Orthopedic Board Review: Shoulder & Trauma MCQs Part 68

Question 1

Which of the following intraoperative modifications is most effective at preventing scapular notching during a reverse total shoulder arthroplasty?

Explanation

Scapular notching is a frequent complication in reverse total shoulder arthroplasty (rTSA). It is caused by mechanical impingement of the humeral cup against the inferior scapular neck during adduction. Placing the glenosphere with an inferior translation (overhanging the inferior rim) and an inferior tilt minimizes this impingement.

Question 2

In the manufacturing of highly cross-linked polyethylene (HXLPE) for total hip arthroplasty, which of the following best describes the primary trade-off of the 'remelting' process used after gamma irradiation?

Explanation

Irradiating polyethylene creates highly cross-linked bonds, which significantly reduces wear. However, it leaves free radicals that can oxidize and degrade the plastic. To eliminate these free radicals, the polyethylene is heated above its melting point (remelting). While remelting eliminates free radicals and improves oxidative resistance, it decreases the crystallinity of the polyethylene, thereby decreasing its mechanical properties, including ultimate tensile strength and fatigue crack resistance.

Question 3

A 28-year-old male is brought to the trauma bay following a motorcycle collision. He is hypotensive with a heart rate of 130 bpm. Pelvic radiograph shows an anteroposterior compression type III (APC-III) injury. When applying a noninvasive pelvic binder, the device should be centered directly over which of the following anatomic landmarks to optimally reduce pelvic volume?

Explanation

To effectively reduce pelvic volume and provide stability in an open-book pelvic ring injury (such as an APC-III), a pelvic binder must be applied directly over the greater trochanters. Placement over the iliac crests or ASIS can paradoxically open the pelvis further or fail to provide adequate closure of the posterior ring.

Question 4

During a primary posterior-stabilized total knee arthroplasty, after making the standard bone cuts, the surgeon notices that the knee is perfectly balanced and stable in extension, but is excessively tight in flexion. Which of the following adjustments is the most appropriate next step to correct this mismatch?

Explanation

A knee that is balanced in extension but tight in flexion has a tight flexion gap. Because the extension gap is already balanced, altering the distal femur or changing the poly thickness will negatively affect extension. Downsizing the femoral component (using anterior referencing) decreases the posterior condylar offset by taking more posterior condylar bone, thereby specifically increasing the flexion gap without altering the extension gap.

Question 5

In the evaluation of proximal humerus fractures, which of the following combinations of radiographic findings represents the highest risk for developing avascular necrosis of the humeral head according to Hertel's criteria?

Explanation

Hertel et al. described reliable radiographic predictors for humeral head ischemia following proximal humerus fractures. The highest risk of avascular necrosis occurs when there is a disruption of the medial hinge, a short metaphyseal head extension (calcar length) of < 8 mm, and an anatomic neck fracture pattern. These factors indicate severe disruption of the ascending branch of the anterior humeral circumflex artery and intraosseous collateral blood supply.

Question 6

A 32-year-old healthy male sustains an isolated, displaced, vertically oriented (Pauwels type III) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability against vertical shear forces for this specific fracture pattern?

Explanation

Pauwels type III femoral neck fractures have a high vertical angle, subjecting the fracture to massive vertical shear forces and high rates of nonunion and failure. Biomechanical studies have repeatedly demonstrated that a fixed-angle device, such as a dynamic hip screw (DHS) supplemented with a derotation screw, provides superior resistance to vertical shear and varus collapse compared to multiple parallel cannulated screws.

Question 7

Based on the 2018 International Consensus Meeting (ICM) criteria for periprosthetic joint infection (PJI), which of the following synovial fluid analysis results in a patient 2 years status-post total hip arthroplasty provides the strongest evidence for a definitive diagnosis of chronic PJI?

Explanation

According to the 2018 ICM criteria for chronic PJI (>90 days post-op), a synovial fluid white blood cell (WBC) count > 3,000 cells/µL or a polymorphonuclear (PMN) percentage > 80% yields major points toward diagnosing a PJI. Therefore, a WBC count of 3,500 with 85% PMNs strongly points to infection, well above the diagnostic threshold. Note that thresholds are lower for acute PJI or within the first 6 weeks post-op.

Question 8

During a Latarjet procedure for recurrent anterior shoulder instability with significant glenoid bone loss, the coracoid process is transferred to the anterior glenoid. The primary dynamic stabilizing effect of this procedure is provided by which of the following mechanisms?

Explanation

The Latarjet procedure provides stability through a 'triple blocking' effect. While the bone block increases the glenoid articular surface (static stability), the primary dynamic stabilizing mechanism is the 'sling effect' created by the conjoint tendon (short head of the biceps and coracobrachialis). In abduction and external rotation, the conjoint tendon tensions across the inferior subscapularis and anteroinferior capsule, preventing anterior humeral translation.

Question 9

A 45-year-old male sustains a bicondylar tibial plateau fracture with a large, displaced posteromedial shear fragment. The surgeon elects to use a posteromedial approach for optimal buttress plating. Which of the following surgical intervals is primarily utilized in this approach?

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly/laterally) and the pes anserinus (which is retracted anteriorly). This provides excellent direct access to the posteromedial tibial metaphysis for placing an anti-glide or buttress plate to support a posteromedial shear fragment.

Question 10

A 65-year-old female presents 14 months after a primary posterior-stabilized (PS) total knee arthroplasty complaining of a painful catching sensation in her anterior knee when extending from a flexed position. What is the most likely pathophysiologic mechanism responsible for this complication?

Explanation

Patellar clunk syndrome is classically associated with posterior-stabilized (PS) total knee arthroplasty designs. It is caused by the formation of a fibrosynovial nodule on the undersurface of the quadriceps tendon just proximal to the superior pole of the patella. As the knee extends from a flexed position (usually around 30-45 degrees of flexion), this nodule catches in the intercondylar box of the femoral component, then abruptly pops out, creating a painful 'clunk'.

Question 11

A 72-year-old male presents with a periprosthetic femur fracture around his total hip arthroplasty. Radiographs demonstrate a fracture propagating around the tip of the femoral stem. The stem is radiographically loose, but there is adequate circumferential femoral bone stock. According to the Vancouver classification, what is the most appropriate surgical treatment?

Explanation

This is a Vancouver type B2 fracture (fracture around or just below the stem, the stem is loose, but bone stock is good). The standard of care for a B2 fracture is revision arthroplasty using a long extensively porous-coated or fluted tapered modular diaphyseal-engaging stem. The new stem must bypass the fracture site by at least two cortical diameters to ensure adequate distal fixation.

Question 12

A 30-year-old female is evaluated 8 weeks after undergoing open reduction and internal fixation of a Hawkins Type II talar neck fracture. An AP radiograph of the ankle demonstrates a linear subchondral radiolucent band in the talar dome. What is the clinical significance of this radiographic finding?

Explanation

The finding described is the 'Hawkins sign,' which appears as a subchondral radiolucent band in the talar dome on an AP or mortise radiograph, typically seen 6 to 8 weeks after a talar neck fracture. It indicates subchondral osteopenia secondary to hyperemia and bone resorption. Because this resorptive process requires an intact blood supply, the presence of a Hawkins sign is a highly reliable indicator that the talar body retains its vascularity and is unlikely to develop avascular necrosis.

Question 13

Which of the following describes the fundamental biomechanical alteration created by a reverse total shoulder arthroplasty (rTSA) that enables elevation of the arm in a patient with a massive, irreparable rotator cuff tear?

Explanation

The design of the reverse total shoulder arthroplasty (rTSA) shifts the glenohumeral center of rotation medially and inferiorly relative to the native shoulder. This biomechanical shift significantly increases the moment arm of the deltoid muscle and recruits more of its anterior and posterior fibers, allowing the deltoid to effectively elevate the arm even in the absence of a functional rotator cuff.

