Orthopedic Board Review MCQs: Fracture, Hip & Knee Pt 39

Question 1

A 72-year-old female presents with a periprosthetic fracture around a cemented total hip arthroplasty implanted 10 years ago. Radiographs demonstrate a fracture around the tip of the stem with radiolucent lines indicating a loose stem, but with adequate remaining proximal bone stock (Vancouver Type B2). What is the most appropriate management?

Explanation

This is a Vancouver B2 periprosthetic hip fracture (loose stem, adequate bone stock). The standard of care is revision arthroplasty using a long cementless stem (often fluted and tapered) that bypasses the fracture by at least 2 cortical diameters to achieve diaphyseal fixation. ORIF alone is contraindicated when the stem is loose.

Question 2

A 32-year-old male is involved in a motorcycle collision and sustains a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). Which of the following describes the optimal lag screw trajectory for maximum biomechanical stability?

Explanation

Hoffa fractures are coronal plane fractures of the femoral condyle (most commonly lateral). Biomechanical studies have shown that posterior-to-anterior (PA) directed lag screws provide superior biomechanical stability compared to AP screws, although AP screws are frequently used clinically due to the ease of an anterior surgical approach.

Question 3

A 45-year-old male sustains a high-energy medial tibial plateau fracture with widening and depression (Schatzker IV). Preoperative CT scan reveals a significant posteromedial shear fragment. Which surgical approach is most critical for adequate buttress plating of this specific fragment?

Explanation

Schatzker IV fractures frequently involve a posteromedial fragment that represents a major destabilizing injury. This fragment requires anti-glide or buttress plating from its posterior aspect to prevent displacement. The posteromedial approach allows direct visualization and orthogonal plating of this fragment.

Question 4

When evaluating the adequacy of fixation for an intertrochanteric femur fracture treated with a sliding hip screw (SHS), the Tip-Apex Distance (TAD) is measured on postoperative radiographs. Maintaining a TAD of less than 25 mm primarily decreases the risk of which complication?

Explanation

Baumgaertner et al. demonstrated that a Tip-Apex Distance (TAD) greater than 25 mm is the strongest predictive factor for lag screw cut-out in the treatment of intertrochanteric fractures. A TAD < 25 mm is universally recommended.

Question 5

A 28-year-old male sustains a vertical shear femoral neck fracture (Pauwels type III). What is the biomechanical rationale for using a sliding hip screw (SHS) with a derotation screw rather than multiple parallel cancellous screws?

Explanation

Pauwels III fractures (angle > 50 degrees) are highly unstable due to significant vertical shear forces. A fixed-angle construct like a sliding hip screw (SHS) with a derotation screw provides far greater biomechanical stability against shear forces than multiple parallel cancellous screws, leading to lower failure rates in vertical fracture patterns.

Question 6

A 65-year-old female on long-term alendronate therapy for osteoporosis presents with atraumatic thigh pain. Radiographs reveal lateral cortical thickening and a transverse incomplete radiolucent line in the subtrochanteric region. Which of the following is considered an indication for prophylactic intramedullary nailing?

Explanation

In the setting of an incomplete atypical femoral fracture (AFF) associated with bisphosphonate use, prophylactic intramedullary nailing is indicated if the patient experiences prodromal thigh pain with weight-bearing, or if the radiolucent line traverses > 50% of the cortex, as these strongly predict impending complete fracture.

Question 7

During intramedullary nailing of a closed, isolated subtrochanteric femur fracture in a 30-year-old male, what is the typical deformity of the proximal fragment induced by the surrounding musculature?

Explanation

In subtrochanteric fractures, the proximal fragment is typically flexed (by the iliopsoas), abducted (by the gluteus medius and minimus), and externally rotated (by the short external rotators). Recognizing this deforming force is crucial for achieving accurate reduction prior to nail passage.

Question 8

A 22-year-old male sustains a posterior hip dislocation and a posterior wall acetabular fracture. The hip is reduced in the emergency department. Which of the following CT findings is an absolute indication for operative fixation of the posterior wall?

Explanation

A posterior wall fracture involving > 50% of the articular surface renders the hip uniformly unstable and is an absolute indication for open reduction and internal fixation. Fractures < 20% are typically stable, while those between 20% and 50% often require dynamic stress testing to determine stability.

Question 9

A 70-year-old female sustains a periprosthetic distal femur fracture (Su Type 3) proximal to a posterior-stabilized (PS) total knee arthroplasty. The femoral component is well-fixed, but the fracture is highly comminuted with a very short distal segment. What is the most appropriate fixation method?

Explanation

Su Type 3 fractures occur very distal to the superior pole of the femoral component. The presence of a posterior-stabilized (PS) box typically precludes the use of a retrograde intramedullary nail. For a well-fixed component with comminution, lateral locked plating (often using minimally invasive techniques) is the standard of care to achieve stable fixation.

Question 10

A 40-year-old male is brought to the trauma bay after a high-energy knee dislocation. The knee was reduced prior to arrival. Pulses are palpable and symmetric to the contralateral limb, but the Ankle-Brachial Index (ABI) is 0.8. What is the next most appropriate step in management?

Explanation

In the setting of a knee dislocation, an ABI < 0.9 is highly suspicious for a vascular injury (specifically popliteal artery intimal tear or occlusion) despite palpable pulses. The gold standard next step is advanced imaging, currently most commonly a CT angiogram, to definitively evaluate the vascular tree.

Question 11

A 30-year-old female sustains a Pipkin Type IV fracture-dislocation of the hip (femoral head fracture with an associated posterior wall acetabular fracture). Which surgical approach provides optimal access to address both fractures simultaneously?

Explanation

A Pipkin IV injury involves a fracture of the femoral head and a posterior acetabular wall fracture. The Kocher-Langenbeck (posterior) approach is favored because it allows direct access to reduce and fix the posterior wall, and the femoral head can be accessed either through the traumatic arthrotomy, by extending the capsulotomy, or via a surgical dislocation of the hip.

Question 12

When comparing a cephalomedullary nail to a sliding hip screw (SHS) for the treatment of an unstable reverse oblique intertrochanteric fracture (OTA 31-A3), what is the primary biomechanical advantage of the intramedullary nail?

Explanation

Reverse oblique fractures (OTA 31-A3) disrupt the lateral wall and have a tendency for medial displacement of the femoral shaft. Intramedullary devices (cephalomedullary nails) are biomechanically superior because they reside closer to the mechanical axis, providing a shorter lever arm for deforming forces and acting as an intramedullary buttress against medial displacement.

Question 13

A 25-year-old male with an isolated, displaced transverse patella fracture undergoes tension band wiring (TBW). For the tension band construct to function optimally, where must the wires be placed relative to the patella?

Explanation

The tension band principle relies on placing the implant on the tension side of the bone. In the patella, flexion creates tension anteriorly and compression posteriorly (articular side). Wires placed on the anterior surface convert the tensile forces generated during knee flexion into compressive forces at the articular surface.

