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9. Shoulder and Elbow MCQs

Practice Set 21 of 197

This practice set contains high-yield board review questions covering key concepts in 9. Shoulder and Elbow. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 401

Topic: Shoulder Arthroplasty & Arthritis

A 65-year-old male is undergoing a reverse total shoulder arthroplasty (RTSA) for cuff tear arthropathy. To minimize the risk of scapular notching, which of the following describes the optimal positioning of the glenoid baseplate?

. Superiorly translated with superior tilt.
. Centered on the glenoid with superior tilt.
. Inferiorly translated with neutral or slight inferior tilt.
. Flush with the anterior rim and significant superior tilt.
. Centered on the glenoid with neutral tilt.

Correct Answer & Explanation

. Inferiorly translated with neutral or slight inferior tilt.

Explanation

Scapular notching in RTSA is primarily caused by mechanical impingement of the humeral component against the inferior scapular neck. It can be minimized by placing the glenoid baseplate inferiorly (flush or slightly overhanging the inferior rim) and using neutral or slight inferior tilt.

Question 402

Topic: 9. Shoulder and Elbow

A 69-year-old female with primary glenohumeral osteoarthritis and an intact rotator cuff is scheduled for an anatomic total shoulder arthroplasty. Preoperative CT scan reveals a Walch B2 glenoid with 25 degrees of retroversion. If the surgeon attempts to correct the retroversion to neutral using asymmetric anterior reaming alone, what is the most significant biomechanical risk?

. Immediate anterior dislocation of the humeral component.
. Removal of the dense subchondral bone leading to glenoid component subsidence and peg perforation.
. Shortening of the subscapularis muscle causing postoperative internal rotation weakness.
. Injury to the suprascapular nerve at the spinoglenoid notch.
. Postoperative acromial stress fracture.

Correct Answer & Explanation

. Removal of the dense subchondral bone leading to glenoid component subsidence and peg perforation.

Explanation

Correcting severe glenoid retroversion (>15 degrees) via asymmetric reaming alone sacrifices critical anterior subchondral bone stock. This decreases the structural support for the glenoid component, increasing the risk of vault perforation, subsidence, and premature loosening.

Question 403

Topic: 9. Shoulder and Elbow

A 75-year-old female undergoes a reverse total shoulder arthroplasty. Six months postoperatively, she reports sudden lateral shoulder pain without trauma, accompanied by a decline in active forward elevation. Radiographs demonstrate a fracture at the base of the acromion. Which of the following biomechanical alterations is the primary risk factor for this complication?

. Inadequate deltoid tension from placing the baseplate too high.
. Excessive arm lengthening and medialization of the center of rotation, significantly increasing deltoid tension.
. Lateralization of the center of rotation causing increased tension on the intact rotator cuff.
. Failure to repair the subscapularis tendon.
. Use of a larger humeral head augment.

Correct Answer & Explanation

. Excessive arm lengthening and medialization of the center of rotation, significantly increasing deltoid tension.

Explanation

Acromial stress fractures after RTSA are strongly associated with excessive lengthening of the arm and significant medialization of the center of rotation. These changes dramatically increase the tension and resting tone of the deltoid, predisposing the acromion to stress fractures.

Question 404

Topic: Shoulder Arthroplasty & Arthritis

A 64-year-old female suffers a displaced 3-part proximal humerus fracture and is treated with a reverse total shoulder arthroplasty. The surgeon uses strong sutures to repair the greater tuberosity to the proximal humerus and the implant. Successful osseous healing of the greater tuberosity is most closely associated with which clinical outcome?

. Increased postoperative active internal rotation.
. Increased postoperative active external rotation.
. Decreased risk of postoperative acromial stress fracture.
. Decreased risk of scapular notching.
. Complete restoration of supraspinatus function.

Correct Answer & Explanation

. Increased postoperative active external rotation.

Explanation

In the setting of RTSA for proximal humerus fractures, anatomic reduction and healing of the greater tuberosity strictly correlate with improved active external rotation. This is because it restores the tension and function of the attached teres minor and infraspinatus.

Question 405

Topic: 9. Shoulder and Elbow

A 70-year-old male with an anatomic total shoulder arthroplasty presents with gradually worsening shoulder pain and decreased range of motion. Radiographs demonstrate superior migration of the humeral head and eccentric superior wear of the glenoid component. What phenomenon is primarily responsible for the subsequent loosening of the glenoid component in this scenario?

