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 2321
Topic: 2. Trauma
During the deltopectoral approach for an open reduction and internal fixation of a proximal humerus fracture, the cephalic vein is identified. Which of the following describes the most appropriate management of the cephalic vein?
Correct Answer & Explanation
. It is retracted laterally with the deltoid to preserve its venous drainage.
Explanation
During a deltopectoral approach, the cephalic vein is usually retracted laterally with the deltoid muscle. This preserves the primary venous drainage of the deltoid and minimizes postoperative swelling, although medial retraction is occasionally preferred by some surgeons.
Question 2322
Topic: 2. Trauma
A 19-year-old male presents with a spine injury following an athletic collision. Radiographs demonstrate an avulsion fracture of the spinous process of C7. He is neurologically intact. What is the most appropriate management?
Correct Answer & Explanation
. Symptomatic treatment with a soft collar and early mobilization
Explanation
An avulsion fracture of the lower cervical spinous processes (C6 or C7) is known as a Clay Shoveler's fracture. It is a stable injury, and conservative management with symptomatic pain control and a soft collar or early mobilization is the standard of care.
Question 2323
Topic: 2. Trauma
A 65-year-old male with an untreated proximal humerus fracture presents at 6 months with a symptomatic, symptomatic nonunion at the surgical neck characterized by a 30-degree varus deformity. Which surgical intervention provides the most reliable biomechanical stability for healing?
Correct Answer & Explanation
. Valgus-producing osteotomy, bone grafting, and locked plate fixation
Explanation
Surgical neck nonunions with a varus deformity require correction of the mechanical axis to succeed. A valgus-producing osteotomy combined with bone grafting and rigid locked plate fixation converts shear forces into compressive forces, optimizing the environment for union.
Question 2324
Topic: 2. Trauma
Which artery has been demonstrated in recent anatomical studies to provide the primary blood supply to the articular segment of the humeral head in a proximal humerus fracture?
Correct Answer & Explanation
. Posterior circumflex humeral artery
Explanation
Recent anatomic injection studies demonstrate that the posterior circumflex humeral artery provides the predominant blood supply (up to 64%) to the humeral head. This challenges the historical belief that the anterior circumflex humeral artery and its anterolateral branch (arcuate artery) were the primary sources.
Question 2325
Topic: 2. Trauma
During open reduction and internal fixation of a 3-part proximal humerus fracture using a locking plate, the surgeon inserts inferomedial calcar screws. What is the primary biomechanical purpose of these screws?
Correct Answer & Explanation
. To prevent varus collapse of the humeral head
Explanation
Inferomedial calcar screws provide critical structural support to the medial column in proximal humerus fractures. Their proper placement significantly increases the biomechanical stability of the construct and reduces the risk of postoperative varus collapse and secondary screw cut-out.
Question 2326
Topic: 2. Trauma
According to the Neer classification system for proximal humerus fractures, what specific criteria must be met for a fracture segment to be officially considered a separate "part"?
Correct Answer & Explanation
. Displacement > 1 cm or angulation > 45 degrees
Explanation
The Neer classification defines a distinct fracture "part" only if the fragment is displaced by more than 1 centimeter or angulated by more than 45 degrees relative to the other major fragments.
Question 2327
Topic: Lower Extremity Trauma
When evaluating a patient for patella alta, the Caton-Deschamps index is measured using which of the following radiographic landmarks on a true lateral radiograph?
Correct Answer & Explanation
. Ratio of the distance from the lower articular margin of the patella to the anterior tibial angle to the articular length of the patella
Explanation
The Caton-Deschamps index relies on articular margins, making it useful even if the patellar poles are morphologically abnormal. It is the ratio of the distance from the inferior articular margin of the patella to the anterior angle of the tibial plateau, divided by the patellar articular length.
Question 2328
Topic: 2. Trauma
During a first MTP joint arthrodesis, a surgeon chooses to add an interfragmentary lag screw to a dorsal locking plate construct. What is the primary biomechanical advantage of this technique?
Correct Answer & Explanation
. It significantly increases compression across the fusion site
Explanation
Adding an interfragmentary lag screw (either independently or through the plate) provides dynamic compression across the arthrodesis site. This increased compression enhances construct stability and significantly improves the rate of successful fusion compared to a dorsal plate alone.
