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7. Hand and Wrist MCQs

Practice Set 52 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 1021

Topic: 7. Hand and Wrist
A 38-year-old recreational basketball player presents to your clinic 3 days after 'jamming' his left ring finger. He reports immediate pain and an inability to fully straighten the tip of his finger. On examination, his DIP joint rests in approximately 30 degrees of flexion, and he has a 30-degree active extensor lag. Passively, the DIP joint can be fully extended. Radiographs show no evidence of fracture or subluxation. According to the Doyle classification, what type of injury does this patient most likely have, and what is the most appropriate initial management?
. Type II; Surgical repair with K-wire fixation.
. Type III; Open reduction and internal fixation.
. Type I; Continuous DIP joint extension splinting for 6-8 weeks.
. Type IV; Referral to a pediatric hand specialist for growth plate assessment.
. Type I; Immediate active and passive range of motion exercises to prevent stiffness.

Correct Answer & Explanation

. Type I; Continuous DIP joint extension splinting for 6-8 weeks.

Explanation

The patient's presentation of a 'jammed' finger, inability to actively extend the DIP joint, a resting flexion deformity, and full passive extension, coupled with normal radiographs, is classic for a soft tissue mallet finger. According to the Doyle classification, this is a Type I injury, which involves a soft tissue avulsion of the terminal extensor tendon from its insertion on the distal phalanx without significant bony involvement. The vast majority of acute soft tissue mallet injuries are successfully managed non-operatively. The core principle of non-operative management is continuous immobilization of the DIP joint in full extension or slight hyperextension (0-10 degrees) for a prolonged period, typically 6 to 8 weeks, followed by a gradual weaning phase.

Question 1022

Topic: 7. Hand and Wrist

A 55-year-old female presents with a chronic soft tissue mallet finger of her right long finger, sustained 6 months prior. She initially attempted splinting but was non-compliant due to discomfort. She now has a persistent 35-degree extensor lag at the DIP joint and has developed a noticeable hyperextension deformity at her PIP joint. Which of the following anatomical structures is primarily responsible for the characteristic flexion deformity at the DIP joint in a soft tissue mallet finger?

. Extensor Digitorum Communis (EDC) tendon
. Central slip of the extensor mechanism
. Flexor Digitorum Superficialis (FDS) tendon
. Flexor Digitorum Profundus (FDP) tendon
. Lumbrical muscles

Correct Answer & Explanation

. Flexor Digitorum Profundus (FDP) tendon

Explanation

Correct Answer: DThe case explicitly states that in a soft tissue mallet injury (Type I), the terminal extensor tendon is ruptured from its insertion, disrupting the extensor moment arm at the DIP joint. This disruption leaves the DIP joint extension unopposed, and the powerful pull of theflexor digitorum profundus (FDP)tendon, which inserts on the volar aspect of the distal phalanx, creates the characteristic flexion deformity. The FDP is the sole flexor of the DIP joint.Option A (Extensor Digitorum Communis)is an extrinsic extensor, but its terminal tendon is what is disrupted, leading to the deformity, not causing it.Option B (Central slip of the extensor mechanism)primarily extends the PIP joint and is typically intact in a pure soft tissue mallet finger. Its overactivity can contribute to a swan neck deformity, but it does not cause DIP flexion.Option C (Flexor Digitorum Superficialis)inserts on the middle phalanx and primarily flexes the PIP joint, not the DIP joint.Option E (Lumbrical muscles)are intrinsic muscles that contribute to MCP joint flexion and PIP/DIP extension, but they are not the primary cause of the DIP flexion deformity in a mallet finger.

Question 1023

Topic: Nerve & Tendon

A 28-year-old carpenter presents with a 4-month-old soft tissue mallet finger of his index finger. He initially tried splinting for 3 weeks but removed it due to work demands. He now has a fixed 25-degree extensor lag at the DIP joint and complains of difficulty picking up small objects. He is considering surgical intervention. Which of the following is a critical supporting structure of the extensor mechanism at the DIP joint that stabilizes the lateral bands and prevents their volar subluxation?

