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7. Hand and Wrist MCQs

Practice Set 149 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 2961

Topic: Nerve & Tendon

A 45-year-old woman undergoes surgical decompression of the ulnar nerve for severe cubital tunnel syndrome. During the approach, the primary structure causing compression between the olecranon and the medial epicondyle is identified and released. Which of the following anatomical structures forms the true roof of the cubital tunnel in this region?

. Medial intermuscular septum
. Arcade of Struthers
. Osborne's ligament
. Aponeurosis of the flexor carpi ulnaris (FCU)
. Anconeus epitrochlearis

Correct Answer & Explanation

. Medial intermuscular septum

Explanation

Osborne's ligament (also known as the cubital tunnel retinaculum) forms the roof of the cubital tunnel, spanning from the medial epicondyle to the olecranon. The floor is formed by the posterior band of the medial collateral ligament (MCL) and the joint capsule. Other potential sites of ulnar nerve compression include the Arcade of Struthers (proximal to the epicondyle), the medial intermuscular septum, and the aponeurotic heads of the FCU (distal to the tunnel).

Question 2962

Topic: 7. Hand and Wrist

A 30-year-old male presents with an irreversible high radial nerve palsy following a midshaft humerus fracture sustained 18 months ago. A standard Jones tendon transfer is planned. Which of the following tendon transfers is classically utilized to restore wrist extension in this procedure?

. Pronator teres to extensor carpi radialis brevis
. Flexor carpi ulnaris to extensor digitorum communis
. Palmaris longus to extensor pollicis longus
. Flexor digitorum superficialis to extensor digitorum communis
. Flexor carpi radialis to extensor carpi radialis longus

Correct Answer & Explanation

. Pronator teres to extensor carpi radialis brevis

Explanation

In a classic Jones transfer for radial nerve palsy, wrist extension is restored by transferring the pronator teres (PT) to the extensor carpi radialis brevis (ECRB). The ECRB is chosen over the ECRL because it inserts more centrally (base of the 3rd metacarpal), producing pure wrist extension and minimizing radial deviation. The rest of the classic Jones transfer includes transferring the flexor carpi ulnaris (FCU) to the extensor digitorum communis (EDC) for finger extension, and the palmaris longus (PL) to the extensor pollicis longus (EPL) for thumb extension.

Question 2963

Topic: Wrist & Carpus

A 55-year-old female presents 6 months after a volar locking plate fixation of a distal radius fracture. She complains of suddenly losing the ability to actively flex the interphalangeal joint of her thumb. Radiographs show the fracture has healed, but the plate was placed on and slightly distal to the watershed line. Which of the following tendons is most commonly ruptured in this scenario?

. Flexor digitorum profundus to the index finger
. Flexor pollicis longus
. Flexor carpi radialis
. Extensor pollicis longus
. Abductor pollicis longus

Correct Answer & Explanation

. Flexor digitorum profundus to the index finger

Explanation

The flexor pollicis longus (FPL) tendon is at the highest risk for iatrogenic attritional rupture following volar plate fixation of distal radius fractures, particularly when the hardware is placed at or distal to the watershed line. The prominent distal edge of the plate causes friction and attritional wear of the overlying FPL tendon. Conversely, Extensor pollicis longus (EPL) ruptures are more common with non-operative management of nondisplaced distal radius fractures (due to ischemia or callus in the 3rd dorsal compartment) or from dorsally protruding screws piercing the dorsal cortex.

Question 2964

Topic: 7. Hand and Wrist

A 38-year-old carpenter presents with an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. He cannot form an 'OK' sign. Sensation in the hand and forearm is completely normal. Which of the following muscles is most likely to also demonstrate weakness on physical examination?

. Flexor carpi ulnaris
. Pronator teres
. Pronator quadratus
. Opponens pollicis
. Flexor digitorum superficialis

Correct Answer & Explanation

. Flexor carpi ulnaris

Explanation

The patient's presentation is classic for Anterior Interosseous Nerve (AIN) syndrome, which is characterized by paralysis of the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) to the index (and sometimes middle) finger. The AIN is a pure motor branch of the median nerve that also innervates the pronator quadratus. Weakness in resisted pronation with the elbow fully flexed (to neutralize the pronator teres) tests the pronator quadratus.

