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1. General Principles & Basic Science MCQs

Practice Set 204 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 4061

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach for an open reduction internal fixation (ORIF) of a proximal humerus fracture, the surgeon must be mindful of the axillary nerve. On average, at what distance distal to the lateral border of the acromion does the axillary nerve cross the deep surface of the deltoid?

. 2 cm
. 5 cm
. 9 cm
. 12 cm
. 15 cm

Correct Answer & Explanation

. 2 cm

Explanation

The axillary nerve courses circumferentially from posterior to anterior on the deep surface of the deltoid muscle. Classic anatomic studies (e.g., Burkhead et al.) demonstrate that the axillary nerve is located approximately 5 cm (range 4-7 cm depending on patient size) distal to the lateral border of the acromion. This is a critical landmark to avoid iatrogenic injury during lateral or deltoid-splitting approaches.

Question 4062

Topic: 1. General Principles & Basic Science

A 30-year-old male bodybuilder feels a sudden "pop" and tearing sensation in his anterior chest and axilla while performing a heavy bench press. MRI confirms a complete rupture of the sternal head of the pectoralis major muscle from its humeral insertion. The clavicular head is intact. Anatomically, how does the sternal head of the pectoralis major insert onto the humerus relative to the clavicular head?

. Superficial and distal
. Superficial and proximal
. Deep and distal
. Deep and proximal
. At the exact same level as a conjoint tendon

Correct Answer & Explanation

. Deep and distal

Explanation

The pectoralis major tendon undergoes a 90-degree twist before it inserts onto the lateral lip of the bicipital groove of the humerus. The clavicular head fibers run linearly to insert distally and superficially. The lower (sternal/costal) fibers twist behind the upper fibers, resulting in their insertion being deep and proximal. The sternal head is the most commonly ruptured segment during heavy eccentric loading activities like the bench press.

Question 4063

Topic: 1. General Principles & Basic Science

An 18-year-old football player presents after a direct blow to the medial clavicle. He is complaining of severe pain, shortness of breath, mild stridor, and difficulty swallowing. Clinical examination and plain radiographs are suggestive of a posterior sternoclavicular (SC) joint dislocation.

What is the most appropriate next step in management?

. Immediate closed reduction in the emergency department using a towel clip
. CT scan of the chest and neck with intravenous contrast
. MRI of the brachial plexus
. Immediate open reduction and internal fixation with a locking plate
. Sling immobilization and elective thoracic surgery consultation

Correct Answer & Explanation

. CT scan of the chest and neck with intravenous contrast

Explanation

A posterior sternoclavicular joint dislocation is a true orthopedic emergency due to the high risk of compression or injury to posterior mediastinal structures (trachea, esophagus, great vessels), as evidenced by this patient's stridor and dysphagia. The crucial next step is a CT scan of the chest/neck (ideally with IV contrast) to accurately assess the displacement of the medial clavicle and its relationship to the mediastinal anatomy. Closed reduction should be attempted in the operating room (not the ED) with a cardiothoracic surgeon available, given the risk of massive hemorrhage if a great vessel is lacerated upon reduction.

Question 4064

Topic: 1. General Principles & Basic Science

A 19-year-old rugby player presents to the emergency department after a direct blow to the medial clavicle. He is complaining of chest pain, dyspnea, and dysphagia. Physical examination reveals a palpable defect over the medial clavicle. An AP radiograph and CT scan confirm a posterior sternoclavicular dislocation. What is the most appropriate next step in management?

. Immediate closed reduction in the emergency department with procedural sedation
. Closed reduction in the operating room with cardiothoracic surgery available
. Immediate open reduction and internal fixation with a hook plate
. Sling immobilization and observation
. Excision of the medial clavicle

Correct Answer & Explanation

. Closed reduction in the operating room with cardiothoracic surgery available

Explanation

Posterior sternoclavicular dislocations are orthopedic emergencies due to the risk of compression of mediastinal structures (trachea, esophagus, great vessels). Closed reduction should be attempted in the operating room under general anesthesia with cardiothoracic surgery backup in case of great vessel injury during the reduction maneuver.

Question 4065

Topic: 1. General Principles & Basic Science

A 22-year-old gymnast sustains an anterior sternoclavicular (SC) joint dislocation. She complains of an unsightly bump on her chest but has no respiratory or swallowing difficulties. After a trial of conservative management, she continues to have pain and instability. If surgery is considered, which of the following is the most appropriate procedure?

