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7. Hand and Wrist MCQs

Practice Set 36 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 701

Topic: Wrist & Carpus

A 55-year-old active patient undergoes open reduction and internal fixation of a comminuted distal radius fracture with a volar locking plate. Post-fixation fluoroscopy confirms excellent restoration of radial length, radial inclination, and volar tilt. However, during intraoperative assessment, the surgeon notes persistent dorsal subluxation of the ulnar head relative to the sigmoid notch during forearm rotation, despite adequate radial reduction. Which of the following is the MOST appropriate next step in management?

. Proceed with wound closure, as DRUJ instability often resolves spontaneously after distal radius fixation.
. Apply a long arm cast with the forearm in full supination to stabilize the DRUJ.
. Perform a temporary DRUJ stabilization with K-wires, typically with the forearm in neutral rotation.
. Perform an ulnar shortening osteotomy to address the positive ulnar variance.
. Remove the volar plate and re-reduce the distal radius, suspecting an inadequate reduction.

Correct Answer & Explanation

. Perform a temporary DRUJ stabilization with K-wires, typically with the forearm in neutral rotation.

Explanation

Correct Answer: CThe case explicitly states: 'After plate fixation, meticulous assessment of potential DRUJ and carpal instability is paramount. ... If unstable, consider intraoperative TFCC repair (via arthroscopy or open approach), or K-wire stabilization of the DRUJ (typically 2 K-wires across the DRUJ, with the forearm in neutral rotation).' Persistent DRUJ instability after anatomical reduction of the distal radius indicates a significant TFCC injury or gross incongruity that requires direct intervention. Temporary K-wire stabilization in neutral rotation is a common and effective method to allow the TFCC to heal in a reduced position, preventing chronic instability and subsequent arthritis.Option A is incorrect. Unaddressed DRUJ instability leads to chronic pain, restricted forearm rotation, and early degenerative changes, directly impacting long-term function and increasing CRPS risk.Option B is incorrect. While immobilization is needed, full supination can put stress on the DRUJ ligaments and may not be the optimal position for healing, especially if the instability is dorsal. Neutral rotation is generally preferred for DRUJ stabilization.Option D is incorrect. An ulnar shortening osteotomy is a salvage procedure for chronic positive ulnar variance and ulnar impaction syndrome, not an acute treatment for intraoperative DRUJ instability after radial length has been restored. The problem here is instability, not necessarily positive ulnar variance if radial length is restored.Option E is incorrect. The question states 'excellent restoration of radial length, radial inclination, and volar tilt,' implying the distal radius reduction is adequate. Removing the plate would be unnecessary and detrimental.

Question 702

Topic: 7. Hand and Wrist

A 72-year-old female with osteoporosis undergoes open reduction and internal fixation of a comminuted distal radius fracture with a volar locking plate. Postoperatively, she develops disproportionate pain, swelling, allodynia, and skin color changes in her hand and wrist, consistent with early Complex Regional Pain Syndrome (CRPS). Which of the following pre-operative prophylactic measures, if implemented, has the strongest evidence for reducing the incidence of CRPS type I after distal radius fractures?

. Pre-operative administration of a single dose of intravenous corticosteroids.
. Daily oral Vitamin C supplementation (500mg daily for 50 days).
. Routine pre-operative stellate ganglion block.
. Aggressive pre-operative physical therapy focusing on wrist strengthening.
. Strict immobilization of the wrist for 6 weeks post-operatively.

Correct Answer & Explanation

. Daily oral Vitamin C supplementation (500mg daily for 50 days).

Explanation

Correct Answer: BThe case explicitly states: 'A meta-analysis by Zollinger et al. (2007) and subsequent studies have suggested that prophylactic oral Vitamin C (e.g., 500mg daily for 50 days) can significantly reduce the incidence of CRPS type I after distal radius fractures. This is a simple, cost-effective intervention with minimal side effects, and its use is increasingly integrated into pre-operative protocols.' This is the prophylactic measure with the strongest evidence mentioned in the case.Option A (Corticosteroids) is not mentioned as a prophylactic measure for CRPS in the case.Option C (Stellate ganglion block) is a treatment for established CRPS, not a routine pre-operative prophylactic measure.Option D (Aggressive pre-operative physical therapy focusing on wrist strengthening) is inappropriate for an acute fracture and could worsen pain and swelling, potentially increasing CRPS risk. Early gentle mobilization of uninvolved joints is part of CRPS prevention, but not aggressive wrist strengthening pre-operatively.Option E (Strict immobilization for 6 weeks) is contrary to the principle of early mobilization for CRPS prevention, which the case emphasizes: 'Early, pain-free active range of motion, coupled with effective perioperative pain management (including regional blocks), is consistently emphasized in guidelines as a cornerstone of CRPS prevention.'