Question 2329
Topic: 2. Trauma
A 38-year-old male presents to the emergency department after a high-energy motor vehicle collision, sustaining a severe injury to his right ankle. Initial radiographs show a comminuted intra-articular fracture of the distal tibia with significant displacement and impaction of the plafond. The fibula is also fractured. Clinically, there is marked swelling, tense skin, and multiple large blisters over the anteromedial aspect of the ankle. There is no open wound. A CT scan confirms extensive articular fragmentation involving multiple irreducible fragments and substantial subchondral bone loss, along with severe metaphyseal comminution and segmental defects. Based on the GusilloโAnderson (G-A) Classification System, what is the most appropriate classification for this injury?
Correct Answer & Explanation
. Type C, Subtype 3, Grade S3
Explanation
Correct Answer: CThe patient's presentation aligns with a G-A Type C, Subtype 3, Grade S3 classification. Let's break down the components:Articular Involvement (G-A Type):The description of 'extensive articular fragmentation involving multiple irreducible fragments and substantial subchondral bone loss' directly corresponds toType C, which signifies severe articular comminution.Metaphyseal Comminution (G-A Subtype):'Severe metaphyseal comminution and segmental defects' matchesSubtype 3, characterized by extensive bone loss and challenging anatomical reduction.Soft Tissue Envelope (G-A Grade):'Marked swelling, tense skin, and multiple large blisters' indicates a severe soft tissue injury. While not an open fracture, the presence of significant edema and blistering, especially with tense skin, points towardsGrade S3, which includes severe crush injury or impending skin necrosis, necessitating a prolonged staged approach. Grade S2 typically involves significant edema and blistering but might not have the 'tense skin' or 'impending necrosis' implication of S3. Given the high-energy mechanism and severe osseous injury, the soft tissue compromise is likely severe enough to warrant S3.Therefore, the most appropriate classification is Type C, Subtype 3, Grade S3.
Question 2330
Topic: 2. Trauma
A 55-year-old construction worker sustains a G-A Type B, Subtype 2, Grade S2 pilon fracture after falling from a height. He presents with significant ankle swelling and tense skin, but no open wounds. Initial management involves closed reduction and application of a spanning external fixator. Two weeks later, the swelling has significantly decreased, and the 'wrinkle sign' is positive. The patient is medically optimized. What is the most appropriate next step in management?
Correct Answer & Explanation
. Proceed with definitive open reduction internal fixation (ORIF).
Explanation
Correct Answer: BThe case describes a G-A Grade S2 injury, which mandates a staged approach with initial external fixation. The key indicator for proceeding to definitive open reduction internal fixation (ORIF) is the resolution of soft tissue edema, clinically assessed by the 'wrinkle sign.' The case explicitly states that the 'wrinkle sign' is positive and the patient is medically optimized, indicating that the soft tissue envelope has recovered sufficiently for definitive surgery. The literature consistently supports this staged approach to minimize wound complications.A. Initiate immediate full weight-bearing in a CAM walker:This is incorrect. The fracture is a G-A Type B, Subtype 2, requiring anatomical reduction and stable fixation. Immediate full weight-bearing without definitive fixation would lead to collapse and malunion.C. Continue external fixation for another 4 weeks to ensure complete soft tissue healing:This is incorrect. While soft tissue healing is paramount, the 'wrinkle sign' indicates readiness for definitive fixation. Prolonged external fixation beyond this point unnecessarily delays anatomical reduction and increases the risk of pin tract infection and joint stiffness.D. Perform an ankle arthrodesis due to the severity of the injury:This is incorrect. Ankle arthrodesis is a salvage procedure for severe post-traumatic arthritis or failed reconstruction, not a primary treatment for an acute pilon fracture, especially when anatomical reduction is achievable.E. Discharge the patient with a cast and instruct on non-weight-bearing:This is incorrect. A G-A Type B, Subtype 2 fracture is a displaced intra-articular injury requiring operative management to restore articular congruity and prevent post-traumatic arthritis. Non-operative management is reserved for non-displaced, stable Type A fractures.
Question 2331
Topic: 2. Trauma
A 42-year-old male presents with a G-A Type C, Subtype 3, Grade S2 pilon fracture following a fall from a ladder. After initial external fixation, a definitive surgical plan is being formulated. Which of the following imaging modalities is considered mandatory and most crucial for detailed pre-operative planning, especially for the articular component of this fracture?