. Galvanic corrosion at the glenoid peg interface.
. The "rocking horse" phenomenon due to unbalanced eccentric loading.
. Subscapularis failure leading to anterior subluxation.
. Trunnionosis of the glenosphere.
. Polyethylene oxidation from sterilization in argon.

Correct Answer & Explanation

. The "rocking horse" phenomenon due to unbalanced eccentric loading.

Explanation

Superior migration of the humeral head (often due to progressive rotator cuff dysfunction) causes eccentric superior loading of the glenoid component. This off-axis loading creates a "rocking horse" phenomenon, which is the most common biomechanical mechanism leading to aseptic glenoid loosening in anatomic TSA.

Question 406

Topic: 9. Shoulder and Elbow

Reverse total shoulder arthroplasty radically alters the biomechanics of the glenohumeral joint compared to its native state. Which of the following accurately describes the primary biomechanical advantage conferred by the Grammont RTSA design?

. Lateralization and superior translation of the center of rotation, restoring normal rotator cuff mechanics.
. Medialization and inferior translation of the center of rotation, lengthening the deltoid moment arm and increasing its efficiency.
. Medialization of the center of rotation, effectively lengthening the rotator cuff to improve internal rotation.
. Lateralization and inferior translation of the center of rotation to restore anatomic head-neck alignment.
. Superior displacement of the center of rotation to maximize the anterior deltoid's line of pull.

Correct Answer & Explanation

. Medialization and inferior translation of the center of rotation, lengthening the deltoid moment arm and increasing its efficiency.

Explanation

The classic Grammont reverse shoulder design medializes and inferiorly translates the center of rotation. This dramatically increases the moment arm of the deltoid, recruiting more anterior and posterior fibers for elevation and allowing the deltoid to compensate for a deficient rotator cuff.

Question 407

Topic: 9. Shoulder and Elbow

A 75-year-old female undergoes reverse total shoulder arthroplasty. Six months postoperatively, she develops localized pain over the superior-posterior shoulder and a visible contour defect. Radiographs reveal an acromial stress fracture. Which of the following intraoperative factors most significantly increases the risk of this complication?

. Placement of the glenosphere with inferior tilt
. Excessive lengthening of the arm and deltoid overtensioning
. Use of a larger diameter glenosphere
. Inadequate retroversion of the humeral stem
. Release of the subscapularis tendon

Correct Answer & Explanation

. Excessive lengthening of the arm and deltoid overtensioning

Explanation

Acromial stress fractures in RTSA are frequently caused by excessive deltoid tension resulting from over-lengthening the arm. Inferiorizing and medializing the center of rotation optimally recruits the deltoid, but excessive lengthening places supraphysiologic stress on the acromion.

Question 408

Topic: Shoulder Arthroplasty & Arthritis

In reverse total shoulder arthroplasty (RTSA), biomechanical stability and function rely on altering the native center of rotation (COR). How is the COR characteristically changed compared to the native shoulder?

. Medialized and superiorized
. Medialized and inferiorized
. Lateralized and superiorized
. Lateralized and inferiorized
. Maintained in its native anatomic position

Correct Answer & Explanation

. Medialized and inferiorized

Explanation

Grammont's original design for RTSA medializes and inferiorizes the center of rotation. Medialization decreases torque on the glenoid component to prevent loosening, while inferiorization recruits more deltoid fibers and increases its moment arm to restore active elevation.

Question 409

Topic: 9. Shoulder and Elbow

Scapular notching is a well-recognized complication following reverse total shoulder arthroplasty. Which of the following surgical techniques best minimizes this risk?

. Superior placement of the glenosphere baseplate
. Inferior overhang of the glenosphere baseplate by 2 to 4 mm
. Increasing the retroversion of the humeral stem to 40 degrees
. Using a smaller diameter glenosphere
. Medialization of the humeral tray

Correct Answer & Explanation

. Inferior overhang of the glenosphere baseplate by 2 to 4 mm

Explanation

Scapular notching occurs when the medial humeral metaphysis impinges on the inferior scapular neck during adduction. Placing the baseplate with an inferior overhang of 2-4 mm shifts the impingement point, significantly reducing the incidence of notching.

Question 410

Topic: 9. Shoulder and Elbow

Six months after an anatomic total shoulder arthroplasty, a patient presents with sudden weakness in internal rotation and increased anterior shoulder pain. The belly-press test is newly positive. What is the most likely cause of this presentation?