. Resection of the medial clavicle alone
. Open reduction and internal fixation with Kirschner wires
. Figure-of-eight ligamentous reconstruction using a soft tissue graft
. Sternoclavicular arthrodesis
. Hook plate fixation

Correct Answer & Explanation

. Figure-of-eight ligamentous reconstruction using a soft tissue graft

Explanation

The preferred surgical treatment for symptomatic, chronic anterior sternoclavicular joint instability that has failed conservative management is a ligamentous reconstruction, typically using a soft tissue graft (e.g., semitendinosus or palmaris longus) in a figure-of-eight or similar configuration. Transarticular Kirschner wires are strictly contraindicated in the SC joint due to the high risk of catastrophic migration into the heart or great vessels. Medial clavicle excision without reconstruction can lead to continued instability.

Question 4066

Topic: 1. General Principles & Basic Science

A 19-year-old male rugby player presents to the emergency department with severe anterior chest wall pain, dysphagia, and a sensation of choking following a direct blow to the medial clavicle. Suspecting a posterior sternoclavicular dislocation, what is the most appropriate initial imaging modality to confirm the diagnosis and assess associated risks?

. Anteroposterior chest radiograph
. Serendipity view radiograph
. Magnetic Resonance Angiography (MRA)
. Computed Tomography (CT) scan of the chest with IV contrast
. Ultrasound of the clavicle

Correct Answer & Explanation

. Computed Tomography (CT) scan of the chest with IV contrast

Explanation

A posterior sternoclavicular joint dislocation is a true orthopedic emergency due to its proximity to vital mediastinal structures. A CT scan of the chest with IV contrast is the gold standard to assess the dislocation and rule out vascular or tracheal compromise.

Question 4067

Topic: 1. General Principles & Basic Science

A 30-year-old competitive weightlifter ruptures his pectoralis major tendon during a bench press. When performing an anatomic primary repair, where should the sternal head insert on the humerus relative to the clavicular head?

. Proximal and anterior
. Proximal and posterior
. Distal and posterior
. Distal and anterior
. Directly medial

Correct Answer & Explanation

. Proximal and posterior

Explanation

The pectoralis major tendon undergoes a 180-degree twist before inserting onto the humerus. This causes the sternal head to insert deep (posterior) and proximal to the clavicular head.

Question 4068

Topic: 1. General Principles & Basic Science

During an anatomic coracoclavicular (CC) ligament reconstruction for a chronic Type V AC joint separation, the surgeon aims to reconstruct both the conoid and trapezoid ligaments. To accurately replicate their anatomic insertions on the clavicle, where should the tunnels be placed relative to the distal end of the clavicle?

. Conoid 45 mm, Trapezoid 25 mm medial
. Conoid 30 mm, Trapezoid 15 mm medial
. Conoid 45 mm, Trapezoid 30 mm medial
. Conoid 25 mm, Trapezoid 15 mm medial
. Conoid 55 mm, Trapezoid 40 mm medial

Correct Answer & Explanation

. Conoid 45 mm, Trapezoid 30 mm medial

Explanation

The trapezoid ligament inserts more distally/laterally on the clavicle, approximately 15-17 mm medial to the distal clavicle. The conoid ligament inserts more proximally/medially, at the conoid tubercle, which is approximately 30-45 mm (average 30-35 mm) medial to the distal clavicle. Therefore, Conoid ~30-45 mm, Trapezoid ~15 mm is the standard tunnel placement.

Question 4069

Topic: Biology, Genetics & Bone Healing

A 28-year-old male develops severe elbow stiffness 3 months following open reduction and internal fixation of a terrible triad injury. Radiographs show mature heterotopic ossification (HO) bridging the radioulnar joint. He is scheduled for excision of the HO and capsular release. What is the optimal postoperative prophylaxis to prevent recurrence of HO in this patient?

. Low-dose aspirin for 6 weeks
. Indomethacin 75 mg SR daily for 3-6 weeks OR single-dose radiation therapy
. Oral bisphosphonates for 3 months
. Colchicine for 2 weeks
. No prophylaxis is needed once the HO is fully mature

Correct Answer & Explanation

. Indomethacin 75 mg SR daily for 3-6 weeks OR single-dose radiation therapy

Explanation

After surgical excision of heterotopic ossification around the elbow, the risk of recurrence is high. Prophylaxis is standard of care. The two most proven and widely used prophylactic regimens are oral NSAIDs (specifically Indomethacin) for 3 to 6 weeks, or a single dose of localized external beam radiation therapy (typically 700 cGy) given within 24-48 hours postoperatively. Bisphosphonates may delay the mineralization of HO but do not prevent the formation of the osteoid matrix, and therefore HO often forms once the drug is stopped.

Question 4070

Topic: 1. General Principles & Basic Science

A 32-year-old bodybuilder feels a pop in his anterior axilla while performing a heavy bench press. Examination reveals loss of the anterior axillary fold and weakness with internal rotation. MRI confirms a rupture of the pectoralis major tendon at its insertion. What is the anatomic insertion site of the pectoralis major?

