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Shoulder Arthroplasty & Arthritis MCQs

Practice Set 8 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 141

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman with a history of osteoporosis sustains a severely comminuted 4-part proximal humerus fracture. A reverse total shoulder arthroplasty (RTSA) is planned. To optimize outcomes and restore appropriate deltoid tension, which of the following landmarks is most critical for determining the correct height of the humeral prosthesis?

. Bicipital groove
. Superior border of the pectoralis major tendon
. Conjoined tendon insertion
. Lesser tuberosity
. Deltoid tuberosity

Correct Answer & Explanation

. Bicipital groove

Explanation

When performing an RTSA or hemiarthroplasty for a proximal humerus fracture, restoring humeral length and retroversion is critical for proper soft-tissue tensioning, especially of the deltoid. The superior border of the pectoralis major tendon insertion is a reliable landmark. The average distance from the superior border of the pectoralis major insertion to the top of the native humeral head is approximately 5.6 cm.

Question 142

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old right-hand-dominant woman sustains a 4-part proximal humerus fracture. Her medical history includes severe rotator cuff arthropathy with a massive, irreparable rotator cuff tear diagnosed prior to the injury. Which of the following is the most appropriate surgical treatment?

. Open reduction and internal fixation with a locking plate
. Hemiarthroplasty with tuberosity repair
. Reverse total shoulder arthroplasty
. Anatomic total shoulder arthroplasty
. Nonoperative management with a sling

Correct Answer & Explanation

. Open reduction and internal fixation with a locking plate

Explanation

Reverse total shoulder arthroplasty (rTSA) is indicated in elderly patients with a 4-part proximal humerus fracture when there is preexisting severe rotator cuff dysfunction or arthropathy. It is also favored when the bone quality is poor or tuberosity healing is unreliable. Hemiarthroplasty relies on a functional rotator cuff and anatomic healing of the tuberosities for a good outcome, making it inappropriate in this patient.

Question 143

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman with advanced cuff tear arthropathy and pseudoparalysis undergoes a reverse total shoulder arthroplasty (RTSA).

To minimize the risk of inferior scapular notching postoperatively, how should the glenoid baseplate and glenosphere be positioned?

. Superior translation and superior tilt
. Inferior translation and inferior tilt
. Neutral translation and superior tilt
. Anterior translation and superior tilt
. Posterior translation and neutral tilt

Correct Answer & Explanation

. Superior translation and superior tilt

Explanation

Scapular notching is a frequent complication of RTSA resulting from the medial and inferior aspect of the humeral tray impinging against the scapular neck during adduction. The widely accepted technique to minimize this mechanical conflict is positioning the glenoid baseplate with an inferior tilt and inferior translation, allowing the glenosphere to overhang the inferior rim of the native glenoid.

Question 144

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman with a massive, irreparable rotator cuff tear and pseudoparalysis is scheduled to undergo a reverse total shoulder arthroplasty (RTSA). Scapular notching is a well-documented complication of this procedure. Which of the following surgical modifications or implant design choices is most effective in decreasing the incidence of scapular notching?

. Superior translation of the glenosphere
. Inferior translation of the glenosphere past the inferior glenoid rim
. Decreasing the diameter of the glenosphere
. Increasing the neck-shaft angle of the humeral component to 155 degrees
. Medialization of the center of rotation without inferior translation

Correct Answer & Explanation

. Superior translation of the glenosphere

Explanation

Scapular notching occurs when the humeral component impinges against the inferior neck of the scapula during adduction. Placing the glenosphere with an inferior translation (overhanging the inferior glenoid rim by 2 to 4 mm) limits this mechanical impingement. Additionally, lateralization of the glenosphere, a smaller neck-shaft angle (e.g., 135 vs 155 degrees), and a larger glenosphere diameter have also been shown to reduce the risk of scapular notching.

Question 145

Topic: Shoulder Arthroplasty & Arthritis

Scapular notching is a well-recognized complication following reverse total shoulder arthroplasty (RTSA). Which of the following technical adjustments regarding glenosphere positioning most effectively minimizes the risk of inferior scapular notching?

