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1. General Principles & Basic Science MCQs

Practice Set 69 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1361

Topic: 1. General Principles & Basic Science

A 72-year-old male presents to the emergency department with acute right groin pain, disproportionate to physical examination findings, and a tender, non-reducible mass. He reports mild nausea but denies vomiting or obstipation. His past medical history includes a laparoscopic appendectomy 5 years ago. On abdominal CT, a small bowel loop is noted partially entrapped in a femoral hernia sac, with mural thickening and surrounding fat stranding. Which of the following best describes this hernia type?

. Littre hernia
. Spigelian hernia
. Richter hernia
. Amyand hernia
. Sliding hernia

Correct Answer & Explanation

. Richter hernia

Explanation

Correct Answer: CThe scenario describes a Richter hernia, characterized by the incarceration of only a portion of the circumference of the bowel wall. This explains the disproportionate pain, tenderness, and lack of complete obstructive symptoms (like vomiting or obstipation) often seen with complete lumen occlusion. Despite the partial involvement, Richter hernias carry a very high risk of strangulation and gangrene due to the tight constriction of the involved bowel segment. A Littre hernia involves a Meckel's diverticulum, an Amyand hernia involves the appendix, and a Spigelian hernia occurs through the Spigelian aponeurosis. A sliding hernia involves a viscus that forms part of the hernia sac wall, typically retroperitoneal organs like the colon or bladder.

Question 1362

Topic: 1. General Principles & Basic Science

Regarding the pathophysiology of a Richter hernia, which statement is most accurate?

. It always results in complete bowel obstruction early in its course.
. The incarcerated bowel segment is typically fully occluded, leading to rapid necrosis.
. Only a portion of the bowel circumference becomes entrapped, making it prone to strangulation without complete luminal obstruction.
. It is exclusively found in incisional hernias.
. It primarily involves the stomach or colon.

Correct Answer & Explanation

. Only a portion of the bowel circumference becomes entrapped, making it prone to strangulation without complete luminal obstruction.

Explanation

Correct Answer: CA Richter hernia is defined by the incarceration of only a portion of the circumference of the bowel wall, most commonly the anti-mesenteric border. This distinct feature means that the bowel lumen is not fully occluded, explaining why patients may not present with classic signs of complete bowel obstruction such as vomiting, abdominal distention, or obstipation. However, the partial entrapment still subjects the involved bowel segment to severe ischemic compromise, leading to a high risk of strangulation, necrosis, and perforation, often at an accelerated rate compared to other hernia types due to the intense pressure on a small area. It can occur in any hernia type, not exclusively incisional, and most commonly involves the small intestine.

Question 1363

Topic: 1. General Principles & Basic Science

A 45-year-old male with a history of recurrent inguinal hernias presents with acute, localized pain and a tender, firm lump in his left groin. He reports mild discomfort but is able to pass flatus and has had a recent bowel movement. Vital signs are stable. Given the high index of suspicion for a Richter hernia, what is the most critical immediate concern regarding this patient's condition?

. Electrolyte imbalance due to vomiting
. Risk of complete bowel obstruction
. Rapid progression to bowel strangulation and perforation
. Development of a fascial defect requiring extensive repair
. Chronic pain syndrome requiring neuropathic medication

Correct Answer & Explanation

. Rapid progression to bowel strangulation and perforation

Explanation

Correct Answer: CThe most critical immediate concern with a suspected Richter hernia is the rapid progression to bowel strangulation and perforation. While complete bowel obstruction is less common due to the partial involvement of the bowel wall, the tight constriction of the incarcerated segment leads to rapid ischemia, necrosis, and perforation. This can quickly escalate to peritonitis, sepsis, and a life-threatening emergency. Electrolyte imbalance from vomiting is less likely given the absence of complete obstruction, and while a fascial defect is present, the immediate life-threatening complication is strangulation. Chronic pain is a long-term issue, not an immediate critical concern.

Question 1364

Topic: Infection, Pharmacology & VTE

A 68-year-old female presents with acute right groin pain radiating to the medial thigh, associated with a tender, irreducible mass. She has a history of multiple prior abdominal surgeries. Imaging suggests a Richter hernia in a femoral location. As an orthopedic surgeon, what is a crucial aspect of the initial management plan you would emphasize for this patient, considering her immediate risk?

