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 421
Topic: 7. Hand and Wrist
A 35-year-old manual laborer presents with progressive wrist pain 5 years after an untreated scaphoid fracture. Radiographs show scaphoid nonunion advanced collapse (SNAC). The radiocarpal joint shows radioscaphoid arthritis, and there is narrowing of the capitolunate joint. However, the radiolunate joint is spared. Why is the radiolunate joint typically preserved in advanced SNAC and SLAC wrists?
Correct Answer & Explanation
. The radiolunate articulation is congruous and spherical, evenly distributing forces
Explanation
In both SLAC and SNAC wrists, the radiolunate joint is typically spared from osteoarthritis because the spherical lunate maintains a congruent articulation with the lunate fossa of the radius, preserving normal contact mechanics despite carpal collapse.
Question 422
Topic: 7. Hand and Wrist
A 25-year-old male sustains a proximal phalanx shaft fracture of the middle finger with apex volar angulation. Which two muscle groups are primarily responsible for creating this characteristic deformity?
Correct Answer & Explanation
. Interossei flexing the proximal fragment and central slip extending the distal fragment
Explanation
Apex volar angulation in proximal phalanx fractures is caused by the interosseous muscles pulling the proximal fragment into flexion (inserting on the base) and the central slip of the extensor tendon pulling the distal fragment into extension.
Question 423
Topic: Wrist & Carpus
A 24-year-old male is diagnosed with a stage III perilunate dislocation according to Mayfield's classification. Which intercarpal ligamentous connection or joint is disrupted at this stage?
Correct Answer & Explanation
. Scapholunate
Explanation
Mayfield staging of perilunate instability progresses from radial to ulnar. Stage I is scapholunate disruption; Stage II is lunocapitate disruption; Stage III is lunotriquetral disruption; and Stage IV is lunate dislocation (radiolunate failure).
Question 424
Topic: 7. Hand and Wrist
A 28-year-old male presents with severe pain at the base of his right thumb after punching a wall. Radiographs reveal a 3-part, Y-shaped intra-articular fracture of the first metacarpal base. During surgical planning for this Rolando fracture, understanding the deforming forces is critical. Which of the following deforming forces is correctly paired with the displacement of the first metacarpal shaft fragment?
Correct Answer & Explanation
. Proximal and dorsal migration by the Abductor Pollicis Longus (APL)
Explanation
In Rolando and Bennett fractures, the main metacarpal shaft fragment is primarily displaced proximally and dorsally by the pull of the abductor pollicis longus (APL). It is also adducted by the adductor pollicis, while the volar ulnar lip fragment is retained in place by the anterior oblique ligament.
Question 425
Topic: 7. Hand and Wrist
A 24-year-old male complains of deep radial-sided wrist pain 3 months after falling onto an outstretched hand. Initial radiographs at the time of injury were read as normal. Current MRI shows a displaced scaphoid proximal pole fracture with signs of avascular necrosis. The vulnerability of the proximal pole to ischemia is due to its retrograde blood supply, which primarily arises from branches entering the scaphoid at which location?
Correct Answer & Explanation
. Dorsal ridge via the radial artery
Explanation
The scaphoid receives 70-80% of its intraosseous blood supply via retrograde flow from dorsal carpal branches of the radial artery, which enter at the non-articular dorsal ridge. Fractures proximal to this ridge cut off the blood supply to the proximal pole, leading to a high rate of nonunion and avascular necrosis.
Question 426
Topic: 7. Hand and Wrist
A 32-year-old male presents to the emergency department 8 hours after sustaining a laceration over the dorsum of his dominant right hand during an altercation. He admits to striking another individual in the mouth. On examination, a 2 cm transverse laceration is noted over the metacarpophalangeal (MCP) joint of the ring finger. There is moderate swelling and tenderness, and pain with passive flexion of the digit. Which of the following is the most critical immediate step in the management of this patient?
Correct Answer & Explanation
. C. Copiously irrigate the wound, perform thorough debridement, and surgically explore the joint capsule.
