Ortho MCQs: Shoulder, Elbow, Arthroplasty - Part 29

Question 1

Which of the following biomechanical changes occurs following a properly implanted reverse total shoulder arthroplasty (RTSA) compared to the native shoulder anatomy?

Explanation

Reverse total shoulder arthroplasty (RTSA) alters normal shoulder biomechanics by medializing and inferiorizing the center of rotation. This increases the moment arm of the deltoid, recruits more of the anterior and posterior deltoid fibers, and increases the resting tension of the deltoid, allowing it to compensate for a deficient rotator cuff.

Question 2

When performing a total elbow arthroplasty (TEA) for a patient with severe advanced rheumatoid arthritis, what is the primary biomechanical advantage of using a linked (semi-constrained) implant over an unlinked implant?

Explanation

Linked (semi-constrained) TEA implants do not rely on native capsuloligamentous structures for stability. This makes them the implant of choice for patients with profound ligamentous instability, severe bone loss, or extensive deformity, all of which are common in end-stage rheumatoid arthritis or post-traumatic scenarios. Unlinked implants require intact collateral ligaments and adequate bone stock for stability.

Question 3

A 65-year-old male presents with persistent, vague shoulder pain 18 months after an anatomic total shoulder arthroplasty. Inflammatory markers (ESR, CRP) are within normal limits. Radiographs show early radiolucency around the glenoid peg. A joint aspirate is performed. Which of the following is the most appropriate step regarding the microbiological culture?

Explanation

Cutibacterium acnes (formerly Propionibacterium acnes) is an indolent, slow-growing anaerobic Gram-positive bacillus commonly responsible for periprosthetic shoulder infections. It often presents with a normal ESR and CRP. Cultures must be held for 14 to 21 days to accurately detect it.

Question 4

In the surgical management of a 'terrible triad' injury of the elbow (elbow dislocation, radial head fracture, coronoid fracture), which of the following represents the most widely accepted sequence of repair through a lateral approach?

Explanation

The standard surgical sequence for a terrible triad is 'deep to superficial' (or medial to lateral) from the lateral approach: repair/fix the coronoid first (often visualizing it through the defect left by the fractured radial head), then repair or replace the radial head, then repair the LCL complex. The MCL is typically only addressed if the elbow remains unstable in extension after the lateral-sided and intra-articular repairs are complete.

Question 5

A 62-year-old female undergoes an anatomic total shoulder arthroplasty via a deltopectoral approach. Six weeks postoperatively, she describes feeling a 'pop' while pushing open a heavy door. She subsequently demonstrates increased passive external rotation and weakness in internal rotation. What is the most likely diagnosis?

Explanation

Subscapularis failure is a known and serious complication after anatomic TSA, as the tendon is often peeled, tenotomized, or osteotomized during the standard deltopectoral approach. Presentation includes a sudden 'pop', unexpectedly increased passive external rotation, weakness in internal rotation (positive lift-off or belly-press tests), and sometimes anterior instability.

Question 6

A 24-year-old rugby player undergoes an open Latarjet procedure for recurrent anterior shoulder instability with 25% glenoid bone loss. Postoperatively, he has profound weakness in elbow flexion and decreased sensation over the lateral aspect of his forearm. Which nerve was most likely injured during the procedure?

Explanation

The musculocutaneous nerve enters the coracobrachialis 5-8 cm distal to the coracoid process but can have a higher entry point. It is at significant risk during coracoid osteotomy, mobilization, and retraction during the Latarjet procedure. Injury results in biceps/brachialis weakness (diminished elbow flexion) and numbness in the lateral antebrachial cutaneous nerve distribution.

Question 7

A 30-year-old male complains of right shoulder weakness and a prominent shoulder blade after a heavy traction injury to his neck and shoulder. On examination, there is marked prominence of the medial border of the scapula, especially when pushing against a wall. Injury to which of the following nerves is the most likely cause?

Explanation

Medial scapular winging (prominence of the medial border) is caused by serratus anterior palsy, which is innervated by the long thoracic nerve (C5, C6, C7). Lateral winging is caused by trapezius palsy, which is innervated by the spinal accessory nerve.

Question 8

When comparing the single-incision anterior approach to the two-incision approach for distal biceps tendon repair, the single-incision approach is associated with a statistically higher risk of injury to which of the following structures?

Explanation

The single-incision anterior approach carries a higher risk of lateral antebrachial cutaneous nerve (LABC) neuropraxia, as the LABC exits between the biceps and brachialis and runs directly in the superficial field of the anterior approach. The two-incision approach carries a higher risk of heterotopic ossification and radioulnar synostosis.

