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7. Hand and Wrist MCQs

Practice Set 21 of 266

This practice set contains high-yield board review questions covering key concepts in 7. Hand and Wrist. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 401

Topic: 7. Hand and Wrist

A 45-year-old woman is bitten by her indoor cat on the dorsum of her right hand. Within 12 hours, she develops severe pain, swelling, and rapidly spreading erythema. Which of the following is the most likely pathogen responsible for this rapid-onset infection?

. Bartonella henselae
. Staphylococcus aureus
. Eikenella corrodens
. Pasteurella multocida
. Capnocytophaga canimorsus

Correct Answer & Explanation

. Pasteurella multocida

Explanation

Pasteurella multocida is the most common pathogen associated with cat and dog bites, classically presenting with an intense, rapid-onset cellulitis often within 12 to 24 hours of the injury. Treatment requires beta-lactamase inhibitors or other broad-spectrum coverage.

Question 402

Topic: Hand Trauma & Infection

A 30-year-old mechanic presents with severe, throbbing pain in the volar pulp of his right thumb. Examination reveals a tense, erythematous, and exquisitely tender thumb pulp. If an incision and drainage is required, which approach is considered safest to avoid neurovascular injury and painful scarring?

. Volar longitudinal incision
. High mid-lateral incision
. Bilateral longitudinal incisions
. Fish-mouth (circumferential) incision
. Transverse volar incision crossing the distal interphalangeal crease

Correct Answer & Explanation

. Volar longitudinal incision

Explanation

A volar longitudinal incision over the site of maximum fluctuance is generally preferred for a felon, as it avoids crossing the flexion creases and minimizes damage to the digital nerves. "Fish-mouth" incisions are historically discouraged due to high risks of painful scarring and neurovascular injury.

Question 403

Topic: 7. Hand and Wrist

A 50-year-old male presents with classic signs of Volkmann's ischemic contracture following an unrecognized forearm compartment syndrome. Which of the following best describes the expected fixed posture of his affected upper extremity?

. Elbow extended, forearm supinated, wrist extended, and digits extended
. Elbow flexed, forearm pronated, wrist flexed, MCP joints extended, and IP joints flexed
. Elbow flexed, forearm supinated, wrist flexed, MCP joints flexed, and IP joints extended
. Elbow extended, forearm pronated, wrist extended, MCP joints flexed, and IP joints flexed
. Elbow flexed, forearm neutral, wrist extended, and digits clawed

Correct Answer & Explanation

. Elbow flexed, forearm pronated, wrist flexed, MCP joints extended, and IP joints flexed

Explanation

Volkmann's ischemic contracture results from irreversible necrosis and subsequent fibrosis of the deep volar flexors. The classic posture includes elbow flexion, forearm pronation, wrist flexion, MCP extension, and IP flexion.

Question 404

Topic: 7. Hand and Wrist
A 28-year-old male presents with a Bado Type III Monteggia fracture-dislocation after a motorcycle accident. Pre-operative neurovascular examination reveals a partial wrist drop and inability to extend the metacarpophalangeal (MCP) joints of the fingers, with intact sensation. Which nerve is most likely injured in this patient, and why is it particularly vulnerable in this type of Monteggia injury?
. Ulnar nerve, due to its proximity to the ulnar shaft fracture.
. Median nerve, due to anterior displacement of the radial head.
. Posterior Interosseous Nerve (PIN), due to its course through the supinator muscle and proximity to the radial neck.
. Radial sensory nerve, due to traction from the radial head dislocation.
. Anterior Interosseous Nerve (AIN), due to its involvement in forearm pronation.

Correct Answer & Explanation

. Posterior Interosseous Nerve (PIN), due to its course through the supinator muscle and proximity to the radial neck.

Explanation

The clinical presentation of wrist drop and inability to extend the MCP joints of the digits and thumb, with intact sensation, is characteristic of a Posterior Interosseous Nerve (PIN) palsy. The PIN, a deep branch of the radial nerve, passes through the supinator muscle and is particularly vulnerable to injury during Type III Monteggia fractures and during surgical approaches involving the lateral elbow or extensive dissection around the radial neck.

Question 405

Topic: Nerve & Tendon

A 30-year-old male presents with a displaced spiral fracture of the distal third of the humeral shaft. He is scheduled for open reduction and internal fixation via an anterolateral approach. During the deep dissection, the surgeon carefully identifies the interval between the biceps and brachialis muscles. As the dissection proceeds distally to expose the fracture, which critical neurovascular structure must be meticulously identified and protected as it pierces the lateral intermuscular septum to enter the anterior compartment?

