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1. General Principles & Basic Science MCQs

Practice Set 612 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 12221

Topic: Biology, Genetics & Bone Healing

A patient with severe nutritional deficiencies presents with bleeding gums, perifollicular hemorrhages, and impaired wound healing. The underlying enzymatic defect impairs bone formation by disrupting which step in collagen synthesis?

. Cleavage of procollagen C-terminal propeptides
. Hydroxylation of proline and lysine residues
. Glycosylation of hydroxylysine residues
. Cross-linking of collagen fibrils by lysyl oxidase
. Transcription of COL1A1 genes

Correct Answer & Explanation

. Cleavage of procollagen C-terminal propeptides

Explanation

Scurvy is caused by Vitamin C deficiency. Vitamin C acts as an essential cofactor for prolyl and lysyl hydroxylases, which are required for the hydroxylation of proline and lysine residues, a critical step for stable collagen triple helix formation.

Question 12222

Topic: Biomechanics & Biomaterials

A surgeon plans to perform a revision open reduction and internal fixation utilizing both stainless steel plates and titanium screws. This combination is generally avoided due to the risk of which type of corrosion?

. Fretting corrosion
. Crevice corrosion
. Galvanic corrosion
. Pitting corrosion
. Stress corrosion cracking

Correct Answer & Explanation

. Fretting corrosion

Explanation

Galvanic corrosion occurs when two dissimilar metals are placed in physical contact within a conductive electrolyte solution (such as body fluid). The less noble metal (anode) undergoes accelerated corrosion.

Question 12223

Topic: Biology, Genetics & Bone Healing

Secondary bone healing is characterized by intermediate callus formation. According to Perren's strain theory, what is the maximum tissue strain that allows for the formation of lamellar bone?

. Less than 2%
. Between 2% and 10%
. Between 10% and 30%
. Between 30% and 100%
. Greater than 100%

Correct Answer & Explanation

. Less than 2%

Explanation

According to Perren's strain theory, lamellar bone can only form in environments with less than 2% strain. Cartilage can form in 2-10% strain, and granulation tissue forms when strain is 10-100%.

Question 12224

Topic: 1. General Principles & Basic Science
During the proliferative phase of tendon healing (approximately 7 to 21 days post-injury), fibroblasts begin to synthesize a new extracellular matrix. Which collagen type predominates during this early phase of repair before being remodeled?
. Type I
. Type II
. Type III
. Type IV
. Type X

Correct Answer & Explanation

. Type III

Explanation

During the early proliferative phase of tendon and ligament healing, the provisional matrix is primarily composed of Type III collagen. During the remodeling phase, this is gradually replaced by the stronger, more organized Type I collagen.

Question 12225

Topic: 1. General Principles & Basic Science

A 24-year-old male presents after a high-speed motorcycle accident with a flail right arm. On examination, he has ptosis, miosis, and anhidrosis on the right side of his face. Which of the following MRI findings is most consistent with this clinical presentation?

. Pseudomeningocele at C5-C6
. Intact dorsal root ganglia at C8-T1 with distal neuroma
. Torn preganglionic rootlets at C8-T1
. Disruption of the upper trunk
. Isolated postganglionic injury to the lower trunk

Correct Answer & Explanation

. Pseudomeningocele at C5-C6

Explanation

Horner's syndrome (ptosis, miosis, anhidrosis) in the setting of a brachial plexus injury is pathognomonic for a preganglionic root avulsion of C8 and T1, as the sympathetic chain is disrupted proximal to the dorsal root ganglion.

Question 12226

Topic: Surgical Anatomy & Approaches

A 28-year-old female sustains a closed midshaft humerus fracture. Her initial neurovascular examination in the emergency department is entirely intact. Following a closed reduction and application of a coaptation splint, she develops a complete wrist drop and inability to extend her MCP joints. What is the most appropriate next step in management?

. Observation and switch to functional brace in 2 weeks
. Immediate open reduction and internal fixation with nerve exploration
. EMG/NCS in 3 weeks
. MRI of the humerus
. Ultrasound-guided radial nerve block

Correct Answer & Explanation

. Observation and switch to functional brace in 2 weeks

Explanation

A secondary radial nerve palsy (one that develops after a closed reduction attempt) is a well-accepted absolute indication for surgical exploration of the nerve and internal fixation of the fracture, as the nerve may have become entrapped in the fracture site during manipulation.