Question 2965

Topic: Nerve & Tendon

During the repair of an acute distal biceps tendon rupture using a single-incision anterior approach, the surgeon must be particularly careful to protect a specific nerve during the deep dissection and placement of retractors on the radial side of the radial tuberosity. Injury to this nerve leads to an inability to extend the digits. Which nerve is at greatest risk?

. Median nerve
. Ulnar nerve
. Posterior interosseous nerve (PIN)
. Superficial radial nerve
. Lateral antebrachial cutaneous nerve (LABC)

Correct Answer & Explanation

. Median nerve

Explanation

The posterior interosseous nerve (PIN) is at significant risk during a single-incision anterior approach for distal biceps repair. The PIN wraps around the radial neck within the supinator muscle. Aggressive retraction on the radial side of the tuberosity or inadvertent plunging with a drill can injure the PIN, resulting in a loss of finger and thumb extension. The LABC nerve is at risk during the superficial approach, but its injury only causes sensory deficits.

Question 2966

Topic: Wrist & Carpus

A 65-year-old female undergoes volar locking plate fixation for a comminuted distal radius fracture. Six weeks postoperatively, she presents with a sudden inability to flex the interphalangeal joint of her thumb. Radiographs confirm stable fracture fixation, but the plate is positioned distally, crossing the watershed line. Which of the following structures has most likely ruptured?

. Extensor pollicis longus (EPL)
. Flexor pollicis brevis (FPB)
. Flexor carpi radialis (FCR)
. Flexor pollicis longus (FPL)
. Flexor digitorum superficialis (FDS)

Correct Answer & Explanation

. Extensor pollicis longus (EPL)

Explanation

A volar plate placed distal to the watershed line of the distal radius can irritate and eventually cause attrition rupture of the flexor tendons. The Flexor Pollicis Longus (FPL) tendon is the most commonly injured tendon in this scenario due to its proximity to the volar prominent hardware. Conversely, Extensor Pollicis Longus (EPL) rupture is classically associated with prominent dorsal screws or undisplaced distal radius fractures treated non-operatively.

Question 2967

Topic: 7. Hand and Wrist

A 32-year-old manual laborer presents with chronic dorsal wrist pain. Radiographs demonstrate sclerosis, fragmentation, and collapse of the lunate. Additionally, there is a fixed flexed posture of the scaphoid (ring sign) and a decreased carpal height ratio. This clinical and radiographic presentation is most consistent with which Lichtman stage of Kienböck's disease?

. Stage II
. Stage IIIA
. Stage IIIB
. Stage IIIC
. Stage IV

Correct Answer & Explanation

. Stage II

Explanation

Lichtman Stage IIIB Kienböck's disease is characterized by lunate collapse and fragmentation accompanied by fixed scaphoid rotation (scaphoid flexion) and a decrease in carpal height ratio, indicating progressive carpal instability. Stage IIIA has lunate collapse but maintains normal carpal alignment without fixed scaphoid rotation. Stage IV includes secondary degenerative osteoarthritic changes in the radiocarpal or midcarpal joints.

Question 2968

Topic: Hand Trauma & Infection

A 28-year-old skier presents with acute thumb pain and weakness of pinch after a fall with the thumb forcefully abducted. Clinical examination shows significant laxity of the thumb metacarpophalangeal (MCP) joint to valgus stress. MRI reveals a complete rupture of the ulnar collateral ligament (UCL), and the torn distal end of the ligament is displaced superficial to the adductor aponeurosis. What is the most appropriate management?

. Thumb spica cast for 6 weeks
. Figure-of-eight splint for 4 weeks
. Corticosteroid injection and physical therapy
. Surgical repair of the UCL
. MCP joint arthrodesis

Correct Answer & Explanation

. Thumb spica cast for 6 weeks

Explanation

The patient's MRI demonstrates a Stener lesion, which occurs when a completely avulsed ulnar collateral ligament (UCL) of the thumb MCP joint becomes displaced and trapped superficial to the adductor pollicis aponeurosis. This mechanical block prevents the torn ligament ends from apposing and healing. Therefore, conservative treatment is ineffective, and surgical repair is the definitive standard of care.

Question 2969

Topic: Nerve & Tendon

A 45-year-old male laborer undergoes a two-incision approach (modified Boyd-Anderson) for the repair of an acute distal biceps tendon rupture. During the posterolateral approach (second incision) to expose the radial tuberosity, excessive retraction or improper splitting of the supinator muscle places which of the following neurovascular structures at highest risk of iatrogenic injury?

