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Shoulder Arthroplasty & Arthritis MCQs

Practice Set 13 of 14

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

Question 241

Topic: Shoulder Arthroplasty & Arthritis

In planning a Reverse Total Shoulder Arthroplasty (RTSA), the surgeon aims to minimize the risk of inferior scapular notching. According to biomechanical principles, which glenosphere positioning strategy is most effective for preventing this complication?

. Superior translation and superior tilt
. Superior translation and neutral tilt
. Neutral translation and superior tilt
. Inferior translation with inferior overhang and inferior tilt
. Medialization of the center of rotation with superior overhang

Correct Answer & Explanation

. Inferior translation with inferior overhang and inferior tilt

Explanation

Scapular notching occurs when the humeral polyethylene cup abuts the inferior scapular neck during adduction. To minimize this, the glenosphere should be placed low on the glenoid (inferior translation) with an inferior overhang (extending past the inferior glenoid rim) and an inferior tilt.

Question 242

Topic: Shoulder Arthroplasty & Arthritis

In the setting of reverse total shoulder arthroplasty (RTSA), scapular notching is a well-documented and frequent complication. Which surgical technique modification most effectively reduces the incidence of inferior scapular notching?

. Superior placement of the glenosphere
. Using a smaller diameter glenosphere
. Inferior translation and inferior tilt of the glenosphere
. Superior tilt of the glenosphere
. Medialization of the humeral center of rotation

Correct Answer & Explanation

. Inferior translation and inferior tilt of the glenosphere

Explanation

Inferior translation (overhanging the inferior glenoid rim) and inferior tilt of the glenosphere decrease the risk of mechanical impingement of the humeral component against the scapular neck. This is the primary method to prevent scapular notching.

Question 243

Topic: Shoulder Arthroplasty & Arthritis

Which of the following surgical strategies best minimizes the risk of scapular notching during a reverse total shoulder arthroplasty (RTSA)?

. Superior placement of the glenosphere
. Inferior tilt and inferior overhang of the glenosphere
. Superior tilt of the glenosphere
. Lateralization of the humeral component only
. Decreasing the size of the glenosphere

Correct Answer & Explanation

. Inferior tilt and inferior overhang of the glenosphere

Explanation

Scapular notching occurs when the medial aspect of the humeral component impinges on the inferior scapular neck. Inferior placement with an inferior overhang of the glenosphere and inferior tilt alters the impingement-free arc of motion, significantly reducing the incidence of notching.

Question 244

Topic: Shoulder Arthroplasty & Arthritis

A 68-year-old female undergoes an anatomic total shoulder arthroplasty (TSA) for severe primary osteoarthritis. Preoperative CT showed a B2 glenoid with 20 degrees of retroversion. What is the most common mechanism of long-term failure in this patient?

. Humeral component loosening
. Glenoid component loosening
. Infection
. Subscapularis failure
. Periprosthetic fracture

Correct Answer & Explanation

. Glenoid component loosening

Explanation

Glenoid component loosening is the most common cause of late failure in anatomic TSA. Patients with uncorrected B2 glenoids (biconcave, excessive posterior wear) are at a particularly high risk for early eccentric wear and catastrophic glenoid loosening.

Question 245

Topic: Shoulder Arthroplasty & Arthritis

A 70-year-old male with a massive, irreparable posterosuperior rotator cuff tear presents with pseudoparalysis of the shoulder. He is considered for a reverse total shoulder arthroplasty (RTSA). How does the Grammont-style RTSA design biomechanically alter the shoulder to restore active elevation?

. Lateralizes the center of rotation to tension the remaining rotator cuff
. Superiorly translates the humerus to recruit the pectoralis major
. Medializes and distalizes the center of rotation to increase the deltoid moment arm
. Anteriorly translates the center of rotation to optimize the long head of the biceps
. Increases the anatomic neck-shaft angle to 155 degrees to tension the coracoacromial ligament

Correct Answer & Explanation

. Medializes and distalizes the center of rotation to increase the deltoid moment arm

Explanation

The primary biomechanical advantage of a Grammont-style reverse TSA is the medialization and distalization of the joint\'s center of rotation. This dramatically increases the moment arm of the deltoid, allowing it to efficiently elevate the arm despite the lack of a functioning rotator cuff.

Question 246

Topic: Shoulder Arthroplasty & Arthritis

For an 84-year-old lady with a comminuted 4-part proximal humerus fracture, which radiographic feature is most indicative of a potential need for reverse total shoulder arthroplasty (rTSA) over open reduction internal fixation (ORIF)?