Question 14

A 50-year-old female undergoes reamed intramedullary nailing for a closed tibial shaft fracture. On postoperative day 1, she complains of severe, out-of-proportion leg pain, paresthesias in the first web space of the foot, and severe pain with passive toe flexion. Which fascial compartment of the leg is most likely experiencing elevated pressure?

Explanation

The patient's symptoms localize to the anterior compartment, which contains the deep peroneal nerve (sensation to the 1st web space) and the extensor hallucis longus and extensor digitorum longus (pain with passive toe flexion). The anterior compartment is the most commonly involved compartment in acute compartment syndrome of the leg.

Question 15

To minimize the risk of avascular necrosis during open reduction of a displaced intracapsular femoral neck fracture in a young adult, the surgeon must be meticulous to avoid damaging the predominant blood supply to the femoral head. Which artery provides this primary supply?

Explanation

The medial femoral circumflex artery (MFCA) gives rise to the lateral epiphyseal artery system, which provides the vast majority of the blood supply to the adult femoral head. Protecting its branches (especially posterosuperiorly) is critical during surgical approaches and reduction.

Question 16

An 82-year-old nursing home resident sustained a minimally displaced femoral neck fracture treated with in situ percutaneous pinning. Nine months later, she presents with severe, progressive groin pain. Radiographs demonstrate advanced avascular necrosis with structural collapse of the femoral head. What is the most appropriate salvage procedure?

Explanation

In an elderly patient with failed internal fixation of a femoral neck fracture due to AVN and structural collapse, conversion to a total hip arthroplasty (or hemiarthroplasty depending on baseline functional status) is the treatment of choice to reliably relieve pain and restore early mobility.

Question 17

A 45-year-old male sustains a posterior dislocation of the right hip. Closed reduction is performed urgently in the emergency department. Post-reduction CT scan reveals a concentrically reduced hip, but shows a 4 mm intra-articular osteochondral fragment lodged within the weight-bearing dome of the acetabulum. What is the most appropriate next step in management?

Explanation

A retained intra-articular fragment within the joint space, especially in the weight-bearing zone, will rapidly lead to third-body wear, cartilage destruction, and post-traumatic arthritis. It is an absolute indication for operative intervention (via arthroscopy, arthrotomy, or surgical dislocation) for removal.

Question 18

In the management of a 'floating knee' injury (ipsilateral diaphyseal fractures of the femur and tibia) in a hemodynamically stable polytrauma patient, which sequence of operative fixation is generally recommended?

Explanation

The general consensus for a floating knee is to stabilize the femur first. This converts a complex, multidirectional instability into a simpler scenario, allows easier manipulation and positioning of the leg for subsequent tibial nailing, and addresses the larger source of bleeding and potential fat emboli sooner.

Question 19

A 55-year-old male sustains a Schatzker II (split-depression) lateral tibial plateau fracture. Which of the following describes the most mechanically sound surgical sequence for restoring joint congruity and stability during open reduction and internal fixation?

Explanation

The standard surgical sequence for a Schatzker II fracture is: 1) open the lateral split to access the depression, 2) elevate the depressed articular segment to restore joint congruity, 3) pack the metaphyseal void with bone graft/substitute to support the elevation, 4) compress the lateral split with lag screws, and 5) apply a lateral buttress plate.

Question 20

A 35-year-old female presents with a highly comminuted patella fracture. Operative fixation with an anterior locking plate and screws is chosen over traditional tension band wiring. Which of the following is an advantage of anterior plating for highly comminuted patella fractures?

Explanation

In highly comminuted patella fractures, the anterior cortex is often deficient, making the tension band principle impossible to achieve (as it requires anterior cortical apposition to convert tension to compression). Anterior locking plates provide a rigid, fixed-angle construct that bridges the comminution, allowing for stable fixation and early range of motion even without intact anterior bone.

Question 21

An 82-year-old female presents with groin pain after a mechanical fall. X-rays show a periprosthetic fracture around a cemented femoral stem. The fracture extends just below the tip of the stem. The stem is radiographically loose with subsidence, but there is adequate proximal femoral bone stock. According to the Vancouver classification, what is the most appropriate management?

Explanation

This is a Vancouver B2 fracture (fracture around the stem, loose component, good proximal bone stock). The standard of care is revision arthroplasty using a long, fully porous-coated or fluted tapered diaphyseal-engaging uncemented stem that bypasses the fracture by at least two cortical diameters.

Question 22

A 74-year-old female sustains a distal femur fracture above a posterior-stabilized (PS) total knee arthroplasty. Radiographs reveal a comminuted fracture 5 cm above the anterior flange, and the femoral component remains well-fixed. Which of the following statements regarding fixation is true?

Explanation

In Lewis-Rorabeck Type II fractures (well-fixed component), fixation is indicated. Retrograde intramedullary nailing (RIMN) is possible through many PS boxes if the intercondylar notch of the implant accommodates the nail diameter. It is not strictly contraindicated if the specific implant design allows. Distal femoral replacement is reserved for loose components (Type III) or unfixable bone.

Question 23

A 45-year-old male is involved in a high-speed motor vehicle collision. An AP pelvis radiograph demonstrates an acetabular fracture with a pathognomonic 'spur sign'. Which of the following Letournel fracture patterns is most likely present?

Explanation

The 'spur sign' is pathognomonic for a both-column fracture of the acetabulum. It represents the intact posterior ilium that remains attached to the axial skeleton, projecting posterior and superior to the displaced articular segment, best seen on the obturator oblique radiograph.

Question 24

During a primary total knee arthroplasty, trial reduction reveals that the knee is well-balanced in full extension, but the flexion gap is unacceptably tight. The surgeon has used a measured resection, posterior referencing technique. Which of the following intraoperative adjustments is most appropriate to balance the gaps?

Explanation

If the flexion gap is tight but the extension gap is balanced, the goal is to increase the flexion gap without affecting the extension gap. Using posterior referencing, downsizing the femoral component reduces the AP dimension by resecting more posterior condylar bone, thus increasing the flexion gap. Using the same thickness polyethylene insert ensures the extension gap remains unchanged.

Question 25

In displaced intracapsular femoral neck fractures, osteonecrosis of the femoral head is a major concern. Which of the following vessels provides the primary blood supply to the weight-bearing dome of the femoral head in an adult?

Explanation

The medial femoral circumflex artery (MFCA) is the predominant blood supply to the femoral head in adults. Specifically, its lateral epiphyseal artery branch supplies the weight-bearing superolateral aspect of the head. It is at high risk of disruption in displaced femoral neck fractures.

Question 26

A 28-year-old male presents after a knee dislocation (Schenck KD-III). The knee is successfully reduced in the emergency department. His dorsalis pedis and posterior tibial pulses are palpable but slightly diminished compared to the contralateral side. His Ankle-Brachial Index (ABI) is calculated to be 0.85. What is the most appropriate next step in management?