Question 14

In the surgical management of a 'terrible triad' injury of the elbow (elbow dislocation, radial head fracture, and coronoid fracture), what is the generally accepted sequence of surgical repair to predictably restore elbow stability?

Explanation

The classic, systematic 'inside-out' approach to repairing a terrible triad injury involves starting deep/medially and working laterally. The standard sequence is: 1) Fixation of the coronoid fracture or repair of the anterior capsule to restore the anterior buttress; 2) Fixation or prosthetic replacement of the radial head to restore the lateral column; 3) Repair of the lateral collateral ligament (LCL) complex to the lateral epicondyle. The medial collateral ligament (MCL) is generally only addressed if the elbow remains grossly unstable after these steps.

Question 15

A 55-year-old male presents with new-onset groin pain and a palpable mass 6 years after an uncomplicated metal-on-polyethylene total hip arthroplasty. Radiographs show a well-fixed construct with no osteolysis. A aspiration yields sterile, turbid fluid. Blood tests reveal elevated serum cobalt levels. What is the most likely etiology of this condition?

Explanation

This patient is presenting with an adverse local tissue reaction (ALTR) secondary to mechanically assisted crevice corrosion (MACC), commonly referred to as 'trunnionosis'. Even in metal-on-polyethylene implants, fretting and corrosion can occur at the modular junction between the femoral head and the stem trunnion. This releases cobalt and chromium ions, leading to a local inflammatory response, pseudotumor formation, and elevated serum metal ions.

Question 16

When evaluating a midshaft clavicle fracture for conservative versus operative management, which of the following patient or fracture characteristics is most strongly associated with an increased risk of nonunion if treated nonoperatively?

Explanation

Several factors increase the risk of nonunion in midshaft clavicle fractures treated nonoperatively. The most critical radiographic predictors include initial shortening of > 2 cm (or > 100% displacement) and significant comminution. Other clinical risk factors include advancing age and female gender. Simple transverse fractures and younger age are associated with higher union rates.

Question 17

A 25-year-old male suffers a comminuted tibia fracture. In the emergency department, his blood pressure is 120/70 mmHg. He has severe pain out of proportion to the injury. Compartment pressure monitoring is performed. Which of the following absolute compartment pressure or 'Delta P' values is the universally accepted threshold indicating the need for emergent four-compartment fasciotomy?

Explanation

The diagnosis of acute compartment syndrome is primarily clinical, but when objective measurement is needed, the 'Delta P' is the most reliable parameter. Delta P is calculated as the diastolic blood pressure minus the absolute intracompartmental pressure. A Delta P of 30 mmHg or less (e.g., Diastolic BP is 70, compartment pressure is 45; Delta P = 25) indicates severe ischemia and is an absolute indication for emergent fasciotomy.

Question 18

The direct anterior (Smith-Petersen) approach for total hip arthroplasty utilizes a true internervous plane. Which of the following best describes the nerves supplying the muscles that form the superficial boundary of this interval?

Explanation

The direct anterior (Smith-Petersen) approach exploits a true internervous plane. Superficially, the interval is between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). Deeply, the interval is between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 19

A 68-year-old male is 6 weeks status-post an anatomic total shoulder arthroplasty using a lesser tuberosity osteotomy approach. He presents with sudden onset of anterior shoulder pain and subjective weakness after attempting to lift a heavy box. On examination, he demonstrates a positive 'belly-press' test and increased passive external rotation compared to the contralateral side. What is the most likely diagnosis?

Explanation

Subscapularis failure is a known complication following anatomic total shoulder arthroplasty, particularly when a subscapularis peel, tenotomy, or lesser tuberosity osteotomy is utilized for anterior access. Clinical signs of subscapularis failure include a positive belly-press or lift-off test, weakness in internal rotation, an unexpected increase in passive external rotation, and anterior shoulder pain.

Question 20

A 50-year-old female undergoes open reduction and internal fixation of a distal radius fracture with a volar locking plate. Six months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. Which of the following technical errors during the index procedure is most likely responsible for this complication?

Explanation

The patient has sustained an iatrogenic rupture of the flexor pollicis longus (FPL) tendon. This is a well-documented complication of volar locked plating for distal radius fractures. It most commonly occurs when the plate is positioned too far distally, extending past the 'watershed line' (the bony ridge at the distal margin of the pronator fossa). This prominent distal hardware creates mechanical friction against the FPL tendon, ultimately leading to fraying and rupture.

Question 21

A 72-year-old female undergoes a reverse total shoulder arthroplasty (rTSA) for cuff tear arthropathy. The surgeon decides to use a lateralized glenosphere rather than a traditional medialized Grammont-style design. Which of the following biomechanical effects is most likely to result from this design choice?

Explanation

Lateralized glenospheres in rTSA shift the center of rotation laterally compared to traditional medialized designs. This lateralization improves the resting tension of the remaining posterior rotator cuff (improving active external rotation), improves the overall contour of the shoulder, and decreases the incidence of inferior scapular notching. However, it does increase the shear stress at the glenoid baseplate interface compared to medialized designs.

Question 22

A 25-year-old male sustains a vertically oriented (Pauwels III) femoral neck fracture. He undergoes closed reduction and internal fixation with three parallel cancellous screws. Due to the biomechanics of this specific fracture pattern, which mode of mechanical failure is he at the greatest risk for?

Explanation

Pauwels III fractures are characterized by a highly vertical fracture line (angle > 50 degrees). This orientation exposes the fracture site to high shear forces and minimizes compressive forces across the fracture during weight-bearing. Consequently, these fractures are highly unstable and prone to shear displacement, leading most commonly to varus collapse and nonunion when fixed with parallel screws. Many surgeons prefer a sliding hip screw or an off-axis screw (e.g., femoral neck system) to better resist these shear forces in young patients.

Question 23

A 45-year-old male with a ceramic-on-ceramic total hip arthroplasty presents 3 years postoperatively complaining of a loud squeaking noise with walking. Radiographs demonstrate well-fixed components. Which of the following factors is most strongly associated with the etiology of this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is a well-documented complication occurring in approximately 1-10% of patients. It is most strongly associated with edge loading of the ceramic bearings, which disrupts the fluid film lubrication. Edge loading typically occurs due to component malposition (e.g., excessive acetabular anteversion, high abduction angle), which leads to 'stripe wear' on the ceramic head and subsequent squeaking. While a titanium stem might be present, the edge loading mechanism is the primary cause.

Question 24

A 32-year-old male presents with shoulder pain and weakness 6 weeks after a blunt trauma to the posterolateral neck. Physical examination reveals prominent medial winging of the scapula when the patient pushes against a wall. Which muscle and associated nerve have most likely been injured?

Explanation

Medial winging of the scapula is caused by dysfunction of the serratus anterior muscle, which is innervated by the long thoracic nerve. The serratus anterior normally holds the medial border of the scapula against the thoracic wall. In contrast, injury to the spinal accessory nerve results in trapezius dysfunction, causing lateral winging of the scapula.

Question 25

A 40-year-old male sustains a bicondylar tibial plateau fracture with a large, displaced posteromedial shear fragment. The surgeon elects to use a posteromedial surgical approach. During this approach, which specific anatomical interval is utilized to access the posteromedial tibia?

Explanation

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

Question 26

A 65-year-old female develops a painful 'clunk' at approximately 40 degrees of flexion as she actively extends her knee, 1 year following a posterior-stabilized total knee arthroplasty. What is the primary anatomic etiology of this condition?

