct Answer & Explanation
. Volar wedge grafting and screw fixation
Explanation
A scaphoid waist nonunion with a "humpback" deformity requires correction of the volar intercalated segment instability (VISI) posture. This is best achieved via a volar approach using an anterior wedge structural bone graft and rigid fixation.
Question 1214
Topic: 2. Trauma
A 28-year-old male suffers a closed tibial shaft fracture. Twelve hours later, he complains of severe leg pain out of proportion to the injury, worsening with passive toe stretch. During a dual-incision four-compartment fasciotomy, which compartment is most commonly missed?
Correct Answer & Explanation
. Deep posterior
Explanation
The deep posterior compartment is the most frequently missed or incompletely decompressed compartment during leg fasciotomies due to its deep anatomical location and proximity to the posterior neurovascular bundle.
Question 1215
Topic: 2. Trauma
Which of the following fracture fixation constructs relies entirely on endochondral ossification (secondary bone healing) to achieve union?
Correct Answer & Explanation
. Intramedullary nail
Explanation
Intramedullary nails provide relative stability, allowing for controlled micromotion at the fracture site. This mechanical environment stimulates callus formation, leading to secondary bone healing via endochondral ossification.
Question 1216
Topic: 2. Trauma
A 38-year-old male sustains a highly comminuted, segmental femoral shaft fracture after a high-energy motor vehicle collision. He is otherwise healthy. The orthopedic surgeon opts for intramedullary nailing. Biomechanically, what is the primary advantage of an intramedullary nail over a conventional locking plate for this specific fracture pattern?
Correct Answer & Explanation
. It acts as a load-sharing device, converting bending moments into axial compression, which is advantageous for comminuted fractures.
Explanation
Correct Answer: CThe correct answer is C. Intramedullary nails are load-sharing implants, meaning they bear a portion of the physiological loads (axial, bending, torsion) while allowing the bone to carry the remainder. Their central placement along the mechanical axis of the bone minimizes the bending moment arm, effectively converting significant bending stresses (common in comminuted and segmental fractures) into more favorable compressive forces. This load-sharing mechanism is particularly advantageous in highly comminuted or segmental fractures where the bone itself cannot provide inherent stability, as it reduces the risk of implant fatigue failure and promotes secondary bone healing through callus formation.Option A is incorrect because IM nails typically provide relative stability, which encourages secondary bone healing with callus formation, not absolute stability and primary bone healing. Absolute stability is usually the goal for simple, reducible fractures treated with compression plating or lag screws.Option B is incorrect. While IM nails can reduce stress shielding compared to rigid, eccentrically placed plates, they do not eliminate it entirely. Stress shielding is a phenomenon where the implant carries too much load, leading to bone resorption.Option D describes a surgical technique advantage (minimally invasive approach) rather than a primary biomechanical advantage related to load transfer and fracture stability.Option E is incorrect. While IM nailing often allows for earlier weight-bearing compared to some other fixation methods, it does not guarantee immediate full weight-bearing without risk, especially in highly comminuted fractures where the construct still relies on biological healing and patient compliance.
Question 1217
Topic: 2. Trauma
A 55-year-old male presents with a spiral mid-shaft tibial fracture, classified as an AO/OTA 42-A2. The surgeon plans for intramedullary nailing. Given the fracture pattern, what biomechanical strategy is most crucial to prevent post-operative malrotation?
Correct Answer & Explanation
. Employing multiple interlocking screws in different planes at both the proximal and distal fragments.
Explanation
Correct Answer: CThe correct answer is C. Spiral fractures are inherently rotationally unstable. In such comminuted or unstable fracture patterns, the bone fragments themselves cannot resist torsional forces. Therefore, the primary biomechanical mechanism for achieving rotational stability relies entirely on the interlocking screws. Using multiple screws, especially when placed in different planes (e.g., anteroposterior and mediolateral), creates a more robust construct that resists rotation more effectively than fewer screws or screws in a single plane. This 'multi-planar' locking maximizes the bone-implant interface and leverage to counteract torsional forces, preventing malrotation.Option A (longest possible nail) primarily helps distribute stress and prevent stress risers at the nail ends, but does not directly provide rotational stability in a comminuted fracture.Option B (largest possible diameter) increases the bending and torsional stiffness of the nail itself, but without adequate interlocking, a tight fit alone cannot prevent rotation in a spiral fracture where the bone fragments are not interlocked.Option D (lower Young's Modulus) relates to stress shielding and material flexibility, not directly to rotational stability.Option E (dynamic locking at both ends) would allow for axial micromotion and potentially rotational micromotion, which is counterproductive to preventing malrotation in a spiral fracture. Static locking is generally preferred for rotational control.
Question 1218
Topic: 2. Trauma
A 72-year-old female with severe osteoporosis sustains a comminuted subtrochanteric femoral fracture. She is treated with an intramedullary nail. During the procedure, the surgeon considers the optimal nail diameter. Biomechanically, what is the most critical rationale for selecting the largest possible nail diameter that can safely fit the reamed medullary canal in this patient?