. Volar plate
. Annular pulleys
. Triangular ligament
. Sagittal bands
. Transverse retinacular ligament

Correct Answer & Explanation

. Triangular ligament

Explanation

Correct Answer: CThe 'Surgical Anatomy & Biomechanics' section clearly identifies theTriangular Ligamentas a crucial supporting structure. It states: 'Located dorsally, it stabilizes the lateral bands, preventing their volar subluxation and maintaining their position for efficient DIP joint extension.'Option A (Volar plate)is a ligamentous structure on the volar aspect of the joint that prevents hyperextension, but it is not involved in stabilizing the dorsal extensor mechanism.Option B (Annular pulleys)are part of the flexor tendon sheath system, crucial for maintaining the mechanical advantage of the flexor tendons, not the extensor mechanism.Option D (Sagittal bands)are located at the MCP joint level and stabilize the extensor digitorum communis tendon over the MCP joint, not the DIP joint.Option E (Transverse retinacular ligament)is mentioned as influencing joint movement and preventing dorsal migration of the lateral bands, but the triangular ligament is specifically highlighted for preventing volar subluxation and maintaining position for efficient DIP extension.

Question 1024

Topic: Nerve & Tendon

A 42-year-old accountant presents with a 3-month history of a soft tissue mallet finger on his dominant middle finger. He initially attempted non-operative management with a Stack splint for 8 weeks, but he admits to removing it frequently for hygiene and work-related tasks. He now has a persistent 20-degree extensor lag at the DIP joint and is frustrated with his inability to fully extend his finger. He is considering surgical repair. Which of the following is a strong indication for surgical management in this patient?

. Acute presentation within 4-6 weeks of injury.
. Patient compliance with continuous splinting.
. Persistent extensor lag of more than 15-20 degrees after an adequate course of continuous splinting.
. Absence of secondary deformity like a fixed swan neck.
. Minimal initial extensor lag (e.g., <15 degrees).

Correct Answer & Explanation

. Persistent extensor lag of more than 15-20 degrees after an adequate course of continuous splinting.

Explanation

Correct Answer: CThe 'Indications & Contraindications' section explicitly lists 'Failed Non-Operative Management: Persistent extensor lag of more than 15-20 degrees after an adequate course of continuous splinting (typically 8 weeks, followed by night splinting)' as a primary indication for surgical management. This patient fits this criterion, having a 20-degree lag after an attempted 8-week splinting course (albeit with poor compliance).Option A (Acute presentation within 4-6 weeks of injury)is an indication for non-operative management, not surgical.Option B (Patient compliance with continuous splinting)is a factor for successful non-operative management, not an indication for surgery.Option D (Absence of secondary deformity like a fixed swan neck)would typically favor non-operative management if the injury is acute and correctable, or it means the surgery would be less complex if performed for other reasons. The presence of a fixed swan neck, however, would be an indication for surgery.Option E (Minimal initial extensor lag)would typically favor non-operative management.

Question 1025

Topic: Nerve & Tendon
A 60-year-old diabetic patient presents with a chronic soft tissue mallet finger of 8 months duration, complicated by a fixed swan neck deformity of the same finger. She is scheduled for surgical repair. During pre-operative planning, the surgeon reviews imaging. Which of the following imaging modalities is considered mandatory for initial evaluation of a mallet finger to rule out bony involvement?
. Magnetic Resonance Imaging (MRI) of the finger.
. Computed Tomography (CT) scan of the finger.
. Standard AP, lateral, and oblique plain radiographs of the affected digit.
. Ultrasound of the extensor tendon.
. Bone scan.

Correct Answer & Explanation

. Standard AP, lateral, and oblique plain radiographs of the affected digit.

Explanation

Standard AP, lateral, and oblique views of the affected digit are mandatory. These are crucial to rule out bony avulsion fractures (Doyle Type II, III, IV), DIP joint subluxation, and pre-existing arthritis. A true lateral view is essential to accurately assess the joint alignment and presence of bony avulsion.

Question 1026

Topic: Nerve & Tendon

A 25-year-old professional musician undergoes surgical repair for a chronic soft tissue mallet finger with significant tendon retraction. The surgeon decides to perform a tendon-to-bone reattachment using drill holes and a pull-out suture technique. Post-operatively, the DIP joint is immobilized with a transarticular K-wire. The image below shows a typical K-wire placement for this procedure.

What is the primary purpose of this K-wire fixation in the immediate post-operative period?