Explanation
Correct Answer: CThe correct answer is C because the most critical immediate step for a suspected 'fight bite' over an MCP joint is aggressive surgical management. This involves copious irrigation, thorough debridement of devitalized tissue, and surgical exploration to assess for joint capsule violation, tendon injury, or retained foreign bodies (e.g., tooth fragments). Delaying aggressive management significantly increases the risk of severe complications like septic arthritis, osteomyelitis, and tenosynovitis. Oral antibiotics alone (A) are insufficient for deep infections. Radiographs (B) are important but should not delay definitive surgical intervention if indicated. Topical antibiotics (D) are ineffective for deep-seated infections. Awaiting culture results (E) is impractical and dangerous, as empiric antibiotics must be initiated promptly.
Question 427
Topic: Hand Trauma & Infection
Regarding the microbiology of human bite infections, particularly 'fight bites,' which of the following statements is most accurate?
Correct Answer & Explanation
. C. Polymicrobial infections involving both aerobic and anaerobic bacteria are characteristic.
Explanation
Correct Answer: CThe correct answer is C because human bite infections, including 'fight bites,' are characteristically polymicrobial, involving a complex mixture of aerobic and anaerobic bacteria from the oral flora. Common aerobes include Staphylococcus aureus (which can be MRSA), Streptococcus species, and Corynebacterium. Key anaerobes include Bacteroides, Fusobacterium, and Peptostreptococcus. Eikenella corrodens, a fastidious Gram-negative rod, is a hallmark pathogen of human bite wounds and is found in over 25% of infections, even in immunocompetent individuals. Monomicrobial S. aureus (A) is inaccurate. Eikenella is not rare (B). Fungal (D) and viral (E) infections are uncommon in the acute setting of a fight bite.
Question 428
Topic: 7. Hand and Wrist
What is the primary reason for performing an X-ray in a suspected 'fight bite' injury to the hand?
Correct Answer & Explanation
. B. To identify potential foreign bodies such as tooth fragments or associated fractures.
Explanation
Correct Answer: BThe correct answer is B because the primary reasons for obtaining plain radiographs in a suspected fight bite injury are to identify associated fractures (most commonly a 'boxer's fracture' of the metacarpal neck or head) and to detect retained foreign bodies, particularly tooth fragments, which can be radiopaque. Tooth fragments can act as a nidus for ongoing infection. While X-rays can show gross soft tissue swelling, they do not directly visualize the joint capsule (E) or assess for intrinsic muscle atrophy (A) or carpal tunnel syndrome (C). Assessing soft tissue edema (D) is a secondary finding, not the primary indication.
Question 429
Topic: 7. Hand and Wrist
A patient is undergoing surgical exploration for a fight bite over the third MCP joint. What position should the finger be held in during the initial assessment and irrigation to best expose potential joint capsule violation and aid in debridement?
Correct Answer & Explanation
. A. Full flexion
Explanation
Correct Answer: AThe correct answer is A because for a suspected 'fight bite' over an MCP joint, the finger should be held in full flexion during initial assessment and irrigation. The injury typically occurs with the hand clenched in a fist, which causes the skin and extensor tendon to shift proximally relative to the MCP joint capsule. When the hand is then extended, the damaged joint capsule and any penetrating wound tract move distally and are no longer aligned with the initial skin laceration, effectively sealing off the wound and potentially trapping bacteria within the joint. Flexing the finger realigns the entry portal, allowing for thorough irrigation and exploration of the joint capsule. Full extension (B) or neutral (C) will obscure the primary injury tract.
Question 430
Topic: 7. Hand and Wrist
Following surgical debridement and intravenous antibiotics for a septic MCP joint secondary to a fight bite, which of the following splinting positions is most appropriate for initial immobilization?
Correct Answer & Explanation
. B. MCP joints in approximately 70-90 degrees of flexion, IP joints in full extension.