. Immediate physical therapy consultation for groin strain
. Trial of manual reduction with sedation and Trendelenburg position
. Urgent general surgery consultation for surgical exploration
. Prescription of NSAIDs and rest for presumed adductor tendinopathy
. MRI of the hip to rule out avascular necrosis

Correct Answer & Explanation

. Urgent general surgery consultation for surgical exploration

Explanation

Correct Answer: CFor a suspected Richter hernia, especially one that is tender and irreducible, urgent general surgery consultation for surgical exploration is paramount. Richter hernias carry a very high risk of strangulation and bowel necrosis, making them a surgical emergency. Delay can lead to catastrophic consequences like bowel perforation, peritonitis, and sepsis. Physical therapy, NSAIDs, and MRI of the hip are appropriate for orthopedic conditions but would be dangerously delayed and incorrect for an acute surgical emergency like an incarcerated hernia. While manual reduction can be attempted forsomeincarcerated hernias, it is often difficult and potentially harmful (e.g., reduction en masse) in a suspected Richter hernia, especially with signs of ischemia or tenderness, and should only be considered under specific circumstances and surgical readiness.

Question 1365

Topic: 1. General Principles & Basic Science

In a patient presenting with an incarcerated hernia, what feature specifically raises the suspicion for a Richter hernia over a complete lumen obstructing hernia?

. Presence of vomiting and obstipation
. Lack of abdominal distention despite strangulation risk
. Palpable crepitus over the hernia sac
. Systemic signs of sepsis like high fever and hypotension
. Radiographic evidence of air-fluid levels in the small bowel

Correct Answer & Explanation

. Lack of abdominal distention despite strangulation risk

Explanation

Correct Answer: BThe most distinguishing feature of a Richter hernia, especially in its early stages, is the lack of complete bowel obstruction symptoms, such as significant abdominal distention, vomiting, and obstipation. This is because only a portion of the bowel wall is entrapped, allowing the lumen to remain patent. Despite this, the constricted portion is highly prone to strangulation. Vomiting and obstipation are classic signs of complete bowel obstruction, which are less typical for anearlyRichter hernia. Palpable crepitus suggests gas in soft tissues, often from perforation. Systemic signs of sepsis indicate a very late and complicated stage, and air-fluid levels indicate obstruction, which, again, is often absent or delayed in a Richter hernia.

Question 1366

Topic: Infection, Pharmacology & VTE

Post-operatively, a patient who underwent reduction and repair of a Richter hernia should be monitored closely for which of the following complications specific to ischemic bowel?

. Deep vein thrombosis (DVT)
. Wound infection
. Perforation of the reduced, previously ischemic bowel segment
. Urinary retention
. Pulmonary embolism

Correct Answer & Explanation

. Perforation of the reduced, previously ischemic bowel segment

Explanation

Correct Answer: CPerforation of the reduced, previously ischemic bowel segment (known as 'reperfusion injury' or 'retained ischemic segment' complications) is a critical post-operative concern after Richter hernia repair, especially if the viability of the bowel was questionable or borderline during surgery. Even if the segment appears viable at the time of reduction, ongoing ischemia can lead to delayed necrosis and perforation. All other options (DVT, wound infection, urinary retention, PE) are general post-operative complications, but delayed perforation due to a compromised bowel segment is highly specific and dangerous after ischemic bowel events.

Question 1367

Topic: 1. General Principles & Basic Science

What is the primary reason Richter hernias carry a higher mortality rate compared to typical incarcerated hernias that cause complete bowel obstruction?

. They are always larger and more complex to repair.
. The lack of typical obstructive symptoms often delays diagnosis, leading to advanced strangulation.
. They commonly involve multiple loops of bowel, complicating resection.
. They are exclusively seen in elderly, frail patients.
. The associated pain is often less severe, leading to patient complacency.

Correct Answer & Explanation

. The lack of typical obstructive symptoms often delays diagnosis, leading to advanced strangulation.

Explanation

Correct Answer: BThe primary reason for higher mortality in Richter hernias is the delayed diagnosis. Because the bowel lumen is not completely obstructed, patients often do not experience the classic symptoms of complete obstruction (vomiting, abdominal distention, obstipation). This subtle presentation can lead to a delay in seeking medical attention and, consequently, a delay in diagnosis and surgical intervention. By the time the diagnosis is made, the incarcerated segment has often progressed to strangulation, necrosis, and perforation, leading to severe peritonitis and sepsis, significantly increasing morbidity and mortality. Richter hernias are not necessarily larger or more complex, do not always involve multiple loops, and can occur in various age groups. While pain can be disproportionate, it's not always less severe; rather, thetypeof symptoms (lack of obstruction) causes diagnostic delay.