Question 9

A 72-year-old female presents with pseudoparalysis of the right shoulder. Radiographs reveal an acromiohumeral interval of 3 mm, acetabularization of the acromion, and femoralization of the humeral head, but no distinct glenohumeral joint space narrowing. According to the Hamada classification for rotator cuff tear arthropathy, what is her grade?

Explanation

Hamada classification: Grade 1: Acromiohumeral interval (AHI) > 6 mm. Grade 2: AHI < 7 mm (often < 5 mm). Grade 3: Acetabularization of the acromion. Grade 4: Glenohumeral arthritis (narrowed joint space). Grade 5: Humeral head collapse (osteonecrosis). This patient has Grade 3.

Question 10

A 78-year-old female sustains a displaced 4-part proximal humerus fracture. Which of the following factors makes primary reverse total shoulder arthroplasty (RTSA) a more appropriate choice than open reduction internal fixation (ORIF) or anatomic hemiarthroplasty?

Explanation

RTSA is highly indicated in elderly patients with 4-part proximal humerus fractures, particularly in the setting of pre-existing rotator cuff dysfunction (cuff tear arthropathy) or when bone quality makes tuberosity healing doubtful. Hemiarthroplasty relies heavily on tuberosity healing for good function, and ORIF has high failure rates in elderly osteoporotic bone with comminution.

Question 11

A 21-year-old collegiate baseball pitcher presents with posterior shoulder pain during the late cocking phase of throwing. Examination shows a 25-degree loss of internal rotation compared to the contralateral side. Which of the following pathologic mechanisms is primarily responsible for internal impingement in this athlete?

Explanation

Internal impingement in overhead throwing athletes occurs during extreme abduction and external rotation (late cocking phase). This position causes the articular (undersurface) side of the posterosuperior rotator cuff (supraspinatus/infraspinatus) to impinge against the posterosuperior glenoid and labrum. GIRD (glenohumeral internal rotation deficit) from posterior capsular contracture frequently contributes.

Question 12

A 45-year-old female falls on an outstretched hand and sustains a capitellum fracture. The fracture extends medially to include the lateral aspect of the trochlea, but the posterior condylar bone remains intact. According to the Dubberley classification, what type of fracture is this?

Explanation

Dubberley classification of capitellum fractures: Type 1: involves capitellum with or without lateral trochlear ridge. Type 2: involves capitellum and lateral trochlea as a single piece. Type 3: comminuted capitellum and lateral trochlea. 'A' indicates the posterior condyle is intact; 'B' indicates a posterior condylar fracture (loss of posterior support). The described fracture is Type 2A.

Question 13

When evaluating recurrent anterior shoulder instability, a 3D CT scan is often obtained to quantify glenoid bone loss using the 'best-fit circle' method. What is the classic critical threshold of glenoid bone loss above which isolated soft tissue stabilization (Bankart repair) has unacceptably high failure rates?

Explanation

The traditional 'critical' threshold for glenoid bone loss is 20-25%. Although recent literature suggests 'subcritical' bone loss (13.5-20%) can also lead to poorer outcomes, 20-25% remains the classic board answer threshold indicating the definitive need for a bony augmentation procedure (e.g., Latarjet).

Question 14

A 40-year-old laborer undergoes an open subpectoral biceps tenodesis. Postoperatively, he presents with profound weakness in wrist extension, finger extension, and numbness over the dorsal web space of the hand. Which of the following technical errors most likely occurred during the procedure?

Explanation

The radial nerve runs posterior to the humerus in the spiral groove and is at risk if a drill plunges through the posterior cortex during a subpectoral biceps tenodesis (especially with bicortical button fixation). Deficits in wrist/finger extension and dorsal web space numbness are classic for a radial nerve injury. Medial retractor placement endangers the musculocutaneous nerve.

Question 15

Scapular notching is a common radiographic finding after reverse total shoulder arthroplasty (RTSA). According to the Sirveaux classification, a notch that extends past the inferior screw of the glenoid baseplate is classified as:

Explanation

Sirveaux classification of scapular notching: Grade 1: Notching confined to the scapular pillar. Grade 2: Notching reaches the inferior screw of the baseplate. Grade 3: Notching extends past the inferior screw. Grade 4: Notching extends to the central peg.

Question 16

A 17-year-old football player sustains a posterior sternoclavicular joint dislocation. He complains of hoarseness and difficulty swallowing. After a careful assessment by a multidisciplinary team, closed reduction in the operating room is planned. What is the most appropriate technique for reduction?