. Median nerve
. Posterior interosseous nerve
. Lateral antebrachial cutaneous nerve
. Radial artery
. Ulnar nerve

Correct Answer & Explanation

. Median nerve

Explanation

The posterior interosseous nerve (PIN) traverses the supinator muscle and wraps around the radial neck. It is at significant risk during the posterolateral aspect of a two-incision distal biceps repair if the supinator is bluntly split or forcefully retracted. Conversely, the lateral antebrachial cutaneous nerve is most at risk during the superficial dissection of the anterior single-incision approach.

Question 2970

Topic: 7. Hand and Wrist

A 32-year-old carpenter presents with progressive, activity-related dorsal wrist pain. Radiographs reveal Kienböck's disease (Lichtman Stage IIIA) with sclerosis and early fragmentation of the lunate, and a notable negative ulnar variance. There is no evidence of radioscaphoid arthritis. Which of the following surgical interventions is most appropriate to unload the lunate and halt disease progression?

. Proximal row carpectomy
. Scaphoid-trapezium-trapezoid (STT) fusion
. Radial shortening osteotomy
. Ulnar shortening osteotomy
. Total wrist arthrodesis

Correct Answer & Explanation

. Proximal row carpectomy

Explanation

In early to moderate stages of Kienböck's disease (Stage II or IIIA) associated with negative ulnar variance (ulna minus) and preserved carpal cartilage, joint-leveling procedures are indicated. A radial shortening osteotomy unloads the radiolunate joint and redistributes forces across the wrist. Ulnar lengthening is an alternative but carries higher complication rates (e.g., nonunion). Ulnar shortening would exacerbate the negative variance.

Question 2971

Topic: Nerve & Tendon

A 55-year-old male undergoes an in situ decompression of the ulnar nerve for severe cubital tunnel syndrome. During the release of Osborne's fascia, the surgeon identifies and meticulously protects the first motor branch of the ulnar nerve in the forearm. Which of the following muscles is innervated by this specific branch?

. Flexor carpi ulnaris
. Flexor digitorum profundus to the small finger
. Abductor digiti minimi
. Adductor pollicis
. First dorsal interosseous

Correct Answer & Explanation

. Flexor carpi ulnaris

Explanation

The first motor branch of the ulnar nerve in the forearm typically innervates the flexor carpi ulnaris (FCU) muscle. It branches off the main ulnar nerve just distal to the medial epicondyle as the nerve passes between the humeral and ulnar heads of the FCU (Osborne's fascia). Iatrogenic injury to this branch during decompression or transposition can lead to functional deficits.

Question 2972

Topic: 7. Hand and Wrist

A 30-year-old chef sustains a deep volar laceration to his left index finger at the level of the proximal phalanx (Zone II), cleanly transecting the flexor tendons. He is indicated for primary flexor tendon repair. To safely permit an early active motion rehabilitation protocol, which of the following variables is most directly correlated with the ultimate tensile strength of the repair?

. The number of core suture strands crossing the repair site
. The caliber and material of the epitendinous suture
. The use of a monofilament rather than a braided suture material
. The specific configuration of the core suture knot (e.g., square vs. surgeon's knot)
. The location of the core knot (inside vs. outside the tendon interface)

Correct Answer & Explanation

. The number of core suture strands crossing the repair site

Explanation

Biomechanical studies have consistently proven that the ultimate tensile strength of a flexor tendon repair is directly proportional to the number of core suture strands crossing the repair site. Modern protocols relying on early active motion generally require at least a 4-strand or 6-strand repair to prevent gap formation and subsequent rupture. While an epitendinous suture adds strength and minimizes gliding resistance, the core strand count is the primary determinant of strength.

Question 2973

Topic: 7. Hand and Wrist

A 25-year-old man presents with chronic wrist pain and is diagnosed with a scaphoid waist fracture nonunion with a humpback deformity. Radiographs demonstrate a dorsal intercalated segment instability (DISI) pattern and a shortened scaphoid. There is no evidence of avascular necrosis or arthritis. Which of the following is the most appropriate surgical management?