Explanation
Correct Answer: BThe correct answer is B because the 'intrinsic plus' or 'safe position' splint is generally recommended for hand immobilization following injury or surgery to prevent joint contractures. This position involves placing the wrist in 20-30 degrees of extension, the MCP joints in approximately 70-90 degrees of flexion, and the IP joints in full extension. This position maintains the collateral ligaments of the MCP joints in their elongated state, preventing shortening contractures, and avoids shortening of the IP collateral ligaments. Full extension of MCPs (A, C) can lead to MCP collateral ligament shortening. Full flexion of IP joints (A, D) can lead to IP collateral ligament shortening. Active range of motion (E) is generally not indicated initially for a severe infection requiring immobilization.
Question 431
Topic: 7. Hand and Wrist
A patient presents with a persistent discharging sinus tract over the third metacarpal following a poorly managed fight bite 6 weeks ago. Plain radiographs reveal cortical irregularity and lucency of the metacarpal head. What is the most likely diagnosis?
Correct Answer & Explanation
. C. Osteomyelitis
Explanation
Correct Answer: CThe correct answer is C because a persistent discharging sinus tract, especially following a human bite with radiographic evidence of cortical irregularity and lucency of the bone, is highly suggestive of chronic osteomyelitis. The fight bite can directly inoculate bacteria into the bone or lead to septic arthritis which then spreads to the bone. Chronic tenosynovitis (A) would primarily involve the tendon sheath. Septic non-union (B) would be if there was a fracture that failed to heal and became infected, but the question describes bone changes not specifically related to a fracture non-union. Reactive arthritis (D) is a sterile inflammatory arthritis following infection elsewhere. Chronic cellulitis (E) is a soft tissue infection that typically would not present with bone changes or a persistent sinus tract for this duration.
Question 432
Topic: 7. Hand and Wrist
Which specific anatomic structure is most commonly violated in a 'fight bite' injury over the dorsal aspect of the MCP joint?
Correct Answer & Explanation
. C. Joint capsule
Explanation
Correct Answer: CThe correct answer is C because the joint capsule of the metacarpophalangeal (MCP) joint is the most commonly violated specific anatomical structure in a 'fight bite' injury. The injury typically occurs with the hand clenched in a fist, where the MCP joint is exposed. The opponent's tooth directly impacts and often lacerates the skin and the underlying joint capsule, inoculating bacteria directly into the joint space. Flexor tendon sheaths (A) are on the palmar side. Digital nerves (B) and dorsal veins (E) can be injured, but the joint capsule is the most characteristic and critical violation. The palmar aponeurosis (D) is on the palmar aspect of the hand.
Question 433
Topic: 7. Hand and Wrist
A 35-year-old male presents with a displaced scaphoid fracture. Surgical planning reveals a fracture through the proximal third of the scaphoid, with significant displacement.
Given this fracture pattern, which statement accurately describes the primary blood supply to the proximal pole and its implication for healing?
Correct Answer & Explanation
. Primarily supplied by the dorsal carpal artery branch of the radial artery, providing a retrograde flow to the proximal pole, increasing AVN risk.
Explanation
Correct Answer: CThe text explicitly states that the scaphoid's blood supply is highly vulnerable. Thedorsal carpal artery branch (from the radial artery)supplies the majority (70-80%) of the scaphoid via intraosseous branches entering the dorsal ridge. Crucially, these vessels provide aretrograde blood supply to the proximal pole. Fractures through the scaphoid waist or proximal pole often compromise this retrograde flow, especially if displaced, which explains the heightened susceptibility of the proximal pole toavascular necrosis (AVN).Incorrect Options:A) Primarily supplied by the palmar superficial branch of the radial artery, leading to a low risk of AVN:The palmar superficial branch supplies only the distal tubercle and a small portion of the distal pole (20-30%), not the majority of the scaphoid or the proximal pole.B) Primarily supplied by the dorsal carpal artery branch of the radial artery, providing an antegrade flow to the proximal pole:While the dorsal carpal artery branch is the primary supply, the flow to the proximal pole is retrograde, not antegrade.D) Primarily supplied by direct branches from the ulnar artery, ensuring robust vascularity:The primary blood supply to the scaphoid is from the radial artery, not the ulnar artery.E) Receives dual blood supply from both dorsal and palmar branches, making AVN rare:While there are dorsal and palmar contributions, the proximal pole's reliance on retrograde flow makes it highly susceptible to AVN, not rare.