Question 1368

Topic: Biology, Genetics & Bone Healing

During fracture healing, endochondral ossification requires an intermediate cartilage template. Which of the following transcription factors is essential for driving the differentiation of mesenchymal stem cells into chondrocytes?

. Runx2
. Sox9
. Osterix
. Beta-catenin
. MyoD

Correct Answer & Explanation

. Sox9

Explanation

Sox9 is the master transcription factor for chondrogenesis, directing mesenchymal stem cells to differentiate into chondrocytes. In contrast, Runx2 and Osterix are the key transcription factors required for osteoblast differentiation.

Question 1369

Topic: 1. General Principles & Basic Science

A 22-year-old soccer player undergoes evaluation for a suspected ACL tear. During the pivot shift test, a clunk is felt as the knee is flexed past 20-30 degrees. Which anatomical structure is responsible for reducing the tibia during this maneuver?

. Popliteus tendon
. Biceps femoris
. Medial collateral ligament
. Iliotibial band
. Patellar tendon

Correct Answer & Explanation

. Iliotibial band

Explanation

During the pivot shift test, the iliotibial band (ITB) acts as an extensor when the knee is in extension, maintaining the subluxation. As the knee flexes past 20-30 degrees, the ITB shifts posterior to the axis of rotation, becoming a flexor and reducing the tibia with a palpable clunk.

Question 1370

Topic: Biology, Genetics & Bone Healing

According to Perren's strain theory, primary bone healing occurs without callous formation under conditions of absolute stability. For primary bone healing to occur, the interfragmentary strain must be maintained below what percentage?

. 2%
. 10%
. 20%
. 30%
. 50%

Correct Answer & Explanation

. 2%

Explanation

Perren's strain theory states that primary bone healing (via cutting cones) requires absolute stability, defined as interfragmentary strain less than 2%. Strain between 2% and 10% promotes secondary bone healing with callus formation.

Question 1371

Topic: Biology, Genetics & Bone Healing

Which of the following best describes the mechanism of action of denosumab in the treatment of a giant cell tumor of bone?

. Binds to the RANK receptor on osteoclasts
. Binds to RANKL, preventing interaction with RANK
. Inhibits the formation of the osteoclast ruffled border
. Binds directly to osteoprotegerin (OPG)
. Inhibits cathepsin K activity

Correct Answer & Explanation

. Binds to RANKL, preventing interaction with RANK

Explanation

Denosumab is a monoclonal antibody that directly binds to RANKL. This prevents RANKL from binding to the RANK receptor on osteoclasts and their precursors, thereby inhibiting bone resorption and tumor progression.

Question 1372

Topic: 1. General Principles & Basic Science

A 50-year-old patient undergoes flexor tendon repair in Zone II of the middle finger. Intraoperatively, the surgeon notes that both the FDS and FDP tendons are completely lacerated. After meticulous repair of both tendons, the surgeon is concerned about potential bulk at the repair site compromising gliding. According to the case, which of the following is a valid consideration in this specific scenario?

. Excise the FDP tendon entirely to prioritize FDS gliding and reduce bulk.
. Repair only one slip of the FDS tendon and excise the other to reduce bulk.
. Perform a tenodesis of the FDS to the FDP to ensure synchronized motion.
. Leave both tendons unrepaired and proceed directly to a staged reconstruction.
. Perform a complete excision of the A2 and A4 pulleys to accommodate the bulk.

Correct Answer & Explanation

. Repair only one slip of the FDS tendon and excise the other to reduce bulk.