Explanation

For posterior SC joint dislocation, closed reduction is typically performed with a bolster between the scapulae. Lateral traction on the abducted arm is applied, and a towel clip or fingers are used to grasp the medial clavicle and pull it anteriorly. Thoracic surgery backup should be available due to the proximity of mediastinal structures (trachea, esophagus, great vessels).

Question 17

A 28-year-old male bodybuilder feels a tearing sensation in his anterior axilla while bench-pressing. Physical examination reveals a loss of the anterior axillary fold. MRI confirms a complete rupture of the sternocostal head of the pectoralis major. Where does the sternocostal head normally insert on the humerus relative to the clavicular head?

Explanation

The pectoralis major tendon twists 90 degrees before inserting on the lateral lip of the bicipital groove. The clavicular head inserts distally and anteriorly, while the sternocostal head twists to insert proximally and posteriorly (deep) to the clavicular head insertion. The sternocostal head is most commonly torn during the eccentric phase of heavy lifting.

Question 18

A 45-year-old male undergoes radial head arthroplasty for a highly comminuted radial head fracture. Intraoperatively, the surgeon inadvertently inserts an implant that is 3 mm longer than the native radial head. What is the most likely clinical consequence of 'overstuffing' the radiocapitellar joint?

Explanation

Overstuffing the radial head causes pathologically increased radiocapitellar contact pressures. This leads to capitellar cartilage erosion, early arthritis, lateral elbow pain, and a mechanical loss of elbow flexion and extension.

Question 19

A 50-year-old weightlifter presents with an inability to actively extend his elbow against gravity following a sudden pop. MRI shows a complete avulsion of the triceps tendon from the olecranon. During surgical repair, an anatomic reattachment is planned. Where is the true anatomic footprint of the triceps tendon located on the olecranon?

Explanation

The triceps footprint is located approximately 1 to 2 cm distal to the very tip of the olecranon on the posterior surface. Reattaching it too proximally (at the very tip) can cause mechanical impingement in the olecranon fossa during extension, leading to a loss of full terminal extension.

Question 20

A 26-year-old cyclist falls directly onto his right shoulder. Radiographs reveal superior displacement of the distal clavicle. The axillary view clearly demonstrates the distal clavicle displaced posteriorly into the trapezius muscle fascia. What is the Rockwood classification of this acromioclavicular injury?

Explanation

Rockwood classification: Type I (sprain), Type II (AC torn, CC sprained), Type III (AC and CC torn, clavicle superiorly displaced up to 100%), Type IV (clavicle displaced posteriorly into or through the trapezius muscle), Type V (clavicle displaced superiorly >100-300%), Type VI (clavicle displaced inferiorly under the coracoid or acromion). The posterior displacement into the trapezius defines a Type IV injury.

Question 21

A 70-year-old female presents with new-onset lateral shoulder pain 4 months after undergoing an uncomplicated reverse total shoulder arthroplasty (RTSA). Radiographs demonstrate a Levy Type II acromial stress fracture at the base of the acromion. What is the most appropriate initial management?

Explanation

Levy Type II acromial stress fractures (located at the base of the acromion) following RTSA are typically managed nonoperatively in the initial stages with a sling and conservative care. Surgery is generally reserved for severe, progressive displacement or symptomatic nonunion after an adequate trial of conservative management, due to the high complication rates associated with internal fixation of these osteopenic fractures.

Question 22

A 65-year-old male with primary glenohumeral osteoarthritis presents for anatomic total shoulder arthroplasty (TSA). Preoperative CT scanning demonstrates a Walch B2 glenoid with 22 degrees of retroversion and posterior humeral head subluxation. During the procedure, which strategy best addresses the glenoid deformity while minimizing the risk of early component loosening?

Explanation

In Walch B2 glenoids with severe retroversion (>15 degrees), high-side anterior eccentric reaming to achieve neutral version removes excessive subchondral bone, risking peg or keel perforation into the vault and compromising fixation. The use of augmented (posteriorly stepped or wedged) glenoid components allows for correction of retroversion while preserving critical anterior glenoid bone stock, reducing the risk of component loosening.

Question 23

A 68-year-old female with severe rheumatoid arthritis undergoes a linked total elbow arthroplasty (TEA). At her 5-year follow-up, she complains of progressive weakness in her pinch grip and numbness in her ring and small fingers. What is the most common cause of this specific neurological presentation following TEA?

Explanation

Ulnar neuropathy is a frequently reported complication following TEA (historically up to 10-15%). It can occur due to direct surgical manipulation, excessive traction, postoperative scarring, or proximity to the hardware/cement mantle. The clinical presentation includes paresthesias in the ring and small fingers and weakness in ulnar-innervated intrinsics (affecting pinch grip and finger abduction/adduction).