. Superior placement with a superior tilt
. Inferior placement with an inferior tilt
. Central placement with a superior tilt
. Superior placement with neutral tilt
. Medialized placement with superior tilt

Correct Answer & Explanation

. Superior placement with a superior tilt

Explanation

Scapular notching in RTSA occurs when the medial aspect of the humeral tray or liner impinges against the inferior scapular neck during arm adduction. To minimize this, biomechanical and clinical studies have shown that placing the glenosphere low on the glenoid (inferior placement) with an inferior tilt (typically 0 to 10 degrees) increases the impingement-free range of motion. Lateralization of the center of rotation also decreases notching, whereas medialization and superior placement increase the risk of impingement and subsequent notching.

Question 146

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman with a history of a massive, irreparable rotator cuff tear and pseudoparalysis undergoes a reverse total shoulder arthroplasty (RTSA). Biomechanically, how does the RTSA restore active forward elevation in the setting of a deficient rotator cuff?

. It lateralizes the center of rotation and decreases the deltoid moment arm.
. It medializes and distalizes the center of rotation, thereby increasing the deltoid moment arm.
. It superiorly shifts the center of rotation to recruit the intact subscapularis.
. It increases tension on the coracoacromial ligament to provide a static restraint.
. It medializes the humerus and proximalizes the center of rotation.

Correct Answer & Explanation

. It lateralizes the center of rotation and decreases the deltoid moment arm.

Explanation

The reverse total shoulder arthroplasty (RTSA) functions by altering the biomechanics of the shoulder. Grammont's original design medializes and distalizes the center of rotation relative to the native shoulder. Medialization recruits more deltoid muscle fibers for elevation, while distalization tensions the deltoid, increasing its resting tone and effectively lengthening its moment arm, which compensates for the absent rotator cuff.

Question 147

Topic: Shoulder Arthroplasty & Arthritis

A 76-year-old woman with a history of severe osteoporosis sustains a 4-part proximal humerus fracture after a mechanical fall. Radiographs demonstrate severe comminution of the tuberosities and a valgus-impacted head with varus collapse. She is functionally active and desires to return to her previous daily activities. Which surgical intervention is associated with the most predictable restoration of active forward elevation in this patient profile?

. Open reduction and internal fixation with a locking plate
. Hemiarthroplasty of the shoulder
. Reverse total shoulder arthroplasty (RTSA)
. Closed reduction and percutaneous pinning
. Intramedullary nailing

Correct Answer & Explanation

. Open reduction and internal fixation with a locking plate

Explanation

Reverse total shoulder arthroplasty (RTSA) has become the preferred surgical treatment for displaced 3- and 4-part proximal humerus fractures in elderly patients with poor bone quality. Compared to hemiarthroplasty and ORIF, RTSA provides more predictable pain relief and restoration of active forward elevation because its function relies on the deltoid muscle rather than anatomic tuberosity healing. Hemiarthroplasty outcomes are notoriously unreliable in this population due to the high rate of tuberosity nonunion or resorption in osteoporotic bone.

Question 148

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old man underwent a reverse total shoulder arthroplasty (RTSA) for massive rotator cuff tear arthropathy 2 years ago. He now complains of progressive lateral shoulder pain and a 'clunking' sensation. Radiographs demonstrate severe scapular notching that extends beyond the inferior screw of the baseplate. What is the primary modifiable surgical risk factor for scapular notching in RTSA?

. Superior placement of the glenosphere
. Use of a lateralized glenosphere
. Inferior tilt of the glenosphere
. Anterior placement of the glenosphere
. Use of a smaller diameter humeral cup

Correct Answer & Explanation

. Superior placement of the glenosphere

Explanation

Scapular notching in reverse total shoulder arthroplasty (RTSA) is caused by mechanical impingement of the medial edge of the humeral cup against the inferior scapular neck during adduction. The most significant surgeon-controlled risk factor for notching is a superiorly placed glenosphere. To minimize notching, the baseplate and glenosphere should be placed inferiorly on the glenoid, often flush with or slightly overhanging the inferior rim, and with a slight inferior tilt. Lateralizing the center of rotation also helps to decrease scapular notching by increasing the clearance between the humerus and the scapular neck.

