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1. General Principles & Basic Science MCQs

Practice Set 564 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 11261

Topic: 1. General Principles & Basic Science

An orthopedic surgeon is performing an anatomic coracoclavicular (CC) ligament reconstruction for a chronic Type V AC joint separation. To accurately recreate the biomechanics, the surgeon must understand the anatomy of the native CC ligaments. Which of the following best describes the normal anatomical attachment of the CC ligaments on the clavicle?

. The conoid ligament attaches posteromedial to the trapezoid ligament.
. The conoid ligament attaches anterolateral to the trapezoid ligament.
. The trapezoid ligament attaches posteromedial to the conoid ligament.
. The trapezoid ligament attaches directly anterior to the conoid ligament.
. Both ligaments attach at the exact same footprint on the medial clavicle.

Correct Answer & Explanation

. The conoid ligament attaches posteromedial to the trapezoid ligament.

Explanation

The coracoclavicular (CC) ligaments consist of the conoid and trapezoid. The conoid ligament attaches posteromedially on the conoid tubercle of the clavicle. The trapezoid ligament attaches anterolaterally on the trapezoid line. This anatomical relationship is crucial for drilling tunnels during anatomic reconstruction.

Question 11262

Topic: Surgical Anatomy & Approaches

In the management of proximal biceps tendon pathology, a surgeon elects to perform an open subpectoral biceps tenodesis instead of an arthroscopic suprapectoral tenodesis. What is the primary theoretical advantage of a subpectoral tenodesis?

. It is technically easier to perform completely arthroscopically.
. It avoids any risk of injury to the musculocutaneous nerve.
. It removes the tendon completely from the bicipital groove, eliminating groove-related pain.
. It guarantees a perfectly preserved aesthetic contour of the biceps without risk of cramping.
. It requires a substantially less aggressive postoperative rehabilitation protocol.

Correct Answer & Explanation

. It is technically easier to perform completely arthroscopically.

Explanation

The primary advantage of a subpectoral biceps tenodesis is that it removes the diseased long head of the biceps tendon completely from the bicipital groove. This eliminates persistent pain caused by tenosynovitis or friction within the groove, which can occasionally persist after a suprapectoral tenodesis where a segment of the tendon remains in the upper groove.

Question 11263

Topic: Surgical Anatomy & Approaches

A 45-year-old female is 6 months post-ORIF for a proximal humerus fracture. She complains of severe shoulder stiffness. Radiographs show a healed fracture with implants in good position, and no intra-articular screw penetration. She has failed conservative management and is scheduled for an arthroscopic capsular release. Which nerve must be most carefully protected when releasing the inferior capsule (closest to the 6 o'clock position)?

. Suprascapular nerve
. Musculocutaneous nerve
. Axillary nerve
. Radial nerve
. Median nerve

Correct Answer & Explanation

. Suprascapular nerve

Explanation

The axillary nerve courses intimately close to the inferior aspect of the glenohumeral joint capsule, passing through the quadrilateral space. During an arthroscopic inferior capsular release (specifically at the 6 o'clock position), the axillary nerve is at high risk of iatrogenic injury if the release extends too deep.

Question 11264

Topic: 1. General Principles & Basic Science

A 28-year-old competitive weightlifter feels a 'pop' in his anterior axilla while performing a heavy bench press. Examination reveals bruising over the anterior chest wall and a palpable defect in the anterior axillary fold. If surgical repair is planned, which portion of the pectoralis major is most commonly ruptured and in what anatomical relationship does it insert?

. Clavicular head; inserts deep to the sternocostal head
. Sternocostal head; inserts deep and proximal to the clavicular head
. Sternocostal head; inserts superficial and distal to the clavicular head
. Clavicular head; inserts superficial and distal to the sternocostal head
. Abdominal head; inserts deep to the coracobrachialis

Correct Answer & Explanation

. Clavicular head; inserts deep to the sternocostal head

Explanation

Pectoralis major ruptures most commonly occur at the musculotendinous junction or tendinous insertion of the sternocostal head. The tendon of the pectoralis major undergoes a 180-degree twist before insertion. The sternocostal (lower) head twists to insert deep and proximal to the clavicular (upper) head on the lateral lip of the bicipital groove.

Question 11265

Topic: Biology, Genetics & Bone Healing

A 68-year-old female on chronic alendronate therapy for osteoporosis complains of 3 months of vague left thigh pain. Radiographs reveal a transverse radiolucent line with focal cortical thickening on the lateral aspect of her left femoral shaft. What is the fundamental biomechanical reason these atypical femur fractures typically initiate at the lateral cortex?