Question 24

During a revision shoulder arthroplasty for a painful, stiff TSA, intraoperative cultures are obtained. At 10 days, the cultures grow Cutibacterium acnes. Which characteristic of this organism makes it particularly challenging to diagnose and treat in the setting of shoulder arthroplasty?

Explanation

Cutibacterium acnes (formerly Propionibacterium acnes) is a slow-growing, Gram-positive, anaerobic rod commonly found in the sebaceous glands of the shoulder. It often causes indolent, low-grade periprosthetic joint infections lacking classic clinical signs (e.g., normal CRP/ESR, no fever, no erythema). Its ability to form a protective biofilm on implants makes both diagnosis (requiring extended culture times) and eradication challenging.

Question 25

A 45-year-old male sustains a terrible triad injury of the elbow. He undergoes operative management comprising radial head replacement, coronoid fracture fixation, and lateral ulnar collateral ligament (LUCL) repair. What is the most appropriate early postoperative rehabilitation protocol to maintain stability while promoting motion?

Explanation

Following a terrible triad repair (which intrinsically involves LUCL repair), early active motion is preferred to prevent stiffness. Active extension should be performed with the forearm in pronation. Pronation engages the radial head against the capitellum and protects the repaired lateral collateral ligament complex from excessive varus and posterolateral rotatory stress. Flexion is generally safe in any forearm position.

Question 26

A 72-year-old male who underwent a reverse total shoulder arthroplasty (RTSA) returns for his 3-year follow-up. Radiographs demonstrate a Sirveaux grade 3 scapular notch. Which surgical technique during the initial index procedure would have most effectively decreased the risk of this complication?

Explanation

Scapular notching in RTSA is caused by mechanical impingement of the medial edge of the humeral cup against the inferior scapular neck during adduction. Techniques to prevent notching include placing the glenosphere inferiorly (creating an inferior overhang), lateralizing the center of rotation (via bone graft or metallic augmentation), using a larger diameter glenosphere, and placing the glenosphere with an inferior tilt.

Question 27

A 60-year-old male undergoes an anatomic TSA for osteoarthritis. The surgeon utilizes a lesser tuberosity osteotomy (LTO) for joint access. At 8 weeks postoperatively, the patient reports increased pain and an inability to actively internally rotate against resistance. Which physical exam finding is most indicative of failure of the LTO and subscapularis repair?

Explanation

The belly-press test evaluates the integrity of the subscapularis. A positive test indicates subscapularis weakness or failure (such as an LTO nonunion or tendon rupture). It is characterized by the patient dropping their elbow posteriorly and flexing the wrist to press on the abdomen, thereby substituting wrist flexion and shoulder extension for internal rotation. Hornblower's sign tests the teres minor.

Question 28

A 38-year-old male undergoes a single-incision anterior distal biceps tendon repair using a cortical button technique. Postoperatively, he exhibits a complete inability to actively extend his thumb and fingers at the metacarpophalangeal (MP) joints, though his wrist extension is preserved with radial deviation. This complication is most likely due to injury to which structure, and during which surgical step?

Explanation

The posterior interosseous nerve (PIN) is at risk during the single-incision distal biceps repair, particularly when drilling the posterior (far) cortex of the radius or passing the cortical button. If the forearm is not fully pronated during this step, the PIN wraps closer to the drill trajectory. Injury results in PIN palsy: loss of finger and thumb MP extension (finger drop), but preserved wrist extension (with radial deviation) because the extensor carpi radialis longus is innervated by the radial nerve proper proximal to the PIN bifurcation.

Question 29

During an anatomic total shoulder arthroplasty, the surgeon is selecting the appropriate humeral head component. Overstuffing the glenohumeral joint with a humeral head component that is too thick will most likely result in which of the following postoperative issues?

Explanation

Overstuffing the joint in anatomic TSA (by using an excessively thick humeral head or placing it too high) tightens the soft tissue envelope excessively. This typically limits the patient's arc of motion, specifically restricting external rotation, and places undue tension on the anterior structures, increasing the risk of postoperative subscapularis repair failure. It also accelerates polyethylene wear due to increased joint reactive forces.

Question 30

A 75-year-old male is undergoing a total elbow arthroplasty (TEA) for a severely comminuted distal humerus fracture. The surgeon elects to use a triceps-sparing (triceps-on) approach. Compared to the classic triceps-reflecting (Bryan-Morrey) approach, the triceps-sparing approach has a significantly lower risk of which specific complication?