. Axillary nerve palsy
. Failure of the subscapularis repair
. Glenoid component loosening
. Rotator interval contracture
. Suprascapular nerve entrapment

Correct Answer & Explanation

. Failure of the subscapularis repair

Explanation

A positive belly-press test and internal rotation weakness indicate a subscapularis failure, which is a known and devastating complication after anatomic TSA if a tenotomy or peel fails to heal. This can lead to anterior instability and pain.

Question 411

Topic: 9. Shoulder and Elbow

A 65-year-old male with primary glenohumeral osteoarthritis undergoes an anatomic total shoulder arthroplasty. During closure, a lesser tuberosity osteotomy is repaired. What postoperative rehabilitation restriction is most crucial to protect this specific repair?

. Limit passive internal rotation to neutral
. Limit passive external rotation strictly to 30 degrees for 6 weeks
. Avoid active internal rotation and limit passive external rotation
. Immediate active external rotation strengthening to prevent stiffness
. Strict immobilization in internal rotation for 8 weeks with no ROM

Correct Answer & Explanation

. Avoid active internal rotation and limit passive external rotation

Explanation

Repair of the subscapularis (whether via peel, tenotomy, or lesser tuberosity osteotomy) is at risk during external rotation stretch or active internal rotation contraction. Postoperative protocols generally restrict active internal rotation and limit passive external rotation to protect the repair.

Question 412

Topic: 9. Shoulder and Elbow

A 72-year-old female undergoes a reverse total shoulder arthroplasty for rotator cuff tear arthropathy. Compared to an anatomic total shoulder arthroplasty, how does the reverse design alter the biomechanics of the shoulder joint to restore forward elevation?

. Lateralizes and superiorly translates the center of rotation
. Medializes and distalizes the center of rotation
. Medializes and superiorly translates the center of rotation
. Lateralizes and distalizes the center of rotation
. Maintains the native center of rotation but increases the deltoid moment arm

Correct Answer & Explanation

. Medializes and distalizes the center of rotation

Explanation

Reverse total shoulder arthroplasty medializes and distalizes the center of rotation. This increases the deltoid moment arm, allowing the deltoid to effectively elevate the arm in the absence of a functional rotator cuff.

Question 413

Topic: Shoulder Arthroplasty & Arthritis

A 75-year-old male presents for his 3-year follow-up after a reverse total shoulder arthroplasty. Radiographs demonstrate inferior scapular notching extending beyond the inferior glenoid screw (Sirveaux Grade 3). Which of the following surgical techniques most effectively minimizes the risk of this complication during the index procedure?

. Superior tilt of the glenosphere
. Neutral tilt with superior placement of the baseplate
. Inferior translation of the baseplate with inferior overhang of the glenosphere
. Lateralization of the humerus using a thicker polyethylene insert
. Use of a smaller diameter glenosphere

Correct Answer & Explanation

. Inferior translation of the baseplate with inferior overhang of the glenosphere

Explanation

Scapular notching is a frequent complication of RTSA caused by mechanical impingement of the humeral component against the scapular neck. Inferior placement of the baseplate with a 2 to 4 mm inferior overhang of the glenosphere is the most effective technique to prevent it.

Question 414

Topic: 9. Shoulder and Elbow

A 60-year-old male with primary glenohumeral osteoarthritis presents for total shoulder arthroplasty. Preoperative CT scan demonstrates a biconcave glenoid with 25 degrees of retroversion. What is the maximum acceptable amount of retroversion correction achievable via asymmetric anterior glenoid reaming before risking catastrophic failure from violation of the subchondral bone vault?

. 5 degrees
. 15 degrees
. 25 degrees
. 35 degrees
. 45 degrees

Correct Answer & Explanation

. 15 degrees

Explanation

In cases of Walch B2 glenoids, correcting more than 15 degrees of retroversion via asymmetric reaming violates the dense subchondral bone. This significantly increases the risk of early glenoid component loosening and failure, necessitating augmented implants or bone grafting for severe defects.

Question 415

Topic: 9. Shoulder and Elbow

A 70-year-old female presents with sudden onset of lateral shoulder pain 4 months following a reverse total shoulder arthroplasty, denying any trauma. Radiographs reveal a Levy Type II stress fracture of the acromion. Which of the following intraoperative factors is most strongly associated with an increased risk of this complication?