Explanation

An ABI < 0.9 in the setting of a knee dislocation is highly sensitive for an occult vascular injury and mandates advanced vascular imaging, most commonly CT Angiography (CTA). Immediate exploration is reserved for hard signs of vascular injury (e.g., expanding hematoma, absent pulses post-reduction). Observation alone is inappropriate with an abnormal ABI.

Question 27

A 40-year-old male sustains a subtrochanteric femur fracture. During closed reduction, the proximal fragment is noted to be flexed, abducted, and externally rotated. Which muscle is primarily responsible for the flexion deformity of the proximal fragment?

Explanation

In subtrochanteric fractures, the proximal fragment is notoriously difficult to control. It is flexed by the iliopsoas (attaching to the lesser trochanter), abducted by the gluteus medius and minimus (greater trochanter), and externally rotated by the short external rotators.

Question 28

A 32-year-old female sustains a coronal plane fracture of the lateral femoral condyle (Hoffa fracture) extending into the intercondylar notch. To optimize biomechanical stability, in which direction should the lag screws ideally be directed during open reduction and internal fixation?

Explanation

Hoffa fractures are coronal plane fractures of the distal femoral condyles. Biomechanical studies have demonstrated that posterior-to-anterior (PA) directed lag screws provide significantly stronger fixation and greater resistance to shear forces compared to anterior-to-posterior (AP) directed screws.

Question 29

A 65-year-old osteoporotic female falls from standing and sustains a lateral compression type 1 (LC-1) pelvic ring injury, consisting of a unilateral superior and inferior pubic ramus fracture with an ipsilateral sacral ala impaction fracture. She is hemodynamically stable but has severe pain with mobilization. What is the currently accepted indication for operative fixation of her pelvic ring?

Explanation

Most LC-1 fractures are mechanically stable and treated non-operatively with weight-bearing as tolerated. However, operative fixation (e.g., percutaneous pelvic fixation) is indicated in patients who fail non-operative management, specifically those who cannot mobilize due to intractable mechanical pain, to prevent complications of immobility.

Question 30

A 45-year-old male undergoes open reduction and internal fixation of a displaced transverse patella fracture using an anterior tension band wiring construct. The principle of the tension band in this application relies on which of the following biomechanical conversions?

Explanation

The tension band principle relies on applying a tension band (wire) on the tension side of a bone. In the patella, the anterior surface experiences tension during knee flexion. The anterior wire converts these anterior distraction/tension forces into dynamic compression forces at the articular surface, promoting stability and primary bone healing.

Question 31

A 60-year-old male with a metal-on-polyethylene total hip arthroplasty (THA) placed 6 years ago presents with new-onset groin pain. Radiographs show a well-fixed stem and cup. Serum metal ion testing reveals elevated cobalt levels with normal chromium levels. MRI with MARS sequencing shows a cystic periarticular mass. What is the most likely etiology of his symptoms?

Explanation

The combination of elevated cobalt with normal chromium in a metal-on-polyethylene THA is classic for mechanically assisted crevice corrosion (MACC) or trunnionosis at the head-neck taper junction. This adverse local tissue reaction (ALTR/ALVAL) can result in a pseudotumor (cystic mass) and necessitates revision of the bearing/head if symptomatic.

Question 32

A 42-year-old skier sustains a high-energy varus injury to the knee, resulting in a displaced medial tibial plateau fracture (Schatzker IV). Which of the following structures is at highest risk of iatrogenic injury during a standard posteromedial surgical approach to the proximal tibia?

Explanation

The posteromedial approach to the tibia utilizes the interval between the medial gastrocnemius (retracted posteriorly/laterally) and the pes anserinus (retracted anteriorly). The saphenous nerve and great saphenous vein run superficially in this region and are at highest risk of iatrogenic injury during the superficial dissection.

Question 33

A 70-year-old female on long-term alendronate therapy presents with a diaphyseal femur fracture after a minor fall. According to the ASBMR Task Force criteria, which of the following is a REQUIRED major feature to diagnose an atypical femoral fracture?

Explanation

According to the ASBMR criteria, major features of atypical femoral fractures (AFFs) include: location anywhere from distal to the lesser trochanter to proximal to the supracondylar flare, associated with minimal/no trauma, transverse or short oblique configuration, noncomminuted or minimally comminuted, complete fractures extending through both cortices with a medial spike, and the fracture line MUST originate at the lateral cortex.

Question 34

During a primary total hip arthroplasty utilizing the direct anterior approach, the surgeon develops the superficial internervous plane. This plane lies between muscles innervated by which two nerves?

Explanation

The direct anterior (Smith-Petersen) approach to the hip utilizes the true internervous plane between the tensor fasciae latae (supplied by the superior gluteal nerve) and the sartorius (supplied by the femoral nerve).

Question 35

A 25-year-old male suffers a dashboard injury resulting in an irreducible posterior hip dislocation. CT imaging reveals an entrapped osteochondral fragment in the acetabular fossa preventing concentric reduction. Which of the following associated injuries is most common with this specific mechanism and direction of dislocation?

Explanation

Posterior hip dislocations are commonly caused by a dashboard injury (axial load on a flexed knee). The sciatic nerve (specifically the peroneal division) is the most commonly injured neurologic structure in posterior hip dislocations, occurring in approximately 10-20% of cases.

Question 36

A 78-year-old female undergoes fixation of an unstable intertrochanteric femur fracture with a sliding hip screw (DHS). Which of the following radiographic parameters is most predictive of hardware cutout and mechanical failure?

Explanation

Baumgaertner et al. established that a Tip-Apex Distance (TAD) greater than 25 mm on AP and lateral radiographs is the strongest independent predictor of lag screw cutout in both sliding hip screws and cephalomedullary nails for intertrochanteric fractures.

Question 37

A 30-year-old male polytrauma patient sustains an ipsilateral midshaft femur fracture and a midshaft tibia fracture (floating knee). He is hemodynamically stable but has bilateral pulmonary contusions. The multidisciplinary team decides on Damage Control Orthopedics (DCO) rather than Early Total Care (ETC). Which of the following laboratory values most strongly supports the decision for DCO over ETC?

Explanation

In polytrauma patients, markers of physiologic exhaustion and systemic inflammatory response dictate the choice between ETC and DCO. A serum lactate > 2.5 mmol/L, base deficit > 2.0 (more negative than -2.0), or markedly elevated inflammatory markers (like IL-6) indicate a borderline or unstable patient who is at high risk for 'second hit' phenomena (like ARDS) if subjected to prolonged ETC procedures like bilateral reamed intramedullary nailing.

Question 38

A 24-year-old professional athlete undergoes microfracture for a 1.5 cm^2 symptomatic full-thickness chondral defect on the medial femoral condyle. The reparative tissue that fills the defect over the next several months is primarily composed of which type of collagen?