. Vascularized bone graft from the distal radius
. Scaphoid excision and four-corner fusion
. Proximal row carpectomy
. Volar wedge structural bone grafting and internal fixation
. Percutaneous screw fixation without bone graft

Correct Answer & Explanation

. Vascularized bone graft from the distal radius

Explanation

The patient has a scaphoid waist fracture nonunion with a humpback deformity (flexion of the scaphoid leading to a shortened volar length) and a secondary DISI deformity. Correction of the deformity is crucial to restore carpal kinematics and prevent progression to SNAC (scaphoid nonunion advanced collapse) arthritis. The standard of care for a humpback scaphoid nonunion without AVN is a volar approach, using a structural interposition wedge bone graft (typically from the iliac crest) to restore scaphoid length and correct the deformity, followed by rigid internal fixation. Percutaneous fixation without grafting will not address the deformity. Vascularized bone grafting is typically reserved for nonunions with avascular necrosis (proximal pole). Salvage procedures (four-corner fusion, PRC) are indicated if advanced arthritic changes (SNAC) are present.

Question 2974

Topic: 7. Hand and Wrist

In the evaluation of a patient with Kienböck's disease (avascular necrosis of the lunate), negative ulnar variance is often observed. Which of the following biomechanical effects does negative ulnar variance have on the wrist joint?

. It decreases the load transmitted through the radiocarpal joint.
. It increases the load transmitted across the radiolunate joint.
. It decreases the load transmitted across the radiolunate joint.
. It increases the load transmitted across the ulnocarpal joint.
. It shifts the center of rotation of the wrist distally.

Correct Answer & Explanation

. It decreases the load transmitted through the radiocarpal joint.

Explanation

Ulnar variance refers to the relative lengths of the distal articular surfaces of the radius and ulna. Negative ulnar variance means the ulna is shorter than the radius. Biomechanically, negative ulnar variance decreases the load transmitted through the ulnocarpal joint and correspondingly increases the load transmitted across the radiocarpal joint, specifically the radiolunate articulation. This increased mechanical stress on the lunate is thought to be a contributing factor to the pathogenesis of Kienböck's disease, as it may lead to microtrauma and compromise of the lunate's precarious blood supply. Joint leveling procedures (e.g., radial shortening osteotomy) aim to decrease this radiolunate load by restoring neutral variance.

Question 2975

Topic: 7. Hand and Wrist

A 35-year-old manual laborer presents with chronic progressive wrist pain 5 years after an untreated fall on his outstretched hand. Radiographs reveal a scaphoid nonunion with advanced radioscaphoid and capitolunate arthritis, but the radiolunate joint is spared. What is the most appropriate surgical management to provide pain relief while preserving motion?

. Scaphoid open reduction and internal fixation with vascularized bone grafting
. Proximal row carpectomy (PRC)
. Scaphoid excision and four-corner fusion
. Total wrist arthrodesis
. Radial styloidectomy

Correct Answer & Explanation

. Scaphoid open reduction and internal fixation with vascularized bone grafting

Explanation

This patient has a Scaphoid Nonunion Advanced Collapse (SNAC) stage III wrist (characterized by radioscaphoid and capitolunate arthritis, with a preserved radiolunate joint). A proximal row carpectomy (PRC) is contraindicated in SNAC III because the capitate articular surface is degenerated, which would articulate with the lunate fossa in a PRC. Therefore, scaphoid excision and a four-corner fusion (capitate, hamate, lunate, triquetrum) is the preferred motion-sparing procedure.

Question 2976

Topic: 7. Hand and Wrist

A 42-year-old male bodybuilder undergoes a single-incision anterior approach for a distal biceps tendon rupture repair using cortical button fixation. Postoperatively, he is noted to have weakness in thumb and finger extension, but normal wrist extension with radial deviation. Which of the following nerves was most likely injured during the procedure?

. Median nerve
. Ulnar nerve
. Posterior interosseous nerve
. Superficial radial nerve
. Lateral antebrachial cutaneous nerve

Correct Answer & Explanation

. Median nerve

Explanation

The posterior interosseous nerve (PIN) is at risk during the anterior single-incision approach to the distal biceps, particularly if retractors are placed too vigorously on the lateral side or during drilling of the radius. Injury to the PIN results in weakness of finger and thumb extensors and the extensor carpi ulnaris. Wrist extension is preserved but deviates radially because the extensor carpi radialis longus and brevis are innervated by the radial nerve proper, which branches proximal to the PIN.