. Presence of an intact lesser tuberosity
. Minimal metaphyseal comminution
. Head split component
. Valgus-impacted fracture pattern
. Intact rotator cuff tendons (inferred)

Correct Answer & Explanation

. Head split component

Explanation

A head split component (fracture extending through the articular surface of the humeral head) or significant articular damage makes anatomical reduction difficult or impossible, often leading to poor outcomes with ORIF. In the elderly, especially with osteoporotic bone, rTSA is often preferred for complex 3- and 4-part fractures, particularly when articular comminution or displacement suggests avascular necrosis risk or inability to achieve stable fixation with ORIF. Valgus-impacted fractures are generally more stable. Intact tuberosities or minimal comminution would favor ORIF. Intact rotator cuff tendons would be important for an anatomic TSA, but rTSA bypasses a non-functional cuff.

Question 247

Topic: Shoulder Arthroplasty & Arthritis

An 84-year-old lady has a history of right shoulder replacement. Her current X-ray shows an anatomic total shoulder arthroplasty (TSA). Which components would you expect to see on the X-ray?

. Humeral head prosthesis only
. Humeral stem and glenoid cup only
. Humeral stem with a modular head component, and a polyethylene glenoid component cemented into a metallic glenoid baseplate
. Humeral stem with a reverse ball component and a glenoid socket
. A prosthetic ball cemented to the glenoid and a prosthetic cup on the humerus

Correct Answer & Explanation

. Humeral stem with a modular head component, and a polyethylene glenoid component cemented into a metallic glenoid baseplate

Explanation

An anatomic Total Shoulder Arthroplasty (TSA) aims to replicate normal anatomy. It consists of a humeral component (stem with a modular head, typically metal) and a glenoid component (a polyethylene liner usually cemented into a metallic baseplate that is fixated to the glenoid bone). Option A is hemiarthroplasty. Option D is a reverse TSA. Option E describes a reverse TSA setup with components flipped. Option B is incomplete.

Question 248

Topic: Shoulder Arthroplasty & Arthritis

On the X-ray of an 84-year-old lady with a Reverse Total Shoulder Arthroplasty (rTSA), what is the key radiographic characteristic differentiating it from an anatomic TSA?

. A larger humeral head prosthesis
. A metallic glenosphere fixed to the scapula and a humeral socket
. Absence of a humeral stem
. A smaller glenoid component
. The presence of a polyethylene humeral head

Correct Answer & Explanation

. A metallic glenosphere fixed to the scapula and a humeral socket

Explanation

In a reverse total shoulder arthroplasty (rTSA), the 'ball' (glenosphere) is fixed to the glenoid bone, and the 'socket' (humeral cup/liner) is on the humeral side, effectively reversing the native anatomy. This allows the deltoid to act as the primary elevator, compensating for a deficient rotator cuff. An anatomic TSA has the ball on the humerus and socket on the glenoid.

Question 249

Topic: Shoulder Arthroplasty & Arthritis

Which radiographic finding is a common long-term complication specifically associated with Reverse Total Shoulder Arthroplasty (rTSA)?

. Instability of the humeral head in the glenoid
. Scapular notching
. Resorption of the greater tuberosity
. Dislocation of the metal humeral head
. Avascular necrosis of the glenoid

Correct Answer & Explanation

. Scapular notching

Explanation

Scapular notching is a common and specific complication of reverse total shoulder arthroplasty, occurring when the medial aspect of the humeral implant impinges on the inferior scapular neck during adduction and internal rotation, leading to bony erosion. Instability of the humeral head in the glenoid is for anatomic TSA. Resorption of the greater tuberosity is more relevant to proximal humerus fractures or hemiarthroplasty. Dislocation of the metal humeral head is for anatomic TSA. Avascular necrosis of the glenoid is rare.

Question 250

Topic: Shoulder Arthroplasty & Arthritis

What is the primary radiographic feature used to diagnose scapular notching in an X-ray of an rTSA patient?

. Glenoid component subsidence
. Erosion of the inferior scapular neck by the humeral component
. Fracture of the coracoid process
. Increased joint space
. Periprosthetic osteolysis around the humeral stem

Correct Answer & Explanation

. Erosion of the inferior scapular neck by the humeral component

Explanation

Scapular notching is precisely defined as the erosion of the inferior scapular neck by the humeral component of the rTSA, specifically the polyethylene liner impacting the bone during certain movements. It's a progressive, visually distinct radiographic finding. Glenoid subsidence is different, and the other options are not directly related to notching.

Question 251

Topic: Shoulder Arthroplasty & Arthritis

When formulating a management plan for a proximal humerus fracture in an elderly, low-demand patient, what is the most appropriate initial approach for a Neer two-part surgical neck fracture with minimal displacement?