. A. Musculocutaneous nerve
. B. Median nerve
. C. Ulnar nerve
. D. Radial nerve
. E. Brachial artery

Correct Answer & Explanation

. D. Radial nerve

Explanation

Correct Answer: DThe case content explicitly states: 'The radial nerve is the most frequently injured nerve in humeral shaft fractures. It courses in the spiral groove posteriorly, crossing from medial to lateral. Approximately 10-14 cm proximal to the lateral epicondyle, it pierces the lateral intermuscular septum to enter the anterior compartment, lying between the brachialis and brachioradialis muscles in the distal arm. For direct anterior or anterolateral approaches to the shaft, the radial nerve is generally posterior to the plane of dissection (i.e., posterior to the brachialis). However, extensive distal anterior dissection or inadvertent posterior extension of the plane places the nerve at risk.'Option A (Musculocutaneous nerve):The musculocutaneous nerve pierces the coracobrachialis more proximally and lies between the biceps and brachialis. While important, it is not the nerve that pierces the lateral intermuscular septum in the distal arm.Option B (Median nerve):The median nerve lies medially within the neurovascular bundle and does not pierce the lateral intermuscular septum.Option C (Ulnar nerve):The ulnar nerve also lies medially and then courses posteriorly around the medial epicondyle distally; it does not pierce the lateral intermuscular septum.Option E (Brachial artery):The brachial artery lies medially with the median nerve and does not pierce the lateral intermuscular septum.

Question 406

Topic: 7. Hand and Wrist
A 28-year-old male sustains a Bado Type III Monteggia fracture-dislocation. He exhibits a nerve palsy characterized by an inability to extend the fingers at the metacarpophalangeal joints, but retains normal wrist extension with radial deviation. Which nerve is injured?
. Anterior interosseous nerve
. Ulnar nerve
. Posterior interosseous nerve
. Superficial radial nerve
. Median nerve

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

The posterior interosseous nerve (PIN) is frequently injured in Bado Type III (lateral) Monteggia fractures. Injury results in loss of finger extension, but wrist extension is maintained (though radially deviated) via the ECRL, which is innervated by the radial nerve proper.

Question 407

Topic: 7. Hand and Wrist

A 52-year-old female presents with a 2-year history of progressive pain, stiffness, and swelling in her bilateral index finger PIP joints. She reports acute flares of inflammation and notes that her mother had similar hand deformities. Radiographs are obtained, one of which is shown below.

Based on the clinical presentation and radiographic findings, which of the following statements regarding her condition is most accurate?

. The condition is most likely rheumatoid arthritis, given the inflammatory component and bilateral involvement.
. The characteristic radiographic finding shown is a 'pencil-in-cup' deformity, typical of psoriatic arthritis.
. Erosive osteoarthritis predominantly affects middle-aged and older women, often with a familial predisposition.
. The primary treatment for this stage of disease should be immediate surgical arthroplasty to preserve motion.
. The central erosion seen is a hallmark of classic osteoarthritis, indicating advanced cartilage loss.

Correct Answer & Explanation

. Erosive osteoarthritis predominantly affects middle-aged and older women, often with a familial predisposition.

Explanation

Correct Answer: CThe clinical vignette describes a middle-aged woman with progressive pain, stiffness, swelling, acute inflammatory flares, and a familial history of hand deformities, affecting the PIP joints. The provided radiograph (Figure 1) clearly demonstrates the classic 'gull-wing' deformity with central erosion and peripheral osteophytes, which is pathognomonic for erosive osteoarthritis (EOA). The case content explicitly states that EOA predominantly affects middle-aged and older women, with a female-to-male ratio ranging from 5:1 to 12:1, and a familial predisposition has been suggested. Therefore, statement C is the most accurate.Incorrect Options:A:While EOA has an inflammatory component and can mimic seronegative inflammatory arthritis, the specific radiographic 'gull-wing' deformity and the typical demographic (middle-aged women, familial history) are more characteristic of EOA than rheumatoid arthritis (RA). RA typically presents with symmetrical polyarthritis, often involving MCP and wrist joints, and characteristic marginal erosions, not central 'gull-wing' erosions.B:The 'pencil-in-cup' deformity is characteristic of psoriatic arthritis, where the proximal phalanx head erodes into the middle phalanx base. The image clearly shows a central erosion of the middle phalanx base with peripheral osteophytes, creating a 'gull-wing' appearance, not a 'pencil-in-cup' deformity.D:The case describes a progressive condition, but immediate surgical arthroplasty is not the primary treatment for this stage. Management of EOA follows a staged approach, starting with non-operative measures (NSAIDs, splinting, injections, therapy) for early disease and acute flares. Surgical intervention is reserved for persistent severe pain, progressive joint destruction, or significant functional loss refractory to conservative care.E:While classic osteoarthritis (OA) involves cartilage loss and osteophyte formation, the characteristic central erosion and 'gull-wing' deformity are specific to erosive osteoarthritis, which has a distinct inflammatory component leading to more aggressive joint destruction. Classic OA typically presents with joint space narrowing, subchondral sclerosis, and osteophytes, but not usually central erosions of this nature.