Question 2977

Topic: Nerve & Tendon

During an in situ ulnar nerve decompression for cubital tunnel syndrome, the surgeon releases the nerve from the cubital tunnel. To prevent proximal entrapment, the surgeon explores the medial arm. Which fascial structure represents a potential site of ulnar nerve compression up to 8 cm proximal to the medial epicondyle?

. Osborne's ligament
. Arcade of Struthers
. Ligament of Struthers
. Arcuate ligament
. Lacertus fibrosus

Correct Answer & Explanation

. Osborne's ligament

Explanation

The Arcade of Struthers is a fascial band extending from the medial head of the triceps to the medial intermuscular septum, located approximately 8 cm proximal to the medial epicondyle. It is a known potential site of ulnar nerve compression, particularly if the nerve is transposed anteriorly and this arcade is not adequately released. In contrast, the Ligament of Struthers is associated with median nerve compression, and Osborne's ligament forms the roof of the cubital tunnel itself.

Question 2978

Topic: Wrist & Carpus

A 55-year-old woman undergoes volar locked plating for a displaced distal radius fracture. At her 6-week postoperative visit, she reports a sudden inability to actively flex her thumb interphalangeal joint. Radiographs show a healed fracture with the plate positioned distally, volar to the watershed line. Which of the following tendons was most likely injured?

. Extensor pollicis longus
. Flexor pollicis longus
. Flexor carpi radialis
. Extensor digitorum communis
. Flexor digitorum profundus to the index finger

Correct Answer & Explanation

. Extensor pollicis longus

Explanation

The flexor pollicis longus (FPL) tendon is the most commonly ruptured flexor tendon following volar plating of distal radius fractures. The mechanism is typically attrition and rupture due to the plate being placed too distally, projecting volar to the 'watershed line' where the FPL tendon is in intimate contact with the radius. Extensor pollicis longus (EPL) rupture occurs due to dorsal screw prominence, but presents with loss of thumb extension, not flexion.

Question 2979

Topic: Nerve & Tendon

A 45-year-old male presents with persistent medial elbow pain, constant numbness in the ring and small fingers, and intrinsic muscle weakness 12 months after an in situ ulnar nerve decompression at the cubital tunnel. Postoperative EMG/NCS confirms persistent, severe ulnar neuropathy localized to the elbow. Which of the following revision procedures is most appropriate?

. Repeat in situ decompression and neurolysis
. Subcutaneous ulnar nerve transposition
. Submuscular ulnar nerve transposition
. Medial epicondylectomy
. Distal anterior interosseous nerve to deep ulnar nerve transfer

Correct Answer & Explanation

. Repeat in situ decompression and neurolysis

Explanation

For failed primary in situ decompression of the ulnar nerve, revision surgery typically involves transposition of the nerve to move it out of the scarred bed. Submuscular transposition is widely favored in revision settings because it places the previously mobilized and potentially ischemic nerve into an unscarred, well-vascularized muscle bed, reducing the risk of recurrent perineural fibrosis and providing maximum protection. While subcutaneous transposition is an option, submuscular is generally preferred for revisions.

Question 2980

Topic: 7. Hand and Wrist

A 42-year-old male undergoes a single-incision anterior approach for the repair of an acute distal biceps tendon rupture using a cortical button technique. Postoperatively, he is unable to actively extend his thumb and fingers. However, he is able to extend his wrist, though it deviates radially during the movement. Which nerve has been injured, and what is the most common iatrogenic mechanism?

. Median nerve; direct laceration during dissection
. Radial nerve; traction injury at the spiral groove
. Posterior interosseous nerve (PIN); compression from retractors placed around the radial neck
. Lateral antebrachial cutaneous nerve; superficial traction injury
. Ulnar nerve; malpositioning on the arm board

Correct Answer & Explanation

. Median nerve; direct laceration during dissection

Explanation

The clinical presentation describes a posterior interosseous nerve (PIN) palsy. The PIN is the deep motor branch of the radial nerve. Injury results in the inability to extend the digits and thumb. Wrist extension is preserved because the extensor carpi radialis longus (ECRL) is innervated by the radial nerve proper proximal to the bifurcation; however, because the extensor carpi ulnaris (ECU) is innervated by the PIN, wrist extension occurs with unopposed radial deviation. The PIN is particularly at risk during the single-incision approach to the distal biceps when retractors (such as Hohmanns) are placed blindly or aggressively around the radial neck.

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