. The lateral cortex has diminished vascularity compared to the medial cortex
. The lateral cortex undergoes repetitive tensile stress during normal weight-bearing
. Bisphosphonates selectively concentrate in the lateral cortex
. The medial cortex is under tensile stress, pushing the fracture laterally
. The iliotibial band creates a continuous shear force across the lateral diaphysis

Correct Answer & Explanation

. The lateral cortex has diminished vascularity compared to the medial cortex

Explanation

Atypical femoral fractures (AFFs) associated with prolonged bisphosphonate use characteristically begin at the lateral cortex. Biomechanically, the normal bow of the femur causes the lateral cortex to be placed under repetitive tensile stress during weight-bearing, while the medial cortex is under compressive stress. Over-suppression of targeted bone remodeling leads to accumulation of microdamage, which eventually manifests as a stress fracture on the tension (lateral) side.

Question 11266

Topic: Surgical Anatomy & Approaches

A 30-year-old male falls from a ladder and sustains an intra-articular distal radius fracture. The surgeon opts for a volar surgical approach utilizing the modified Henry interval. After retracting the flexor carpi radialis (FCR) ulnarly, which structure forms the floor of the approach and must be incised to directly expose the pronator quadratus?

. The superficial palmar aponeurosis
. The deep sheath of the FCR tendon
. The flexor pollicis longus muscle belly
. The interosseous membrane
. The transverse carpal ligament

Correct Answer & Explanation

. The superficial palmar aponeurosis

Explanation

The modified Henry approach to the distal radius utilizes the internervous plane between the FCR (median nerve) and the brachioradialis (radial nerve). Upon incising the superficial sheath and retracting the FCR tendon ulnarly, the deep layer of the FCR tendon sheath forms the floor. Incising this deep sheath allows direct access to the pronator quadratus muscle and protects the palmar cutaneous branch of the median nerve.

Question 11267

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach for an anterior column acetabular fracture, significant hemorrhage is encountered just superior to the superior pubic ramus. This bleeding is most likely originating from a vascular anastomosis between which of the following two systems?

. Internal pudendal and obturator
. External iliac and obturator
. Internal iliac and superior gluteal
. Inferior epigastric and internal pudendal
. External iliac and internal pudendal

Correct Answer & Explanation

. Internal pudendal and obturator

Explanation

The 'Corona Mortis' is a critical, potentially life-threatening vascular anastomosis between the obturator vessels (internal iliac system) and the external iliac or inferior epigastric vessels. It is located over the superior pubic ramus and is at high risk of iatrogenic injury during anterior pelvic approaches.

Question 11268

Topic: 1. General Principles & Basic Science

Based on the Lower Extremity Assessment Project (LEAP) study evaluating severe, mangled lower extremity injuries, which of the following statements is true comparing amputation versus limb salvage?

. Limb salvage patients report significantly less pain at 2-year follow-up.
. Amputees have a quicker return to work and higher overall employment rates.
. Functional outcomes at 2 and 7 years are similar between the two groups.
. Limb salvage is associated with lower total healthcare costs over the patient's lifetime.
. The MESS score accurately predicts long-term functional outcomes in salvaged limbs.

Correct Answer & Explanation

. Limb salvage patients report significantly less pain at 2-year follow-up.

Explanation

The LEAP study demonstrated no significant difference in functional outcomes at 2 and 7 years between patients who underwent amputation versus limb salvage. Both groups experienced high rates of chronic pain and disability, and scoring systems like MESS were not predictive of ultimate functional outcome.

Question 11269

Topic: Surgical Anatomy & Approaches

In a patient with a severely mangled lower extremity following an industrial crush injury, which of the following is considered an absolute indication for primary amputation?

. Anatomically complete transection of the sciatic nerve
. Warm ischemia time greater than 6 hours
. Severe soft tissue loss requiring a free flap
. Segmental tibial bone loss greater than 10 cm
. Transection of the posterior tibial nerve in an adult

Correct Answer & Explanation

. Anatomically complete transection of the sciatic nerve

Explanation

While severe nerve injuries and massive bone loss are relative indications, a warm ischemia time exceeding 6 hours is widely considered an absolute indication for primary amputation. Prolonged warm ischemia leads to irreversible muscle necrosis and severe reperfusion toxicity.

Question 11270

Topic: Surgical Anatomy & Approaches

A 38-year-old male falls from a height and sustains a transverse with posterior wall acetabular fracture. Which surgical approach provides the most direct and appropriate access for anatomic reduction and fixation of this specific fracture pattern?