Question 703

Topic: Wrist & Carpus

A 48-year-old carpenter sustains a displaced, comminuted distal radius fracture with significant loss of volar tilt and radial shortening. He undergoes open reduction and internal fixation with a volar locking plate. During the procedure, after plate application, the surgeon uses fluoroscopy to confirm optimal screw length and trajectory. Which of the following fluoroscopic findings, if present, would indicate an immediate need for screw revision?

. A distal screw tip extending 1 mm beyond the dorsal cortex.
. A distal screw tip extending 2 mm into the subchondral bone.
. A proximal screw engaging both cortices of the radial shaft.
. A distal screw trajectory parallel to the articular surface.
. A distal screw tip positioned just proximal to the critical watershed line.

Correct Answer & Explanation

. A distal screw tip extending 1 mm beyond the dorsal cortex.

Explanation

Correct Answer: AThe case states: 'Fluoroscopy in both AP and lateral views is crucial to confirm optimal screw length and trajectory, ensuring screws do not violate the joint space or protrude dorsally.' A screw tip extending 1 mm beyond the dorsal cortex, while seemingly small, constitutes dorsal protrusion. This can lead to significant complications such as extensor tendon irritation, tenosynovitis, or even rupture, especially for the extensor pollicis longus (EPL) tendon which courses over Lister's tubercle dorsally. Therefore, any dorsal protrusion requires immediate revision.Option B (2 mm into the subchondral bone) is generally acceptable and desired, as distal screws are designed to buttress the articular surface by engaging the subchondral bone for stable fixation.Option C (Proximal screw engaging both cortices) is the standard for cortical screws in the shaft, providing robust fixation.Option D (Distal screw trajectory parallel to the articular surface) is often ideal for maximizing subchondral bone purchase without violating the joint.Option E (Distal screw tip positioned just proximal to the critical watershed line) refers to plate positioning, not screw tip position. The plate's distal edge should be just proximal to the watershed line to maximize subchondral screw support without impinging on flexor tendons. Screw tips should be within the bone, not violating the joint or protruding dorsally.

Question 704

Topic: 7. Hand and Wrist

A 28-year-old male presents with a distal radius fracture. Radiographs show a significantly displaced intra-articular fracture with a large dorsal fragment and marked dorsal angulation. He is scheduled for open reduction and internal fixation. During pre-operative planning, the surgeon reviews the CT scan. Which of the following anatomical structures is MOST critical to restore to prevent post-traumatic arthritis and maintain long-term wrist function, as highlighted by the case?

. The attachment of the brachioradialis tendon to the radial styloid.
. The integrity of the palmar cutaneous branch of the median nerve.
. The normal volar tilt and articular congruity of the distal radius.
. The dorsal cortex of the distal radius, which is relatively straight.
. The origin of the pronator quadratus muscle on the distal radius.

Correct Answer & Explanation

. The normal volar tilt and articular congruity of the distal radius.

Explanation

Correct Answer: CThe case repeatedly emphasizes the importance of anatomical restoration for preventing long-term complications. Under 'Biomechanics of Distal Radius Fractures,' it states: 'The hallmark of a well-reduced DRF is the restoration of normal radiographic parameters: Volar Tilt... Articular Congruity: Intra-articular step-off or gap of >1-2 mm is strongly correlated with the development of post-traumatic arthritis.' And under 'Key Literature and Guidelines Summary': 'A consistent theme in the literature is the correlation between anatomical reduction and improved long-term outcomes, directly impacting the prevention of post-traumatic arthritis and CRPS. Articular Congruity: Intra-articular step-off or gap exceeding 1-2 mm is widely recognized as a predictor of post-traumatic arthritis.'Option A (Brachioradialis attachment) is important for radial length but less critical for preventing post-traumatic arthritis than articular congruity and volar tilt.Option B (Palmar cutaneous branch of the median nerve) is important to protect during surgery to prevent iatrogenic nerve injury, but its integrity does not directly prevent post-traumatic arthritis.Option D (Dorsal cortex) is a structural feature, but its 'straightness' is less critical than the overall restoration of volar tilt and articular surface.Option E (Pronator quadratus origin) is important for DRUJ stability and covering the plate, but its origin itself is not the primary factor in preventing post-traumatic arthritis compared to the articular surface and overall alignment.