Question 408

Topic: 7. Hand and Wrist

A 60-year-old female with erosive osteoarthritis of the index finger PIP joint presents with increasing pain and a fixed flexion contracture of 40 degrees, significantly impairing her ability to perform fine motor tasks. Non-operative management over 6 months, including NSAIDs, splinting, and hand therapy, has failed to provide adequate relief. Surgical intervention is planned. Considering the surgical anatomy of the PIP joint, which of the following structures is primarily responsible for preventing hyperextension and provides significant volar stability?

. True collateral ligaments
. Accessory collateral ligaments
. Volar plate
. Central slip of the extensor digitorum communis
. Oblique retinacular ligament

Correct Answer & Explanation

. Volar plate

Explanation

Correct Answer: CThe case content explicitly states that the 'Volar Plate' is a strong, fibrocartilaginous structure located on the volar aspect of the joint that prevents hyperextension and provides significant volar stability. Its paired check-rein ligaments anchor it to the proximal phalanx.Incorrect Options:A:True collateral ligaments originate dorsal to the axis of rotation and are taut in flexion, contributing significantly to mediolateral stability, particularly at 30-45 degrees of flexion. They do not primarily prevent hyperextension.B:Accessory collateral ligaments originate volarly to the true collaterals and insert into the volar plate. They are taut in extension and relaxed in flexion, but their primary role is to reinforce the volar plate and contribute to overall stability, not solely prevent hyperextension as the main structure. The volar plate itself is the primary hyperextension block.D:The central slip of the extensor digitorum communis tendon inserts onto the dorsal base of the middle phalanx and directly extends the PIP joint. It has no role in preventing hyperextension or providing volar stability.E:The oblique retinacular ligament courses volarly to the PIP axis, connecting the flexor sheath to the terminal extensor tendon, and plays a role in coordinating DIP and PIP motion, but it is not a primary stabilizer against hyperextension of the PIP joint.

Question 409

Topic: Nerve & Tendon

A 55-year-old female presents with insidious onset of pain at the base of her right thumb, exacerbated by pinch and grasp. She reports similar, milder symptoms in her left thumb. Her mother also suffered from "thumb arthritis." Which of the following is the most accurate statement regarding the epidemiology and risk factors for this condition?

. Thumb CMC OA is less common in women than men over 50 years due to protective hormonal effects.
. Generalized ligamentous laxity is a protective factor against CMC OA by distributing joint stress.
. The prevalence of thumb CMC OA is estimated to be between 16% and 25% in the general adult population, with a notable female predominance.
. Repetitive thumb use, while a risk factor for De Quervain's tenosynovitis, has not been definitively linked to CMC OA.
. Prior trauma to the joint is an absolute contraindication to surgical management of CMC OA.

Correct Answer & Explanation

. The prevalence of thumb CMC OA is estimated to be between 16% and 25% in the general adult population, with a notable female predominance.

Explanation

Correct Answer: CThe case states: "Epidemiological studies estimate its prevalence to be between 16% and 25% in the general adult population, with a notable increase with age, affecting over 30% of women and 10% of men over 50 years. Women are disproportionately affected..." This directly supports option C.Option A is incorrect as the prevalence is higher in women. Option B is incorrect; the case lists generalized ligamentous laxity as a risk factor, not a protective factor. Option D is incorrect; the case explicitly states, "Repetitive thumb use... are also implicated" as risk factors for thumb CMC OA. Option E is incorrect; prior trauma is a risk factor for developing CMC OA, but it is not listed as an absolute contraindication to surgical management, although it might influence the choice of procedure or prognosis.