Explanation

Triceps-sparing approaches (such as the paratricipital or triceps-split approach) leave the extensor mechanism attached to the olecranon. This drastically reduces the risk of postoperative triceps insufficiency, weakness, or avulsion compared to approaches that require detachment and subsequent repair of the triceps tendon (like the Bryan-Morrey reflecting approach or the olecranon osteotomy).

Question 31

A 55-year-old manual laborer presents with a massive, irreparable posterosuperior rotator cuff tear (supraspinatus and infraspinatus). He has an intact subscapularis, a severe external rotation lag, but pseudoparalysis is absent. Which tendon transfer is most appropriate to restore active external rotation and forward elevation in this patient?

Explanation

The latissimus dorsi transfer (and increasingly the lower trapezius transfer) is indicated for young, active patients with massive, irreparable posterosuperior rotator cuff tears (involving the supraspinatus and infraspinatus). It aims to restore active external rotation and forward elevation. Key prerequisites include an intact subscapularis, intact deltoid, minimal glenohumeral arthritis, and the absence of true pseudoparalysis. Pectoralis major transfers are reserved for irreparable subscapularis tears.

Question 32

A 68-year-old female undergoes a reverse total shoulder arthroplasty (RTSA). Six weeks postoperatively, she presents to the emergency department with an anterior dislocation of the prosthesis. Which of the following is considered the most significant mechanical risk factor for instability following a RTSA?

Explanation

The stability of a reverse total shoulder prosthesis is primarily provided by the resting tension and compressive force of the deltoid muscle across the joint. Inadequate restoration of humeral length (failure to sufficiently lengthen the humerus and tension the deltoid) is the most significant mechanical risk factor for dislocation following RTSA.

Question 33

A 32-year-old male falls on an outstretched hand and sustains an anteromedial facet fracture of the coronoid. What is the primary mechanism of injury causing this specific coronoid fracture pattern, and which ligament is most critically involved?

Explanation

Anteromedial facet fractures of the coronoid are the hallmark of posteromedial rotatory instability (PMRI) of the elbow. The mechanism typically involves an axial load with varus stress on an extended elbow. The lateral collateral ligament (LCL) complex (specifically the LUCL) invariably fails first, leading to varus subluxation and subsequent impingement/fracture of the anteromedial coronoid facet against the medial trochlea.

Question 34

A 45-year-old male with an irreparable supraspinatus tear undergoes a Superior Capsular Reconstruction (SCR) utilizing a thick dermal allograft. What is the primary biomechanical function of the graft in this procedure?

Explanation

The primary biomechanical rationale for Superior Capsular Reconstruction (SCR) is to use a robust graft (like dermal allograft or fascia lata) to span the gap from the superior glenoid to the greater tuberosity. The graft acts as a static spacer and tether (a "trampoline" effect) to physically restrain superior migration of the humeral head, thereby restoring the stable fulcrum necessary for the deltoid to initiate and maintain active elevation.

Question 35

A 70-year-old male presents with deep shoulder pain 6 years after an anatomic TSA. Radiographs demonstrate superior migration of the humeral head and a "rocking horse" loosening pattern of the polyethylene glenoid component. This specific mechanism of glenoid loosening is most commonly associated with which underlying pathology?

Explanation

The "rocking horse" phenomenon describes the eccentric loading of the glenoid component that leads to catastrophic early loosening. This most frequently occurs in anatomic TSA when the rotator cuff (specifically the supraspinatus) fails, causing the humeral head to migrate superiorly. The superiorly migrated head applies eccentric, unbalanced cyclic forces to the superior edge of the glenoid, levering it out of the cement mantle.

Question 36

A surgeon is considering the use of an unlinked (unconstrained) total elbow arthroplasty for a 65-year-old female with advanced post-traumatic arthritis. Which of the following is an absolute prerequisite for the successful implantation and stability of an unlinked total elbow prosthesis?

Explanation

Unlinked (unconstrained) total elbow prostheses do not have a mechanical hinge connecting the humeral and ulnar components. Therefore, they rely heavily on the native soft tissue envelope—specifically competent medial and lateral collateral ligaments—and adequate epicondylar and columnar bone stock for stability. If the ligaments are incompetent or the columns are destroyed, a linked (semi-constrained) prosthesis is required to prevent dislocation.

Question 37

A 24-year-old rugby player undergoes an open Latarjet procedure for recurrent anterior shoulder instability associated with 25% glenoid bone loss. In the recovery room, he exhibits marked weakness in elbow flexion and forearm supination. Which nerve was most likely injured during the procedure, and what is its normal anatomic relationship to the transferred coracoid?