Question 705

Topic: Wrist & Carpus

A 40-year-old patient undergoes open reduction and internal fixation of a distal radius fracture. Six months post-operatively, the patient presents with chronic pain, limited forearm rotation, and a clicking sensation on the ulnar side of the wrist. Radiographs show a healed distal radius fracture with neutral ulnar variance. Physical examination reveals tenderness over the DRUJ and instability on stress testing. Based on the case, which of the following is the MOST likely underlying cause of the patient's symptoms?

. Persistent positive ulnar variance leading to ulnar impaction syndrome.
. Unaddressed scapholunate ligament dissociation.
. Chronic flexor pollicis longus (FPL) tendon rupture.
. Unrecognized or inadequately treated triangular fibrocartilage complex (TFCC) injury.
. Post-traumatic arthritis of the radiocarpal joint due to articular step-off.

Correct Answer & Explanation

. Unrecognized or inadequately treated triangular fibrocartilage complex (TFCC) injury.

Explanation

Correct Answer: DThe patient's symptoms of chronic pain, limited forearm rotation, clicking, and DRUJ instability, despite a healed distal radius fracture and neutral ulnar variance, strongly point to an issue with the DRUJ stabilizers. The case highlights: 'The DRUJ is a complex trochoid joint critical for forearm rotation. It is formed by the ulnar head articulating with the sigmoid notch of the distal radius. Stability is primarily conferred by the triangular fibrocartilage complex (TFCC)... Unaddressed DRUJ instability leads to chronic pain, restricted forearm rotation, and early degenerative changes.' An unrecognized or inadequately treated TFCC injury during the initial fracture management would lead to these chronic DRUJ symptoms.Option A (Persistent positive ulnar variance) is incorrect because the radiographs show neutral ulnar variance. Positive ulnar variance is a common cause of DRUJ pathology, but it's ruled out here.Option B (Unaddressed scapholunate ligament dissociation) would primarily cause carpal instability and pain, often with a dorsal intercalated segmental instability (DISI) deformity, but less directly explain isolated DRUJ instability and limited forearm rotation.Option C (Chronic FPL tendon rupture) would cause loss of thumb IP flexion, not DRUJ instability or limited forearm rotation.Option E (Post-traumatic arthritis of the radiocarpal joint) would cause generalized wrist pain and stiffness, but the specific symptoms of clicking and instability on the ulnar side, with limited forearm rotation, are more characteristic of DRUJ pathology rather than primary radiocarpal arthritis, especially with neutral ulnar variance.

Question 706

Topic: 7. Hand and Wrist

A 50-year-old male undergoes open reduction and internal fixation of a distal radius fracture. Two months post-operatively, he develops progressive pain and inability to actively flex his thumb interphalangeal (IP) joint. Examination reveals tenderness over the volar aspect of the distal forearm and a palpable 'bowstringing' of the FPL tendon. Radiographs confirm a healed fracture with the volar plate in situ. Which of the following is the MOST likely cause of this complication?

. Acute carpal tunnel syndrome requiring immediate release.
. Iatrogenic injury to the median nerve during the surgical approach.
. Plate prominence or sharp edges causing chronic irritation and rupture of the FPL tendon.
. Infection of the surgical site leading to tendon necrosis.
. Malunion of the distal radius causing altered FPL mechanics.

Correct Answer & Explanation

. Plate prominence or sharp edges causing chronic irritation and rupture of the FPL tendon.