Correct Answer & Explanation
. Computed Tomography (CT) scan with 3D reconstructions
Explanation
Correct Answer: CThe case explicitly states that for all G-A Type B and C fractures, a Computed Tomography (CT) scan is mandatory. Fine-cut (1-2mm) CT scans with 3D reconstructions are indispensable for defining articular comminution, fragment size, location, and depression. This allows for precise surgical planning, including approach selection, identification of key fragments for reduction, and assessment of bone loss. Given the G-A Type C classification, which denotes severe articular comminution, the CT scan is the most crucial imaging modality.A. Plain radiographs (AP, lateral, mortise views):While essential initial assessments, plain radiographs provide limited information regarding the extent of articular comminution, impaction, and fragment orientation in complex intra-articular fractures like pilon fractures.B. Magnetic Resonance Imaging (MRI):Rarely indicated unless there is suspicion of significant ligamentous injury beyond the syndesmosis, or for assessing occult soft tissue lesions (e.g., tendon rupture). It is not the primary modality for detailed osseous fracture planning.D. Bone scintigraphy:This is a nuclear medicine study used to detect bone pathology, such as stress fractures, infections, or tumors. It has no role in acute fracture planning for pilon fractures.E. Arteriogram:An arteriogram is used to visualize blood vessels and is indicated if there is suspicion of vascular injury, typically in cases of severe open fractures or signs of ischemia. It is not a routine pre-operative planning tool for the fracture morphology itself.
Question 2332
Topic: 2. Trauma
During definitive ORIF of a G-A Type C pilon fracture, the surgeon has successfully reduced and fixed the associated fibula fracture. The next critical step, as emphasized by the literature and surgical technique, is to address the articular surface. Which of the following best describes the primary goal and technique for articular reconstruction in this scenario?
Correct Answer & Explanation
. Directly visualize and anatomically reduce articular fragments, filling subchondral defects with bone graft.
Explanation
Correct Answer: CThe case and key literature emphasize that anatomical reduction of the articular surface is the primary determinant of long-term outcome, especially for G-A Type B and C fractures. For a G-A Type C fracture, which involves severe articular comminution and often substantial subchondral bone loss, direct visualization and meticulous reconstruction are paramount. This involves elevating depressed fragments and filling subchondral bone voids with autogenous or allograft bone to support the articular surface.A. Achieve indirect reduction of the articular fragments using ligamentotaxis and bridge plating:While indirect reduction and bridge plating are valuable for metaphyseal comminution (G-A Subtype 2 & 3) to preserve vascularity, they are generally insufficient for achieving anatomical articular reduction in complex intra-articular fractures. Direct visualization is usually required for the articular surface.B. Prioritize metaphyseal reduction and fixation, then address articular fragments if easily accessible:This is incorrect. The case explicitly states that articular reconstruction is the primary determinant of long-term outcome and should be addressed first, often after fibular fixation, to provide a stable base for metaphyseal reconstruction.D. Perform a limited arthrotomy and stabilize the largest articular fragment with a single lag screw:While a limited arthrotomy may be used, stabilizing only the largest fragment with a single screw is unlikely to achieve anatomical reduction and stable fixation of a severely comminuted G-A Type C articular surface. Multiple fragments often need to be reduced and fixed.E. Bypass the articular comminution entirely with an external ring fixator:While external ring fixators are an option for definitive fixation in highly comminuted open fractures or severe soft tissue injuries, the primary goal for articular fractures is still anatomical reduction. Ring fixators can achieve this, but the option implies bypassing reduction, which is not the goal.
Question 2333
Topic: 2. Trauma
A 28-year-old male presents with a G-A Type B, Subtype 2, Grade S1 pilon fracture with an associated displaced fibula fracture. During definitive ORIF, after exposing the fracture, the surgeon's initial step is to address the fibula. What is the primary biomechanical reason for prioritizing the restoration of fibular length and rotation in the management of pilon fractures?
Correct Answer & Explanation
. It provides a stable external frame and template for restoring tibial length and rotation.
Explanation
Correct Answer: CThe case highlights the importance of fibular integrity: 'The fibula plays a critical role in maintaining the length and rotation of the distal tibia and serves as a buttress against talar displacement.' The surgical technique section further states: 'If the fibula is fractured and displaced, restore its length, rotation, and alignment first. This provides an anatomical template for tibial reconstruction.' Therefore, the primary biomechanical reason is that the fibula acts as a stable external frame and template for restoring the more complex tibial length and rotation.A. To prevent compartment syndrome in the lateral compartment:While compartment syndrome is a risk, fixing the fibula primarily addresses stability and alignment, not directly preventing compartment syndrome, which is managed by fasciotomy.B. The fibula is a non-weight-bearing bone, so its early fixation simplifies later steps:While the fibula bears less weight than the tibia, its role in maintaining ankle mortise stability and acting as a template is crucial, not just a simplification.D. To facilitate the placement of syndesmotic screws later in the procedure:While fibular fixation is a prerequisite for assessing and potentially fixing the syndesmosis, its primary role is as a template for the tibia, not just to facilitate screw placement.E. To reduce the risk of superficial peroneal nerve injury during subsequent tibial plating:While nerve protection is always important, fixing the fibula first does not directly reduce the risk of superficial peroneal nerve injury during tibial plating. This nerve is at risk during anterolateral approaches to the tibia regardless of fibular fixation timing.