Explanation

The musculocutaneous nerve is at significant risk during the Latarjet procedure due to its proximity to the operative field. It typically enters the coracobrachialis muscle on its medial aspect, approximately 3 to 8 cm distal to the tip of the coracoid. Vigorous medial retraction of the conjoined tendon can cause a traction neuropraxia, presenting as weakness in the biceps and brachialis (elbow flexion and forearm supination).

Question 38

A 50-year-old weightlifter with recalcitrant, isolated acromioclavicular (AC) joint osteoarthritis is undergoing an arthroscopic distal clavicle excision. To prevent postoperative iatrogenic anteroposterior instability of the clavicle, the surgeon must be careful to preserve which of the following structures during the resection?

Explanation

During a distal clavicle excision (Mumford procedure), it is crucial to resect an adequate amount of bone to prevent impingement (usually 5-8 mm) but not so much that the stabilizing ligaments are compromised. The superior and posterior AC ligaments are the primary restraints to anteroposterior translation of the distal clavicle. Excessive resection (>10-15 mm) risks disrupting these capsular ligaments, leading to AP instability. The coracoclavicular (conoid and trapezoid) ligaments prevent superior translation and are located further medially.

Question 39

A 32-year-old bodybuilder feels a sudden 'pop' in his anterior axilla while performing a heavy bench press. He presents with loss of the anterior axillary fold and profound weakness in internal rotation and adduction. MRI confirms a complete tear of the pectoralis major at the sternal head insertion. Which of the following describes the accurate anatomical footprint of the sternal head to guide an anatomic repair?

Explanation

The pectoralis major tendon undergoes a unique 180-degree twist before its insertion onto the lateral lip of the bicipital groove of the humerus. Due to this twist, the sternal (and abdominal) head fibers insert deep and proximal to the fibers of the clavicular head. Recognizing this layered footprint is essential for accurate anatomic footprint restoration during surgical repair.

Question 40

A 58-year-old former gymnast presents with chronic lateral elbow pain, clicking, and a 15-degree extension deficit. Radiographs demonstrate isolated severe radiocapitellar osteoarthritis with a completely preserved, healthy ulnohumeral joint. If nonoperative management fails, what is the most appropriate surgical intervention to relieve pain while preserving elbow kinematics and stability?

Explanation

For isolated severe radiocapitellar arthritis in a relatively young/active patient with a preserved ulnohumeral joint, radiocapitellar arthroplasty (which includes radial head replacement and potentially capitellar resurfacing) is the most appropriate joint-preserving surgery. Simple radial head resection is associated with proximal migration of the radius, longitudinal forearm instability, and progressive ulnohumeral overload/valgus instability, and is therefore generally avoided in this population unless absolutely indicated.

Question 41

Which of the following describes the ideal positioning of the glenosphere in a reverse total shoulder arthroplasty to minimize the risk of inferior scapular notching?

Explanation

Inferior scapular notching is a common complication of reverse total shoulder arthroplasty. Placing the glenosphere with inferior translation (overhanging the inferior glenoid rim) and inferior tilt minimizes impingement of the humeral component on the scapular neck during adduction.

Question 42

A 68-year-old male with primary glenohumeral osteoarthritis presents with a Walch B2 glenoid. If an anatomic total shoulder arthroplasty is planned, which of the following is the most appropriate management of the glenoid to prevent early component failure?

Explanation

A Walch B2 glenoid is characterized by posterior wear and biconcavity. Management requires correcting the retroversion to within 10 degrees of neutral, typically achieved by eccentric reaming of the anterior, unworn bone or utilizing a posteriorly augmented glenoid component to prevent posterior instability and early loosening.

Question 43

In a patient undergoing total elbow arthroplasty (TEA) for a comminuted distal humerus fracture, what is the primary biomechanical advantage of incorporating an anterior flange on the humeral component?

Explanation

The anterior flange of the humeral component in a TEA rests against the anterior humeral cortex. This design effectively resists posterior displacing forces generated during active elbow extension and triceps loading, thereby reducing the risk of posterior component loosening.

Question 44

A 72-year-old female undergoes an anatomic total shoulder arthroplasty. Six weeks postoperatively, she reports acute onset of anterior shoulder pain and inability to actively internally rotate her arm after a minor fall. Radiographs reveal anterior subluxation of the humeral head. Which of the following is the most likely cause?

Explanation

Subscapularis tendon failure after anatomic TSA typically presents with anterior shoulder pain, weakness in internal rotation, increased passive external rotation, and anterior subluxation of the humeral head. Early diagnosis and repair are critical to restore function and stability.

Question 45

Which of the following best describes the principle of radial mismatch in anatomic total shoulder arthroplasty?