. Excessive inferior overhang of the glenosphere
. Inadequate deltoid tensioning
. Overtensioning of the deltoid through excessive distalization of the humerus
. Use of a lateralized humeral stem
. Placement of the superior baseplate screw strictly in the coracoid base

Correct Answer & Explanation

. Overtensioning of the deltoid through excessive distalization of the humerus

Explanation

Acromial stress fractures after RTSA are strongly associated with overtensioning of the deltoid muscle, often caused by excessive distalization or lengthening of the arm. Excessive tension increases the biomechanical load across the acromion, leading to fatigue failure.

Question 416

Topic: 9. Shoulder and Elbow

A 65-year-old patient undergoes open reduction and internal fixation of a comminuted distal radius fracture. Post-operatively, the rehabilitation protocol emphasizes early active range of motion (AROM) for the fingers, elbow, and shoulder, along with elevation and pain control. Which of the following is the primary goal of these specific early rehabilitation interventions?

. To accelerate fracture healing and bone consolidation.
. To prevent post-traumatic arthritis of the radiocarpal joint.
. To minimize the risk of Complex Regional Pain Syndrome (CRPS) and prevent joint stiffness in uninvolved joints.
. To restore full wrist range of motion within the first two weeks.
. To strengthen the wrist flexor and extensor muscles immediately.

Correct Answer & Explanation

. To minimize the risk of Complex Regional Pain Syndrome (CRPS) and prevent joint stiffness in uninvolved joints.

Explanation

Correct Answer: CThe case, under 'Postoperative Rehabilitation,' states the goals for Phase 1 (Protective Rehabilitation): 'Protect surgical repair, minimize pain and swelling, prevent joint stiffness in uninvolved joints, initiate CRPS prevention.' Specifically, for 'Early Active Motion,' it lists 'Fingers: Active range of motion (AROM) exercises... Elbow & Shoulder: AROM exercises for the elbow and shoulder to prevent stiffness.' And under 'CRPS Prevention,' it states: 'Emphasize elevation, pain control, active finger/shoulder/elbow ROM.' This clearly indicates that preventing CRPS and stiffness in uninvolved joints are primary goals of these early interventions.Option A (Accelerate fracture healing) is not the primary goal of earlyjointmotion; fracture healing is a biological process influenced by stability and biology, not directly by finger/elbow/shoulder motion.Option B (Prevent post-traumatic arthritis) is primarily achieved by anatomical reduction and stable fixation of the fracture, not directly by early motion of uninvolved joints.Option D (Restore full wrist range of motion within the first two weeks) is incorrect. The case explicitly states 'NO active or passive wrist motion, forearm rotation' in Phase 1, which typically lasts several weeks. Full wrist ROM is a later goal.Option E (Strengthen wrist muscles immediately) is incorrect. Strengthening exercises are introduced in Phase 3, after initial healing and restoration of basic motion, to protect the repair.

Question 417

Topic: 9. Shoulder and Elbow

A 75-year-old patient presents with a massive, irreparable rotator cuff tear (Goutallier Stage 3 fatty infiltration of supraspinatus and infraspinatus) and significant glenohumeral arthritis, characterized by superior migration of the humerus, joint destruction, and subchondral osteoporosis. She has failed all conservative management. Which of the following is the most appropriate surgical treatment option?

. Hemiarthroplasty
. Total shoulder arthroplasty
. Latissimus dorsi tendon transfer
. Arthroscopic rotator cuff repair
. Reverse total shoulder arthroplasty

Correct Answer & Explanation

. Reverse total shoulder arthroplasty

Explanation

Correct Answer: EThe patient presents with a massive, irreparable rotator cuff tear (Goutallier Stage 3) and significant glenohumeral arthritis, specifically described as cuff-tear arthropathy (superior migration, joint destruction, subchondral osteoporosis). The discussion explicitly states that a reverse total shoulder arthroplasty (RTSA) is the procedure of choice in patients with cuff-tear arthropathy. RTSA eliminates pain from arthritis and restores functional motion by creating an inferior force-couple and a fulcrum, allowing the deltoid to abduct and flex the shoulder without superior migration. The image (Figure 2-17) shows characteristic X-rays of cuff tear arthropathy, which is a key indication for RTSA. Hemiarthroplasty (Option A) reliably relieves pain but does not restore function as well as RTSA. Total shoulder arthroplasty (Option B) is contraindicated in cuff-tear arthropathy due to the risk of glenoid component loosening ('rocking-horse' glenoid). Latissimus dorsi tendon transfer (Option C) is an option for younger, active patients without arthritis. Arthroscopic rotator cuff repair (Option D) is contraindicated given the Goutallier Stage 3 fatty infiltration, which predicts poor outcomes and high failure rates.