. To provide dynamic compression across the DIP joint to promote bone healing.
. To allow early active range of motion of the DIP joint while protecting the repair.
. To protect the tendon repair and maintain the DIP joint in full extension or slight hyperextension.
. To prevent volar plate injury during rehabilitation exercises.
. To facilitate tendon gliding and prevent adhesions.

Correct Answer & Explanation

. To protect the tendon repair and maintain the DIP joint in full extension or slight hyperextension.

Explanation

Correct Answer: CThe 'Internal Fixation (K-wire)' section states: 'After the tendon repair, transarticular K-wire fixation of the DIP joint is almost always performed to protect the repair and maintain the joint in the desired position during healing.' It further specifies: 'The DIP joint is gently placed in full extension or slight hyperextension (0-10 degrees).' The image clearly depicts a K-wire traversing the DIP joint, holding it in extension.Option A is incorrectbecause the K-wire is not primarily for dynamic compression or bone healing in a soft tissue injury. Its role is static immobilization.Option B is incorrectbecause the K-wire prevents active range of motion at the DIP joint, which is crucial to protect the healing tendon. Early active motion is contraindicated.Option D is incorrectbecause while over-extension should be avoided to prevent volar plate injury, the primary purpose of the K-wire is not to prevent this specific injury during rehabilitation, but rather to immobilize the joint for tendon healing.Option E is incorrectbecause the K-wire immobilizes the joint and tendon, which can actually contribute to stiffness if not managed properly in rehabilitation. It does not facilitate tendon gliding or prevent adhesions directly.

Question 1027

Topic: 7. Hand and Wrist

A 30-year-old athlete undergoes surgical repair for a chronic soft tissue mallet finger. During the procedure, the surgeon identifies significant retraction of the proximal tendon stump and a very short distal stump. The image below shows a K-wire used for post-operative immobilization.

Which of the following surgical techniques is most appropriate for re-establishing the attachment of the terminal extensor tendon to the distal phalanx in this scenario?

. Direct tendon-to-tendon repair using a Bunnell stitch.
. Tendon advancement and reattachment to the distal phalanx using bone tunnels or suture anchors.
. Primary DIP joint arthrodesis (fusion).
. Central slip tenotomy to reduce tension.
. Lateral band reconstruction without addressing the terminal tendon.

Correct Answer & Explanation

. Tendon advancement and reattachment to the distal phalanx using bone tunnels or suture anchors.

Explanation

Correct Answer: BThe 'Detailed Surgical Approach / Technique' section, under 'Repair Technique,' describes 'Tendon-to-Bone Reattachment (Direct Repair)' as the most common technique for acute and subacute mallets, involving drill holes or suture anchors. For chronic injuries, it states: 'For chronic injuries with significant retraction and scar tissue, direct reattachment may lead to excessive tension. The tendon may be advanced distally and reattached to the distal phalanx as described above.' This directly addresses the scenario of significant retraction and a short distal stump, where advancement and reattachment to the bone are necessary.Option A (Direct tendon-to-tendon repair)is typically used when a sufficient distal tendon stump remains, which is rare in Type I mallet injuries, especially chronic ones with a 'very short distal stump.' It's more common for lacerations.Option C (Primary DIP joint arthrodesis)is a salvage procedure for severe, irreparable damage with significant functional impairment, not a primary repair technique for a chronic mallet finger, especially in an athlete.Option D (Central slip tenotomy)would weaken PIP extension and is not a technique for repairing a mallet finger; it might be considered in severe swan neck deformities but not as a primary mallet repair.Option E (Lateral band reconstruction without addressing the terminal tendon)is incomplete and would not restore DIP extension. Lateral band involvement may be addressed in chronic cases, but the primary issue is the terminal extensor tendon.

Question 1028

Topic: Nerve & Tendon

A 48-year-old painter undergoes surgical repair of a chronic soft tissue mallet finger. Post-operatively, the DIP joint is immobilized with a K-wire as shown in the image. During the rehabilitation phase, which of the following is the MOST critical instruction for the patient during the initial 6-week immobilization period?

. Actively flex the DIP joint to 30 degrees daily to prevent stiffness.
. Perform passive DIP joint extension exercises to maintain full range of motion.
. Ensure absolutely no active or passive DIP joint flexion is permitted.
. Begin light resistive exercises for DIP extension at 3 weeks post-op.
. Remove the K-wire at home if it becomes uncomfortable.