Question 2334
Topic: 2. Trauma
A 68-year-old female with severe osteoporosis sustains a G-A Type C, Subtype 3, Grade S2 pilon fracture. After initial external fixation and soft tissue recovery, definitive ORIF is planned. Given the severe metaphyseal comminution and osteoporosis, which surgical principle is most appropriate for managing the metaphyseal component of this fracture?
Correct Answer & Explanation
. Indirect reduction techniques and minimally invasive plate osteosynthesis (MIPO) with locking plates.
Explanation
Correct Answer: CFor G-A Subtype 3 fractures with significant metaphyseal comminution, especially in the context of osteoporosis, the case and literature emphasize the use of indirect reduction maneuvers and Minimally Invasive Plate Osteosynthesis (MIPO) techniques. These approaches aim to preserve the blood supply to comminuted fragments, minimizing soft tissue stripping. Locking plates are ideally suited for bridging comminuted zones and providing stable fixation in osteoporotic bone without requiring direct bone-plate contact.A. Extensive soft tissue stripping to achieve direct visualization and anatomical reduction of every comminuted fragment:This is a 'mistake to avoid' as per the literature. Extensive stripping increases devascularization and the risk of nonunion and infection, particularly in G-A S3 injuries or comminuted fractures.B. Primary use of a non-locking buttress plate with multiple lag screws for interfragmentary compression:While buttress plates are used, non-locking plates rely on compression to the bone, which is less effective in severely comminuted or osteoporotic bone. Locking plates provide angular stability independent of bone quality and are preferred for bridging comminution. Lag screws are for articular fragments, not typically for bridging comminuted metaphysis.D. Immediate full weight-bearing post-operatively to promote bone healing:This is incorrect and highly risky. Severe comminution and osteoporosis necessitate a conservative, delayed weight-bearing protocol to allow for adequate bone healing and prevent hardware failure or collapse.E. Exclusive use of external fixation as the definitive treatment without internal fixation:While external fixators can be definitive in some severe cases (e.g., open fractures, infection), for a G-A Type C, Subtype 3 fracture, the goal is usually to achieve internal fixation after soft tissue recovery to allow for better articular reduction and earlier functional recovery, unless internal fixation is absolutely contraindicated.
Question 2335
Topic: 2. Trauma
A 35-year-old male undergoes definitive ORIF for a G-A Type C, Subtype 2, Grade S2 pilon fracture. Post-operatively, at 3 weeks, he develops increasing pain, redness, swelling, and purulent discharge from one of the surgical incisions. Radiographs show no loss of reduction. What is the most likely complication and the appropriate initial salvage strategy?
Correct Answer & Explanation
. Deep surgical site infection; urgent surgical debridement, irrigation, and IV antibiotics.
Explanation
Correct Answer: CThe patient's symptoms of increasing pain, redness, swelling, and purulent discharge from a surgical incision, 3 weeks post-operatively, are classic signs of a deep surgical site infection. The case lists deep infection as a common complication with an incidence of 5-15%, especially in G-A S2/S3 injuries. The appropriate initial salvage strategy for a deep infection is urgent surgical debridement, irrigation, obtaining cultures, and initiating IV antibiotics tailored to sensitivities. Retention of hardware may be possible if stable and reduction is maintained, but debridement is paramount.A. Post-traumatic arthritis; initiate aggressive physical therapy:Post-traumatic arthritis is a long-term complication, typically developing months to years after the injury, not 3 weeks post-op. Aggressive physical therapy would be inappropriate in the presence of an active infection.B. Nonunion; revise ORIF with bone grafting:Nonunion is a failure of fracture healing, which takes months to diagnose. While infection can contribute to nonunion, the immediate problem is the acute infection.D. Hardware irritation; schedule hardware removal at 6 months:Hardware irritation typically presents as localized pain or prominence after fracture union (12-18 months), not with signs of acute infection and purulent discharge at 3 weeks.E. Complex Regional Pain Syndrome (CRPS); start sympathetic blocks:CRPS presents with disproportionate pain, swelling, skin changes, and autonomic dysfunction, but typically without purulent discharge. While CRPS can occur, the purulent discharge points directly to infection.