Explanation

Correct Answer: BExplanation:The case discusses specific considerations for Zone II injuries, particularly regarding FDS repair when both tendons are lacerated. It states: "If both FDS and FDP are lacerated, repair of both tendons is generally recommended, especially if more than 50% of the FDS slips are involved. However, if the FDS repair adds significant bulk or impedes FDP gliding, one slip of the FDS can be excised to reduce bulk, or in some cases, the FDS may be excised entirely if the FDP is fully functional and its gliding needs to be prioritized. Current evidence often favors repair of both if technically feasible without excessive bulk."Option B is correct:This option directly aligns with the case's guidance for managing bulk in Zone II when both FDS and FDP are lacerated. Excising one slip of the FDS can reduce bulk while still providing some FDS function.Option A is incorrect:Excising the FDP entirely would result in a complete loss of DIP flexion, which is a critical function. The case suggests FDS excision if FDP gliding needs to be prioritized, not FDP excision.Option C is incorrect:Tenodesis of FDS to FDP is not a standard primary repair technique described in the case for acute lacerations.Option D is incorrect:Leaving both tendons unrepaired is not an appropriate primary management strategy for acute lacerations. A staged reconstruction is reserved for chronic cases or failed primary repairs.Option E is incorrect:The case strongly emphasizes the preservation of A2 and A4 pulleys due to their biomechanical importance. Complete excision would lead to significant bowstringing and loss of mechanical advantage, which is a major complication.

Question 1373

Topic: 1. General Principles & Basic Science

A 25-year-old factory worker sustains a complete laceration of the FDP tendon in Zone I of his index finger. During the surgical repair, after placing a 4-strand core suture, the surgeon proceeds to apply an epitendinous suture. According to the case, what is the primary purpose of this epitendinous suture?

. To provide the majority of the repair's tensile strength and resistance to gapping.
. To prevent muscle contracture in the forearm.
. To smooth the repair site, reduce friction, and add 10-50% to the tensile strength.
. To re-establish the fibro-osseous pulley system.
. To facilitate early active extension against dynamic traction.

Correct Answer & Explanation

. To smooth the repair site, reduce friction, and add 10-50% to the tensile strength.

Explanation

Correct Answer: CExplanation:The case clearly outlines the purpose of the epitendinous suture under "Tendon Repair Principles."Option C is correct:The case states: "Epitendinous Suture: Purpose: Smoothes the repair site, reducing friction and adhesion formation. Adds 10-50% to the tensile strength of the repair, depending on the technique. Closes the tendon sheath, preventing the core suture from catching on surrounding tissues."Option A is incorrect:The core suture is responsible for the majority of the repair's tensile strength and resistance to gapping, not the epitendinous suture.Option B is incorrect:The epitendinous suture is applied at the repair site in the digit, not to prevent muscle contracture in the forearm.Option D is incorrect:The fibro-osseous pulley system is a separate anatomical structure. While pulleys may be incised for access and sometimes repaired, the epitendinous suture's role is not to re-establish the pulley system itself.Option E is incorrect:This describes a function related to dynamic traction protocols (like Kleinert) and is not the primary purpose of the epitendinous suture.

Question 1374

Topic: 1. General Principles & Basic Science

A 29-year-old patient presents with a complete flexor digitorum profundus (FDP) laceration in Zone II of the ring finger. During pre-operative planning, the surgeon emphasizes the importance of a bloodless field and precise visualization. Which of the following equipment is highlighted in the case as critical for precise tendon identification, suture placement, and neurovascular repair?

. Large bone-holding clamps
. Standard operating room headlights without magnification
. Loupe magnification (2.5x to 4.5x)
. A pneumatic lower extremity tourniquet
. Absorbable sutures for core repair

Correct Answer & Explanation

. Loupe magnification (2.5x to 4.5x)

Explanation

Correct Answer: CExplanation:The case details the necessary equipment for flexor tendon repair under "Pre-Operative Planning & Patient Positioning."Option C is correct:The case states: "Equipment: Loupe magnification (2.5x to 4.5x) is critical for precise tendon identification, suture placement, and neurovascular repair."Option A is incorrect:Large bone-holding clamps are typically used in fracture fixation, not for delicate flexor tendon repair.Option B is incorrect:While headlights provide light, the case specifically emphasizes thecriticalneed for magnification for precision, implying standard headlights alone are insufficient.Option D is incorrect:A pneumatic tourniquet is used, but it is applied to theupper armfor a bloodless field in hand surgery, not the lower extremity.Option E is incorrect:The case specifies: "Non-absorbable monofilament sutures (e.g., 3-0, 4-0, 5-0 Prolene or Ethibond) for core repair," not absorbable sutures.

Question 1375

Topic: 1. General Principles & Basic Science

When performing a primary repair of a lacerated flexor tendon, which factor is the strongest predictor of the initial tensile strength of the repair?