Explanation

Correct Answer: CThe patient's symptoms of progressive pain, inability to actively flex the thumb IP joint, and palpable 'bowstringing' of the FPL tendon are classic signs of a flexor pollicis longus (FPL) tendon rupture. The case explicitly lists 'Tendon Rupture (FPL most common)' as a complication, with the etiology being 'Plate prominence (especially if too distal or proud), sharp plate edges, rough screw heads, chronic irritation.' The time frame (2 months post-op) is consistent with chronic irritation leading to rupture. The case also emphasizes the importance of pronator quadratus repair to cover the hardware and reduce tendon irritation.Option A (Acute carpal tunnel syndrome) would present with median nerve symptoms (numbness/tingling in thumb, index, middle fingers, weakness of thenar muscles), not isolated FPL rupture.Option B (Iatrogenic median nerve injury) would also present with median nerve deficits, not isolated FPL rupture.Option D (Infection) would typically present with signs of inflammation, fever, purulent discharge, and generalized pain, not specifically FPL rupture, although infection can contribute to tendon damage.Option E (Malunion) could cause altered mechanics and pain, but it's less likely to cause an isolated FPL rupture with 'bowstringing' compared to direct hardware irritation.

Question 707

Topic: 7. Hand and Wrist

A 22-year-old male sustains a high-energy distal radius fracture with significant comminution and shortening. Pre-operative CT scan reveals a complex intra-articular pattern. During the surgical approach, the surgeon utilizes a finger trap traction setup. Which of the following is the primary biomechanical principle leveraged by this setup in the initial reduction phase?

. Direct manipulation of articular fragments with K-wires.
. Restoration of the volar buttress through direct visualization.
. Ligamentotaxis, using tension in intact carpal ligaments to indirectly reduce fragments.
. Application of a dorsal buttress plate to prevent dorsal collapse.
. Direct compression of the fracture fragments to achieve stable fixation.

Correct Answer & Explanation

. Ligamentotaxis, using tension in intact carpal ligaments to indirectly reduce fragments.

Explanation

Correct Answer: CThe case, under 'Reduction and Fixation Techniques,' describes 'Indirect Reduction (Ligamentotaxis)': 'Application of longitudinal traction (manual or using a finger trap setup) can help distract the fracture fragments and indirectly reduce them by tensioning the intact carpal ligaments. This is particularly useful for comminuted fractures.' This technique uses the intact soft tissue envelope and ligaments to pull the fragments into a more anatomical position.Option A (Direct manipulation with K-wires) is a direct reduction technique, often used after initial ligamentotaxis, but not the primary principle of finger trap traction itself.Option B (Restoration of the volar buttress through direct visualization) is a goal of direct reduction and plate application, not the mechanism of finger trap traction.Option D (Application of a dorsal buttress plate) is a fixation strategy for specific fracture patterns, not a reduction principle of traction.Option E (Direct compression of the fracture fragments) is typically achieved with plate fixation or external compression, not primarily by finger trap traction, which aims to distract and reduce.

Question 708

Topic: Wrist & Carpus

A 65-year-old female undergoes volar locking plate fixation for a displaced distal radius fracture. Six months postoperatively, she presents with a sudden inability to actively flex the interphalangeal joint of her thumb. What is the most likely cause?

. Extensor pollicis longus rupture
. Flexor pollicis longus rupture
. Anterior interosseous nerve palsy
. Trigger thumb
. Flexor digitorum profundus rupture

Correct Answer & Explanation

. Flexor pollicis longus rupture

Explanation

Flexor pollicis longus (FPL) tendon rupture is a well-documented complication of volar plating. It is most often caused by attrition from plate prominence over the watershed line of the distal radius.

Question 709

Topic: 7. Hand and Wrist

A 24-year-old male sustains a highly comminuted intra-articular distal radius fracture with severe metaphyseal bone loss. A dorsal spanning plate is utilized for damage control. Which two bones are typically fixated by this device?

. Radius and scaphoid
. Radius and lunate
. Radius and the second or third metacarpal
. Ulna and the third metacarpal
. Radius and the capitate

Correct Answer & Explanation

. Radius and the second or third metacarpal

Explanation

A dorsal spanning plate provides distraction ligamentotaxis and stability by anchoring proximally to the radial diaphysis and distally to the second or third metacarpal. It bypasses the radiocarpal and midcarpal joints entirely.

Question 710

Topic: Wrist & Carpus

In the anatomic evaluation and treatment of distal radius fractures, what is the normal radiographic volar tilt of the distal articular surface of the radius on a lateral radiograph?

. 0 degrees
. 5 degrees
. 11 degrees
. 22 degrees
. 30 degrees

Correct Answer & Explanation

. 11 degrees

Explanation

The normal anatomic volar tilt of the distal radius is approximately 11 to 12 degrees. Restoration of volar tilt is important to re-establish normal load transmission across the radiocarpal joint.