Explanation

Patellar clunk syndrome is a complication classically seen with posterior-stabilized TKA designs. It is caused by the formation of a fibrosynovial nodule at the superior pole of the patella. As the knee extends from a flexed position, this nodule catches in the intercondylar box of the femoral component and then pops out with a painful 'clunk' at around 30 to 45 degrees of flexion. Treatment is typically arthroscopic excision of the nodule.

Question 27

Superior capsular reconstruction (SCR) using a dermal allograft is being considered for a 60-year-old laborer with a massive, irreparable posterosuperior rotator cuff tear. Which of the following is considered an absolute contraindication to performing this procedure?

Explanation

Superior capsular reconstruction (SCR) is indicated for massive, irreparable posterosuperior rotator cuff tears in patients with an intact or repairable subscapularis, a functioning deltoid, and minimal arthritis. Advanced glenohumeral osteoarthritis (Hamada Grade 4 or 5) is an absolute contraindication for SCR; these patients are better served with a reverse total shoulder arthroplasty (rTSA). Pseudoparalysis is a relative contraindication, though some studies suggest SCR can reverse it if the deltoid is functional, but rTSA is often preferred in severe pseudoparalysis.

Question 28

A 28-year-old motorcyclist sustains a complex intra-articular distal femur fracture. Computed tomography (CT) reveals a coronal shear fracture of the lateral femoral condyle. What is the optimal surgical fixation strategy for this specific fracture fragment?

Explanation

A coronal shear fracture of the femoral condyle is known as a Hoffa fracture. It most commonly affects the lateral condyle. Because it is an intra-articular shear fracture, it requires anatomical reduction and stable fixation, which is best achieved with anterior-to-posterior oriented interfragmentary lag screws (often countersunk or headless) placed perpendicular to the fracture plane. Depending on the size and comminution, an anti-glide plate may also be added.

Question 29

A patient undergoes a primary total hip arthroplasty (THA) via a posterior approach. Six weeks postoperatively, the patient sustains a posterior dislocation while sitting in a low chair. Which combination of component malpositioning most commonly predisposes to this specific pattern of instability?

Explanation

Posterior dislocation of a THA typically occurs with a combination of hip flexion, internal rotation, and adduction. Component malposition that decreases the anterior coverage or opens the hip up posteriorly predisposes to this. Specifically, retroversion of the acetabular component and/or retroversion of the femoral stem significantly increases the risk of posterior dislocation.

Question 30

In the surgical reconstruction of a chronic Type V acromioclavicular (AC) joint dislocation, anatomic reconstruction of the coracoclavicular (CC) ligaments is planned. What are the precise anatomical insertion sites of the conoid and trapezoid ligaments on the clavicle relative to the distal clavicle tip?

Explanation

Anatomic studies of the coracoclavicular (CC) ligaments have demonstrated that the trapezoid inserts anterolaterally on the clavicle, averaging 3.0 cm medial to the distal tip. The conoid inserts posteromedially, averaging 4.5 cm medial to the distal tip. Knowledge of these footprints is crucial for anatomical CC ligament reconstruction.

Question 31

A 35-year-old male sustains a Gustilo-Anderson Type IIIB open tibial shaft fracture. Following initial aggressive surgical debridement and skeletal stabilization, what is the optimal timeframe for definitive soft-tissue coverage to minimize the risk of deep infection?

Explanation

Early soft-tissue coverage for Gustilo-Anderson Type IIIB open tibia fractures is critical for minimizing infection and promoting bone healing. The classic Godina study (1986) demonstrated significantly lower infection and failure rates when flaps were performed within 72 hours. While some modern protocols extend this safely to 5-7 days under negative pressure wound therapy, 'within 72 hours' remains the gold standard benchmark answer for board examinations to define 'early coverage'.

Question 32

During a primary total knee arthroplasty for a patient with a severe, fixed 15-degree varus deformity, the surgeon performs a sequential medial release to balance the knee. After resecting deep MCL osteophytes, the knee remains tight medially in extension, but is perfectly balanced in 90 degrees of flexion. Which structure should be selectively released next to correct this specific mismatch?

Explanation

In TKA, a knee that is tight medially in extension but balanced in flexion requires release of structures that are under tension primarily in extension. The posterior medial capsule and the posteromedial corner are the primary stabilizers against medial opening in extension, while the superficial MCL is the primary stabilizer in flexion. Releasing the posteromedial capsule will correct the extension gap without significantly altering the flexion gap.

Question 33

Recent quantitative anatomical studies of humeral head perfusion (e.g., Hettrich et al.) have challenged traditional teaching regarding the primary blood supply to the proximal humerus. Based on current evidence, which vessel provides the majority of the blood supply to the humeral head?

Explanation

Historically, the arcuate branch of the anterior humeral circumflex artery was taught as the primary blood supply to the humeral head. However, landmark modern quantitative studies (e.g., Hettrich et al., JBJS 2010) demonstrated that the posterior humeral circumflex artery actually provides the vast majority (approximately 64%) of the blood supply to the humeral head. This is frequently tested on OITE and ABOS exams.

Question 34

A 42-year-old male is brought to the trauma bay after a crush injury. Radiographs reveal a completely disrupted pubic symphysis with a diastasis of 4 cm, and vertical displacement with complete widening of the posterior sacroiliac joint bilaterally. He is hemodynamically unstable. According to the Young-Burgess classification, what type of pelvic ring injury does this represent?

Explanation

Anteroposterior Compression Type III (APC III) injuries are characterized by complete disruption of the anterior ring (symphysis diastasis) AND complete disruption of the posterior ring, including both the anterior AND posterior sacroiliac ligaments. This results in complete hemipelvic instability (external rotation). The key distinguishing factor between APC II and APC III is the disruption of the posterior SI ligaments in APC III. While it mentions vertical displacement, the primary vector described by the 4cm diastasis and complete anterior/posterior widening fits an APC III. (Note: True vertical shear requires cranial displacement of the hemipelvis, but extreme APC forces cause massive diastasis and total SI disruption).

Question 35

An 80-year-old female presents with a periprosthetic femur fracture around a cemented total hip arthroplasty stem. Radiographs show a fracture at the tip of the stem. The stem has subsided 5 mm with a varus tilt, indicating macroscopic loosening. The cortical bone stock of the proximal femur is thick and of good quality. What is the most appropriate surgical treatment according to the Vancouver classification?

Explanation

This is a Vancouver Type B2 periprosthetic fracture (fracture around or just below the stem, the stem is loose, but there is good proximal bone stock). The standard of care for a Vancouver B2 fracture is revision of the loose component using a long stem that bypasses the fracture by at least 2 cortical diameters, typically achieved with a modular fluted tapered uncemented stem. ORIF alone (Option A) is contraindicated for a loose stem. Proximal femoral replacement (Option D) is reserved for Vancouver B3 (loose stem with poor bone stock).

Question 36

A 22-year-old collegiate baseball pitcher presents with anterior shoulder pain and a 'dead arm' feeling during the late cocking phase of throwing. MRI arthrogram reveals a SLAP tear. Diagnostic arthroscopy confirms a Type II SLAP tear. Which of the following anatomical findings defines a Type II SLAP tear?

Explanation

The Snyder classification of SLAP tears is as follows: Type I: Fraying of the superior labrum, biceps anchor intact. Type II: Detachment of the superior labrum and biceps anchor from the glenoid. Type III: Bucket-handle tear of the labrum, biceps anchor intact. Type IV: Bucket-handle tear of the labrum that extends into the biceps tendon. Therefore, Type II is defined by detachment of the labrum and biceps anchor.

Question 37

In evaluating a patient with a suspected intra-articular calcaneus fracture, lateral radiographs are obtained to measure Böhler's angle. Which of the following accurately describes the two lines used to construct this angle?