. Ilioinguinal approach
. Anterior intrapelvic (Stoppa) approach
. Kocher-Langenbeck approach
. Extended iliofemoral approach
. Smith-Petersen approach

Correct Answer & Explanation

. Ilioinguinal approach

Explanation

The Kocher-Langenbeck approach provides excellent direct exposure to the posterior column and posterior wall. It is the preferred and most commonly utilized approach for transverse with posterior wall acetabular fractures.

Question 11271

Topic: Surgical Anatomy & Approaches

A 29-year-old motorcyclist presents after a high-speed crash with severe left shoulder pain, a completely flail upper extremity, and absent radial and ulnar pulses. Radiographs show a laterally displaced scapula and an intact clavicle. Which neurovascular structure is at highest risk of severe avulsion injury?

. Axillary nerve
. Brachial plexus and subclavian artery
. Musculocutaneous nerve
. Thoracodorsal artery
. Suprascapular nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

Scapulothoracic dissociation is characterized by complete disruption of the scapulothoracic articulation. The massive lateral traction force frequently causes severe, often irreversible avulsion injuries to the brachial plexus and the subclavian or axillary vessels.

Question 11272

Topic: 1. General Principles & Basic Science

When evaluating a severely mangled lower extremity, which of the following clinical findings—historically considered an absolute indication for primary amputation—is now recognized as unreliable for predicting successful limb salvage?

. Absent plantar sensation on initial presentation
. Warm ischemia time exceeding 8 hours
. Irreparable complete disruption of the popliteal artery
. Severe crush injury with massive tissue loss

Correct Answer & Explanation

. Absent plantar sensation on initial presentation

Explanation

Absent plantar sensation on initial presentation is no longer considered an absolute indication for amputation. Studies like the LEAP trial demonstrated that initial lack of sensation does not accurately predict long-term functional recovery or permanent nerve deficit.

Question 11273

Topic: Infection, Pharmacology & VTE

A 78-year-old female on chronic warfarin therapy sustains a displaced femoral neck fracture. Her admission INR is 3.5. To facilitate urgent surgical intervention within 24 hours, what is the best agent for rapid reversal of her anticoagulation?

. Intravenous Vitamin K
. Fresh Frozen Plasma (FFP)
. Prothrombin Complex Concentrate (PCC)
. Cryoprecipitate
. Protamine sulfate

Correct Answer & Explanation

. Intravenous Vitamin K

Explanation

Prothrombin Complex Concentrate (PCC) is the preferred agent for rapid, reliable reversal of vitamin K antagonists like warfarin in urgent surgical scenarios. It works faster and has lower volume overload risks compared to FFP.

Question 11274

Topic: 1. General Principles & Basic Science

When evaluating a severely crushed lower extremity for salvage versus amputation, the Mangled Extremity Severity Score (MESS) is often referenced. Which of the following is NOT a component of the MESS?

. Patient age
. Limb ischemia time
. Skeletal and soft tissue injury energy
. Presence of a major nerve transection
. Presence of shock

Correct Answer & Explanation

. Patient age

Explanation

The MESS evaluates skeletal/soft-tissue injury, limb ischemia, shock, and patient age. Although major nerve injuries (e.g., tibial nerve) strongly influence the clinical decision for amputation, it is not a direct numerical component of the MESS.

Question 11275

Topic: Biology, Genetics & Bone Healing

A 72-year-old female on prolonged oral bisphosphonates presents with unremitting anterior thigh pain. Radiographs reveal focal lateral cortical thickening (the 'beak' sign) and a transverse radiolucent line in the proximal third of the femur. What is the prophylactic treatment of choice?

. Prophylactic cephalomedullary nailing
. Prophylactic locked plating
. Immediate cessation of medication and restricted weight-bearing
. Administration of teriparatide and observation

Correct Answer & Explanation

. Prophylactic cephalomedullary nailing

Explanation

Atypical femur fractures associated with bisphosphonate use often present as a symptomatic incomplete fracture on the tension (lateral) side. Prophylactic cephalomedullary nailing is the standard of care to prevent a catastrophic complete fracture.

Question 11276

Topic: 1. General Principles & Basic Science

Articular cartilage relies on a precise microscopic architecture to withstand compressive and shear forces. Which zone of normal articular cartilage contains the highest concentration of proteoglycans, the lowest water content, and collagen fibers arranged perpendicular to the joint surface?

. Superficial (tangential) zone
. Middle (transitional) zone
. Deep (radial) zone
. Calcified cartilage zone
. Tidemark

Correct Answer & Explanation

. Superficial (tangential) zone

Explanation

The deep (radial) zone of articular cartilage is responsible for providing resistance to compressive forces. It is characterized by having the largest diameter collagen fibers oriented perpendicular to the joint surface, the highest concentration of proteoglycans (which provide compressive strength), and the lowest water content. The superficial zone has collagen parallel to the surface to resist shear, the highest water content, and the lowest proteoglycan content.