Correct Answer & Explanation

. Ensure absolutely no active or passive DIP joint flexion is permitted.

Explanation

Correct Answer: CThe 'Post-Operative Rehabilitation Protocols' section, under 'Phase 1: Immobilization (Weeks 0-6),' explicitly states for DIP Joint Immobilization: 'Crucial Principle: Absolutely no active or passive DIP joint flexion is permitted. The patient must be meticulously educated on this, particularly for activities of daily living.' This is the most critical instruction to protect the healing tendon repair.Option A is incorrectbecause active DIP flexion would directly stress and likely rupture the healing tendon.Option B is incorrectbecause passive DIP extension is already maintained by the K-wire/splint, and passive flexion is contraindicated.Option D is incorrectbecause light resistive exercises for DIP extension are typically introduced much later, in Phase 3 (Weeks 12+), after the tendon has had significant time to heal.Option E is incorrectbecause K-wires should only be removed by a medical professional, typically at 6 weeks post-operatively, not by the patient at home due to discomfort, as this could lead to complications like infection or re-injury.

Question 1029

Topic: Nerve & Tendon

A 70-year-old retired teacher presents with a persistent 25-degree extensor lag after 10 weeks of continuous splinting for an acute soft tissue mallet finger. She is now developing a mild, flexible hyperextension of her PIP joint. The surgeon is considering surgical intervention. Which of the following complications is most commonly associated with unsatisfactory outcomes after soft tissue mallet finger repair, and what is a potential salvage strategy for a severe, irreparable case?

. Infection; Salvage with aggressive physical therapy.
. Stiffness / Loss of Motion; Salvage with early active DIP flexion.
. Extensor Lag / Re-rupture; Salvage with DIP joint arthrodesis (fusion).
. Nail Deformity; Salvage with nerve release/neurolysis.
. Skin Necrosis; Salvage with prolonged splinting.

Correct Answer & Explanation

. Extensor Lag / Re-rupture; Salvage with DIP joint arthrodesis (fusion).

Explanation

Correct Answer: CThe 'Complications & Management' section identifies 'Extensor Lag / Re-rupture' as the 'Most common (5-20%), higher in chronic cases' and 'the most common reason for unsatisfactory outcomes.' For salvage strategies, it states: 'For persistent, functionally significant lag, revision surgery may be considered. Options include repeat direct repair, tendon advancement (if proximal tissue allows), tenodesis (using a portion of the lateral band or a small palmaris longus graft), or, in cases of severe, irreparable damage with significant functional impairment, DIP joint arthrodesis (fusion) in a functional position (typically 10-15 degrees of flexion).'Option A (Infection)is a complication, but its incidence is low (1-5%), and aggressive physical therapy is not the primary salvage for infection.Option B (Stiffness / Loss of Motion)is common, but early active DIP flexion is contraindicated and would worsen the outcome, not salvage it.Option D (Nail Deformity)is often cosmetic and not typically salvaged with nerve release/neurolysis, which is for nerve irritation/neuroma.Option E (Skin Necrosis)is low incidence (1-3%), and prolonged splinting is not a salvage for skin necrosis; it requires wound care, debridement, or skin grafting.

Question 1030

Topic: Nerve & Tendon

A 35-year-old construction worker presents with an acute open mallet finger injury to his small finger, sustained from a laceration over the DIP joint. On examination, there is a clear disruption of the extensor tendon, and he has a significant extensor lag. Which of the following statements best reflects the consensus on managing this specific type of mallet finger injury?

. Open mallet injuries are typically managed non-operatively with continuous splinting, similar to closed injuries.
. Surgical debridement and primary repair are required to prevent infection and restore tendon integrity.
. The primary concern is the development of a swan neck deformity, which should be addressed first.
. MRI is mandatory to assess the extent of tendon retraction before any intervention.
. DIP joint arthrodesis is the preferred initial treatment for open mallet injuries to ensure stability.

Correct Answer & Explanation

. Surgical debridement and primary repair are required to prevent infection and restore tendon integrity.