Explanation

Microfracture stimulates the release of mesenchymal stem cells from the underlying bone marrow. These cells differentiate and produce fibrocartilage, which is biomechanically inferior and primarily composed of Type I collagen, as opposed to normal hyaline articular cartilage, which is predominantly Type II collagen.

Question 39

A 38-year-old male sustains a posterior hip dislocation with an associated femoral head fracture that involves the weight-bearing surface superior to the fovea capitis. According to the Pipkin classification, what type of fracture is this, and what is the preferred surgical approach for open reduction and internal fixation?

Explanation

Pipkin Type II fractures involve the femoral head superior to the fovea (the primary weight-bearing portion). For Pipkin I and II fractures requiring fixation, an anterior (Smith-Petersen) approach or a surgical hip dislocation (Ganz) is preferred to directly visualize the head, provide perpendicular access for screw fixation, and preserve the remaining posterior blood supply (MFCA).

Question 40

A 45-year-old active male is undergoing a medial opening wedge high tibial osteotomy (HTO) for varus gonarthrosis. A known complication of this procedure is an unintended increase in the posterior tibial slope. Which of the following technical errors most commonly leads to this increase in slope?

Explanation

Because the native proximal tibia is triangular (wider posteriorly than anteriorly), opening the medial wedge equally at the anteromedial and posteromedial cortices will inadvertently increase the posterior tibial slope. To maintain the native slope, the posteromedial gap must be opened approximately twice as much as the anteromedial gap.

Question 41

A 70-year-old male sustains a fall 5 years after undergoing a right total hip arthroplasty. Radiographs reveal a spiral fracture around the distal aspect of a fully porous-coated femoral stem. The fracture extends 5 cm distal to the tip of the stem. Radiographic and clinical evaluation confirms the stem is solidly fixed. According to the Vancouver classification, what is the most appropriate surgical management?

Explanation

This is a Vancouver B1 periprosthetic femur fracture, defined as a fracture around or just distal to the stem with a well-fixed component and adequate bone stock. The standard of care for a B1 fracture is open reduction and internal fixation (ORIF), typically utilizing a combination of a lateral locking plate, cables, and potentially structural allograft struts. Revision arthroplasty (Options 0 and 3) is indicated for B2 (loose stem, good bone) or B3 (loose stem, poor bone) fractures.

Question 42

An 82-year-old female presents with an intertrochanteric femur fracture. On the preoperative anteroposterior radiograph, the lateral wall thickness is measured at 18 mm. What is the clinical implication of this measurement when planning surgical fixation?

Explanation

The lateral wall thickness is a critical predictor of postoperative instability in intertrochanteric fractures. Hsu et al. demonstrated that a lateral wall thickness of less than 20.5 mm is an independent predictor for lateral wall fracture when a sliding hip screw (DHS) is used. When the lateral wall fractures, the fracture effectively becomes a reverse obliquity equivalent, leading to medial medialization of the shaft and fixation failure. Therefore, cephalomedullary nailing is the preferred implant for fractures with an intact but thin (< 20.5 mm) lateral wall.

Question 43

A 65-year-old female who has been taking alendronate for 10 years presents with 3 months of progressive lateral thigh pain. Radiographs reveal a transverse radiolucent line in the lateral cortex of the subtrochanteric femur with associated focal cortical thickening ('beaking'). There is no history of trauma. What is the most appropriate management?

Explanation

This patient has an impending atypical femur fracture (AFF) associated with long-term bisphosphonate use. Hallmarks include lateral cortical beaking and a transverse radiolucent line. Because she has progressive pain (suggesting mechanical instability/microfracture propagation), prophylactic intramedullary nailing is the gold standard to prevent a complete, displaced fracture, which carries a high risk of nonunion and complication. Discontinuing the bisphosphonate is essential, but medical management alone is insufficient for a symptomatic impending AFF.

Question 44

A 35-year-old male involved in a motorcycle collision sustains a high-energy distal femur fracture. CT scan reveals a coronal shear fracture of the lateral femoral condyle (Hoffa fracture). Regarding the biomechanical fixation of this specific fracture fragment, which of the following statements is true?

Explanation

A Hoffa fracture is a coronal plane fracture of the distal femur, most commonly involving the lateral condyle. Biomechanical studies have demonstrated that posterior-to-anterior (PA) directed lag screws placed perpendicular to the fracture plane provide superior pull-out strength and compression compared to anterior-to-posterior (AP) screws. This is due to the denser bone in the posterior condyle allowing for better thread purchase, whereas AP screws often engage the less dense anterior metaphysis.

Question 45

A 45-year-old male sustains a high-energy tibial plateau fracture. CT imaging identifies a large posteromedial coronal split fragment. What is the optimal surgical approach and fixation strategy for this specific fragment?

Explanation

A posteromedial shear fragment in a tibial plateau fracture (often a Schatzker IV or component of Schatzker V/VI) tends to displace distally and posteriorly. Lateral locked plating with long screws directed medially is insufficient to maintain reduction of a posteromedial coronal split due to the lack of direct buttressing and the trajectory of the screws (which often parallel the fracture line). The optimal treatment is a direct posteromedial approach with the application of an anti-glide or buttress plate to mechanically counteract the displacing forces.

Question 46

A 28-year-old male presents with a high-energy Pauwels type III (vertical shear) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability for this fracture pattern?

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle > 50 degrees), which subjects the fracture site to high shear forces rather than compressive forces. Multiple cancellous screws (length-stable but shear-weak) have a high failure rate in this pattern. Biomechanical studies have shown that a fixed-angle device, such as a sliding hip screw (DHS), supplemented with an anti-rotation screw, provides superior stability and resists the varus collapse and shear forces much better than multiple cancellous screws.

Question 47

When utilizing a sliding hip screw to stabilize an intertrochanteric femur fracture, minimizing the Tip-Apex Distance (TAD) is critical. Which of the following statements regarding the TAD rule is correct?

Explanation

The Tip-Apex Distance (TAD), described by Baumgaertner, is the sum of the distance from the tip of the lag screw to the apex of the femoral head on both the AP and lateral radiographs. A TAD of less than 25 mm has been strongly correlated with a successful outcome, whereas a TAD greater than 25 mm is associated with a significantly increased risk of screw cut-out. The goal is deep, central placement of the screw in the femoral head.

Question 48

A 72-year-old female who underwent a posterior stabilized (PS) total knee arthroplasty 10 years ago sustains a displaced distal femur fracture 4 cm superior to the femoral component flange. Radiographs show the component remains well-fixed. The original operative note confirms the use of a standard closed-box PS femoral component. What is the most appropriate fixation strategy?

Explanation

This is a Su Type II (or Lewis-Rorabeck Type II) periprosthetic distal femur fracture, defined as a displaced fracture proximal to a well-fixed component. While both retrograde intramedullary nailing and lateral locked plating are valid options for periprosthetic fractures, a closed-box design of a posterior stabilized (PS) femoral component physically blocks the entry point in the intercondylar notch, precluding the use of a retrograde nail. Therefore, lateral locked plating is the procedure of choice.