. Medial lip of the bicipital groove
. Lateral lip of the bicipital groove
. Lesser tuberosity
. Coracoid process
. Deltoid tuberosity

Correct Answer & Explanation

. Lateral lip of the bicipital groove

Explanation

The pectoralis major tendon inserts onto the lateral lip of the bicipital groove of the humerus. The latissimus dorsi inserts onto the floor of the groove, and the teres major inserts onto the medial lip. 'A miss between two majors' is a helpful mnemonic (Latissimus dorsi between Pectoralis major and Teres major).

Question 4071

Topic: 1. General Principles & Basic Science

A 20-year-old male is involved in a high-speed MVA and sustains a posterior sternoclavicular joint dislocation. He is hemodynamically stable but complains of dysphagia and mild dyspnea. A closed reduction is planned in the operating room. Which surgical specialty must be immediately available during this procedure?

. Neurosurgery
. Cardiothoracic surgery
. General surgery
. Otolaryngology
. Plastic surgery

Correct Answer & Explanation

. Neurosurgery

Explanation

Posterior sternoclavicular dislocations can compress mediastinal structures, including the trachea, esophagus, and great vessels. Reduction of the joint carries a significant risk of catastrophic hemorrhage if a great vessel was lacerated and temporarily tamponaded by the displaced clavicle. Therefore, a cardiothoracic surgeon must be available.

Question 4072

Topic: Surgical Anatomy & Approaches

A 30-year-old female sustains a shear fracture of the capitellum extending into the trochlea. During open reduction and internal fixation via a lateral approach, the surgeon decides to use the Kocher approach to visualize the capitellum while minimizing risk to the LUCL. The Kocher approach utilizes the internervous plane between which two muscles?

. Brachioradialis and Pronator Teres
. Extensor Carpi Radialis Brevis and Extensor Digitorum Communis
. Anconeus and Extensor Carpi Ulnaris
. Triceps and Brachialis
. Flexor Carpi Ulnaris and Flexor Digitorum Superficialis

Correct Answer & Explanation

. Brachioradialis and Pronator Teres

Explanation

The Kocher approach utilizes the internervous plane between the anconeus (innervated by the radial nerve) and the extensor carpi ulnaris (innervated by the posterior interosseous nerve). The Kaplan approach utilizes the plane between the ECRB and EDC, which is more anterior.

Question 4073

Topic: 1. General Principles & Basic Science

A 32-year-old competitive powerlifter experiences a sudden tearing sensation in his anterior chest wall while performing a heavy bench press. Examination reveals a palpable defect and loss of the normal anterior axillary fold contour. MRI confirms a complete rupture of the pectoralis major tendon. Which portion of the muscle is most commonly injured in this mechanism, and what is its normal anatomic insertion relative to the other head?

. Clavicular head; inserts anterior and proximal to the sternocostal head
. Sternocostal head; inserts posterior and proximal to the clavicular head
. Sternocostal head; inserts anterior and distal to the clavicular head
. Clavicular head; inserts posterior and distal to the sternocostal head
. Sternal head; inserts anterior and medial to the clavicular head

Correct Answer & Explanation

. Clavicular head; inserts anterior and proximal to the sternocostal head

Explanation

Pectoralis major ruptures most commonly involve the sternocostal head, especially during weightlifting (e.g., bench pressing). The sternocostal head fibers twist 180 degrees before inserting onto the lateral lip of the bicipital groove, such that the inferior fibers of the sternocostal head insert most proximally and deep (posteriorly) relative to the clavicular head.

Question 4074

Topic: 1. General Principles & Basic Science

Historically, the arcuate artery (a branch of the anterior humeral circumflex artery) was thought to provide the main blood supply to the humeral head. However, recent quantitative cadaveric studies have demonstrated that the principal blood supply to the humeral head is derived from which of the following vessels?

. Thoracoacromial artery
. Posterior humeral circumflex artery
. Suprascapular artery
. Circumflex scapular artery
. Subscapular artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Recent studies (e.g., Hettrich et al.) demonstrated that the posterior humeral circumflex artery provides the majority (approximately 64%) of the blood supply to the humeral head, challenging the historical belief that the anterior humeral circumflex was the primary supply.

Question 4075

Topic: 1. General Principles & Basic Science

A 22-year-old male presents to the emergency department after a high-speed motor vehicle collision. He complains of chest pain, shortness of breath, and pain in the right medial clavicle region. Examination shows a posterior sternoclavicular dislocation. What is the most appropriate next step in management?

. Immediate closed reduction in the emergency department using traction
. CT scan of the chest and planned closed/open reduction in the OR with a cardiothoracic surgeon on standby
. Application of a figure-of-eight brace and discharge
. Immediate open reduction and plating of the medial clavicle
. Observation as most remodel over time

Correct Answer & Explanation

. CT scan of the chest and planned closed/open reduction in the OR with a cardiothoracic surgeon on standby

Explanation

Posterior sternoclavicular dislocations can compress mediastinal structures (trachea, esophagus, great vessels). Due to the high risk of catastrophic vascular injury during reduction, it must be performed in the OR with a cardiothoracic surgeon on standby after a CT scan evaluates the mediastinum.