Question 12227

Topic: 1. General Principles & Basic Science

A 25-year-old motorcyclist presents with a flail upper limb after a high-speed collision. Physical examination reveals complete motor and sensory loss of the right upper extremity, ptosis, miosis, and anhidrosis on the right side of the face. A histamine test produces a flare response in the anesthetic C5-T1 dermatomes. What is the most likely anatomic level of this nerve injury?

. Postganglionic trunk level
. Preganglionic root level
. Cord level
. Peripheral nerve level
. Divisions level

Correct Answer & Explanation

. Postganglionic trunk level

Explanation

The presence of Horner's syndrome (ptosis, miosis, anhidrosis) and an intact histamine flare test in an anesthetic area indicates a preganglionic root avulsion injury. The intact flare test demonstrates that the sensory cell bodies in the dorsal root ganglion and their distal axons are intact, meaning the lesion is proximal to the DRG (preganglionic).

Question 12228

Topic: Surgical Anatomy & Approaches

A 45-year-old bodybuilder undergoes repair of a retracted distal biceps tendon rupture using a two-incision technique. Postoperatively, the patient reports an inability to extend the fingers and thumb, though wrist extension is preserved with radial deviation. Which nerve was most likely injured, and what is the mechanism in this surgical approach?

. Lateral antebrachial cutaneous nerve from anterior dissection
. Posterior interosseous nerve from the anterior dissection
. Posterior interosseous nerve from splitting the supinator during the posterior approach
. Radial nerve from the anterior dissection
. Ulnar nerve from the posterior approach

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve from anterior dissection

Explanation

The two-incision technique for distal biceps repair carries a specific risk of injuring the Posterior Interosseous Nerve (PIN) during the posterior approach if the supinator muscle is not split properly or if the forearm is not fully pronated (which draws the PIN away from the surgical field). PIN palsy presents with loss of finger and thumb extension, while ECRL (innervated by the radial nerve proper) preserves radially-deviated wrist extension.

Question 12229

Topic: Biomechanics & Biomaterials

Following a primary repair of a lacerated flexor digitorum profundus (FDP) and superficialis (FDS) in Zone II of the index finger, a patient begins a controlled mobilization protocol. Which of the following biomechanical principles best supports early active motion protocols compared to prolonged immobilization?

. Early active motion decreases tendon excursion thereby minimizing rupture
. Early active motion increases peritendinous adhesion formation
. Early active motion stimulates intrinsic tendon healing and increases tensile strength
. Prolonged immobilization leads to stronger core suture biomechanics
. Immobilization increases the gliding coefficient of the tendon

Correct Answer & Explanation

. Early active motion decreases tendon excursion thereby minimizing rupture

Explanation

Early motion (whether active or passive) applies controlled mechanical stress to the repaired tendon, which stimulates intrinsic healing (via tenocyte proliferation and parallel collagen orientation). This process reduces restrictive peritendinous adhesions and ultimately increases the ultimate tensile strength of the repair compared to static immobilization.

Question 12230

Topic: Surgical Anatomy & Approaches

A 42-year-old female sustains a complex coronal shear fracture of the capitellum that extends medially into the trochlea (Dubberley Type IV). Which surgical approach provides the most extensile visualization for anatomic reduction of the articular surface?

. Standard Kocher approach
. Kaplan approach
. Extended lateral approach
. Posterior approach with olecranon osteotomy
. Medial over-the-top approach

Correct Answer & Explanation

. Standard Kocher approach

Explanation

The extended lateral approach provides excellent exposure of the anterior capitellum and trochlea by elevating the common extensor origin and anterior capsule. Olecranon osteotomies are typically reserved for distal humerus fractures involving both columns, not isolated anterior shear fractures.

Question 12231

Topic: 1. General Principles & Basic Science

A 32-year-old competitive weightlifter feels a pop in his anterior chest during a heavy bench press. Examination reveals an asymmetric chest wall and weakness with internal rotation. Which portion of the pectoralis major is most commonly injured in this scenario?