Question 49

A 40-year-old male sustains a proximal third subtrochanteric femur fracture. During closed reduction maneuvers prior to intramedullary nailing, the proximal fracture fragment is noted to be severely flexed, abducted, and externally rotated. Which muscle group is primarily responsible for the external rotation of the proximal fragment?

Explanation

In subtrochanteric femur fractures, the classic deforming forces on the proximal fragment include flexion (via the iliopsoas attaching to the lesser trochanter), abduction (via the gluteus medius and minimus attaching to the greater trochanter), and external rotation (via the short external rotators inserting into the greater trochanteric region). The distal fragment is typically adducted (adductors) and translated proximally (hamstrings and quadriceps).

Question 50

A 30-year-old male is brought to the trauma bay after a motorcycle crash. He has a grossly deformed knee consistent with a multiligamentous knee dislocation, which is immediately reduced. Following reduction, symmetric pedal pulses are palpable. The Ankle-Brachial Index (ABI) is measured as 0.85 on the injured side and 1.0 on the uninjured side. What is the next best step in management?

Explanation

In the setting of a knee dislocation, vascular injury (specifically to the popliteal artery) is a major concern. 'Hard signs' of vascular injury (expanding hematoma, absent pulses, pulsatile bleeding) warrant immediate surgical exploration. If hard signs are absent but the Ankle-Brachial Index (ABI) is less than 0.90 (as in this case with an ABI of 0.85), a vascular injury is suspected, and advanced imaging with a CT angiogram (CTA) is indicated. An ABI > 0.90 typically allows for observation and serial exams.

Question 51

A 25-year-old male suffers a dashboard injury resulting in a posterior hip dislocation and an associated femoral head fracture that extends superior to the fovea capitis (Pipkin II). The hip is closed reduced, but CT shows the fracture fragment is displaced 3 mm. What is the optimal surgical approach to maximize direct visualization for anatomic fixation of this specific fragment while minimizing avascular necrosis risk?

Explanation

A Pipkin II fracture involves the femoral head superior to the fovea capitis (the weight-bearing portion). For isolated femoral head fractures requiring ORIF (Pipkin I and II), the anterior approach (Smith-Petersen) or anterolateral (Watson-Jones) approach is preferred. It provides direct visualization of the anteriorly located femoral head fragment and avoids further damage to the remaining posterior blood supply (medial circumflex femoral artery) that was not torn during the posterior dislocation. The Ganz trochanteric flip is also an excellent option but the Smith-Petersen is the classic correct answer among these choices.

Question 52

A 12-year-old boy sustains a completely displaced tibial eminence fracture (Meyers and McKeever Type III) while skiing. During an arthroscopically assisted reduction and internal fixation, the surgeon finds the fracture cannot be anatomically reduced despite clearing the fracture hematoma. Which anatomical structure is most commonly entrapped, blocking reduction?

Explanation

Tibial eminence avulsion fractures are the pediatric equivalent of an ACL tear. When they are completely displaced (Type III), closed reduction is often unsuccessful due to soft tissue interposition. The most common structures that become entrapped under the fracture fragment and block reduction are the anterior horn of the medial meniscus and the intermeniscal (transverse) ligament. These must be extracted anatomically (often arthroscopically) to allow the fragment to seat in its bed.

Question 53

A 22-year-old male is admitted after a high-speed motor vehicle collision with an ipsilateral midshaft femur and midshaft tibia fracture (Fraser Type I floating knee). He is hemodynamically stable without head or chest trauma. To minimize the risk of acute respiratory distress syndrome (ARDS) and fat embolism syndrome, what is the most appropriate management sequence?

Explanation

In a hemodynamically stable polytrauma patient (without significant traumatic brain injury or severe lung contusions precluding early total care), early definitive intramedullary nailing of long bone fractures within 24 hours is the standard of care. Early total care (ETC) stabilizes the fractures, decreases the systemic inflammatory response, permits early mobilization, and has been proven to significantly lower the incidence of ARDS, fat embolism syndrome, and pulmonary complications compared to delayed fixation.

Question 54

A 55-year-old male presents with a completely displaced basicervical femoral neck fracture. Which of the following statements regarding the biomechanics and clinical behavior of this specific fracture pattern is true?

Explanation

Basicervical femoral neck fractures occur at the junction of the femoral neck and the intertrochanteric line. Although technically extracapsular, they lack the broad cancellous bony interdigitation found in standard intertrochanteric fractures. As a result, they are highly mechanically unstable, particularly in rotation, and behave uniquely. They carry a significantly higher risk of implant failure, screw cut-out, and nonunion compared to standard IT fractures. Fixation requires a rigid, rotationally stable device such as a cephalomedullary nail or a DHS supplemented with a derotation screw.

Question 55

A 35-year-old female undergoes intramedullary nailing of a midshaft tibia fracture utilizing a suprapatellar approach. During the procedure, a protective trocar and cannula system is used. If this cannula is inadequately seated or the knee is positioned incorrectly, which intra-articular structure is at highest risk of iatrogenic damage?

Explanation

The suprapatellar approach to tibial nailing involves passing the instruments and nail through the patellofemoral joint. A specialized cannula/trocar system must be properly seated in the intercondylar notch to protect the joint surfaces. The structure at greatest risk of iatrogenic damage from reamers or the nail itself, particularly if the knee is not adequately flexed (usually 10-20 degrees is ideal) or the cannula slips, is the articular cartilage of the femoral trochlea or the deep surface of the patella.

Question 56

A healthy, independent, and highly active 68-year-old male sustains a displaced femoral neck fracture. The decision is made to perform a Total Hip Arthroplasty (THA) rather than a Bipolar Hemiarthroplasty. In this specific patient population, THA is associated with which of the following outcomes compared to hemiarthroplasty?

Explanation

In active, healthy, and independent elderly patients with displaced femoral neck fractures, Total Hip Arthroplasty (THA) has been shown to provide better functional outcomes (e.g., Harris Hip Scores), less residual pain, and lower long-term reoperation rates (often due to avoiding acetabular wear/erosion seen with hemiarthroplasty). However, THA is associated with a higher initial risk of dislocation, longer operative time, and greater blood loss compared to hemiarthroplasty.

Question 57

A 42-year-old male undergoes tension band wiring for a transverse mid-pole patella fracture. For the tension band principle to function effectively during active knee extension and weight-bearing flexion, it dynamically converts tensile forces into compressive forces at the articular surface. The primary tensile forces being neutralized are generated on which anatomic aspect of the patella?

Explanation

The biomechanical principle of a tension band is to place the fixation on the tension side of a bone subject to eccentric loading. In the patella, the pull of the quadriceps tendon and patellar tendon creates tensile forces on the anterior cortical surface during flexion. By placing the wire construct on the anterior surface, these tensile forces are converted into compressive forces at the posterior (articular) surface, promoting stability and healing.