Question 4076

Topic: 1. General Principles & Basic Science

A 30-year-old male weightlifter felt a sudden "tearing" sensation in his chest while performing a heavy bench press. Examination reveals loss of the anterior axillary fold contour and weakness in internal rotation. Operative repair of the pectoralis major is planned. Which anatomical statement correctly describes the insertion of the most commonly ruptured portion of this muscle?

. The sternal head inserts superficial and distal to the clavicular head.
. The sternal head twists 180 degrees to insert deep and proximal to the clavicular head.
. The clavicular head inserts deep and proximal to the sternal head.
. Both heads insert at the exact same level on the medial lip of the bicipital groove.
. The sternal head inserts onto the coracoid process.

Correct Answer & Explanation

. The sternal head twists 180 degrees to insert deep and proximal to the clavicular head.

Explanation

The pectoralis major tendon undergoes a 180-degree twist before inserting on the lateral lip of the bicipital groove. This causes the inferior (sternal) fibers to insert deep and proximal to the superior (clavicular) fibers. The sternal head is the most commonly ruptured.

Question 4077

Topic: Surgical Anatomy & Approaches

A 34-year-old female presents with elbow pain after a fall. Radiographs and CT demonstrate a coronal shear fracture of the capitellum that extends medially to include the majority of the trochlea, with a separate comminuted fracture of the posterior trochlea. According to the Dubberley classification, what is the most appropriate surgical approach for open reduction and internal fixation of this Type 3B injury?

. Kocher approach
. Kaplan approach
. Extended lateral approach
. Universal posterior approach with olecranon osteotomy
. Anterior approach

Correct Answer & Explanation

. Universal posterior approach with olecranon osteotomy

Explanation

Dubberley Type 3B fractures involve the capitellum and trochlea with significant posterior articular comminution. A universal posterior approach with an olecranon osteotomy is required to adequately visualize and rigidly fix the articular surface while managing the posterior comminution.

Question 4078

Topic: 1. General Principles & Basic Science

A 17-year-old male sustains a direct blow to the medial chest wall during a football game. He presents with severe chest pain, shortness of breath, and dysphagia. Examination reveals a palpable depression at the medial end of the clavicle. What is the most appropriate next step in management?

. Immediate closed reduction in the emergency department
. CT scan of the chest and consultation with cardiothoracic surgery
. Sling immobilization and outpatient orthopedic follow-up
. Urgent open reduction and plate fixation of the medial clavicle
. MRI of the sternoclavicular joint

Correct Answer & Explanation

. CT scan of the chest and consultation with cardiothoracic surgery

Explanation

Posterior sternoclavicular dislocations can cause life-threatening compression of mediastinal structures, leading to dyspnea and dysphagia. A CT angiogram of the chest is critical to evaluate the great vessels, and cardiothoracic surgery must be available during reduction in case of sudden vascular injury.

Question 4079

Topic: 1. General Principles & Basic Science

A 30-year-old male bodybuilder feels a pop in his anterior axilla while performing a heavy bench press. Examination reveals an asymmetric chest wall with a loss of the anterior axillary fold contour and weakness in adduction and internal rotation. The rupture most commonly involves which part of the muscle complex and at what location?

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

Correct Answer & Explanation

. Sternal head at the humeral insertion

Explanation

Pectoralis major ruptures most frequently occur in weightlifters (particularly during the bench press) during eccentric loading. The most common site of rupture is an avulsion of the sternal head tendon from its insertion on the humerus. The sternal head tendon typically twists and inserts deep and superior to the clavicular head tendon, placing it at the greatest biomechanical disadvantage during the lowest part of the bench press.

Question 4080

Topic: 1. General Principles & Basic Science

A 19-year-old male is tackled during an American football game and sustains a posterior sternoclavicular joint dislocation. He complains of mild shortness of breath and dysphagia. What is the most appropriate next step in management?

. Immediate closed reduction in the emergency department without imaging
. CT scan of the chest and formal closed reduction in the operating room with cardiothoracic surgery available
. Figure-of-eight brace and observation
. Open reduction and internal fixation using K-wires
. MRI of the brachial plexus

Correct Answer & Explanation

. Immediate closed reduction in the emergency department without imaging

Explanation

Posterior sternoclavicular dislocations are orthopedic emergencies due to the proximity of vital mediastinal structures (trachea, esophagus, great vessels). Management requires a CT scan to confirm the diagnosis and delineate the relationship to mediastinal structures. Reduction should be performed in the operating room with cardiothoracic surgery backup available, as there is a risk of catastrophic vascular injury during reduction.

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