Question 711

Topic: Wrist & Carpus

A patient undergoing open reduction and internal fixation of a distal radius fracture with a volar locking plate develops an inability to flex the interphalangeal joint of the thumb 6 months postoperatively. Which of the following technical errors during the initial surgery is the most likely cause?

. Placement of the plate proximal to the watershed line
. Placement of the plate distal to the watershed line
. Penetration of screws into the distal radioulnar joint
. Over-penetration of dorsal screws
. Failure to repair the pronator quadratus completely

Correct Answer & Explanation

. Placement of the plate distal to the watershed line

Explanation

Placement of a volar plate distal to the watershed line of the distal radius causes prominence of the hardware. This can lead to attritional rupture of the flexor pollicis longus (FPL) tendon over the plate edge.

Question 712

Topic: Wrist & Carpus

A 60-year-old male undergoes non-operative treatment for a non-displaced distal radius fracture. Eight weeks later, he presents with the sudden inability to actively extend his thumb interphalangeal joint. What is the most appropriate surgical treatment?

. Direct primary repair of the extensor pollicis longus tendon
. Extensor indicis proprius to extensor pollicis longus tendon transfer
. Flexor carpi radialis to extensor pollicis longus tendon transfer
. Thumb interphalangeal joint arthrodesis
. Palmaris longus autograft interposition

Correct Answer & Explanation

. Extensor indicis proprius to extensor pollicis longus tendon transfer

Explanation

Extensor pollicis longus (EPL) rupture after a distal radius fracture occurs due to ischemia or mechanical attrition at Lister's tubercle. Because the tendon ends are typically retracted and degenerate, an extensor indicis proprius (EIP) to EPL transfer is the gold standard treatment.

Question 713

Topic: 7. Hand and Wrist

A 25-year-old male is treated with a volar locking plate for a comminuted distal radius fracture. Six months later, he suddenly loses the ability to actively flex the interphalangeal joint of his thumb. What is the most likely cause of this complication?

. Anterior interosseous nerve neuropraxia
. Extensor pollicis longus rupture
. Flexor pollicis longus attrition rupture
. Delayed median nerve compression
. Ischemic contracture of the flexor compartment

Correct Answer & Explanation

. Flexor pollicis longus attrition rupture

Explanation

Flexor pollicis longus (FPL) rupture is a known complication of volar plating when the plate is placed distal to the watershed line. This prominent hardware causes mechanical friction and eventual attrition of the tendon.

Question 714

Topic: 7. Hand and Wrist

A 60-year-old female sustains a minimally displaced distal radius fracture treated non-operatively in a cast. Six weeks later, she notes a new inability to actively extend her thumb out of the palm. What is the pathophysiology behind this finding?

. Posterior interosseous nerve entrapment at the Arcade of Frohse
. Ischemia and mechanical attrition of the tendon at Lister's tubercle
. Unrecognized avulsion of the flexor pollicis longus
. Avulsion of the extensor pollicis brevis at the base of the first metacarpal
. Volar subluxation of the distal radioulnar joint

Correct Answer & Explanation

. Ischemia and mechanical attrition of the tendon at Lister's tubercle

Explanation

Extensor pollicis longus (EPL) rupture classically occurs after minimally displaced distal radius fractures. The mechanism involves hematoma/swelling causing ischemia in the tight third extensor compartment, combined with mechanical attrition over Lister's tubercle.

Question 715

Topic: Wrist & Carpus

During volar plating of a comminuted distal radius fracture, the surgeon suspects a screw may be protruding past the dorsal cortex into the extensor compartments. Which intraoperative fluoroscopic view is most sensitive to evaluate for this specific complication?

. Standard posteroanterior (PA) view
. Standard lateral view
. 11-degree elevated PA view
. Dorsal tangential (skyline) view
. 45-degree pronated oblique view

Correct Answer & Explanation

. Dorsal tangential (skyline) view

Explanation

The dorsal tangential (skyline) view is specifically designed to profile the dorsal cortex of the distal radius. It accurately assesses dorsal screw prominence, which can lead to extensor tendon irritation or rupture.

Question 716

Topic: 7. Hand and Wrist

A 62-year-old female presents with the sudden inability to actively flex the interphalangeal joint of her thumb six months after undergoing volar locking plate fixation for a displaced distal radius fracture. Radiographs show a healed fracture with the distal edge of the plate resting completely distal to the watershed line. Which of the following is the most likely etiology?