Explanation

Radial mismatch means the radius of curvature of the glenoid component is slightly larger than that of the humeral head (typically by 2 to 4 mm). This non-conforming design allows necessary physiologic translation of the humeral head and reduces eccentric rim loading, which protects the glenoid from early loosening.

Question 46

A 55-year-old male with an acute, highly comminuted intra-articular distal humerus fracture is being considered for elbow arthroplasty. Which of the following is an absolute contraindication for a distal humeral hemiarthroplasty?

Explanation

Distal humeral hemiarthroplasty relies on the native proximal ulna and radius for stability and containment. The absence of an intact or reconstructable radial head and coronoid process is an absolute contraindication because it results in a highly unstable joint.

Question 47

In reverse total shoulder arthroplasty (RTSA), moving the center of rotation medially and distally achieves which of the following biomechanical effects?

Explanation

Grammont's reverse shoulder design shifts the center of rotation medially and distally compared to the native shoulder. This increases the deltoid moment arm, improving its mechanical advantage, and converts deforming shear forces into stabilizing compressive forces at the bone-baseplate interface.

Question 48

A 76-year-old female presents with acute elbow pain and weakness in extension 3 months after a total elbow arthroplasty utilizing a triceps-reflecting approach. Radiographs show no implant loosening. Which of the following physical examination findings is most specific for triceps avulsion?

Explanation

Triceps insufficiency or avulsion post-TEA presents with an extension lag or complete loss of active elbow extension against gravity, while passive extension remains intact. A triceps-reflecting approach carries a recognized risk of this complication if the repair fails.

Question 49

Which of the following nerve injuries is most likely to occur due to excessive medial retraction of the conjoined tendon during the deltopectoral approach for a total shoulder arthroplasty?

Explanation

The musculocutaneous nerve enters the coracobrachialis approximately 3-8 cm distal to the coracoid process. Excessive or prolonged medial retraction of the conjoined tendon during a deltopectoral approach places this nerve at high risk for neuropraxia.

Question 50

A 68-year-old male with glenohumeral osteoarthritis presents for an anatomic total shoulder arthroplasty. Preoperative CT scan demonstrates a Walch B2 glenoid with 20 degrees of retroversion. What is the most appropriate surgical strategy for managing the glenoid to minimize the risk of early component loosening?

Explanation

Walch B2 glenoids feature biconcave wear and posterior subluxation. Uncorrected retroversion (>15 degrees) leads to high failure rates; augmented components or bone grafting are preferred over excessive eccentric reaming, which dangerously compromises the subchondral bone.

Question 51

A 74-year-old male presents with pseudoparalysis of the shoulder and a massive, irreparable rotator cuff tear involving the supraspinatus, infraspinatus, and teres minor. Clinical exam reveals a positive Hornblower's sign. Which of the following is the most appropriate surgical intervention to optimize his functional outcome?

Explanation

A positive Hornblower's sign indicates severe teres minor deficiency. An isolated RTSA will restore forward elevation but not active external rotation; combining RTSA with a latissimus dorsi or lower trapezius transfer is necessary to restore external rotation in these patients.

Question 52

A 45-year-old male manual laborer with severe, painful post-traumatic osteoarthritis of his right dominant elbow requests a total elbow arthroplasty (TEA) to return to heavy lifting work. Which of the following represents the most significant contraindication to performing a TEA in this patient?

Explanation

A strict, permanent lifting restriction of 5 to 10 pounds is generally required following TEA to prevent aseptic loosening and mechanical failure. Therefore, TEA is absolutely contraindicated in young patients expecting to perform heavy manual labor.

Question 53

During a radial head arthroplasty for a comminuted radial head fracture, the surgeon inadvertently inserts an implant that is 4 mm too thick. What is the most likely biomechanical consequence of this 'overstuffed' radiocapitellar joint?

Explanation

Overstuffing the radiocapitellar joint excessively loads the capitellum, causing rapid cartilage wear, lateral elbow pain, and a significant loss of elbow flexion and extension. It artificially tensions the lateral ligamentous complex, rather than causing laxity.

Question 54

A 62-year-old male with glenohumeral osteoarthritis presents with a Walch B2 glenoid. When performing an anatomic total shoulder arthroplasty (aTSA), what is the most appropriate management of the glenoid to prevent early component failure?

Explanation

Posteriorly augmented glenoids correct retroversion while preserving subchondral bone in Walch B2 glenoids. Eccentric reaming >15 degrees removes excessive subchondral bone and significantly increases the risk of component loosening.

Question 55

A 70-year-old female presents with sudden-onset superior shoulder pain 4 months after a reverse total shoulder arthroplasty (RTSA). Radiographs reveal a Levy type II acromial base fracture. What is the most appropriate initial management?