Question 2336
Topic: 2. Trauma
A 48-year-old female undergoes ORIF for a G-A Type B, Subtype 1, Grade S1 pilon fracture. The fixation is deemed stable intraoperatively. According to the general principles of post-operative rehabilitation, when would the surgeon most likely consider initiating gradual partial weight-bearing (PWB) for this patient?
Correct Answer & Explanation
. At 6-12 weeks post-operatively, guided by clinical and radiographic healing.
Explanation
Correct Answer: CThe rehabilitation protocol outlines a phased approach. Phase 1 (Weeks 0-6) is strictly Non-Weight-Bearing (NWB). Phase 2 (Weeks 6-12) involves 'Progressive Weight-Bearing & Strengthening.' The case states: 'The transition to PWB is guided by clinical and radiographic evidence of healing (callus formation, absence of hardware loosening). For G-A Type C/Subtype 3 fractures, this may be delayed until 8-10 weeks or longer.' For a G-A Type B, Subtype 1 fracture with stable fixation, initiating gradual PWB typically falls within the 6-12 week window, once initial healing is evident.A. Immediately post-operatively (Week 0-1):This is incorrect. The initial phase (Weeks 0-6) is strictly NWB to protect the surgical repair.B. At 2-3 weeks post-operatively, once sutures are removed:This is incorrect. While early gentle range of motion may begin, weight-bearing is still NWB during this period.D. Only after 6 months, once full union is confirmed radiographically:This is too conservative for a G-A Type B, Subtype 1 fracture with stable fixation. While full union takes longer, progressive weight-bearing starts much earlier.E. Never, as pilon fractures always require strict non-weight-bearing indefinitely:This is incorrect. The goal of surgery and rehabilitation is to restore weight-bearing capacity.
Question 2337
Topic: 2. Trauma
A 50-year-old male, 2 years after sustaining a G-A Type C, Subtype 3 pilon fracture and undergoing ORIF, presents with persistent, debilitating ankle pain, stiffness, and radiographic evidence of severe post-traumatic osteoarthritis. He has failed conservative management including NSAIDs and injections. What is the most appropriate long-term salvage option for this patient?
Correct Answer & Explanation
. Ankle arthrodesis or total ankle arthroplasty.
Explanation
Correct Answer: BThe case's 'Complications & Management' and 'Summary of Key Literature' sections discuss post-traumatic arthritis as a common long-term complication, especially for G-A Type C fractures. When conservative management fails for severe pain and deformity due to post-traumatic arthritis, the advanced options are ankle arthrodesis (fusion) or total ankle arthroplasty (joint replacement). The choice between these depends on patient factors, deformity, and remaining bone stock.A. Repeat ORIF with revision plating:This is incorrect. Revision ORIF is for nonunion or malunion, not for established severe post-traumatic arthritis where the joint surface is already destroyed.C. Aggressive physical therapy and manipulation under anesthesia:While physical therapy is part of initial management for stiffness, it is unlikely to resolve debilitating pain from severe, established post-traumatic osteoarthritis. Manipulation under anesthesia is for stiffness, not joint destruction.D. Hardware removal alone:Hardware removal is indicated for symptomatic hardware irritation after fracture union, but it will not address the underlying severe post-traumatic arthritis and joint destruction.E. Long-term opioid therapy for pain management:While pain management is necessary, long-term opioid therapy is generally not considered a definitive 'salvage option' for a structural problem like severe osteoarthritis due to its significant risks and side effects. Surgical intervention is typically preferred for functional restoration.
Question 2338
Topic: 2. Trauma
A 68-year-old female presents with a closed, comminuted mid-shaft humeral fracture after a fall. She has a history of severe osteoporosis and is on anticoagulation for atrial fibrillation. She is otherwise healthy and lives independently. Given her comorbidities and fracture pattern, which treatment strategy offers the best balance of stability and minimal surgical risk?