Explanation

Correct Answer: BThe 'Indications & Contraindications' section, under 'Operative Indications,' lists 'Open Mallet Injuries: Lacerations over the DIP joint with extensor tendon disruption, which require surgical debridement and primary repair to prevent infection and facilitate healing.' The 'Summary of Key Literature / Guidelines' further reinforces this: 'Acute open mallet finger lacerations require surgical debridement and primary repair, irrespective of the degree of lag, to prevent infection and restore tendon integrity.'Option A is incorrectbecause open injuries carry a high risk of infection and require surgical intervention, unlike most closed injuries.Option C is incorrectbecause while swan neck deformity is a potential secondary complication, the immediate priority for an open injury is infection prevention and primary tendon repair.Option D is incorrectbecause MRI is generally not indicated for routine mallet finger, and for an acute open injury, surgical exploration and repair are more urgent than advanced imaging.Option E is incorrectbecause DIP joint arthrodesis is a salvage procedure for severe, irreparable cases, not the preferred initial treatment for an acute open mallet finger, especially in a young, active patient.

Question 1031

Topic: Hand Trauma & Infection

A 35-year-old right-hand dominant male presents with acute right thumb pain and instability after a skiing accident. He fell while gripping a ski pole, which forced his thumb into violent abduction and hyperextension. He reported an immediate 'pop' and profound weakness in pinch grip. Which of the following statements best describes the biomechanical sequence of ligamentous failure in this classic injury pattern?

. A. The proper ulnar collateral ligament fails first in extension, followed by the accessory ulnar collateral ligament in flexion.
. B. The volar plate is the primary restraint in both extension and flexion, failing before the ulnar collateral ligament components.
. C. The accessory ulnar collateral ligament and volar plate bear initial stress in extension, with the proper ulnar collateral ligament failing as the joint is forced into flexion and abduction.
. D. The adductor pollicis aponeurosis ruptures first, leading to secondary failure of the ulnar collateral ligament.
. E. The radial collateral ligament is primarily affected due to the abduction force, with secondary involvement of the ulnar collateral ligament.

Correct Answer & Explanation

. C. The accessory ulnar collateral ligament and volar plate bear initial stress in extension, with the proper ulnar collateral ligament failing as the joint is forced into flexion and abduction.

Explanation

Correct Answer: CThe case explicitly states, 'When the metacarpophalangeal joint is in extension during the traumatic event, the accessory ulnar collateral ligament and volar plate bear the initial stress. However, as the joint is forced into flexion and abduction, the proper ulnar collateral ligament becomes the primary restraint and subsequently fails.' This accurately describes the sequential failure of the ulnar collateral ligament complex in a Skier's Thumb injury.Option A is incorrectbecause the proper UCL is the primary restraint in flexion, not extension, and the accessory UCL bears initial stress in extension.Option B is incorrectbecause while the volar plate contributes to stability in extension, it is not the primary restraint in both positions, nor does it typically fail before the entire UCL complex in this specific mechanism.Option D is incorrectbecause the adductor pollicis aponeurosis is a muscular aponeurosis, not a primary ligamentous restraint, and its interposition (Stener lesion) occurs after the UCL rupture, not as a primary failure leading to it.Option E is incorrectbecause a forced abduction injury primarily stresses the ulnar collateral ligament, not the radial collateral ligament, which resists varus forces.

Question 1032

Topic: 7. Hand and Wrist

During the clinical examination of the patient, a distinct, firm, highly tender, pea-sized mass was appreciated proximally and ulnarly to the metacarpophalangeal joint line. This finding is pathognomonic for which of the following conditions?

. A. A partial tear of the accessory ulnar collateral ligament.
. B. An acute avulsion fracture of the ulnar base of the proximal phalanx.
. C. A Stener lesion, indicating interposition of the adductor pollicis aponeurosis.
. D. A ganglion cyst arising from the metacarpophalangeal joint capsule.
. E. A rupture of the flexor pollicis longus tendon.

Correct Answer & Explanation

. C. A Stener lesion, indicating interposition of the adductor pollicis aponeurosis.