Explanation

Böhler's angle is measured on a lateral radiograph of the foot/calcaneus. It is formed by the intersection of two lines: one line drawn from the highest point of the anterior process to the highest point of the posterior facet, and a second line drawn from the highest point of the posterior facet to the highest point of the posterior tuberosity. The normal angle is 20 to 40 degrees. It is typically flattened (decreased) in intra-articular calcaneus fractures.

Question 38

According to the 2018 Evidence-Based International Consensus Meeting (ICM) criteria, which of the following is considered a major criterion, sufficient on its own, to definitively diagnose a periprosthetic joint infection (PJI)?

Explanation

According to the 2018 ICM criteria (and the MSIS criteria), there are two major criteria for diagnosing PJI, either of which is definitive: 1) A sinus tract communicating with the joint, or 2) Two positive periprosthetic cultures with phenotypically identical organisms. The other options (elevated CRP/ESR, elevated synovial fluid WBC, positive LE strip) are minor criteria, requiring a combination of points to establish the diagnosis.

Question 39

A 28-year-old competitive weightlifter feels a sudden 'pop' in his anterior chest while performing a heavy bench press. Examination reveals a loss of the anterior axillary fold contour and weakness in active internal rotation. MRI confirms a complete rupture of the pectoralis major. In this specific demographic and mechanism, which portion of the muscle-tendon unit is most commonly injured?

Explanation

Pectoralis major ruptures almost exclusively occur in males, most commonly during the bench press exercise. The most common pattern of injury is an avulsion of the sternocostal (sternal) head from its insertion on the humerus. The sternal head is under maximal stretch when the humerus is extended, abducted, and externally rotated (the bottom of the bench press). The clavicular head usually remains intact.

Question 40

Following a severe bicondylar tibial plateau fracture, a patient develops acute compartment syndrome of the leg and undergoes a four-compartment fasciotomy via a standard two-incision technique. Through the medial incision, the superficial posterior compartment is released. To ensure complete release of the deep posterior compartment through this medial incision, the surgeon must detach the soleus bridge from which specific structure?

Explanation

In a two-incision fasciotomy of the leg, the medial incision is used to release the superficial and deep posterior compartments. The deep posterior compartment is located deep to the soleus. To access and adequately release the fascia of the deep posterior compartment (containing the tibialis posterior, FDL, FHL, and posterior tibial vessels/tibial nerve), the surgeon must detach the soleus muscle from its origin along the posteromedial border of the tibia.

Question 41

A 72-year-old female undergoes a reverse total shoulder arthroplasty (RTSA) for severe rotator cuff tear arthropathy. Compared to the native anatomic shoulder, how is the center of rotation biomechanically altered in a traditional Grammont-style reverse shoulder prosthesis?

Explanation

The traditional Grammont-style reverse total shoulder arthroplasty is designed to medialize and distalize the center of rotation. Medialization decreases the torque on the glenoid component, reducing the risk of loosening, while simultaneously recruiting more anterior and posterior deltoid fibers for elevation. Distalization tensions the deltoid, thereby increasing its moment arm and improving the mechanical advantage for active shoulder elevation in a rotator cuff–deficient shoulder.

Question 42

During an ilioinguinal approach for the fixation of an anterior column acetabular fracture, life-threatening hemorrhage occurs while dissecting over the superior pubic ramus near the symphysis. Which two vessels commonly anastomose in this region to form the 'corona mortis', the most likely source of this bleeding?

Explanation

The corona mortis ('crown of death') is a highly variable vascular anastomosis between the obturator and external iliac systems. Most commonly, it is an anastomosis between the inferior epigastric artery (or vein) and the obturator artery (or vein). It courses over the superior pubic ramus at a distance of roughly 4-6 cm from the pubic symphysis and is at high risk of iatrogenic injury during the ilioinguinal or Stoppa approaches to the acetabulum and pelvic ring.

Question 43

A 55-year-old manual laborer presents with an irreparable massive posterior-superior rotator cuff tear. He has isolated loss of external rotation but intact subscapularis function and forward elevation. He is deemed a candidate for a lower trapezius tendon transfer. The transferred lower trapezius tendon most closely replicates the force vector of which native muscle?

Explanation

The lower trapezius tendon transfer is increasingly utilized for massive, irreparable posterosuperior rotator cuff tears. Due to its origin, insertion, and line of pull, the lower trapezius muscle most closely replicates the exact force vector of the native infraspinatus. This makes it an excellent option for restoring active external rotation when prolonged by an Achilles tendon or hamstring allograft to reach the greater tuberosity.

Question 44

When evaluating a displaced 4-part proximal humerus fracture, which of the following vessels is currently recognized as providing the primary intraosseous blood supply to the humeral head, and whose disruption strongly correlates with avascular necrosis?

Explanation

Historically, the arcuate artery (a branch of the anterior humeral circumflex artery) was considered the main blood supply to the humeral head. However, modern cadaveric perfusion studies (e.g., Brooks et al., Hettrich et al.) have conclusively demonstrated that the posterior humeral circumflex artery provides the vast majority (approximately 64% to 80%) of the intraosseous blood supply to the humeral head. Preservation of the posteromedial hinge is critical to protecting this vascular supply.

Question 45

A 45-year-old male with a ceramic-on-ceramic total hip arthroplasty presents with a new-onset high-pitched 'squeaking' sound during active hip flexion. Radiographs demonstrate appropriate cup positioning but reveal signs of edge loading. Which of the following factors is most strongly associated with the development of squeaking in a ceramic-on-ceramic bearing surface?

Explanation

Squeaking is a known complication of ceramic-on-ceramic (CoC) total hip arthroplasty, occurring in 1-10% of patients. It is strongly correlated with edge loading of the ceramic liner, which creates linear tracts of wear known as 'stripe wear'. Factors leading to edge loading include cup malposition (steep abduction, excessive anteversion/retroversion), microseparation during the swing phase, and loss of the fluid film lubrication. Ceramic squeaking is less commonly associated with isolated large head sizes.

Question 46

A 48-year-old construction worker presents with deep anterior shoulder pain. An MRI arthrogram demonstrates a Type II SLAP tear. After failing 6 months of conservative management, surgical intervention is planned. Compared to SLAP repair, primary biceps tenodesis in this demographic (workers > 40 years old) is associated with:

Explanation

In older patients, manual laborers, and those with workman's compensation claims, SLAP repair is associated with a high rate of failure, persistent pain, stiffness, and subsequent revision surgery. Current evidence strongly supports primary biceps tenodesis over SLAP repair in patients over 40 years of age, as it yields lower rates of revision surgery, more reliable pain relief, and excellent return-to-work rates while minimizing postoperative stiffness.

Question 47

A 28-year-old male sustains a vertically oriented (Pauwels type III) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability and highest failure load for this specific shear-pattern fracture?

Explanation

Pauwels type III fractures are highly vertical (>50 degrees) and experience massive shear forces, leading to high rates of nonunion and fixation failure. Biomechanical studies have demonstrated that fixed-angle devices, specifically a sliding hip screw (SHS) combined with a derotational cancellous screw, provide superior biomechanical stability and withstand higher shear forces compared to multiple parallel cancellous screws, which are prone to cut-out and varus collapse in these patterns.

Question 48

In a standard measured-resection mechanically aligned total knee arthroplasty, the femoral component is typically externally rotated relative to the posterior condylar axis. What is the primary functional objective of this specific maneuver?

Explanation

In mechanically aligned TKA, the proximal tibia is cut perpendicular to its mechanical axis, removing the native 3 degrees of varus. Because the native posterior femoral condyles are naturally offset, cutting the posterior femur parallel to the posterior condylar axis would result in an asymmetric, tight medial flexion gap. By externally rotating the femoral component (typically 3 degrees, parallel to the surgical transepicondylar axis), the surgeon compensates for the neutral tibial cut, equalizing tension on the medial and lateral collateral ligaments in flexion to create a symmetric, rectangular flexion gap.