Question 58

A 75-year-old female sustains a highly comminuted distal femur fracture, which is stabilized using a modern lateral locking plate. To decrease the stiffness of the construct and promote secondary bone healing via callus formation across the comminuted segment, what technical modification should the surgeon employ?

Explanation

In bridge plating of comminuted fractures with locking plates, overly stiff constructs suppress the micromotion necessary for secondary bone healing (callus formation), leading to nonunion or implant failure. The 'working length' is the distance between the two innermost screws on either side of the fracture. Increasing the working length by leaving holes empty adjacent to the fracture decreases construct stiffness and permits appropriate micromotion. A plate span ratio > 2-3 is recommended in comminuted fractures.

Question 59

A 4-year-old boy sustains a completely displaced midshaft femur fracture. The orthopedic surgeon treats the fracture with immediate spica casting and accepts a reduction with 1.5 cm of overriding (shortening). What is the primary physiologic rationale for accepting this overriding in this age group?

Explanation

In children between the ages of 2 and 10 years, a diaphyseal femur fracture stimulates increased blood flow and physial activity, leading to a phenomenon known as transient overgrowth. The fractured femur will typically overgrow by 1 to 2 cm over the following 1 to 2 years. Therefore, it is standard practice to accept (and actually aim for) 1 to 2 cm of bayonet apposition (shortening) during initial reduction to result in equal leg lengths at skeletal maturity.

Question 60

A 28-year-old male arrives at the emergency department with a traumatic posterior hip dislocation following a motor vehicle collision. Which of the following factors is most strongly associated with an increased risk of developing avascular necrosis (AVN) of the femoral head in this patient?

Explanation

The risk of avascular necrosis (AVN) following a traumatic hip dislocation is directly correlated with the duration the hip remains dislocated. Prolonged dislocation places sustained tension on the retinacular vessels (branches of the medial circumflex femoral artery) and increases intracapsular pressure, leading to ischemia. Evidence strongly supports that reduction within 6 hours significantly decreases the risk of AVN. The other options are not primary drivers of AVN compared to the ischemic time.

Question 61

An 82-year-old male with a history of a cementless total hip arthroplasty presents with a periprosthetic femur fracture following a ground-level fall. Radiographs demonstrate a fracture around the stem with obvious component subsidence and severe proximal osteolysis and bone loss extending to the diaphysis. According to the Vancouver classification, what is the most appropriate surgical management?

Explanation

This is a Vancouver B3 periprosthetic femur fracture, defined as a fracture around a loose stem in the setting of poor proximal bone stock. Because the proximal bone cannot support a standard revision stem, the most reliable treatment in an elderly patient is a proximal femoral replacement (megaprosthesis) to allow for immediate weight-bearing and stability.

Question 62

A 35-year-old female sustains a high-speed motor vehicle collision and is diagnosed with an isolated coronal shear fracture of the lateral femoral condyle (Hoffa fracture). During open reduction and internal fixation, what is the biomechanically optimal direction for lag screw placement to achieve maximum stability?

Explanation

Posterior-to-anterior (PA) lag screws are biomechanically superior for Hoffa fractures. They are directed perpendicular to the fracture plane and maximize thread purchase in the denser anterior cortical bone of the metaphysis, providing significantly greater pull-out strength compared to AP screws.

Question 63

A 65-year-old female experiences recurrent anterior dislocations of her total hip arthroplasty. CT imaging is performed to evaluate component positioning. Which of the following component profiles is the most likely etiology of her anterior instability?

Explanation

Anterior dislocation in THA is typically associated with excessive combined anteversion of the acetabular and femoral components. The normal target for combined anteversion (using the widely accepted Widmer or McKibbin principles) is approximately 25 to 45 degrees. A combined anteversion of 65 degrees is excessive and strongly predisposes to anterior instability, especially in extension and external rotation.

Question 64

A 28-year-old male sustains an acute knee dislocation (Schenck KD III) during a football game. The knee is reduced in the emergency department, and palpable dorsalis pedis and posterior tibial pulses are present. An Ankle-Brachial Index (ABI) is measured at 0.85. What is the most appropriate next step in management?

Explanation

In the setting of a knee dislocation, an ABI of less than 0.9 is a hard indication for advanced vascular imaging, typically a CT angiogram (CTA), to rule out a popliteal artery injury, even if palpable pulses are present. Serial ABIs are appropriate only if the initial ABI is >0.9.

Question 65

A 40-year-old male presents with a posterior hip dislocation, a displaced fracture of the femoral head, and a large displaced posterior wall acetabular fracture (Pipkin IV). Which of the following surgical approaches provides the most optimal simultaneous access for direct visualization and anatomic reduction of both fracture components?

Explanation

A Pipkin IV fracture includes both a femoral head fracture and an acetabular fracture (usually the posterior wall). The Kocher-Langenbeck approach, especially when combined with a trochanteric flip (Ganz surgical hip dislocation), provides excellent extensile exposure to anatomically reduce and fix both the posterior wall of the acetabulum and the femoral head.

Question 66

During a primary posterior cruciate ligament (PCL)-retaining total knee arthroplasty, the surgeon notes that the trial components result in a knee that is well-balanced in extension but exhibits a significantly tight flexion gap with restricted femoral rollback. Which of the following is the most likely cause of this kinematic abnormality?

Explanation

In a PCL-retaining TKA, a tight flexion gap with restricted rollback and anterior lift-off of the tibial tray indicates a tight PCL. Management includes sequential release of the PCL or increasing the posterior slope of the tibial cut to open the flexion gap.

Question 67

A 45-year-old male sustains a high-energy Schatzker IV tibial plateau fracture. Lateral radiographs demonstrate a 'double contour' sign. What is the optimal surgical approach and fixation strategy for this specific fracture pattern?

Explanation

The 'double contour' sign on a lateral radiograph indicates a posteromedial shear fragment in a tibial plateau fracture. The optimal mechanical fixation for a posteromedial shear fracture is a posteromedial approach with an anti-glide plate to buttress the fragment and neutralize vertical shear forces.

Question 68

A 25-year-old male sustains a highly displaced, vertically oriented femoral neck fracture (Pauwels type III). The plan is for joint-preserving internal fixation. Which of the following constructs provides the greatest biomechanical stability against vertical shear forces?

Explanation

Pauwels type III fractures are highly vertical (>50 degrees) and experience massive shear forces, leading to high rates of nonunion and failure with traditional parallel cancellous screws. A sliding hip screw (with a derotation screw) or a proximal femoral locking plate provides superior biomechanical stability against these vertical shear forces compared to multiple cancellous screws.

Question 69

In the surgical treatment of intertrochanteric femur fractures using a sliding hip screw or a cephalomedullary nail, achieving a Tip-Apex Distance (TAD) of less than 25 mm is a critical objective. What is the primary biomechanical rationale for this metric?

Explanation

Described by Baumgaertner, the Tip-Apex Distance (TAD) is the sum of the distance from the tip of the lag screw to the apex of the femoral head on both AP and lateral radiographs. A TAD of less than 25 mm is the most reliable predictor of successful fixation, significantly decreasing the risk of lag screw cut-out through the osteoporotic femoral head.