Question 434
Topic: 7. Hand and Wrist
A 55-year-old patient presents with chronic wrist pain and stiffness, 15 years after an untreated scaphoid nonunion. Radiographs show advanced degenerative changes consistent with a SNAC wrist.
Which of the following accurately describes the typical progression of degenerative arthritis in a SNAC (Scaphoid Nonunion Advanced Collapse) wrist?
Correct Answer & Explanation
. Begins at the radial styloid-scaphoid articulation, progresses to the capitolunate joint, and spares the radiolunate joint until late stages.
Explanation
Correct Answer: CThe text clearly describes the progression of SNAC wrist: "It typically begins at theradial styloid-scaphoid articulation, progresses to thecapitolunate joint, andspares the radiolunate joint until late stages." This specific pattern of degenerative arthritis is a hallmark of SNAC wrist, resulting from altered carpal mechanics due to chronic scaphoid nonunion.Incorrect Options:A) Begins at the radiolunate joint, then progresses to the capitolunate joint, and finally the radioscaphoid articulation:This is incorrect as the radiolunate joint is typically spared until late stages, and the initial involvement is at the radioscaphoid articulation.B) Begins at the capitolunate joint, then progresses to the radioscaphoid articulation, and finally the radiolunate joint:This sequence is incorrect. The radioscaphoid articulation (specifically radial styloid-scaphoid) is the initial site of degeneration.D) Begins simultaneously at all carpal articulations due to global carpal collapse:SNAC wrist follows a predictable, sequential pattern of degeneration, not simultaneous involvement of all joints.E) Primarily affects the scaphotrapeziotrapezoid (STT) joint, with later involvement of the proximal carpal row:While the STT joint can be affected in other carpal pathologies, the primary progression of SNAC wrist is as described in option C.
Question 435
Topic: 7. Hand and Wrist
A surgeon is performing an open reduction and internal fixation of a scaphoid waist fracture via a volar (Henry) approach.
During the deep dissection for this approach, which of the following neurovascular structures must be carefully identified and protected, typically retracted radially?
Correct Answer & Explanation
. Radial artery
Explanation
Correct Answer: CThe text describes the deep dissection for the Volar (Henry) Approach: "Deep to the FCR, theradial arteryis identified. It runs between the FCR and the flexor pollicis longus (FPL). The radial artery is carefully retracted radially, often with the FPL." Protection of the radial artery is critical to prevent vascular compromise.Incorrect Options:A) Ulnar artery:The ulnar artery is located on the ulnar side of the wrist and is not typically encountered or at risk during a volar radial approach to the scaphoid.B) Median nerve:The median nerve is located more centrally in the carpal tunnel and is not the primary neurovascular structure retracted radially in this approach. The palmar cutaneous branch of the median nerve should be protected, but the main trunk is not typically retracted radially.D) Dorsal cutaneous branch of the ulnar nerve:This nerve is on the dorsal aspect of the wrist and is not relevant to a volar approach.E) Posterior interosseous nerve:This nerve is a branch of the radial nerve, located dorsally in the forearm, and is not at risk during a volar approach to the scaphoid.
Question 436
Topic: 7. Hand and Wrist
A 40-year-old patient presents with a symptomatic scaphoid nonunion of the proximal pole, diagnosed 18 months after initial injury. CT scan confirms nonunion with evidence of avascular necrosis (AVN) of the proximal fragment and early carpal collapse.
Given the presence of AVN and early carpal collapse, which of the following is the most appropriate surgical management strategy?
Correct Answer & Explanation
. Vascularized bone grafting (e.g., 2,3-ICSRA pedicled graft) with fixation.