Explanation

Correct Answer: CThe case explicitly states, 'During palpation of the ulnar joint line, a distinct, firm, highly tender, pea-sized mass was appreciated proximally and ulnarly to the metacarpophalangeal joint line. This palpable mass is the pathognomonic clinical hallmark of a Stener lesion. It represents the avulsed, retracted distal end of the ulnar collateral ligament that has displaced superficial to the proximal edge of the adductor pollicis aponeurosis.' This interposition prevents healing and necessitates surgical intervention.Option A is incorrectbecause a partial tear would not typically present with a palpable, retracted mass, and would likely have a firm endpoint on stress testing.Option B is incorrectbecause while an avulsion fracture can occur, the description of a 'pea-sized mass' refers to soft tissue (the ligament stump), and radiographs would be needed to confirm a bony avulsion, which were negative in this case.Option D is incorrectbecause a ganglion cyst is typically a chronic, non-traumatic finding, and while it can be firm, it would not be acutely tender in this context or pathognomonic for an acute ligamentous injury.Option E is incorrectbecause a flexor pollicis longus tendon rupture would present with an inability to flex the IP joint and a different palpable mass location, not specifically at the MCP joint ulnar aspect.

Question 1033

Topic: Hand Trauma & Infection

The case highlights the importance of specific techniques during valgus stress testing of the thumb metacarpophalangeal joint. Which of the following statements represents a critical 'pearl' for accurate assessment of ulnar collateral ligament integrity?

. A. Stress testing should always be performed in full extension first, as this is the most sensitive position for detecting UCL injury.
. B. Stress radiography is mandatory to objectively quantify laxity and should be performed before clinical stress testing.
. C. A local intra-articular anesthetic block is essential to overcome muscle guarding and allow for reliable assessment of laxity.
. D. Palpation for a Stener lesion should only be performed after stress testing to avoid causing discomfort.
. E. The interphalangeal joint should be immobilized during stress testing to prevent confounding motion.

Correct Answer & Explanation

. C. A local intra-articular anesthetic block is essential to overcome muscle guarding and allow for reliable assessment of laxity.

Explanation

Correct Answer: CThe case explicitly states under 'Clinical Pearls and Pitfalls': 'Local Anesthesia is Mandatory: Attempting to grade laxity in an acutely injured, unanesthetized thumb is highly unreliable due to involuntary muscle guarding by the adductor pollicis. A local intra-articular or digital block is essential for an accurate physical examination.' This is a crucial step for accurate diagnosis.Option A is incorrectbecause while testing in extension is part of the assessment, the '30-Degree Flexion Rule' is critical for isolating the proper UCL, which is often the primary injury. Testing only in extension may yield a false negative if the volar plate and accessory ligament are intact.Option B is incorrectbecause the case states, 'in the modern clinical setting, stress radiography is largely contraindicated when a Stener lesion is suspected clinically' due to the risk of iatrogenic Stener lesion formation or conversion of a partial to a complete tear.Option D is incorrectbecause the case advises, 'Palpation Precedes Stress: Always palpate the ulnar joint line for a Stener lesion before applying valgus stress. Forceful stress testing of a non-displaced complete tear can iatrogenically displace the ligament superficial to the aponeurosis, converting a potentially non-operative injury into an operative one.'Option E is incorrectbecause the interphalangeal joint's motion does not significantly confound MCP joint stress testing, and its immobilization is not a standard or critical step for this specific assessment.

Question 1034

Topic: 7. Hand and Wrist

Magnetic Resonance Imaging (MRI) was performed to definitively map the pathoanatomy. The MRI findings were described as a 'yo-yo on a string sign' on coronal T2-weighted fat-suppressed images. Which of the following best describes this specific MRI finding?

. A. A bony avulsion fracture at the ulnar base of the proximal phalanx with associated edema.
. B. Thickening and edema of the ulnar collateral ligament without complete discontinuity.
. C. The torn, retracted ulnar collateral ligament stump (yo-yo) resting superficial and proximal to the adductor pollicis aponeurosis (string).
. D. Disruption of the radial collateral ligament with volar subluxation of the proximal phalanx.
. E. A large intra-articular hematoma without ligamentous disruption.

Correct Answer & Explanation

. C. The torn, retracted ulnar collateral ligament stump (yo-yo) resting superficial and proximal to the adductor pollicis aponeurosis (string).

Explanation

Correct Answer: CThe case explicitly describes the MRI findings: 'Crucially, the MRI demonstrated the classic yo yo on a string sign. The torn, retracted ulnar collateral ligament stump appeared as a balled-up, nodular mass of low signal intensity (the 'yo-yo') resting superficial and proximal to the low-signal band of the adductor pollicis aponeurosis (the 'string'). This confirmed the presence of a Stener lesion.' This is the pathognomonic MRI sign for a Stener lesion.Option A is incorrectbecause plain radiographs already ruled out a bony avulsion, and the 'yo-yo on a string' sign specifically refers to soft tissue interposition.Option B is incorrectbecause this describes a partial sprain (Grade I or II), not a complete rupture with retraction and aponeurotic interposition.Option D is incorrectbecause this describes a radial collateral ligament injury, which is on the opposite side of the joint and has a different mechanism and clinical presentation.Option E is incorrectbecause while an intra-articular hematoma is expected with acute trauma, it does not represent the 'yo-yo on a string' sign, which specifically identifies the displaced ligament stump and aponeurosis.