Question 70

A 50-year-old female suffers an acute tear of the posterior root of the medial meniscus. If left untreated, what is the primary biomechanical consequence of this specific injury on the knee joint?

Explanation

A medial meniscal root tear completely unanchors the meniscus, leading to radial extrusion and a complete loss of circumferential hoop stresses. Biomechanically, this failure of load distribution results in articular contact pressures that are essentially equivalent to those seen after a complete total meniscectomy, rapidly accelerating medial compartment osteoarthritis.

Question 71

A 30-year-old male sustains a posterior wall acetabular fracture following a dashboard injury. Which of the following radiographic findings is the most reliable indicator of posterior hip instability mandating operative fixation?

Explanation

The size of the posterior wall fragment is a primary determinant of hip stability. Fragments involving >50% of the posterior wall width on axial CT are virtually always unstable and require ORIF. Fragments <20% are generally stable. Those between 20-50% are indeterminate and may require an examination under anesthesia (EUA) or dynamic fluoroscopy to assess stability.

Question 72

A 68-year-old female who has been taking alendronate for 8 years presents with a 2-month history of dull ache in her right thigh. Radiographs demonstrate lateral cortical thickening and a transverse radiolucent line involving only the lateral cortex of the subtrochanteric femur. According to AAOS guidelines, what is the primary indication for prophylactic intramedullary nailing in this patient?

Explanation

This patient has an incomplete atypical femur fracture (AFF). The presence of clinical thigh pain in the setting of radiographic evidence of an incomplete AFF (lateral cortical radiolucent line/beaking) is a strong indication for prophylactic intramedullary nailing to prevent catastrophic completion of the fracture.

Question 73

A 45-year-old male is being evaluated for a hip resurfacing arthroplasty (HRA). Which of the following patient factors represents an absolute contraindication to this specific procedure?

Explanation

Hip resurfacing arthroplasty relies on metal-on-metal bearing surfaces, which generate circulating cobalt and chromium ions. These ions are excreted entirely via the kidneys. Therefore, chronic kidney disease (impaired renal clearance) is an absolute contraindication to HRA due to the risk of systemic metal toxicity.

Question 74

According to the 2018 International Consensus Meeting (ICM) criteria for the diagnosis of Periprosthetic Joint Infection (PJI), which of the following is considered a 'major criterion' that is diagnostic of PJI on its own?

Explanation

Under the ICM criteria, there are two major criteria for PJI, either of which is definitively diagnostic on its own: 1) A sinus tract communicating with the prosthesis, or 2) Two positive periprosthetic cultures with phenotypically identical organisms. The other options are minor criteria that contribute to an aggregate score.

Question 75

A 55-year-old male with a ceramic-on-ceramic total hip arthroplasty complains of a loud squeaking noise from his hip during certain phases of his gait cycle. He has no pain, and radiographs show well-fixed components. What is the most common biomechanical etiology of this squeaking phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is fundamentally a problem of fluid-film lubrication failure. The most common biomechanical cause is edge loading, which typically occurs due to component malposition, such as excessive acetabular cup inclination (a 'steep' cup) or malversion. This causes stripe wear on the ceramic head and loss of lubrication.

Question 76

A 35-year-old male undergoes open reduction and internal fixation of a transverse patella fracture utilizing a tension band wiring technique. Biomechanically, for this construct to successfully convert tensile forces anteriorly into compressive forces at the articular surface during knee flexion, which of the following must be present?

Explanation

The tension band principle relies on applying an implant eccentrically on the tension side of a fractured bone to convert tensile forces into compressive forces across the fracture site upon loading. For this to work, the opposite cortex (in the patella, the posterior articular bony surface) must be intact to act as a buttress. If there is comminution on the compressive side, the construct will collapse.

Question 77

A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. The surgeon recommends in situ pinning of the left hip. What is the most widely accepted absolute indication for prophylactic in situ pinning of the asymptomatic, contralateral right hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior pelvic radiation, as their risk of developing a contralateral slip is exceedingly high (up to 100%).

Question 78

A 40-year-old male is brought to the trauma bay with hemodynamic instability following a crush injury to the pelvis. Radiographs demonstrate an Anteroposterior Compression (APC) III pelvic ring injury. A non-invasive pelvic binder is ordered. To optimally reduce pelvic volume and stabilize the ring, over which anatomic landmarks should the binder be centered?

Explanation

To effectively reduce an open-book pelvic injury (APC mechanism) and decrease pelvic volume, the pelvic binder must be centered over the greater trochanters. Placing the binder too high (e.g., over the iliac crests or ASIS) is a common error that fails to close the posterior ring and can paradoxically widen the pelvis.

Question 79

During the gap balancing phase of a primary total knee arthroplasty, the surgeon utilizes tensioning devices and finds that the knee is perfectly balanced in extension, but the flexion gap is excessively tight. Assuming correct soft tissue tensioning, which of the following bony maneuvers is most appropriate to specifically increase the flexion gap without altering the extension gap?

Explanation

A tight flexion gap with a balanced extension gap means more space is needed only in flexion. Options to selectively increase the flexion gap include downsizing the femoral component (which removes more posterior condylar bone when using anterior referencing) or increasing the posterior slope of the tibia (which primarily opens the gap in flexion).

Question 80

An orthopedic surgeon is performing a direct anterior approach (DAA) to the hip. This approach utilizes the Smith-Petersen internervous plane. During the superficial dissection, which nerve is at greatest risk of iatrogenic injury, and between which two muscles is the interval developed?

Explanation

The direct anterior approach (Smith-Petersen) utilizes an internervous plane between the Tensor Fasciae Latae (superior gluteal nerve) and the Sartorius (femoral nerve). The lateral femoral cutaneous nerve (LFCN) crosses over the sartorius and is highly vulnerable to traction or transection during the superficial exposure.

Question 81

A 25-year-old male sustains a high-energy Pauwels Type III femoral neck fracture. Biomechanical studies indicate that which of the following internal fixation constructs provides the greatest stability for this specific fracture pattern?

Explanation

Pauwels Type III fractures have a highly vertical orientation resulting in significant shear forces. A fixed-angle construct, such as a sliding hip screw with a derotation screw, provides superior biomechanical stability and higher load-to-failure compared to parallel cannulated screws.

Question 82

In a subtrochanteric femur fracture, the proximal fragment is predictably displaced by the deforming forces of the regional musculature. Which of the following best describes the position of the proximal fragment?

Explanation

The proximal fragment is flexed by the iliopsoas, abducted by the gluteus medius and minimus, and externally rotated by the short external rotators. Understanding these forces is critical for proper intraoperative reduction and implant placement.