Question 11277

Topic: Biology, Genetics & Bone Healing

A 71-year-old female who has been taking oral alendronate for 9 years presents with atraumatic lateral thigh pain. Radiographs demonstrate focal lateral cortical thickening of the proximal femoral diaphysis with a subtle transverse radiolucent line. What is the mechanism of action of the medication most strongly associated with this fracture pattern?

. Direct inhibition of osteoblast bone matrix synthesis
. Inhibition of farnesyl pyrophosphate synthase, leading to osteoclast apoptosis
. Blockade of RANKL, preventing osteoclast activation and survival
. Competitive inhibition of calcium absorption in the gastrointestinal tract
. Simulation of Wnt/beta-catenin signaling, causing brittle cortical hypertrophy

Correct Answer & Explanation

. Direct inhibition of osteoblast bone matrix synthesis

Explanation

The patient has a classic atypical femur fracture (AFF) associated with long-term bisphosphonate use. Bisphosphonates (like alendronate) are endocytosed by osteoclasts during bone resorption and act by inhibiting farnesyl pyrophosphate synthase (FPPS), an enzyme in the mevalonate pathway. This disrupts small GTPase signaling, ultimately causing osteoclast apoptosis. Denosumab blocks RANKL. Long-term osteoclast inhibition prevents targeted remodeling of microdamage, leading to AFFs.

Question 11278

Topic: 1. General Principles & Basic Science
What is the optimal timing for surgical reconstruction of a multi-ligament knee injury (e.g., Schenck KD-III) in a hemodynamically stable patient with normal vascular status and no open wounds?
. Within 24 hours to prevent capsular retraction
. 2 to 3 weeks to allow capsular healing and decrease arthrofibrosis risk
. 6 to 8 weeks to allow complete resolution of soft tissue edema
. Greater than 3 months after completion of a pre-habilitation program
. Immediate primary repair of all torn ligaments in the acute setting

Correct Answer & Explanation

. 2 to 3 weeks to allow capsular healing and decrease arthrofibrosis risk

Explanation

The optimal timing for multi-ligament knee reconstruction in a stable patient is typically delayed 2 to 3 weeks post-injury. This delay allows for the initial inflammatory phase to subside, recovery of range of motion, and healing of the capsular tissue, which significantly decreases the risk of postoperative arthrofibrosis compared to acute (<1 week) surgery. Delaying beyond 3 weeks makes recognizing and anatomically reconstructing tissue planes more difficult due to extensive scar tissue.

Question 11279

Topic: Biomechanics & Biomaterials
Highly cross-linked polyethylene (HXLPE) is standardly used in total hip arthroplasty to minimize particulate wear debris. While high-dose gamma irradiation followed by remelting decreases wear rates, it results in a clinically relevant decrease in which of the following mechanical properties compared to conventional ultra-high-molecular-weight polyethylene (UHMWPE)?
. Fatigue crack propagation resistance and ultimate tensile strength
. Resistance to in vivo oxidation
. Elastic modulus
. Surface hardness
. Yield strength under direct axial load

Correct Answer & Explanation

. Fatigue crack propagation resistance and ultimate tensile strength

Explanation

Increasing the radiation dose to highly cross-linked polyethylene reduces abrasive wear, which significantly lowers osteolysis rates. However, the process of cross-linking and subsequent thermal treatment (remelting to eliminate free radicals) adversely affects the bulk mechanical properties. Specifically, it significantly decreases ultimate tensile strength, yield strength, and fatigue crack propagation resistance, making the liner theoretically more susceptible to fracture, especially in thinner liners.

Question 11280

Topic: 1. General Principles & Basic Science

During the repair of a zone II flexor digitorum profundus (FDP) laceration, the surgeon must choose an appropriate suture configuration. Biomechanical studies indicate that the overall ultimate tensile strength of a flexor tendon repair and its resistance to gap formation are most directly proportional to which of the following?

. The caliber of the epitendinous suture used
. The number of core suture strands crossing the repair site
. The use of a locking versus non-locking core suture technique
. The distance of the core suture purchase from the laceration edge
. The timing of postoperative active motion initiation

Correct Answer & Explanation

. The caliber of the epitendinous suture used

Explanation

Extensive biomechanical studies have proven that the strength of a flexor tendon repair and its resistance to gap formation are directly proportional to the number of core suture strands that cross the repair site. For example, a 4-strand repair is significantly stronger than a 2-strand repair, and a 6-strand is stronger than a 4-strand.

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