. Open reduction internal fixation (ORIF).
. Reverse total shoulder arthroplasty (RTSA).
. Sling immobilization and early passive range of motion.
. Hemiarthroplasty.
. External fixation.

Correct Answer & Explanation

. Sling immobilization and early passive range of motion.

Explanation

For most minimally displaced two-part proximal humerus fractures, especially in elderly, low-demand patients, non-operative management with sling immobilization followed by early gentle passive and then active range of motion is the preferred initial treatment. Studies have shown comparable functional outcomes to surgical intervention with fewer complications. ORIF, hemiarthroplasty, and RTSA are reserved for displaced or comminuted fractures, or specific patient profiles.

Question 252

Topic: Shoulder Arthroplasty & Arthritis

You are asked about the management of a patient with a chronic, retracted rotator cuff tear who develops severe pseudoparalysis (inability to actively elevate the arm). What is the most appropriate surgical option to restore function?

. Arthroscopic debridement and bursectomy.
. Primary rotator cuff repair.
. Reverse total shoulder arthroplasty (RTSA).
. Latissimus dorsi tendon transfer.
. Hemiarthroplasty.

Correct Answer & Explanation

. Reverse total shoulder arthroplasty (RTSA).

Explanation

For a chronic, retracted rotator cuff tear leading to severe pseudoparalysis (meaning the patient cannot actively elevate the arm), reverse total shoulder arthroplasty (RTSA) is often the most reliable surgical option to restore active elevation and improve pain. The RTSA design bypasses the deficient rotator cuff by utilizing the deltoid for arm elevation. Primary repair is often not feasible due to retraction and chronicity, and debridement is palliative. Latissimus dorsi transfer can be considered but is typically for younger patients without arthropathy. Hemiarthroplasty doesn't address the cuff deficiency biomechanically.

Question 253

Topic: Shoulder Arthroplasty & Arthritis

In the biomechanical design of a Grammont-style reverse total shoulder arthroplasty (RTSA), how is the center of rotation (COR) altered compared to a native anatomic shoulder?

. Medialized and distalized
. Medialized and proximalized
. Lateralized and distalized
. Lateralized and proximalized
. Remains unchanged but constrained

Correct Answer & Explanation

. Medialized and distalized

Explanation

The Grammont-style RTSA medializes and distalizes the center of rotation. Medialization increases the deltoid lever arm and decreases torque on the glenoid component, while distalization tensions the deltoid, improving its efficiency for forward elevation in the absence of a functional rotator cuff.

Question 254

Topic: Shoulder Arthroplasty & Arthritis

To minimize the risk of inferior scapular notching in a reverse total shoulder arthroplasty (RTSA), the glenosphere baseplate should ideally be positioned with which of the following orientations?

. Superior translation and superior tilt
. Superior translation and inferior tilt
. Inferior translation and superior tilt
. Inferior translation and inferior tilt
. Central placement and neutral tilt

Correct Answer & Explanation

. Superior translation and inferior tilt

Explanation

Scapular notching is a well-documented complication of RTSA, caused by mechanical impingement of the humeral polyethylene insert against the inferior scapular neck during adduction. To minimize this, the glenosphere baseplate should be placed as inferiorly as possible on the glenoid, usually flush with or slightly overhanging the inferior rim, and with a neutral to slightly inferior tilt.

Question 255

Topic: Shoulder Arthroplasty & Arthritis

Which of the following design modifications or surgical techniques in a reverse total shoulder arthroplasty (RTSA) most effectively decreases the incidence of inferior scapular notching?

. Superior placement of the baseplate on the glenoid
. Superior tilt of the glenosphere
. Inferior translation of the baseplate with inferior tilt
. Medialization of the center of rotation
. Decreasing the glenosphere diameter

Correct Answer & Explanation

. Inferior translation of the baseplate with inferior tilt

Explanation

Inferior scapular notching in RTSA is caused by mechanical impingement of the humeral component against the scapular neck during adduction. To minimize this, the baseplate should be placed inferiorly (flush or slightly overhanging the inferior glenoid rim) and tilted inferiorly. Lateralizing the center of rotation and using a larger glenosphere also reduce notching.

Question 256

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old female presents with sudden onset of superior shoulder pain 4 months after a reverse total shoulder arthroplasty (rTSA). Radiographs reveal a Levy type II acromial stress fracture (involving the base of the acromion posterior to the acromioclavicular joint). What is the most appropriate initial management?