. Clavicular head at the muscle belly
. Sternal head at the muscle-tendon junction
. Clavicular head at the humeral insertion
. Sternal head at the humeral insertion
. Costal head at the rib origin

Correct Answer & Explanation

. Clavicular head at the muscle belly

Explanation

Pectoralis major ruptures most frequently occur at the humeral insertion or musculotendinous junction of the sternal head. This injury pattern is classic in weightlifters performing the bench press due to extreme eccentric loading.

Question 12232

Topic: Physiology & Rehabilitation

A 55-year-old distance runner presents with intractable lateral hip pain and a Trendelenburg gait. MRI confirms a full-thickness, retracted tear of the gluteus medius tendon without fatty atrophy. During surgical repair, the surgeon must mobilize the tendon to its anatomic footprint. What is the anatomic insertion site of the gluteus medius on the greater trochanter?

. Anterior facet only
. Lateral and superoposterior facets
. Anterior and lateral facets
. Lesser trochanter
. Posterior facet only

Correct Answer & Explanation

. Anterior facet only

Explanation

The footprint of the gluteus medius is located on the lateral and superoposterior facets of the greater trochanter. The gluteus minimus inserts on the anterior facet of the greater trochanter. The posterior facet is generally devoid of direct tendon attachments but is covered by the greater trochanteric bursa.

Question 12233

Topic: 1. General Principles & Basic Science

During a bench press, a 28-year-old weightlifter experiences a sudden tearing sensation in his anterior chest wall. Examination reveals loss of the anterior axillary fold and weakness in internal rotation. MRI confirms a complete rupture of the pectoralis major tendon at its humeral insertion. Which of the following statements correctly describes the anatomy of the pectoralis major footprint on the humerus?

. The sternal head inserts anterior and proximal to the clavicular head
. The clavicular head inserts deep and proximal to the sternal head
. The sternal head tendon twists 180 degrees such that its inferior fibers insert most proximally and deep to the clavicular head
. The clavicular head twists 180 degrees to insert posterior to the sternal head
. Both heads insert at the exact same level with a conjoint, non-twisted tendon

Correct Answer & Explanation

. The sternal head inserts anterior and proximal to the clavicular head

Explanation

The pectoralis major consists of a clavicular head and a sternal head. As the muscle fibers approach the humerus, the sternal head twists 180 degrees such that its most inferior fibers insert most proximally on the humerus, forming the deep/posterior lamina of the tendon. The clavicular head does not twist and forms the anterior/superficial lamina.

Question 12234

Topic: 1. General Principles & Basic Science

A 32-year-old male bodybuilder feels a tearing sensation in his anterior chest while bench pressing. Examination shows ecchymosis and loss of the anterior axillary fold contour. MRI confirms a rupture of the sternocostal head of the pectoralis major muscle. Where does the sternocostal head normally insert relative to the clavicular head on the humerus?

. Deep and proximal
. Deep and distal
. Superficial and proximal
. Superficial and distal
. Directly anterior and adjacent

Correct Answer & Explanation

. Deep and proximal

Explanation

The pectoralis major tendon undergoes a 180-degree twist before inserting onto the lateral lip of the bicipital groove. Due to this twist, the sternocostal head fibers insert deep and proximal to the clavicular head fibers. The sternocostal head is the most commonly ruptured segment during eccentric loading exercises like bench pressing.

Question 12235

Topic: Surgical Anatomy & Approaches

A 40-year-old water skier falls forward, forcing her hip into hyperflexion while her knee remains fully extended. MRI shows a complete, 3-tendon avulsion of the proximal hamstrings from the ischial tuberosity, retracted 4 cm. Which nerve is at greatest risk of iatrogenic injury during open surgical repair of this lesion?

. Pudendal nerve
. Sciatic nerve
. Inferior gluteal nerve
. Posterior femoral cutaneous nerve
. Obturator nerve

Correct Answer & Explanation

. Pudendal nerve

Explanation

The sciatic nerve lies immediately lateral (approximately 1.2 cm) to the ischial tuberosity. In proximal hamstring ruptures, particularly those that are retracted, extensive scarring can tether the sciatic nerve to the stump of the hamstring tendon. Careful neurolysis and visualization of the sciatic nerve are critical during the surgical approach to prevent injury.