Correct Answer & Explanation
. To maximize the area moment of inertia, thereby increasing the bending and torsional stiffness of the construct.
Explanation
Correct Answer: CThe correct answer is C. In osteoporotic bone, the intrinsic strength and stiffness of the bone itself are significantly diminished. Therefore, the intramedullary nail must bear a greater proportion of the physiological load. Biomechanically, the bending and torsional stiffness of a nail are highly dependent on its diameter (specifically, the fourth power of the radius for a solid cylinder). By selecting the largest possible nail diameter that safely fits the reamed canal, the surgeon maximizes the nail's area moment of inertia, which directly translates to a substantial increase in the bending and torsional stiffness of the overall nail-bone construct. This enhanced stiffness provides the most robust support to the weakened bone, reducing the risk of implant deformation, fatigue failure, and loss of reduction.Option A is incorrect. While reaming generates heat, using a larger diameter nail doesn't inherently reduce thermal necrosis; rather, careful reaming technique (sharp reamers, sequential reaming, intermittent reaming with irrigation) is key.Option B is incorrect. A larger, stiffer nail would generally increase, not minimize, stress shielding, as it carries more load. However, in osteoporotic bone, the priority is often stability over minimizing stress shielding.Option D is incorrect. Larger diameter nails do not necessarily facilitate easier insertion of interlocking screws; in fact, a very tight fit might make it slightly more challenging.Option E (controlled axial micromotion) is achieved through dynamic locking, not primarily by nail diameter. A larger diameter nail generally leads to a stiffer construct, which might reduce micromotion if not dynamically locked.
Question 1219
Topic: 2. Trauma
A 45-year-old male sustains a transverse mid-shaft tibial fracture (AO/OTA 42-A1). He is treated with an intramedullary nail with static interlocking screws proximally and distally. Six weeks post-operatively, radiographs show minimal callus formation. The surgeon considers dynamization. What is the primary biomechanical objective of dynamizing this IM nail construct?
Correct Answer & Explanation
. To allow for controlled axial micromotion at the fracture site, stimulating callus formation.
Explanation
Correct Answer: CThe correct answer is C. Dynamization, typically achieved by removing one or more interlocking screws (often from the static end that is not bearing weight or from the end that allows for controlled shortening), converts a static construct into a dynamic one. Biomechanically, this allows for controlled axial micromotion (telescoping) at the fracture site. This axial shortening and compression can stimulate callus formation (secondary bone healing) and accelerate fracture healing, particularly in transverse or short oblique diaphyseal fractures where some cortical contact exists and axial compression is desirable. The micromotion provides the necessary mechanical stimulus for osteogenesis.Option A is incorrect. Dynamization generally reduces, rather than increases, rotational stability, as it removes a constraint.Option B is incorrect. IM nails are load-sharing devices. Dynamization does not convert them into load-bearing devices; it modifies their load-sharing characteristics to allow axial compression.Option D is incorrect. Static locking aims to prevent all axial motion. Dynamization is specifically performed toallowcontrolled motion.Option E is partially true in that it reduces stiffness, but the primary objective is not just to reduce stiffness to prevent stress shielding, but to specifically allow axial micromotion to stimulate healing. Reducing stiffness without controlled motion could lead to instability.
Question 1220
Topic: 2. Trauma
A 28-year-old male presents with a comminuted distal tibia fracture extending into the metaphysis. The soft tissue envelope is compromised due to the open nature of the injury. The surgeon is considering an intramedullary nail. Biomechanically, what is a significant advantage of IM nailing over open reduction and internal fixation with a locking plate in this scenario?
Correct Answer & Explanation
. IM nails allow for less soft tissue stripping and better preservation of periosteal blood supply, promoting biological healing.
Explanation
Correct Answer: CThe correct answer is C. Distal tibia fractures, especially comminuted and open ones, often have a precarious soft tissue envelope (thin skin, limited muscle coverage). Open reduction and internal fixation with plates can necessitate extensive soft tissue stripping, further jeopardizing vascularity and increasing the risk of wound complications, delayed healing, or infection. Intramedullary nailing, by utilizing a minimally invasive approach and being placed centrally within the bone, preserves the crucial periosteal blood supply and minimizes soft tissue disruption. This 'biological fixation' approach is a significant biomechanical and biological advantage for promoting healing in compromised soft tissue environments.Option A is incorrect. IM nails typically provide relative stability, promoting secondary bone healing with callus formation, not absolute stability for primary bone healing.Option B is incorrect. While IM nails generally have a lower infection risk than plates in open fractures due to less soft tissue disruption, they do not completely eliminate the risk of infection.Option D is incorrect. The relative strength and stiffness of IM nails versus locking plates depend on specific designs and fracture patterns; IM nails are load-sharing, while plates are load-bearing, each with different biomechanical profiles. It's not universally true that IM nails are stronger in axial compression.Option E is incorrect. IM nailing can be challenging for precise anatomical reduction of articular fragments, especially in highly comminuted distal tibia fractures, where plates might offer more direct control over fragment alignment. IM nails are better suited for diaphyseal or metaphyseal components.
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