Question 410

Topic: 7. Hand and Wrist

A 62-year-old right-hand dominant female presents with chronic pain at the base of her right thumb, worse with opening jars and turning keys. On examination, she has tenderness over the CMC joint, a positive grind test, and a visible dorsal prominence at the thumb base. Her MCP joint appears hyperextended. Which of the following physical exam findings is most indicative of advanced thumb CMC OA with associated deformity?

. Positive Finkelstein's test.
. Pain with resisted wrist extension.
. Reduced first web space with compensatory MCP joint hyperextension.
. Tenderness over the scaphoid tubercle.
. Pain with resisted thumb IP joint flexion.

Correct Answer & Explanation

. Reduced first web space with compensatory MCP joint hyperextension.

Explanation

Correct Answer: CThe case describes the progression of thumb CMC OA leading to "eventual deformity, including the classic 'shoulder sign' due to subluxation of the first metacarpal on the trapezium, and adduction contracture of the thumb metacarpal leading to secondary hyperextension of the metacarpophalangeal (MCP) joint (Z-deformity)." A reduced first web space is a direct consequence of adduction contracture, and compensatory MCP hyperextension completes the Z-deformity, which is a hallmark of advanced disease.Option A (Positive Finkelstein's test) is primarily indicative of De Quervain's tenosynovitis, although it can sometimes elicit pain at the CMC joint if significant inflammatory synovitis is present; it is not the most indicative sign of advanced deformity. Option B (Pain with resisted wrist extension) suggests extensor carpi radialis or ulnaris pathology. Option D (Tenderness over the scaphoid tubercle) points towards scaphoid pathology. Option E (Pain with resisted thumb IP joint flexion) suggests flexor pollicis longus pathology. None of these are as specific to advanced CMC OA deformity as the Z-deformity.

Question 411

Topic: 7. Hand and Wrist

A 48-year-old male presents with early thumb CMC OA. During a discussion about the biomechanics of the joint, the surgeon emphasizes the role of a specific ligament in preventing dorsoradial subluxation of the first metacarpal. Which ligament is the surgeon most likely referring to as the primary static stabilizer against this subluxation?

. Ulnar Collateral Ligament of the CMC joint
. Posterior Oblique Ligament
. Radial Collateral Ligament of the CMC joint
. Anterior Oblique Ligament (Beak Ligament)
. Intermetacarpal Ligament between the first and second metacarpals

Correct Answer & Explanation

. Anterior Oblique Ligament (Beak Ligament)

Explanation

Correct Answer: DThe case explicitly states under "Ligamentous Stabilizers": "Anterior Oblique Ligament (AOL) / Beak Ligament: Considered the most crucial ligament for resisting dorsoradial subluxation of the metacarpal. ...Degeneration and laxity of this ligament are central to the pathogenesis of thumb CMC OA."Option A (Ulnar Collateral Ligament) provides stability against radial deviation. Option B (Posterior Oblique Ligament) provides dorsal stability but is not considered the primary resistor of dorsoradial subluxation. Option C (Radial Collateral Ligament) provides stability against ulnar deviation. Option E (Intermetacarpal Ligaments) provide static stability and resist axial loading and proximal migration, but not primarily dorsoradial subluxation of the first metacarpal on the trapezium.

Question 412

Topic: 7. Hand and Wrist

A 58-year-old female with long-standing thumb CMC OA is noted to have a "shoulder sign" on clinical examination and radiographs showing significant dorsoradial subluxation of the first metacarpal on the trapezium. This subluxation is a key event in the progression of her arthritis. Which of the following statements best describes the biomechanical consequence of this subluxation?

. It leads to decreased shear forces on the articular cartilage, promoting cartilage regeneration.
. It primarily causes increased compressive forces on the palmar aspect of the joint, leading to osteophyte formation.
. It results in altered kinematics and non-physiological loading patterns, causing high shear and compressive forces on the remaining cartilage.
. It stabilizes the joint by increasing the contact area between the metacarpal and scaphoid.
. It is a compensatory mechanism that improves the first web space and thumb opposition.

Correct Answer & Explanation

. It results in altered kinematics and non-physiological loading patterns, causing high shear and compressive forces on the remaining cartilage.