Explanation
Correct Answer: DThe text outlines the management of nonunion and AVN: "For cases with established AVN of the proximal pole or recalcitrant nonunions,vascularized bone grafts(e.g., 2,3-ICSRA pedicled graft, free medial femoral condyle flap) have shown superior union rates by providing a direct blood supply." The presence of AVN in the proximal pole makes a vascularized graft the preferred option to enhance revascularization and promote healing, especially with early carpal collapse, indicating a need to restore scaphoid integrity.Incorrect Options:A) Non-vascularized bone grafting with revision internal fixation:This is typically used for stable nonunionswithout significant AVN or bone loss. Given the established AVN of the proximal pole, a non-vascularized graft would be less effective in promoting revascularization.B) Scaphoidectomy and four-corner arthrodesis (4CA):This is a salvage procedure foradvanced stages of post-traumatic arthritis (SNAC wrist). While there is early carpal collapse, it's not described as advanced arthritis, and the primary goal should still be to achieve union and preserve the scaphoid if possible.C) Proximal row carpectomy (PRC):Similar to 4CA, PRC is a salvage procedure forestablished arthritis. It involves removing the entire proximal carpal row and is considered when the articular surfaces are significantly damaged.E) Total wrist arthrodesis:This is an end-stage salvage procedure for severe, pan-carpal arthritis or failed previous surgeries, resulting in complete loss of wrist motion. It is too aggressive for a case with early carpal collapse where scaphoid reconstruction is still feasible.
Question 437
Topic: Wrist & Carpus
A 25-year-old patient presents with persistent anatomical snuffbox tenderness after a FOOSH injury. Initial plain radiographs are negative for a scaphoid fracture.
According to current literature and guidelines, which advanced imaging modality has demonstrated superior diagnostic accuracy over plain radiographs and bone scans for detecting occult scaphoid fractures?
Correct Answer & Explanation
. Magnetic Resonance Imaging (MRI)
Explanation
Correct Answer: BThe text states under "Diagnostic Algorithms": "MRI is highly sensitive for occult fractures and bone contusions...Meta-analyses have demonstrated the superior diagnostic accuracy of MRI over plain radiographs and bone scans for occult scaphoid fractures." This directly supports MRI as the superior modality for detecting occult fractures when initial radiographs are negative.Incorrect Options:A) Computed Tomography (CT) Scan:While CT is the gold standard for assessing fracture displacement, comminution, and fragment orientation for surgical planning, MRI is generally considered more sensitive for detecting occult fractures (bone edema/contusion) not visible on initial radiographs or even early CT.C) Diagnostic Ultrasound:Ultrasound has limited diagnostic accuracy for scaphoid fractures, especially occult ones, compared to MRI or CT.D) Arthrography:Arthrography is primarily used to assess ligamentous injuries and cartilage integrity, not for diagnosing occult bone fractures.E) Fluoroscopy with stress views:Fluoroscopy is used intraoperatively for guiding fixation or dynamically assessing carpal instability, but it is not an advanced imaging modality for detecting occult fractures.
Question 438
Topic: Wrist & Carpus
A 24-year-old male sustains a proximal pole scaphoid fracture. Which of the following surgical approaches and screw trajectories offers the best biomechanical stability and biological preservation for this specific injury?
For proximal pole scaphoid fractures, a dorsal approach is preferred as it avoids dividing the critical volar radioscaphocapitate ligament and allows for direct, central-central screw placement which biomechanically provides the greatest load to failure.
Question 439
Topic: 7. Hand and Wrist
A patient presents with a 'fight bite' over the 3rd metacarpophalangeal (MCP) joint. To accurately assess the depth of the injury and potential joint penetration, in which position must the hand be examined?
Correct Answer & Explanation
. Full flexion of the MCP and interphalangeal joints
Explanation
Fight bites occur with a clenched fist. Examining the hand in full flexion replicates the injury position, revealing capsular and extensor tendon lacerations that glide proximally when the hand is extended.
Question 440
Topic: 7. Hand and Wrist
A patient with an established scaphoid nonunion advanced collapse (SNAC) is being evaluated for a salvage procedure. Which of the following carpal articulations is characteristically preserved in SNAC wrists, allowing for a 4-corner fusion?
Correct Answer & Explanation
. Radiolunate joint
Explanation
In both SLAC and SNAC wrists, the radiolunate joint is characteristically spared from arthritic changes. This preservation is the physiological basis for performing a proximal row carpectomy or scaphoid excision with 4-corner fusion.
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