Question 418

Topic: 9. Shoulder and Elbow

A 68-year-old patient undergoes reverse total shoulder arthroplasty for cuff tear arthropathy. One month post-operatively, the patient develops increasing shoulder pain, warmth, and erythema around the incision site. Initial wound cultures are negative after 48 hours. Based on the typical presentation of delayed shoulder prosthetic infections, what is the most likely causative organism?

. Staphylococcus aureus
. Streptococcus pyogenes
. Propionibacterium acnes
. Pseudomonas aeruginosa
. Escherichia coli

Correct Answer & Explanation

. Propionibacterium acnes

Explanation

Correct Answer: CThe patient presents with signs and symptoms of a surgical wound infection one month after reverse total shoulder surgery, and initial cultures are negative. The discussion explicitly states thatPropionibacterium acnes(now known asCutibacterium acnes) is the most common cause of delayed or indolent infections of surgical wounds, and cultures are often negative because it takes a long time (about 14 to 21 days) for it to grow.Staphylococcus aureus(Option A),Streptococcus pyogenes(Option B), andPseudomonas aeruginosa(Option D) are common causes of acute wound infections, which typically present within a week or two of surgery and are more likely to grow out on standard cultures within 48 hours.Escherichia coli(Option E) is a common cause of urinary tract infections and intra-abdominal infections, but less common for shoulder prosthetic infections, especially with a delayed, culture-negative presentation.

Question 419

Topic: 9. Shoulder and Elbow

A 65-year-old patient with a massive, irreparable rotator cuff tear and significant glenohumeral arthritis is being considered for shoulder arthroplasty. The surgeon explains that a total shoulder arthroplasty (TSA) is contraindicated in this specific condition. What is the primary reason for this contraindication?

. Increased risk of deltoid dysfunction
. High rate of humeral component loosening
. Inability to restore active range of motion
. Risk of glenoid component loosening due to superior humeral head translation
. Difficulty with rehabilitation protocols

Correct Answer & Explanation

. Risk of glenoid component loosening due to superior humeral head translation

Explanation

Correct Answer: DThe discussion clearly states that a total shoulder arthroplasty (TSA) is contraindicated in the case of cuff-tear arthropathy because of glenoid component loosening. It explains that 'if a glenoid component is used in this patient, the superior translation of the humeral head component on the glenoid component could cause it to loosen and rock, producing a 'rocking-horse' glenoid component.' This superior translation is a direct consequence of the massive rotator cuff tear, which leads to an unopposed superior pull of the deltoid. Options A, B, C, and E are not the primary or specific contraindications for TSA in the context of cuff tear arthropathy as described in the text.

Question 420

Topic: 9. Shoulder and Elbow

A 72-year-old patient with a massive, irreparable rotator cuff tear and cuff-tear arthropathy undergoes a reverse total shoulder arthroplasty. Which of the following best describes the biomechanical principle by which this prosthesis restores function?

. It directly repairs the torn rotator cuff tendons.
. It relies on the remaining intact rotator cuff muscles for stability.
. It converts the deltoid into an internal rotator.
. It creates an inferior force-couple and a fulcrum, allowing the deltoid to abduct and flex the shoulder.
. It replaces the glenoid with a spherical component to increase joint conformity.

Correct Answer & Explanation

. It creates an inferior force-couple and a fulcrum, allowing the deltoid to abduct and flex the shoulder.

Explanation

Correct Answer: DThe discussion explains that a reverse total shoulder arthroplasty (RTSA) is a semi-constrained prosthesis that restores function in patients with massive rotator cuff tears by 'constraining a concave humeral cap inferior to a semispherical glenoid component (glenosphere). This creates an inferior force-couple and a fulcrum that replaces the stabilizing function of the infraspinatus maintaining a center of rotation around which the shoulder can move. This allows the deltoid to abduct and flex the shoulder without causing the humerus to migrate superiorly and about the acromion.' This detailed explanation directly supports Option D. Option A is incorrect as RTSA is for irreparable tears. Option B is incorrect as the remaining rotator cuff is insufficient. Option C is incorrect as the deltoid's primary function is abduction, and RTSA enhances this. Option E describes part of the design (semispherical glenoid) but not the full biomechanical principle of how it restores function in the absence of a functional rotator cuff.

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