Question 49

A 24-year-old cyclist falls directly onto his shoulder. Clinical examination reveals a prominent distal clavicle. An axillary radiograph demonstrates the distal clavicle is displaced posteriorly, penetrating into the trapezius fascia. According to the Rockwood classification, what is the appropriate injury type and generally accepted management?

Explanation

The Rockwood classification of acromioclavicular (AC) joint injuries defines a Type IV injury as posterior displacement of the distal clavicle into or through the trapezius fascia. This injury is extremely painful, often irreducible closed, and fundamentally disrupts the deltotrapezial fascia. Because of the persistent disability and irreducible nature, Rockwood Type IV, V, and VI injuries are generally treated with surgical reduction and reconstruction.

Question 50

A 32-year-old male sustains a closed comminuted tibia fracture and subsequently develops intense, unrelenting leg pain. His blood pressure is 120/70 mmHg. Intracompartmental pressure monitoring reveals an anterior compartment pressure of 45 mmHg. What is the calculated Delta P, and what is the most appropriate next step in management?

Explanation

Delta P is defined as the diastolic blood pressure minus the absolute intracompartmental pressure (Delta P = DBP - ICP). In this scenario, Delta P = 70 mmHg - 45 mmHg = 25 mmHg. A Delta P of less than 30 mmHg represents inadequate capillary perfusion and is an absolute indication for emergent four-compartment fasciotomy to prevent irreversible ischemic necrosis. Elevating the leg above the heart decreases arterial inflow and would worsen the ischemia.

Question 51

A 65-year-old female presents with a painful total hip arthroplasty. Synovial fluid analysis reveals an elevated alpha-defensin level, prompting a diagnosis of periprosthetic joint infection. What is the primary biological mechanism responsible for the production of alpha-defensin in this setting?

Explanation

Alpha-defensin is a naturally occurring antimicrobial peptide that is rapidly released by activated neutrophils in response to the presence of pathogens. It intercalates into and disrupts the cell membranes of bacteria. The alpha-defensin immunoassay is a highly sensitive and specific biomarker used in synovial fluid to differentiate periprosthetic joint infection (PJI) from aseptic failure, as it is elevated when an infectious stimulus triggers neutrophil activation.

Question 52

A 29-year-old female presents with shoulder weakness and aching pain following a posterior triangle neck lymph node biopsy. On examination, the resting position of her scapula is translated laterally and rotated downwardly. Attempted shoulder abduction results in the medial border of the scapula becoming less prominent (lateral winging). What is the most likely injured nerve?

Explanation

Injury to the spinal accessory nerve (CN XI), commonly occurring during biopsies in the posterior triangle of the neck, denervates the trapezius. This leads to 'lateral winging' of the scapula, characterized by a resting posture that is depressed, laterally translated, and downwardly rotated. Medial winging (prominence of the medial border with the scapula translated medially and superiorly) is caused by serratus anterior denervation secondary to long thoracic nerve injury.

Question 53

During the evaluation of a highly comminuted intra-articular distal femur fracture (OTA/AO type 33-C3), a CT scan reveals a distinct coronal plane fracture of the lateral femoral condyle. What is the eponym for this specific fracture pattern, and what is the optimal vector for its interfragmentary lag screw fixation?

Explanation

A Hoffa fracture is a coronal plane fracture of the femoral condyle (most commonly lateral). Because it is an intra-articular shear fracture (OTA/AO type 33-B3), it demands anatomic reduction and absolute stability. The optimal fixation technique involves interfragmentary lag screws placed from anterior to posterior (A-P) perpendicular to the fracture plane. Although P-A is sometimes required based on surgical approach, A-P placement counters the primary shear forces and utilizes the denser anterior cortical bone for screw head purchase.

Question 54

A 68-year-old male with a history of an anatomic total shoulder arthroplasty presents with progressive pain and decreased elevation. Radiographs demonstrate superior migration of the humeral head with eccentric superior wear and gross loosening of the glenoid component. What is the biomechanical mechanism primarily responsible for this specific mode of failure?

Explanation

The 'rocking horse' phenomenon occurs in anatomic total shoulder arthroplasty when an unrecognized or progressive rotator cuff tear leads to superior migration of the humeral head. The unconstrained humeral head applies eccentric, unbalanced superomedial forces on the superior rim of the glenoid component. This eccentric loading creates a rocking motion that inevitably leads to catastrophic early loosening and failure of the cemented glenoid component.

Question 55

A 22-year-old rugby player presents with recurrent anterior shoulder instability. An MRI arthrogram reveals extravasation of contrast into the axillary pouch with a distinctive 'J-sign', demonstrating an avulsion of the inferior glenohumeral ligament from its anatomic attachment on the humerus. What is the diagnosis?

Explanation

A HAGL (Humeral Avulsion of the Glenohumeral Ligament) lesion occurs when the inferior glenohumeral ligament (IGHL) avulses from its humeral insertion rather than its glenoid origin. On a coronal or oblique MRI arthrogram, the normal U-shape of the axillary recess is lost. Instead, contrast leaks out laterally and inferiorly, converting the U-shape into a characteristic 'J-sign'. Bankart, ALPSA, Perthes, and GLAD lesions all describe pathology at the glenoid attachment side.

Question 56

A 35-year-old male sustains a high-energy injury resulting in a displaced talar neck fracture with associated dislocation of the subtalar, tibiotalar, and talonavicular joints. According to the Hawkins classification, what is the type of fracture and the approximate risk of developing avascular necrosis (AVN) of the talar body?

Explanation

The Hawkins classification for talar neck fractures: Type I is nondisplaced (0-10% AVN). Type II is displaced with subtalar dislocation (20-50% AVN). Type III is displaced with both subtalar and tibiotalar dislocation (50-100% AVN). Type IV involves displacement with subtalar, tibiotalar, and talonavicular dislocation. A Type IV fracture virtually obliterates all extraosseous blood supply to the talus (artery of the tarsal canal, artery of the tarsal sinus, and deltoid branches), carrying a risk of AVN approaching 80-100%.

Question 57

A 58-year-old male with a metal-on-metal total hip arthroplasty presents with a painful groin mass 7 years postoperatively. Serum cobalt and chromium levels are significantly elevated. MRI demonstrates a large cystic fluid collection (pseudotumor) communicating with the joint. Tissue biopsy of the periarticular tissue is most likely to demonstrate which of the following histological findings?

Explanation

Adverse local tissue reactions (ALTR) or pseudotumors in metal-on-metal hips are characterized histologically by Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL). This represents a Type IV delayed hypersensitivity reaction to metal wear debris (cobalt and chromium ions). The histology reveals perivascular lymphocytic cuffing, tissue necrosis, and a distinct lack of acute inflammatory cells like polymorphonuclear leukocytes (which would indicate acute infection).

Question 58

A 28-year-old competitive weightlifter experiences a 'pop' and severe pain in his anterior chest while performing a heavy bench press. Examination reveals loss of the anterior axillary fold, and he is diagnosed with a pectoralis major tendon rupture. Which of the following accurately describes the anatomic relationship of the pectoralis major tendon insertion on the lateral lip of the bicipital groove?

Explanation

The pectoralis major tendon consists of two primary heads: clavicular and sternal (sternocostal). As they course laterally toward their insertion on the lateral lip of the bicipital groove, the sternal head twists 180 degrees beneath the clavicular head. This unique anatomic arrangement results in the sternal head inserting deep (posterior) and proximal to the superficial, distally inserting clavicular head. Weightlifting injuries classically involve rupture of the sternal head while the clavicular head often remains intact.

Question 59

A 40-year-old male sustains a high-energy varus load to his knee, resulting in a displaced fracture of the medial tibial plateau with a large single fragment. Which of the following statements regarding this fracture pattern (Schatzker Type IV) is most accurate?