Question 149

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old man undergoes a reverse total shoulder arthroplasty (RTSA) for massive rotator cuff tear arthropathy. According to Grammont's original biomechanical principles, how does the RTSA prosthesis alter the center of rotation and the deltoid moment arm compared to the native anatomic shoulder?

. Medializes and inferiorizes the center of rotation, increasing the deltoid moment arm
. Lateralizes and superiorizes the center of rotation, increasing the deltoid moment arm
. Medializes and superiorizes the center of rotation, decreasing the deltoid moment arm
. Lateralizes and inferiorizes the center of rotation, decreasing the deltoid moment arm
. Medializes and inferiorizes the center of rotation, decreasing the deltoid moment arm

Correct Answer & Explanation

. Medializes and inferiorizes the center of rotation, increasing the deltoid moment arm

Explanation

Grammont's biomechanical principles for reverse total shoulder arthroplasty (RTSA) involve medializing and inferiorizing the center of rotation of the glenohumeral joint relative to the native anatomy. Medializing the center of rotation recruits more deltoid muscle fibers and significantly increases the deltoid moment arm, making it a more efficient elevator of the arm. Inferiorizing the center of rotation essentially lengthens and tensions the deltoid muscle, compensating for the lack of a functional rotator cuff. This altered biomechanics allows the deltoid to initiate and maintain forward elevation without the superior migration of the humeral head typical of cuff tear arthropathy.

Question 150

Topic: Shoulder Arthroplasty & Arthritis

A 75-year-old female with severe shoulder pseudoparalysis and cuff tear arthropathy undergoes a reverse total shoulder arthroplasty (RTSA). Postoperative radiographs taken 1 year later demonstrate inferior scapular notching. Which of the following surgical technique modifications during the index procedure would have most effectively minimized the risk of this complication?

. Superior placement of the glenosphere
. Superior tilt of the baseplate
. Lateralization of the center of rotation
. Medialization of the humerus
. Use of a smaller diameter glenosphere

Correct Answer & Explanation

. Superior placement of the glenosphere

Explanation

Scapular notching is a well-recognized complication of Grammont-style (medialized) reverse total shoulder arthroplasty, often caused by impingement of the humeral cup against the inferior scapular neck during adduction. Techniques to minimize scapular notching include inferior placement of the baseplate, inferior tilt (not superior), and lateralization of the center of rotation (e.g., using a lateralized glenosphere or bony BIO-RSA). Medialization of the humerus and smaller glenospheres generally increase the risk of notching.

Question 151

Topic: Shoulder Arthroplasty & Arthritis

A 70-year-old woman with advanced rotator cuff tear arthropathy is scheduled for a reverse total shoulder arthroplasty (RTSA). During preoperative templating and intraoperative execution, which of the following glenosphere positioning strategies is most effective in minimizing the risk of scapular notching?

. Superior placement with superior tilt
. Inferior placement with inferior tilt
. Superior placement with neutral tilt
. Medialization of the center of rotation with superior tilt
. Neutral placement with superior tilt

Correct Answer & Explanation

. Inferior placement with inferior tilt

Explanation

Scapular notching is a common and highly recognized complication of reverse total shoulder arthroplasty (RTSA). It occurs due to mechanical impingement of the humeral polyethylene cup against the inferior scapular neck during arm adduction. Inferior placement of the baseplate along with inferior tilt of the glenosphere, and lateralization of the center of rotation, have been proven to significantly decrease the incidence of scapular notching by increasing the impingement-free range of motion.

Question 152

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman is 3 years post Reverse Total Shoulder Arthroplasty (RTSA). Radiographs show Grade 3 scapular notching. Which of the following surgical techniques or implant designs would most effectively minimize the risk of this complication?

. Superior baseplate positioning
. A 155-degree humeral neck-shaft angle
. Medialization of the glenosphere
. Inferior baseplate positioning with inferior tilt
. Decreased glenosphere diameter

Correct Answer & Explanation

. Inferior baseplate positioning with inferior tilt

Explanation

Scapular notching is a well-known complication of RTSA caused by mechanical impingement of the humeral component against the inferior scapular neck during adduction. Factors that decrease the risk of scapular notching include inferior placement of the glenoid baseplate, inferior tilt of the baseplate, lateralization of the glenosphere, use of a larger glenosphere, and a lower humeral neck-shaft angle (e.g., 135 degrees vs 155 degrees).