Question 12236

Topic: 1. General Principles & Basic Science

A 30-year-old weightlifter feels a tearing sensation in his anterior axilla while performing a heavy bench press. Examination reveals loss of the anterior axillary fold and weakness in internal rotation. Which portion of the pectoralis major is most commonly ruptured, and at what anatomical location?

. Clavicular head at the musculotendinous junction
. Sternal head at the musculotendinous junction
. Clavicular head at the humeral insertion
. Sternal head at the humeral insertion
. Sternal head at the sternal origin

Correct Answer & Explanation

. Clavicular head at the musculotendinous junction

Explanation

Pectoralis major ruptures almost exclusively occur during heavy eccentric loading (e.g., bench press). The sternal head is most commonly injured because it is under maximum stretch and tension when the arm is extended, abducted, and externally rotated at the bottom of the bench press. The most common site of rupture is the humeral insertion, typically tearing off the bone.

Question 12237

Topic: 1. General Principles & Basic Science

A 45-year-old female runner complains of chronic lateral hip pain that is severe during single-leg stance. MRI reveals a full-thickness avulsion of the gluteus medius tendon. At which exact anatomical location does the primary tendon of the gluteus medius insert?

. Anterior facet of the greater trochanter
. Lateral and superoposterior facets of the greater trochanter
. Lesser trochanter
. Iliotibial band
. Gluteal tuberosity of the femur

Correct Answer & Explanation

. Anterior facet of the greater trochanter

Explanation

The greater trochanter has four facets. The gluteus medius inserts on the lateral and superoposterior facets. The gluteus minimus inserts on the anterior facet. The posterior facet is generally bare but is intimately related to the trochanteric bursa.

Question 12238

Topic: 1. General Principles & Basic Science

A 30-year-old competitive weightlifter feels a sudden "pop" in his anterior chest while performing a heavy bench press. MRI confirms an isolated rupture of the sternal head of the pectoralis major. To ensure anatomic repair, where should the surgeon reattach the sternal head footprint relative to the clavicular head footprint on the humerus?

. Proximal and anterior to the clavicular head
. Proximal and posterior to the clavicular head
. Distal and anterior to the clavicular head
. Distal and deep to the clavicular head
. Directly superficial to the clavicular head

Correct Answer & Explanation

. Proximal and anterior to the clavicular head

Explanation

The pectoralis major tendon undergoes a 180-degree twist before insertion. The sternal head inserts distal and deep (posterior) to the clavicular head on the lateral lip of the bicipital groove.

Question 12239

Topic: Infection, Pharmacology & VTE
A 22-year-old football running back sustains a grade III medial collateral ligament (MCL) tear. MRI demonstrates an avulsion of the MCL from its distal tibial attachment, with the pes anserinus tendons interposed between the torn ligament and the bone. What is the most appropriate management?
. Protected weight bearing in a hinged knee brace for 6 weeks
. Acute surgical repair of the MCL
. Corticosteroid injection and early range of motion
. Delayed MCL reconstruction at 3 months
. Platelet-rich plasma injection and physical therapy

Correct Answer & Explanation

. Acute surgical repair of the MCL

Explanation

This describes a "Stener-like lesion" of the knee, where the pes anserinus blocks reduction of the distally avulsed MCL to its footprint. This prevents spontaneous healing and is an absolute indication for acute surgical repair.

Question 12240

Topic: 1. General Principles & Basic Science

A 45-year-old female runner complains of recalcitrant lateral hip pain and demonstrates a positive Trendelenburg sign. MRI confirms an isolated, full-thickness tear of the main gluteus medius tendon. During endoscopic repair, the surgeon should reattach the tendon to its primary anatomical footprint located on the:

. Anterior facet of the greater trochanter
. Lateral and superoposterior facets of the greater trochanter
. Posterior and inferior facets of the greater trochanter
. Lesser trochanter
. Intertrochanteric crest

Correct Answer & Explanation

. Anterior facet of the greater trochanter

Explanation

The gluteus medius tendon primarily inserts on the lateral and superoposterior facets of the greater trochanter. The gluteus minimus inserts on the anterior facet.

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