. The caliber of the core suture
. The number of core suture strands crossing the repair site
. The use of a continuous epitendinous suture
. The exact suture material utilized
. The distance of core suture purchase from the cut tendon ends

Correct Answer & Explanation

. The number of core suture strands crossing the repair site

Explanation

The initial tensile strength of a flexor tendon repair is directly proportional to the number of core suture strands that cross the repair site. A 4-strand or 6-strand repair is significantly stronger than a 2-strand repair, permitting early active motion protocols.

Question 1376

Topic: 1. General Principles & Basic Science

Following a 4-strand core repair with a running epitendinous suture for a Zone II FDP laceration, the surgeon prescribes a post-operative rehabilitation protocol. Which of the following is the most widely accepted modern approach to prevent adhesions while protecting the repair?

. Rigid cast immobilization for 6 weeks
. Early active motion using a structured, controlled protocol
. Immediate unresisted heavy grip strengthening
. Immobilization with intrinsic minus splinting for 4 weeks
. Continuous passive motion only, without any active contraction until week 8

Correct Answer & Explanation

. Early active motion using a structured, controlled protocol

Explanation

Modern 4-strand or greater core repairs provide sufficient tensile strength to withstand early active motion. Early controlled active motion protocols promote intrinsic tendon healing and decrease the formation of restrictive adhesions.

Question 1377

Topic: 1. General Principles & Basic Science
A 24-year-old rugby player injures his ring finger while grabbing an opponent's jersey. He cannot actively flex the distal interphalangeal (DIP) joint. Radiographs show a large bony avulsion fragment volar to the DIP joint. According to the Leddy and Packer classification, what type of FDP avulsion injury is this?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type III

Explanation

A Leddy-Packer Type III injury involves a large bony avulsion fragment that catches at the A4 pulley, preventing proximal retraction of the tendon into the palm. Type I retracts to the palm, and Type II retracts to the PIP joint.

Question 1378

Topic: Physiology & Rehabilitation

Radial tears of the meniscus are known to cause rapid progression of knee osteoarthritis compared to simple longitudinal tears. This is primarily because a complete radial tear directly abolishes which meniscal function?

. Direct vertical load shock absorption through the extra-cellular matrix
. The generation and distribution of circumferential hoop stresses
. Distribution of joint lubrication and synovial fluid
. Proprioception mediated by capsular mechanoreceptors
. Secondary restraint to anterior tibial translation

Correct Answer & Explanation

. The generation and distribution of circumferential hoop stresses

Explanation

The primary biomechanical function of the meniscus relies on Type I collagen fibers arranged circumferentially to distribute axial loads as hoop stresses. A radial tear transects these fibers, effectively eliminating this load-sharing capacity.

Question 1379

Topic: 1. General Principles & Basic Science

During a Zone II flexor tendon repair, the surgeon opts for a 4-strand core suture technique instead of a traditional 2-strand technique. What is the primary biomechanical advantage of increasing the number of core suture strands?

. Decreased tendon gliding resistance
. Increased gap formation resistance and ultimate tensile strength
. Reduced risk of flexor pulley rupture
. Enhanced intrinsic tendon healing through increased vascularity
. Prevention of vincula brevis ischemia

Correct Answer & Explanation

. Increased gap formation resistance and ultimate tensile strength

Explanation

The ultimate tensile strength and resistance to gap formation of a flexor tendon repair are directly proportional to the number of core suture strands crossing the repair site. A minimum of a 4-strand repair is generally required to permit safe early active motion protocols.

Question 1380

Topic: 1. General Principles & Basic Science

Which of the following flexor tendon repair techniques provides the greatest ultimate tensile strength to allow for early active motion protocols?

. 2-strand modified Kessler with a running epitendinous suture
. 4-strand cruciate repair without an epitendinous suture
. 6-strand multi-level repair with a running epitendinous suture
. 2-strand Tajima repair with simple interrupted epitendinous sutures
. 4-strand Strickland repair without epitendinous suture

Correct Answer & Explanation

. 6-strand multi-level repair with a running epitendinous suture

Explanation

The ultimate tensile strength of a flexor tendon repair is directly proportional to the number of core suture strands crossing the repair site. A 6-strand repair supplemented with a running epitendinous suture provides superior biomechanical strength, safely permitting early active motion.

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