. Immediate open reduction and internal fixation with a tension band construct
. Immobilization in a sling for 4 to 6 weeks
. Revision to a standard anatomic total shoulder arthroplasty
. Exchange of the glenosphere to a larger size to increase deltoid tension
. Botulinum toxin injection to the deltoid to prevent fracture displacement

Correct Answer & Explanation

. Immobilization in a sling for 4 to 6 weeks

Explanation

Acromial stress fractures after rTSA are a known complication due to the increased tension placed on the deltoid and acromion (increased mechanical advantage). The vast majority of Levy type I and II fractures are initially managed nonoperatively with sling immobilization and activity modification for 4-6 weeks. Surgery is reserved for severely displaced fractures or nonunions that fail conservative management.

Question 257

Topic: Shoulder Arthroplasty & Arthritis

In reverse total shoulder arthroplasty (RTSA), altering the center of rotation (COR) is critical for restoring forward elevation in the setting of rotator cuff arthropathy. Compared to the native anatomic shoulder, how is the COR modified in a classic Grammont-style RTSA?

. Moved superiorly and laterally
. Moved inferiorly and laterally
. Moved inferiorly and medially
. Moved superiorly and medially
. Remains unchanged but becomes highly constrained

Correct Answer & Explanation

. Moved inferiorly and medially

Explanation

The Grammont-style RTSA moves the center of rotation medially and inferiorly. Medialization recruits more deltoid fibers (especially anterior and posterior) by increasing their moment arms, while inferiorization tensions the deltoid, improving its biomechanical efficiency for forward elevation without a functioning rotator cuff.

Question 258

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old female presents with progressive shoulder pain and stiffness 5 years after undergoing a Reverse Total Shoulder Arthroplasty (RTSA) for cuff tear arthropathy. Radiographs reveal scapular notching that is classified as Sirveaux Grade 3. Which of the following best describes this radiographic finding?

. Notch limited entirely to the scapular pillar
. Notch reaching the inferior screw of the baseplate
. Notch extending past the inferior screw but not under the baseplate
. Notch extending underneath the baseplate to the central peg
. Notch with associated gross loosening and baseplate migration

Correct Answer & Explanation

. Notch extending underneath the baseplate to the central peg

Explanation

The Sirveaux classification is used to grade scapular notching after RTSA. Grade 1 involves a notch limited to the scapular pillar. Grade 2 is a notch reaching the inferior screw. Grade 3 is a notch that extends past the inferior screw but does not go under the baseplate. Grade 4 is a notch extending under the baseplate, which is highly correlated with baseplate loosening and clinical failure.

Question 259

Topic: Shoulder Arthroplasty & Arthritis

A 70-year-old female with chronic rotator cuff arthropathy (cuff tear arthropathy) presents with severe shoulder pain and loss of active elevation. Radiographs show superior migration of the humeral head and glenoid erosion. She has failed conservative management. What is the most appropriate surgical treatment?

. Hemiarthroplasty
. Anatomic total shoulder arthroplasty
. Reverse total shoulder arthroplasty
. Arthroscopic debridement
. Rotator cuff repair

Correct Answer & Explanation

. Reverse total shoulder arthroplasty

Explanation

Reverse total shoulder arthroplasty (rTSA) is the gold standard surgical treatment for rotator cuff arthropathy. This condition is characterized by a massive, irreparable rotator cuff tear leading to superior migration of the humeral head, glenoid erosion, and pseudoparalysis. By reversing the ball-and-socket configuration, rTSA medializes and inferiorizes the center of rotation, allowing the deltoid muscle to function effectively even in the absence of a functional rotator cuff, thereby restoring active elevation and alleviating pain. Anatomic total shoulder arthroplasty requires an intact or reparable rotator cuff, which is not the case here.

Question 260

Topic: Shoulder Arthroplasty & Arthritis

When presenting a surgical procedure (e.g., reverse total shoulder arthroplasty), what is the most important biomechanical principle to articulate for scoring highly?

. The length of the humeral stem.
. The material of the glenosphere.
. Medialization of the center of rotation and distalization of the humerus, which increases the deltoid lever arm, allowing the deltoid to compensate for a dysfunctional rotator cuff.
. The number of screws used.
. The type of anesthesia.

Correct Answer & Explanation

. Medialization of the center of rotation and distalization of the humerus, which increases the deltoid lever arm, allowing the deltoid to compensate for a dysfunctional rotator cuff.

Explanation

For Reverse Total Shoulder Arthroplasty (RTSA), understanding its unique biomechanical principles is essential for high marks. The key is to explain how it medializes the center of rotation and distalizes the humerus, thereby increasing the deltoid's lever arm. This biomechanical alteration allows the deltoid muscle to effectively compensate for a deficient or irreparable rotator cuff, enabling active elevation. This demonstrates a deep understanding beyond just the surgical steps.

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