. Flexor carpi radialis attritional rupture
. Anterior interosseous nerve neuropraxia
. Flexor pollicis longus tendon rupture
. Extensor pollicis longus tendon rupture
. Median nerve compression

Correct Answer & Explanation

. Flexor pollicis longus tendon rupture

Explanation

Flexor pollicis longus (FPL) rupture is a well-documented complication of volar plating for distal radius fractures when the plate is placed distal to the watershed line. The prominent hardware causes attritional wear and eventual rupture of the overlying FPL tendon.

Question 717

Topic: Wrist & Carpus

A 55-year-old male treated non-operatively in a cast for a nondisplaced distal radius fracture presents 8 weeks post-injury with a sudden inability to actively extend his thumb interphalangeal joint. The fracture is radiographically healed. What is the most appropriate definitive surgical management?

. Primary end-to-end repair of the ruptured tendon
. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Palmaris longus interposition grafting of the tendon gap
. Flexor digitorum superficialis (FDS) to extensor pollicis longus (EPL) transfer
. Tenodesis of the EPL to the extensor carpi radialis brevis (ECRB)

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer

Explanation

Extensor pollicis longus (EPL) ruptures following distal radius fractures usually result from ischemia and attrition within the tight third dorsal compartment. Because the tendon ends are typically degenerated and retracted, primary repair is rarely feasible, making an EIP to EPL tendon transfer the treatment of choice.

Question 718

Topic: 7. Hand and Wrist

A 42-year-old construction worker undergoes an acute single-incision anterior repair of a distal biceps tendon rupture. Postoperatively, he develops persistent numbness and dysesthesia along the radial aspect of his forearm. Physical examination confirms diminished sensation in this distribution. Motor function is intact.

Which of the following complications is most likely responsible for his symptoms?

. Posterior Interosseous Nerve (PIN) neuropraxia
. Median nerve compression
. Lateral Antebrachial Cutaneous Nerve (LACN) injury
. Brachial artery pseudoaneurysm
. Heterotopic ossification

Correct Answer & Explanation

. Lateral Antebrachial Cutaneous Nerve (LACN) injury

Explanation

Correct Answer: CThe 'Complications & Management' section details neurological injuries. It states:"Lateral Antebrachial Cutaneous Nerve (LACN) injury... Management: Usually neuropraxia/neuroma, leading to numbness/dysesthesia in radial forearm."The PIN is a motor nerve, and its injury would primarily cause motor deficits (e.g., wrist or finger extensor weakness), not sensory changes in the radial forearm. Median nerve compression would affect sensation in the thumb, index, middle, and radial half of the ring finger, and potentially motor function of the thenar muscles. A brachial artery pseudoaneurysm would present with pulsatile mass, pain, and potentially ischemia. Heterotopic ossification is the formation of bone in soft tissues and would cause pain and stiffness, not isolated sensory deficits.

Question 719

Topic: Nerve & Tendon

When performing a single-incision anterior approach for distal biceps tendon repair, blind placement of deep retractors laterally over the radial neck places which of the following structures at highest risk of iatrogenic injury?

. Median nerve
. Ulnar nerve
. Posterior interosseous nerve
. Anterior interosseous nerve
. Brachial artery

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

While the LABC nerve is at risk superficially, deep retractors placed blindly around the radial neck during a single-incision biceps repair put the posterior interosseous nerve (PIN) at significant risk.

Question 720

Topic: 7. Hand and Wrist

A 42-year-old male sustains a posterior interosseous nerve (PIN) injury during a modified 2-incision repair of his distal biceps tendon. Which of the following motor deficits is most expected on his postoperative examination?

. Inability to extend the digits and thumb with preserved radial wrist extension
. Complete inability to extend the wrist and digits
. Inability to flex the interphalangeal joint of the thumb
. Loss of intrinsic hand muscle function
. Inability to pronate the forearm against resistance

Correct Answer & Explanation

. Inability to extend the digits and thumb with preserved radial wrist extension

Explanation

The PIN innervates the extensor digitorum communis, extensor pollicis longus, and other digit extensors. The extensor carpi radialis longus (ECRL) is innervated by the radial nerve proximal to the PIN branch, so radial wrist extension is preserved.

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