Explanation

A Schatzker Type IV fracture is a high-energy medial tibial plateau fracture. Because the medial plateau is structurally much denser than the lateral plateau, fracturing it requires massive force. Consequently, this injury represents a fracture-subluxation or knee dislocation equivalent, carrying a notoriously high association with multi-ligamentous injuries, popliteal artery damage, and compartment syndrome. It must be addressed with a medial buttress plate to counteract the varus displacing forces.

Question 60

A 78-year-old female with a primary cementless total hip arthroplasty sustains a fall. Radiographs demonstrate a displaced spiral fracture traversing the area surrounding the femoral stem. The stem has subsided by 2 cm and the proximal femoral bone stock is severely comminuted and osteopenic. According to the Vancouver classification system, what is the injury type and most appropriate surgical management?

Explanation

This is a Vancouver B3 periprosthetic femur fracture. The Vancouver classification is based on fracture location (B = around the stem), stem stability, and bone quality. B1 indicates a stable stem with good bone stock (treat with ORIF). B2 indicates a loose stem with adequate bone stock (treat with revision to a longer bypassing stem). B3 indicates a loose stem with profoundly poor or comminuted proximal bone stock. B3 injuries necessitate bypassing the deficient proximal femur via a long cementless diaphyseal-engaging fluted tapered stem, or utilizing a proximal femoral replacement (megaprosthesis) if the diaphyseal bone is inadequate.

Question 61

A patient presents with anterior knee pain and a sensation of instability 1 year after a primary total knee arthroplasty (TKA). Examination reveals lateral subluxation of the patella in early flexion. Radiographic and CT evaluation demonstrates malrotation of the components. Which of the following component alignment errors is most likely responsible for this finding?

Explanation

Internal rotation of either the femoral or the tibial component in a TKA shifts the tibial tubercle laterally relative to the trochlear groove, increasing the Q-angle. This dynamic malalignment leads to lateral patellar maltracking, anterior knee pain, and potential instability. External rotation of the components typically improves patellar tracking.

Question 62

During preoperative planning for a revision total hip arthroplasty, the AP pelvic radiograph shows superior migration of the acetabular component of 4 cm, destruction of the teardrop, and medial migration past Kohler's line indicating pelvic discontinuity. According to the Paprosky classification, what type of defect is present?

Explanation

A Paprosky Type 3B defect is characterized by severe acetabular bone loss with >3 cm of superior migration, destruction of the teardrop, and medial migration past Kohler's line. It is highly associated with pelvic discontinuity. Type 3A has >3 cm superior migration but Kohler's line is intact. Type 2 defects have <3 cm of superior migration.

Question 63

A 28-year-old motorcyclist is brought to the trauma bay after a high-speed collision. The chest radiograph reveals a laterally displaced left scapula with a widened scapulothoracic distance. Examination reveals an insensate, flail left upper extremity and an absent radial pulse. Which of the following is the most appropriate next step in management?

Explanation

The clinical picture indicates a scapulothoracic dissociation, defined by lateral scapular displacement, devastating brachial plexus injury, and often subclavian or axillary artery injury. Given the absent pulse, emergent vascular imaging (CT angiography) or immediate surgical vascular intervention is required to address limb-threatening ischemia prior to any orthopedic fixation or nerve reconstruction.

Question 64

A 72-year-old woman returns for a 3-year follow-up after a reverse total shoulder arthroplasty (RTSA). Radiographs show a radiolucent area on the scapular neck that extends past the inferior screw of the baseplate but does not reach the central peg. Which Sirveaux grade of scapular notching does this represent, and what baseplate positioning strategy could have minimized this complication?

Explanation

Sirveaux Grade 3 notching extends beyond the inferior screw to the central peg. Grade 1 involves just the inferior pillar, Grade 2 reaches the inferior screw, and Grade 4 extends past the central peg. Scapular notching is caused by impingement of the humeral component against the scapular neck. It can be minimized by inferior placement of the baseplate, allowing for inferior overhang of the glenosphere, and a neutral or inferior tilt.

Question 65

A 32-year-old competitive weightlifter sustains a pectoralis major tendon rupture while performing a heavy bench press. Which anatomical portion of the muscle-tendon unit is under the greatest tension in the lowest eccentric phase of the bench press, making it the most vulnerable to rupture?

Explanation

The pectoralis major tendon undergoes a 180-degree twist before its insertion on the humerus. The clavicular head inserts anteriorly and distally, while the sternal (and abdominal) head twists to insert posteriorly and proximally. During the eccentric phase of a bench press (extension and abduction), the inferior sternal fibers that insert most proximally and posteriorly are placed under maximum tension, making them most susceptible to failure.

Question 66

An 80-year-old woman sustains a periprosthetic femur fracture around her cemented total hip arthroplasty after a fall. Radiographs demonstrate a fracture at the tip of the stem. The stem is loose, but there is excellent proximal femoral bone stock. According to the Vancouver classification, what is the most appropriate surgical management?

Explanation

This is a Vancouver B2 fracture (fracture around or just below the stem tip, stem is loose, good bone stock). The gold standard for a Vancouver B2 fracture is revision of the femoral component using a long cementless stem that bypasses the fracture site by at least two cortical diameters. Vancouver B3 (poor bone stock) would warrant proximal femoral replacement.

Question 67

A 22-year-old collegiate baseball pitcher complains of posterior shoulder pain during the late cocking phase of throwing. He reports a measurable decrease in throwing velocity. MRI arthrogram is most likely to show which of the following combined pathologic findings?

Explanation

Internal impingement occurs in overhead athletes during the late cocking phase of throwing (maximum abduction and external rotation). In this position, the greater tuberosity impinges against the posterosuperior glenoid, trapping the posterior supraspinatus and anterior infraspinatus tendons. This causes articular-sided partial rotator cuff tears and posterosuperior labral fraying.

Question 68

During a total knee arthroplasty, the surgeon decides to utilize a posterior cruciate retaining (CR) implant. What is the primary biomechanical function of an intact posterior cruciate ligament during active knee flexion in this setting?

Explanation

The posterior cruciate ligament (PCL) functions to cause posterior rollback of the femoral condyles on the tibial plateau during knee flexion. This rollback creates clearance between the posterior femur and the posterior tibia, allowing for greater maximal knee flexion, and improves the lever arm of the extensor mechanism.

Question 69

An 82-year-old woman with severe osteoporosis sustains a heavily comminuted intra-articular distal humerus fracture (AO/OTA 13-C3). She lives independently and performs her own activities of daily living. Compared to open reduction and internal fixation (ORIF), primary total elbow arthroplasty (TEA) in this patient is associated with which of the following?

Explanation

Total elbow arthroplasty (TEA) is an excellent option for comminuted distal humerus fractures in the elderly with poor bone quality. Compared to ORIF, TEA has lower reoperation rates and allows for immediate range of motion. However, a major limitation of TEA is a strict, lifetime weight-lifting restriction (typically 10-15 lbs single event, 5 lbs repetitive) to prevent aseptic loosening.

Question 70

A 65-year-old man presents with a painful right total hip arthroplasty 5 years after surgery. He has a metal-on-polyethylene bearing surface with a 36-mm cobalt-chromium femoral head. Radiographs show a well-fixed stem and cup with no osteolysis. Aspiration reveals fluid with a low white blood cell count. Serum metal ion testing demonstrates significantly elevated cobalt levels with normal chromium levels. What is the most likely diagnosis?

Explanation

Elevated cobalt out of proportion to chromium in the setting of a metal-on-polyethylene total hip arthroplasty is classic for mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. This risk is increased with the use of larger cobalt-chromium heads on titanium stems. Metal-on-metal bearings or edge loading typically present with elevated levels of both cobalt and chromium.