Explanation

Correct Answer: CUnder "Biomechanics of OA Progression," the case details: "1. AOL Laxity/Degeneration: Weakening of the AOL... leads to increased dorsoradial subluxation of the first metacarpal on the trapezium during pinch and grasp. 2. Increased Shear Stress: The altered kinematics result in non-physiological loading patterns, causing high shear and compressive forces on the remaining cartilage."Option A is incorrect; the subluxation leads toincreasedshear forces. Option B is partially correct in that compressive forces increase, but the primary issue is thenon-physiological loading patternsinvolving both shear and compression, leading to cartilage erosion, not primarily osteophyte formation as the initial consequence. Option D is incorrect; subluxationdestabilizesthe joint and leads to incongruent contact, not increased stable contact. Option E is incorrect; subluxation and the resulting adduction contracturelimitthe web space and impair opposition, leading to the Z-deformity.

Question 413

Topic: 7. Hand and Wrist

A patient undergoes trapeziectomy with LRTI. Six months post-operatively, they report persistent pain on the radial aspect of the wrist, particularly with axial loading, and radiographs show some proximal migration of the first metacarpal towards the scaphoid. This is causing impingement. Which of the following complications is most likely occurring, and what is a potential salvage strategy?

. Radial sensory nerve injury; managed with neurolysis.
. Complex Regional Pain Syndrome (CRPS); managed with sympathetic blocks.
. Pillar pain due to proximal metacarpal subsidence; managed with radial styloidectomy or revision suspensionplasty.
. FCR tendon donor site rupture; managed with tendon repair.
. Adduction contracture; managed with web space deepening.

Correct Answer & Explanation

. Pillar pain due to proximal metacarpal subsidence; managed with radial styloidectomy or revision suspensionplasty.

Explanation

Correct Answer: CThe patient's symptoms (persistent pain on the radial aspect of the wrist, worse with axial loading, and radiographic evidence of proximal metacarpal migration causing impingement) are classic for pillar pain, specifically due to proximal metacarpal subsidence. The case lists "Pillar Pain (Radioscaphoid Impingement)" and "Proximal Metacarpal Subsidence" as complications. For management of pillar pain, it suggests "radial styloidectomy or revision trapeziectomy if residual fragments." For symptomatic/severe subsidence, it suggests "Revision surgery with more robust suspension plasty, intermetacarpal arthrodesis, or implant arthroplasty." Option C accurately combines the complication and appropriate salvage strategies.Option A (Radial sensory nerve injury) would typically present with neuropathic pain, dysesthesia, or neuroma, not primarily axial loading pain and radiographic impingement. Option B (CRPS) is a diffuse, disproportionate pain syndrome with autonomic features, not typically localized to mechanical impingement. Option D (FCR tendon donor site rupture) would cause pain at the FCR tendon, not necessarily radial wrist impingement. Option E (Adduction contracture) would present with limited web space and impaired opposition, not primarily radial pillar pain with axial loading.

Question 414

Topic: 7. Hand and Wrist
Following a trapeziectomy with LRTI, a patient is in the early post-operative phase (0-4 weeks). Which of the following is the most appropriate rehabilitation instruction for this phase?
. Initiate immediate active range of motion of the thumb CMC joint to prevent stiffness.
. Begin progressive resistance exercises for pinch and grip strength.
. Maintain strict immobilization of the wrist and thumb CMC joint in a thumb spica splint, with active motion of non-operated digits.
. Perform forceful passive stretching of the thumb web space to prevent adduction contracture.
. Apply heat therapy to the surgical site to promote blood flow and healing.

Correct Answer & Explanation

. Maintain strict immobilization of the wrist and thumb CMC joint in a thumb spica splint, with active motion of non-operated digits.

Explanation

Under 'Post-Operative Rehabilitation Protocols - Phase I: Immobilization and Protection (0-4/6 Weeks),' the case states: 'Immobilization: ...Thumb spica splint or cast, typically immobilizing the wrist in slight extension, the thumb CMC joint in neutral to slight palmar abduction and slight pronation... Gentle Exercises (Non-Operated Digits): Encourage active range of motion (AROM) of the fingers and IP joint of the thumb to prevent stiffness and maintain circulation.' This instruction is critical for protecting the fresh reconstruction. Option A (immediate active CMC ROM) is too aggressive and risks disrupting the tendon reconstruction. Option B (progressive resistance exercises) is appropriate for later phases (Phase III and IV), not immediately post-op. Option D (forceful passive stretching) is contraindicated in the early phase due to the risk of compromising the surgical repair. Option E (heat therapy) is generally avoided in the immediate post-operative period as it can increase swelling and inflammation; cryotherapy is preferred.