Question 153

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman undergoes reverse total shoulder arthroplasty for cuff tear arthropathy. At her 2-year follow-up, radiographs show inferior scapular notching. Which of the following component positionings is most strongly associated with this radiographic finding?

. Superior placement of the glenosphere.
. Inferior tilt of the glenosphere.
. Increased lateralization of the glenosphere.
. Decreased neck-shaft angle of the humeral component.
. Increased retroversion of the humeral component.

Correct Answer & Explanation

. Superior placement of the glenosphere.

Explanation

Scapular notching is a frequent complication following reverse total shoulder arthroplasty, caused by mechanical impingement of the medial humeral metaphysis against the inferior scapular neck during adduction. Superior placement and medialization of the glenosphere significantly increase the risk of notching. Conversely, surgical techniques and implant designs utilizing inferior placement, inferior tilt, and lateralization of the glenosphere help mitigate this impingement.

Question 154

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman presents 3 years after a reverse total shoulder arthroplasty with progressive shoulder pain. Radiographs are shown in Figure 1. What factor most contributes to the complication seen (scapular notching)?

. Superior baseplate tilt
. Inferior baseplate tilt
. Large glenosphere
. Lateralized glenosphere
. Increased humeral retroversion

Correct Answer & Explanation

. Superior baseplate tilt

Explanation

Scapular notching is a frequent complication of reverse total shoulder arthroplasty (RTSA), particularly with Grammont-style prostheses. Risk factors include superior tilt of the baseplate, high placement on the glenoid, and a medialized center of rotation. In contrast, inferior tilt, lateralization, and the use of a larger glenosphere can reduce the incidence of notching by increasing the distance between the humerus and the scapular neck during adduction.

Question 155

Topic: Shoulder Arthroplasty & Arthritis

A 78-year-old female with severe osteoporosis sustains a 3-part proximal humerus fracture. Due to the high risk of avascular necrosis and poor bone quality, a reverse total shoulder arthroplasty (RTSA) is performed. In this setting, healing of which of the following structures is most critical to ensure adequate functional external rotation and optimal clinical outcomes?

. Lesser tuberosity
. Greater tuberosity
. Subscapularis tendon
. Biceps long head tendon
. Coracoacromial ligament

Correct Answer & Explanation

. Greater tuberosity

Explanation

In the setting of reverse total shoulder arthroplasty (RTSA) for proximal humerus fractures, anatomic healing of the greater tuberosity is strongly associated with improved active forward elevation and external rotation. Failure of greater tuberosity healing often leads to decreased functional outcomes due to the loss of the posterior rotator cuff (infraspinatus and teres minor) acting as a force couple and external rotator.

Question 156

Topic: Shoulder Arthroplasty & Arthritis

The Grammont design of a reverse total shoulder arthroplasty (RTSA) alters the biomechanics of the shoulder to compensate for a massive, irreparable rotator cuff tear. Which of the following accurately describes the primary biomechanical advantage of this design?

. It medializes and superiorly translates the center of rotation, decreasing the deltoid moment arm.
. It lateralizes and inferiorly translates the center of rotation, increasing the tension on the remaining rotator cuff.
. It medializes and inferiorly translates the center of rotation, increasing the deltoid moment arm and recruiting more deltoid muscle fibers.
. It lateralizes and superiorly translates the center of rotation, maximizing the joint reaction force.
. It maintains the anatomic center of rotation but constrains the joint to prevent superior migration.

Correct Answer & Explanation

. It medializes and inferiorly translates the center of rotation, increasing the deltoid moment arm and recruiting more deltoid muscle fibers.

Explanation

The Grammont design principles for reverse total shoulder arthroplasty include medializing and inferiorly translating the center of rotation. Medialization decreases the torque on the glenoid component, reducing the risk of loosening, while inferior translation tensions the deltoid muscle. Together, these biomechanical changes significantly increase the deltoid's moment arm and recruit more of its anterior and posterior fibers, allowing the deltoid to compensate for the deficient rotator cuff and elevate the arm effectively.