Correct Answer & Explanation
. Antegrade intramedullary nailing
Explanation
Correct Answer: CFor a comminuted humeral shaft fracture in an elderly patient with severe osteoporosis, achieving stable fixation is paramount. Functional bracing (Option A) is less reliable for comminuted fractures, especially in osteoporotic bone, due to the difficulty in maintaining alignment and higher risk of nonunion or malunion. A hanging cast (Option D) provides even less control over rotation and angulation than a functional brace and is generally not preferred for comminuted patterns. External fixation (Option E) is typically reserved for open fractures with significant soft tissue injury or as a temporary measure, not usually for definitive management of a closed comminuted fracture in this demographic.Between ORIF with a locked compression plate (Option B) and antegrade intramedullary nailing (Option C), intramedullary nailing is often favored in this specific scenario. IMNs are load-sharing devices, which is advantageous in osteoporotic bone as it reduces stress shielding and the risk of implant failure compared to load-bearing plates. They provide good biomechanical stability for comminuted fractures, allow for earlier mobilization, and involve less soft tissue stripping than traditional plating, which can be beneficial in patients on anticoagulation by potentially reducing hematoma formation. While plating with a locking plate can provide angular stability in osteoporotic bone, the load-sharing nature of IMN often makes it a more robust choice for comminuted fractures in poor bone quality.
Question 2339
Topic: 2. Trauma
A 35-year-old male sustains a closed, spiral mid-shaft humeral fracture. On initial presentation, he has a complete radial nerve palsy (wrist drop, inability to extend MCPs of fingers/thumb, sensory loss in radial distribution). He is initially managed with a coaptation splint. Two days later, after a gentle closed reduction attempt, his radial nerve palsy remains complete, and he develops new, severe pain with passive stretch of his fingers. What is the most appropriate next step in management?
Correct Answer & Explanation
. Perform immediate surgical exploration of the radial nerve and open reduction and internal fixation (ORIF) of the fracture
Explanation
Correct Answer: BThis patient presents with a complex scenario involving a primary radial nerve palsy and new symptoms suggestive of a potential compartment syndrome or worsening nerve compression after a reduction attempt. While a primary radial nerve palsy associated with a closed humeral shaft fracture typically warrants observation for 3-6 months (Option A), the development of new, severe pain with passive stretch of the fingers is a hallmark symptom of impending or established forearm compartment syndrome. This, combined with the persistent complete radial nerve palsy after a reduction attempt, raises concern for nerve entrapment or further injury. An iatrogenic or worsening nerve palsy, especially after manipulation, is an absolute indication for immediate surgical exploration.Therefore, the most appropriate next step is immediate surgical exploration of the radial nerve and ORIF of the fracture (Option B). This allows for direct visualization of the nerve to identify and address any entrapment, transection, or compression, and simultaneously provides stable fixation of the fracture. Delaying exploration (Option A, E) in this context risks irreversible nerve damage. While compartment syndrome is a concern, an MRI (Option C) is too slow for an acute emergency; clinical signs and compartment pressure measurements are more critical. Corticosteroids (Option D) are not indicated for traumatic nerve injury or compartment syndrome.
Question 2340
Topic: 2. Trauma
A 50-year-old male sustains a highly comminuted mid-shaft humeral fracture with significant bone loss after a high-energy trauma. He is a heavy smoker and has poorly controlled diabetes. The surgical team decides on operative management. Which biomechanical principle is most advantageous for the chosen fixation method in this patient, aiming for reliable union despite his comorbidities?
Correct Answer & Explanation
. Load-sharing fixation to promote callus formation
Explanation
Correct Answer: DFor a highly comminuted humeral shaft fracture with bone loss, especially in a patient with comorbidities like smoking and diabetes that impair healing, the goal is to provide stable fixation that promotes biological healing. Intramedullary nailing (IMN) is often preferred in such cases due to its load-sharing properties (Option D). Load-sharing means the implant shares axial load with the bone, allowing for some stress at the fracture site. This intermittent stress is crucial for stimulating callus formation and secondary bone healing, which is the desired mode of healing for comminuted fractures. This is particularly important in patients with compromised healing potential.Absolute stability for primary bone healing (Option A) is typically achieved with rigid compression plating for simple fracture patterns, but it can lead to stress shielding and delayed healing in comminuted fractures. The tension band effect (Option B) is a principle used for specific fracture types (e.g., olecranon, patella) and is not the primary biomechanical advantage for comminuted humeral shaft fractures. Load-bearing fixation (Option C) is characteristic of plates, where the plate bears most of the load, potentially leading to stress shielding and delayed union in comminuted fractures. External fixation (Option E) is primarily for open fractures or temporary stabilization, and while it allows for wound care, its biomechanical advantage for definitive healing of a closed comminuted fracture is not superior to internal fixation.
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