Question 415

Topic: 7. Hand and Wrist
A 62-year-old woman presents with severe pain at the base of her thumb. Radiographs demonstrate advanced trapeziometacarpal joint space narrowing, subchondral sclerosis, and a 3 mm radial subluxation of the metacarpal base, but the scaphotrapezial joint is completely spared. What is the Eaton-Littler stage of her thumb arthritis?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage III

Explanation

Eaton-Littler Stage III is characterized by advanced CMC joint destruction (sclerosis, osteophytes, joint space narrowing) and significant metacarpal base subluxation greater than one-third. Stage IV would involve the scaphotrapezial (ST) joint.

Question 416

Topic: 7. Hand and Wrist

A 25-year-old man sustains a closed intra-articular fracture of the base of the thumb metacarpal with a single volar-ulnar fragment. Which of the following muscles is primarily responsible for the proximal and dorsal displacement of the metacarpal shaft?

. Adductor pollicis
. Abductor pollicis longus
. Abductor pollicis brevis
. Extensor pollicis brevis
. Flexor pollicis longus

Correct Answer & Explanation

. Abductor pollicis longus

Explanation

In a Bennett fracture, the volar-ulnar fragment is held anatomically in place by the anterior oblique ligament. The metacarpal shaft is displaced proximally, radially, and dorsally by the strong pull of the abductor pollicis longus (APL).

Question 417

Topic: 7. Hand and Wrist

A 35-year-old man presents with chronic wrist pain and a history of an untreated scaphoid waist fracture 10 years ago. Radiographs reveal scaphoid nonunion with radioscaphoid joint space narrowing, but the radiolunate joint is spared. What is the primary biomechanical reason the radiolunate joint is typically spared in a SNAC (Scaphoid Nonunion Advanced Collapse) wrist?

. The lunate cartilage is thicker and more resilient
. The spherical lunate fossa does not articulate with the scaphoid
. There is no abnormal motion between the lunate and the radius
. The capitate shields the radiolunate joint from axial loading
. The radiolunate ligament provides complete stress shielding

Correct Answer & Explanation

. There is no abnormal motion between the lunate and the radius

Explanation

In a SNAC wrist, the proximal pole of the scaphoid remains attached to the lunate via the intact scapholunate ligament, preserving normal, congruent radiolunate kinematics. Therefore, without abnormal motion, the radiolunate joint is typically spared from arthritic changes.

Question 418

Topic: 7. Hand and Wrist

A 30-year-old basketball player presents with a drooping long finger DIP joint. Radiographs show a dorsal avulsion fracture involving 45% of the articular surface of the distal phalanx with associated volar subluxation of the joint. What is the most appropriate management?

. Continuous extension splinting for 6 weeks
. Closed reduction and percutaneous pinning
. Open reduction and internal fixation of the FDP tendon
. DIP joint arthrodesis
. Observation and early range of motion

Correct Answer & Explanation

. Closed reduction and percutaneous pinning

Explanation

While small, non-subluxated bony mallet injuries can be managed with extension splinting, those involving greater than 30% of the articular surface with volar subluxation of the distal phalanx typically require surgical stabilization, such as extension block pinning.

Question 419

Topic: 7. Hand and Wrist

A 25-year-old male sustains a thumb injury during a fist fight. Radiographs reveal a two-part fracture of the base of the first metacarpal with the shaft displaced proximally and radially. Which of the following structures is primarily responsible for holding the volar ulnar base fragment in its anatomic position?

. Abductor pollicis longus (APL)
. Extensor pollicis brevis (EPB)
. Anterior oblique ligament (AOL)
. Intermetacarpal ligament
. Dorsal radial ligament

Correct Answer & Explanation

. Anterior oblique ligament (AOL)

Explanation

In a Bennett fracture, the volar ulnar beak fragment remains anatomically aligned due to the strong anterior oblique ligament (AOL). The metacarpal shaft is displaced proximally, dorsally, and radially by the pull of the abductor pollicis longus (APL).

Question 420

Topic: Nerve & Tendon

A 32-year-old man presents with a painful, swollen PIP joint after a sports injury. Examination reveals a volar PIP dislocation. Which of the following complications is most likely if the primary injured structure is not properly treated?

. Swan neck deformity
. Boutonniere deformity
. Mallet finger
. Jersey finger
. Quadriga effect

Correct Answer & Explanation

. Boutonniere deformity

Explanation

Volar PIP dislocations frequently result in injury to the central slip of the extensor tendon. If untreated, the lateral bands subluxate volarly, leading to a Boutonniere deformity (PIP flexion and DIP hyperextension).

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