Explanation

Acromial stress fractures after RTSA (Levy types I and II) are typically managed non-operatively initially with sling immobilization. Operative fixation is generally reserved for nonunions or severe displacement (Levy type III) that drastically alters deltoid tension.

Question 56

An 82-year-old female with severe osteoporosis sustains a comminuted, intra-articular distal humerus fracture (AO/OTA 13-C3). Which of the following is an established advantage of primary total elbow arthroplasty (TEA) compared to open reduction and internal fixation (ORIF) in this patient?

Explanation

In elderly patients with poor bone stock, primary TEA provides reliable, rapid return to function and avoids the high short-term complication rates of ORIF, such as nonunion or hardware failure. However, TEA imposes lifetime lifting restrictions and carries a higher long-term risk of aseptic loosening.

Question 57

Which of the following is the most common cause of late failure requiring revision in anatomic total shoulder arthroplasty (aTSA)?

Explanation

Aseptic loosening of the glenoid component is the most frequent cause of late failure and revision following aTSA. Contributing factors include eccentric loading from unaddressed posterior subluxation and particulate wear debris.

Question 58

To minimize the risk of inferior scapular notching during a reverse total shoulder arthroplasty (RTSA), how should the glenosphere ideally be positioned?

Explanation

Inferior overhang (typically 2-4 mm) and a slight inferior tilt of the baseplate shift the center of rotation inferiorly. This minimizes mechanical impingement of the humeral component against the scapular neck during adduction, thus reducing notching.

Question 59

A 60-year-old patient with post-traumatic elbow arthritis is being considered for an unlinked total elbow arthroplasty (TEA). Which of the following is an absolute contraindication for using an unlinked implant?

Explanation

Unlinked TEA implants rely heavily on the native soft-tissue envelope, specifically the collateral ligaments and joint capsule, for stability. Therefore, severe ligamentous insufficiency or gross instability is an absolute contraindication for an unlinked design.

Question 60

A 65-year-old male undergoes anatomic total shoulder arthroplasty. Six weeks postoperatively, he complains of anterior shoulder pain and weakness in internal rotation. Exam shows a positive belly-press test and increased anterior translation. What is the most reliable definitive management for a confirmed complete avulsion of the subscapularis in this setting?

Explanation

Complete subscapularis failure post-aTSA leading to anterior instability and superior migration has a very high failure rate with primary repair or isolated tendon transfers. Revision to an RTSA provides the most reliable restoration of joint stability and function.

Question 61

During implantation of a linked total elbow arthroplasty (TEA) utilizing a Coonrad-Morrey prosthesis, what is the primary biomechanical function of placing bone graft anterior to the anterior flange of the humeral component?

Explanation

The anterior flange of the Coonrad-Morrey humeral component is designed to resist rotational torque and posteriorly directed forces during active elbow extension. Bone grafting anterior to the flange enhances this biomechanical buttress.

Question 62

Which nerve is most at risk of stretch injury during the lengthening and distalization of the humerus often required to properly tension the deltoid in a reverse total shoulder arthroplasty (RTSA)?

Explanation

The axillary nerve runs just inferior to the glenohumeral joint capsule and is highly susceptible to stretch injury when the humerus is excessively lengthened to tension the deltoid in RTSA.

Question 63

When performing a shoulder hemiarthroplasty for a complex 4-part proximal humerus fracture, what factor is the strongest predictor of a successful functional outcome?

Explanation

Functional outcomes following hemiarthroplasty for proximal humerus fractures depend almost exclusively on the anatomic reduction and stable healing of the tuberosities to the shaft and the prosthesis. Failure of tuberosity healing leads to profound weakness and loss of active elevation.

Question 64

A 72-year-old male with massive, irreparable posterosuperior rotator cuff tear pseudoparalysis exhibits a positive hornblower's sign and severe drop sign. He is planned for a reverse total shoulder arthroplasty (RTSA). Which adjunctive procedure should be considered to optimize his functional outcome?

Explanation

A positive hornblower's and drop sign indicate severe teres minor deficiency and loss of active external rotation. Combining RTSA with a latissimus dorsi/teres major transfer (L'Episcopo) reliably restores active external rotation.

Orthopedic Surgery Board Review MCQs: Arthroplasty, Trauma & Spine Part 255

Orthopedic Surgery Board Review MCQs: Shoulder, Elbow & Arthroplasty | Part 29

Key Takeaway

Orthopedic Surgery Board Review MCQs: Shoulder, Elbow & Arthroplasty | Part 29

Chapter Index