Question 71

A 55-year-old woman presents with bilateral snapping and pain at the inferior, medial borders of her scapulae with shoulder movement. MRI of the scapulothoracic articulation reveals bilateral, poorly marginated, soft-tissue masses deep to the latissimus dorsi and serratus anterior with signal intensity similar to skeletal muscle and interspersed streaks of fat. What is the most likely diagnosis?

Explanation

Elastofibroma dorsi is a benign, slow-growing, soft-tissue tumor most commonly found in the subscapular region (deep to the latissimus dorsi and rhomboids) of older individuals. It is bilateral in up to 50% of cases. The MRI appearance is characteristic, showing alternating streaks of fibrous tissue (similar signal to muscle) and adipose tissue. It is a classic cause of snapping scapula syndrome.

Question 72

A 35-year-old man sustains a high-energy trauma resulting in an ipsilateral displaced midshaft clavicle fracture and a displaced scapular neck fracture ('floating shoulder'). Which of the following radiographic findings serves as the strongest indication for operative fixation of the scapular neck fracture?

Explanation

A 'floating shoulder' disrupts the superior shoulder suspensory complex. Indications for operative fixation of the scapula include a glenopolar angle (GPA) of less than 22 degrees, medial translation > 10-20 mm, or severe angulation. A GPA of 20 degrees represents significant rotational malalignment of the glenoid, leading to poor functional outcomes and rotator cuff dysfunction, thus strongly indicating the need for fixation.

Question 73

A 68-year-old man with primary osteoarthritis is planned for an anatomic total shoulder arthroplasty. Preoperative CT reveals a Walch B2 glenoid with 25 degrees of retroversion and posterior humeral head subluxation. What is the primary concern with performing a standard anatomic total shoulder arthroplasty with asymmetric anterior glenoid reaming to correct the version?

Explanation

A Walch B2 glenoid features biconcave wear with posterior subluxation and high retroversion. Attempting to correct retroversion >15 degrees by anterior eccentric reaming requires removing significant amounts of strong anterior subchondral bone, exposing weaker cancellous bone. This drastically increases the risk of glenoid component subsidence, 'rocking horse' loosening, and early failure. Augmented glenoids or RTSA are preferred.

Question 74

A 28-year-old man presents to the emergency department with a closed, spiral fracture of the distal third of the humeral shaft. On initial evaluation, he has full wrist and finger extension. Following application of a coaptation splint and closed reduction, he is re-evaluated and found to have a complete loss of wrist and finger extension. What is the most appropriate next step in management?

Explanation

The patient has a Holstein-Lewis fracture. Primary radial nerve palsy with a closed humeral shaft fracture is generally treated with observation. However, a secondary (iatrogenic) radial nerve palsy that occurs after closed reduction or splinting indicates possible entrapment or laceration of the nerve in the fracture site. This is a strong, absolute indication for surgical exploration and operative fracture fixation.

Question 75

When selecting a cementless femoral component for a primary total hip arthroplasty in a patient with Dorr Type A bone, a surgeon chooses a proximally porous-coated, flat tapered wedge stem over a fully porous-coated cylindrical stem. What is the primary biomechanical advantage of the chosen stem in this patient?

Explanation

Proximally porous-coated, flat tapered wedge stems achieve proximal fixation, transferring stress proximally to the metaphysis. This minimizes stress shielding and subsequent proximal femoral osteolysis, which is a significant problem with fully porous-coated, diaphyseal-engaging cylindrical stems that bypass the proximal femur and transfer load distally.

Question 76

A 29-year-old overhead athlete complains of poorly localized posterior shoulder pain and paresthesias in the lateral upper arm. MRI of the shoulder demonstrates isolated fatty atrophy of the teres minor. Entrapment of a neurovascular bundle is suspected. Which of the following defines the anatomical borders of the space where this entrapment is occurring?

Explanation

The patient is presenting with quadrilateral space syndrome, involving compression of the axillary nerve and posterior humeral circumflex artery. This typically leads to isolated teres minor atrophy on MRI. The borders of the quadrilateral space are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and surgical neck of the humerus (lateral).

Question 77

A 40-year-old construction worker sustains a midshaft clavicle fracture. The treating orthopedic surgeon is discussing the pros and cons of nonoperative management versus plate fixation. Which of the following radiographic characteristics is considered the strongest risk factor for nonunion if this fracture is treated nonoperatively?

Explanation

When treating midshaft clavicle fractures nonoperatively, the most significant risk factor for nonunion is displacement of >100% (lack of cortical contact). Other risk factors include advancing age, smoking, fracture comminution, and female gender.

Question 78

A 52-year-old woman with poorly controlled type 2 diabetes mellitus presents with insidious onset of progressive shoulder stiffness and pain. She is diagnosed with idiopathic adhesive capsulitis in the 'freezing' stage. Histopathologic and biochemical evaluation of her glenohumeral capsule is most likely to reveal which of the following?

Explanation

Adhesive capsulitis is characterized by chronic inflammation and capsular fibrosis. Histologically, there is a dense proliferation of fibroblasts and type III collagen deposition in the joint capsule, particularly the coracohumeral ligament and rotator interval. This fibrotic process is driven by inflammatory cytokines, most notably elevated levels of transforming growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF).

Question 79

A 67-year-old man presents with a painful total knee arthroplasty 2 years after his index procedure. Aspiration of the knee yields synovial fluid with a white blood cell count of 2,800 cells/uL (60% neutrophils). Given the equivocal cell count, synovial fluid alpha-defensin testing is ordered and returns positive. What is the physiologic origin of the alpha-defensin molecule in the setting of periprosthetic joint infection?

Explanation

Alpha-defensin is an antimicrobial peptide stored in the azurophilic granules of neutrophils. In the presence of a pathogen, neutrophils migrate to the joint space and release alpha-defensin. It is an excellent biomarker for periprosthetic joint infection (PJI) with high sensitivity and specificity, as it reflects the host's direct immune response to infection.

Question 80

An 80-year-old woman sustains a 3-part proximal humerus fracture with anterior fracture-dislocation of the humeral head. Which of the following physical examination findings would most accurately indicate a complete injury to the axillary nerve in the acute setting?

Explanation

The axillary nerve provides motor innervation to the deltoid and teres minor, and sensory innervation to the lateral shoulder via the superior lateral cutaneous nerve of the arm. In the acute trauma setting, pain prevents reliable motor testing of the deltoid. Therefore, sensory testing over the lateral aspect of the shoulder (regimental badge area) is the most reliable clinical indicator of an axillary nerve injury.

Question 81

A 72-year-old female undergoes a reverse total shoulder arthroplasty via a deltopectoral approach. During glenoid exposure, a retractor is placed inferiorly on the glenoid neck. Which nerve is at greatest risk of injury from this specific retractor placement?

Explanation

The axillary nerve courses inferior to the glenohumeral joint capsule and is highly vulnerable to compression or traction injury when retractors are placed inferiorly on the glenoid neck. Careful placement and avoiding excessive tension on the inferior retractor are critical to prevent neurapraxia.

Question 82

In modern total hip arthroplasty, what is the primary biomechanical rationale for doping highly cross-linked polyethylene (HXLPE) with Vitamin E (alpha-tocopherol) instead of utilizing a traditional post-irradiation remelting process?

Explanation

Remelting highly cross-linked polyethylene eliminates free radicals but reduces fatigue and yield strength. Vitamin E doping acts as an antioxidant to scavenge free radicals, preserving the mechanical properties and fatigue resistance of the polyethylene.

Question 83

A 32-year-old male sustains a vertically oriented basicervical femoral neck fracture (Pauwels type III) after a fall. Which of the following fixation constructs provides the most biomechanically stable construct for this specific high-shear fracture pattern?