Question 83

An 81-year-old female presents with a Vancouver Type B3 periprosthetic hip fracture around a cemented stem implanted 15 years ago. Radiographs reveal a grossly loose stem and severe osteolysis with nearly complete loss of the proximal medial calcar and lateral cortex. What is the most appropriate surgical management?

Explanation

Vancouver B3 fractures involve a loose implant and inadequate proximal bone stock. In an elderly, low-demand patient, proximal femoral replacement provides immediate stability, bypasses the poor bone stock, and allows for early weight-bearing.

Question 84

During preoperative planning for a 31-A1 intertrochanteric femur fracture, measurement of the lateral wall thickness on the anteroposterior radiograph is performed. A lateral wall thickness below which threshold is considered a significant predictor for iatrogenic lateral wall fracture if a dynamic hip screw (DHS) is used?

Explanation

A lateral wall thickness of less than 20.5 mm is a reliable threshold indicating a high risk for lateral wall blowout during DHS preparation. These patients are better managed with a cephalomedullary nail to prevent lateral wall failure.

Question 85

A 38-year-old male is involved in a high-speed motor vehicle collision and sustains a Pipkin IV fracture-dislocation. Which of the following surgical approaches is most appropriate to adequately address both components of this specific injury pattern?

Explanation

A Pipkin IV injury consists of a femoral head fracture combined with an associated acetabular fracture, most commonly the posterior wall. The posterior (Kocher-Langenbeck) approach allows for visualization and fixation of both the posterior wall and the femoral head.

Question 86

A 30-year-old male sustains a Fraser Type IIa floating knee injury consisting of a diaphyseal femur fracture and an intra-articular tibial plateau fracture. According to damage control principles and optimal functional outcomes in a hemodynamically stable patient, what is the recommended sequence of definitive fixation?

Explanation

In a floating knee injury, definitive stabilization of the femur is generally performed first. This establishes control of the limb, aids in mobilizing the patient, and simplifies the subsequent complex intra-articular reconstruction of the tibial plateau.

Question 87

When performing an intramedullary nailing of a proximal third tibial metaphyseal fracture via an infrapatellar approach, the fracture typically drifts into apex anterior (procurvatum) and valgus deformity. To prevent this, where should the Poller (blocking) screws be placed relative to the intended path of the nail in the proximal segment?

Explanation

Poller screws should be placed on the concave side of the anticipated deformity to substitute for missing cortical bone. To prevent apex anterior and valgus deformities, screws are placed posterior and lateral to the nail track in the proximal segment.

Question 88

A 35-year-old male presents with persistent mid-thigh pain 9 months after undergoing reamed intramedullary nailing for a closed femoral shaft fracture. Radiographs show an oligotrophic nonunion with intact hardware. Infection workup is negative. What is the most appropriate next step in surgical management?

Explanation

Aseptic diaphyseal femoral nonunions treated initially with an IM nail are effectively managed with exchange nailing using a reamed nail larger by 1-2 mm. This enhances both the mechanical stability and the biological healing environment.

Question 89

A 28-year-old male presents after a posterior knee dislocation. The joint is reduced in the emergency department and pulses are palpable. A handheld Doppler reveals an Ankle-Brachial Index (ABI) of 0.8 on the injured side. What is the most appropriate next step in management?

Explanation

An Ankle-Brachial Index (ABI) less than 0.9 after a knee dislocation strongly suggests a significant arterial injury, such as an intimal tear. CT angiography is the diagnostic gold standard and must be performed urgently to localize the injury before potential ischemia.

Question 90

A 68-year-old female who has been taking alendronate for 12 years presents with an atraumatic subtrochanteric fracture characterized by lateral cortical thickening and a transverse fracture pattern. Which of the following best describes the pathophysiology underlying this atypical femoral fracture?

Explanation

Prolonged bisphosphonate use heavily suppresses osteoclast-mediated bone remodeling. This prevents the normal repair of daily microdamage, leading to the accumulation of microcracks and eventually culminating in a tension-sided stress fracture on the lateral cortex.

Question 91

A coronal shear fracture of the femoral condyle (Hoffa fracture) requires precise surgical planning. Based on the biomechanics of knee loading and natural alignment, which anatomic location is most commonly affected by this specific fracture pattern?

Explanation

Hoffa fractures most commonly involve the lateral femoral condyle. This is due to the natural physiologic valgus of the knee, which directs axial transmission forces primarily through the lateral condyle, especially when the knee is flexed.

Question 92

A 75-year-old female with a 12-year-old primary total knee arthroplasty sustains a periprosthetic distal femur fracture classified as Lewis-Rorabeck Type III. Radiographs demonstrate a fracture proximal to the flange with obvious loosening of the femoral component. What is the treatment of choice?

Explanation

Lewis-Rorabeck Type III fractures are characterized by a loose femoral component. The definitive treatment for an elderly patient with this injury is a distal femoral replacement, which simultaneously resolves the fracture and the failed implant, allowing early mobilization.

Question 93

A 35-year-old male is evaluated for persistent groin pain 8 months after internal fixation of a femoral neck fracture. Radiographs reveal a nonunion with hardware cut-out, but MRI confirms the femoral head is viable. What is the most appropriate joint-preserving surgical intervention?

Explanation

In a young patient with a viable femoral head and a femoral neck nonunion, a valgus intertrochanteric osteotomy is indicated. It predictably changes the vertically oriented nonunion site (shear forces) to a more horizontal orientation (compressive forces), promoting union.

Question 94

An adult male sustains a Meyers-McKeever Type III displaced tibial eminence (spine) fracture. During attempted closed reduction or arthroscopic fixation, which of the following anatomic structures is most frequently found entrapped, blocking anatomical reduction?

Explanation

The anterior horn of the medial meniscus, along with the intermeniscal (transverse) ligament, is the most common structure to become entrapped in a displaced tibial eminence fracture in adults, necessitating unblocking prior to definitive fixation.

Question 95

A 70-year-old male presents with an AO/OTA 31-A3 (reverse obliquity) intertrochanteric femur fracture. Why is a sliding hip screw (DHS) considered a suboptimal implant for this specific fracture pattern?

Explanation

Reverse obliquity fractures (31-A3) lack an intact lateral cortical wall for support. A sliding hip screw allows the femoral shaft to displace medially as the lag screw slides, leading to severe lateral translation of the proximal fragment and construct failure.

Question 96

During open reduction and internal fixation of a displaced patella fracture, meticulous soft tissue handling is required to prevent avascular necrosis of the proximal pole. Where does the predominant extraosseous arterial supply enter the patella?

Explanation

The predominant blood supply to the patella enters through the inferior pole via an anastomotic ring. Consequently, displaced fractures or excessive surgical dissection near the inferior pole place the proximal pole at high risk for avascular necrosis.

Orthopedic Surgery Board Review MCQs: Arthroplasty, Trauma & Spine Part 255

Orthopedic Board Review MCQs: Fracture, Hip & Knee | Part 39

Key Takeaway

Orthopedic Board Review MCQs: Fracture, Hip & Knee | Part 39

Chapter Index