Question 157

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old woman undergoes reverse total shoulder arthroplasty for cuff tear arthropathy. Postoperatively, she does well but at 2-year follow-up, radiographs show grade 2 scapular notching. Which of the following surgical modifications would have most likely decreased the risk of this complication?

. Superior tilt of the glenosphere
. Superior placement of the baseplate
. Inferior placement of the glenosphere with overhang
. Decreasing the size of the glenosphere
. Medialization of the center of rotation

Correct Answer & Explanation

. Inferior placement of the glenosphere with overhang

Explanation

Scapular notching is a well-recognized complication of reverse total shoulder arthroplasty (RTSA), occurring when the medial aspect of the humeral tray impinges on the inferior scapular neck during adduction. Placing the glenosphere inferiorly with overhang, using a larger glenosphere, lateralizing the center of rotation, and applying an inferior tilt to the baseplate are technical modifications that reduce the risk of scapular notching. Superior placement, superior tilt, and medialization of the center of rotation increase the risk.

Question 158

Topic: Shoulder Arthroplasty & Arthritis

Scapular notching is a well-documented complication of reverse total shoulder arthroplasty (rTSA). Which of the following baseplate and glenosphere positioning strategies is most strongly associated with a decreased incidence of inferior scapular notching?

. Superior translation and superior tilt
. Inferior translation and inferior tilt
. Medialization of the center of rotation
. Superior translation and inferior tilt
. Decreasing the lateral offset

Correct Answer & Explanation

. Inferior translation and inferior tilt

Explanation

Inferior translation and inferior tilt of the glenosphere, along with lateralization, help reduce the incidence of scapular notching. This positioning minimizes mechanical impingement of the medial aspect of the humeral component against the inferior scapular neck during arm adduction.

Question 159

Topic: Shoulder Arthroplasty & Arthritis

A 72-year-old man with cuff tear arthropathy undergoes a reverse total shoulder arthroplasty. By medializing and inferiorly shifting the center of rotation, which of the following is the primary biomechanical advantage achieved?

. Decreases the deltoid moment arm and increases tension on the remaining rotator cuff
. Increases the deltoid moment arm and recruits more anterior and posterior deltoid fibers for elevation
. Restores the native anatomic center of rotation to optimize pectoralis major function
. Lateralizes the center of rotation to increase the resting tension of the deltoid
. Increases the superior translation of the humerus during active elevation

Correct Answer & Explanation

. Increases the deltoid moment arm and recruits more anterior and posterior deltoid fibers for elevation

Explanation

The Grammont principles of reverse total shoulder arthroplasty involve medializing and moving the center of rotation inferiorly relative to the native glenoid. This design significantly increases the deltoid moment arm and recruits more of the anterior and posterior deltoid fibers to assist in forward elevation and abduction. It also lowers the humerus (distalizes), thereby tensioning the deltoid and increasing its mechanical advantage, compensating for the functionally deficient rotator cuff.

Question 160

Topic: Shoulder Arthroplasty & Arthritis

A 75-year-old woman with a history of severe osteoporosis sustains a 4-part proximal humerus fracture. She is treated with a reverse total shoulder arthroplasty (rTSA). Which of the following tuberosity management strategies during the index procedure is most associated with improved functional outcomes?

. Excision of both the greater and lesser tuberosities
. Routine transfer of the latissimus dorsi
. Anatomic repair and healing of the greater tuberosity
. Nonanatomic healing of the tuberosities to the diaphysis
. Tenodesis of the long head of the biceps to the subscapularis

Correct Answer & Explanation

. Anatomic repair and healing of the greater tuberosity

Explanation

Reverse total shoulder arthroplasty (rTSA) has become an increasingly popular option for complex proximal humerus fractures in the elderly. While the prosthesis itself confers stability, anatomic healing of the tuberosities (particularly the greater tuberosity) is highly correlated with improved patient-reported outcomes, increased forward elevation, and enhanced external rotation. Nonunion, malunion, or excision of the tuberosities typically leads to poorer functional recovery.

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