Explanation

Pauwels type III (vertical) fractures experience high shear forces leading to varus collapse and nonunion. A sliding hip screw combined with a derotational screw provides superior biomechanical stability against shear forces compared to multiple parallel cancellous screws.

Question 84

A 65-year-old male presents with chronic right shoulder pain, pseudoparalysis of elevation, and a positive Hornblower's sign. He has an absent active external rotation in adduction. Which of the following is the most appropriate surgical intervention?

Explanation

A positive Hornblower's sign indicates advanced teres minor dysfunction. For patients with combined loss of active elevation and external rotation (CLEER) and an incompetent teres minor, a reverse total shoulder arthroplasty combined with a latissimus dorsi transfer is indicated to restore function.

Question 85

A 68-year-old female presents with a painful catching sensation in her knee 8 months after a posterior-stabilized total knee arthroplasty. The catch occurs as the knee actively extends from approximately 40 degrees of flexion. What is the most likely etiology?

Explanation

This presentation is classic for patellar clunk syndrome, typically seen in posterior-stabilized TKA. It is caused by a fibrous nodule forming at the superior pole of the patella that engages the femoral intercondylar box during flexion and "clunks" out during active extension.

Question 86

A 45-year-old male sustains a fracture of the medial tibial plateau with extension into the intercondylar eminence (Schatzker IV). The primary fracture line exits posteromedially. Which surgical approach is most appropriate for direct visualization and buttress plating?

Explanation

Schatzker IV fractures involving a posteromedial fragment are prone to varus collapse if not adequately supported. A posteromedial approach allows for direct visualization, reduction, and application of a posterior buttress plate to resist the displacement forces.

Question 87

In a 22-year-old collision athlete undergoing an arthroscopic anterior stabilization for recurrent shoulder instability, which of the following findings is the strongest indication to add an arthroscopic remplissage to the Bankart repair?

Explanation

An "off-track" Hill-Sachs lesion engages the anterior glenoid rim, significantly increasing the risk of recurrent dislocation. Performing a remplissage (infraspinatus tenodesis into the defect) converts the lesion to an "on-track" state, preventing engagement when glenoid bone loss is subcritical.

Question 88

A 70-year-old female with a primary total hip arthroplasty suffers recurrent posterior dislocations. Radiographs reveal an acetabular cup with 10 degrees of anteversion and 35 degrees of abduction. The femoral component has 5 degrees of retroversion. What is the most appropriate definitive management?

Explanation

The patient has recurrent posterior instability driven by a severely retroverted femoral component. The most appropriate corrective surgery addresses the primary anatomic mechanical flaw, which is revising the femoral stem to restore normal anteversion (typically 10-15 degrees).

Question 89

A 29-year-old male with a closed midshaft tibia fracture complains of escalating leg pain out of proportion to injury 4 hours after admission. Which compartment pressure measurement is the most reliable threshold to indicate the need for a fasciotomy?

Explanation

Delta pressure, calculated as diastolic blood pressure minus the measured intra-compartmental pressure, is the most accurate diagnostic metric for acute compartment syndrome. A delta pressure of less than 30 mmHg represents inadequate tissue perfusion and is an indication for emergent fasciotomy.

Question 90

A 35-year-old male complains of a prominent right shoulder blade after heavy weightlifting. Examination demonstrates lateral winging of the scapula that worsens with resisted active abduction. Injury to which of the following nerves is the most likely cause?

Explanation

Lateral winging of the scapula is caused by trapezius muscle paralysis due to spinal accessory nerve (CN XI) injury. In contrast, injury to the long thoracic nerve causes medial winging due to serratus anterior paralysis.

Question 91

A 55-year-old male with an 8-year-old metal-on-metal THA presents with new groin pain. The implants are well-fixed, but serum cobalt/chromium levels are highly elevated. MRI shows a large periarticular cystic mass. What is the most likely histologic finding of the mass?

Explanation

Adverse local tissue reactions (ALTR) or pseudotumors in metal-on-metal arthroplasty are typically characterized histologically by an Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL), representing a delayed type IV hypersensitivity response to metal ions.

Question 92

Six weeks after closed reduction and cast immobilization for a non-displaced distal radius fracture, a 55-year-old female presents with a sudden inability to actively extend her thumb interphalangeal joint. What is the preferred surgical management?

Explanation

Delayed spontaneous rupture of the extensor pollicis longus (EPL) tendon is a known complication of non-displaced distal radius fractures. Because the tendon ends are typically frayed and retracted, primary repair is usually impossible, making an EIP to EPL tendon transfer the gold standard treatment.

Question 93

A 28-year-old male laborer sustains an acromioclavicular (AC) joint injury. Radiographs reveal 100% superior displacement of the clavicle relative to the acromion, with the coracoclavicular distance increased but less than 100% compared to the normal side (Rockwood Type III). What is the preferred initial management?

Explanation

Rockwood Type III AC joint separations are initially treated nonoperatively with a brief sling and early physical therapy. Surgical intervention is generally reserved for patients who remain symptomatic after an exhausted trial of conservative management, or occasionally for high-demand overhead athletes.

Question 94

In total knee arthroplasty, the application of a true kinematic alignment philosophy primarily dictates that the femoral and tibial components are placed to restore which of the following?

Explanation

Kinematic alignment aims to co-align the axes of the prosthetic components with the native kinematic axes of the knee, recreating the patient's specific pre-arthritic joint line and constitutional alignment, rather than enforcing a strict neutral mechanical axis.

Question 95

An 18-year-old male is recovering from a Hawkins type II talar neck fracture. At his 8-week follow-up, an AP mortise radiograph shows a subchondral radiolucent band in the talar dome. What is the clinical significance of this finding?

Explanation

Hawkins sign is the appearance of a subchondral radiolucent band in the talar dome 6 to 8 weeks after a talar neck fracture. It indicates active subchondral osteoclastic resorption, which requires an intact blood supply, thus predicting a low likelihood of avascular necrosis.

Question 96

A 24-year-old elite overhead thrower is diagnosed with a type II SLAP tear that has failed conservative management. If the surgeon elects to perform an arthroscopic SLAP repair, which of the following is the most statistically likely postoperative outcome?

Explanation

Overhead throwing athletes notoriously have poor rates of return to their pre-injury level of play after SLAP repairs (often 50-60%). The most common postoperative mechanical deficit contributing to this is a loss of maximal external rotation in the abducted position.

Question 97

When comparing the direct anterior approach (DAA) to the posterior approach for primary total hip arthroplasty, which of the following complications has a definitively higher incidence in the DAA cohort based on recent large registry and meta-analysis data?

Explanation

The direct anterior approach (DAA) utilizes the internervous plane between the tensor fasciae latae and sartorius. Due to its anatomic proximity in the superficial dissection, the lateral femoral cutaneous nerve is at a significantly higher risk of injury or neurapraxia compared to the posterior approach.

Question 98

A 42-year-old roofer falls from a ladder, sustaining an intra-articular calcaneus fracture with severe depression of the posterior facet. Which of the following best describes the expected radiographic changes to the angle of Gissane and Bohler's angle?

Explanation

In a joint-depression type intra-articular calcaneus fracture, the posterior facet is driven downward into the calcaneal body. This collapse causes Bohler's angle (normally 20-40 degrees) to flatten or decrease, and the angle of Gissane (normally 105-135 degrees) to widen or increase.

OITE & ABOS Orthopedic Exam MCQs: Trauma, Foot & Knee Board Review Part 132

OITE & ABOS Orthopedic Board Review: Shoulder, Arthroplasty & Trauma MCQs | Part 68

Key Takeaway

OITE & ABOS Orthopedic Board Review: Shoulder, Arthroplasty & Trauma MCQs | Part 68

Chapter Index