Question 1035

Topic: Hand Trauma & Infection

Given the patient's clinical presentation and MRI findings, which of the following is the most appropriate management strategy?

. A. Rigid immobilization in a thumb spica cast for 6 weeks, followed by gradual rehabilitation.
. B. Immediate referral for a second opinion to confirm the diagnosis before any intervention.
. C. Open surgical repair of the ulnar collateral ligament with suture anchor fixation.
. D. Percutaneous pinning of the metacarpophalangeal joint to stabilize the joint.
. E. Corticosteroid injection into the metacarpophalangeal joint to reduce pain and inflammation.

Correct Answer & Explanation

. C. Open surgical repair of the ulnar collateral ligament with suture anchor fixation.

Explanation

Correct Answer: CThe case clearly states, 'In this patient's case, the clinical examination demonstrating gross valgus instability lacking a firm endpoint, combined with the palpable mass and definitive MRI evidence of a Stener lesion, served as absolute indications for operative intervention.' The Stener lesion creates a mechanical barrier to healing, making non-operative management futile. Open surgical repair with suture anchor fixation is the standard of care for acute, complete UCL ruptures with a Stener lesion.Option A is incorrectbecause non-operative management is strictly reserved for partial tears or non-displaced bony avulsions, not for complete ruptures with a Stener lesion where spontaneous healing is impossible.Option B is incorrectbecause the diagnosis is highly probable clinically and definitively confirmed by MRI, making a second opinion for diagnosis unnecessary and delaying definitive treatment.Option D is incorrectbecause percutaneous pinning is typically used for fractures or dislocations requiring temporary stabilization, not for direct ligamentous repair in the presence of a Stener lesion which requires open reduction.Option E is incorrectbecause corticosteroid injections are contraindicated in acute ligamentous injuries, especially ruptures, as they can impair healing and increase the risk of further damage. They are also not a definitive treatment for mechanical instability.

Question 1036

Topic: 7. Hand and Wrist

During the surgical repair of the ulnar collateral ligament, the surgeon plans a lazy-S incision over the ulnar aspect of the thumb metacarpophalangeal joint. Which of the following structures is at highest risk of iatrogenic injury during the initial skin and subcutaneous dissection, and requires meticulous protection?

. A. The flexor pollicis longus tendon.
. B. The radial artery.
. C. The dorsal sensory branches of the radial nerve.
. D. The ulnar nerve.
. E. The extensor pollicis brevis tendon.

Correct Answer & Explanation

. C. The dorsal sensory branches of the radial nerve.

Explanation

Correct Answer: CThe case explicitly highlights this surgical pitfall: 'Radial Sensory Nerve Injury: The dorsal sensory branches of the radial nerve are highly variable and course directly through the surgical field. Meticulous blunt dissection and gentle retraction are critical. A postoperative neuroma in this location is often debilitating.' These branches are superficial and easily injured during the initial approach to the ulnar aspect of the thumb MCP joint.Option A is incorrectbecause the flexor pollicis longus tendon is on the volar aspect of the thumb and is not typically encountered or at risk with an ulnar approach to the MCP joint.Option B is incorrectbecause the radial artery is more proximally located in the wrist (anatomic snuffbox) and not directly in the superficial surgical field for a thumb MCP ulnar collateral ligament repair.Option D is incorrectbecause the ulnar nerve is located on the ulnar side of the hand and wrist, but its sensory branches to the thumb are not typically in the immediate superficial field of a thumb MCP ulnar approach.Option E is incorrectbecause the extensor pollicis brevis tendon is on the dorsal-radial aspect of the thumb and while it is part of the extensor mechanism, the dorsal sensory radial nerve branches are more superficial and at higher risk during the initial skin incision.

Question 1037

Topic: 7. Hand and Wrist

A surgeon is performing an open repair of a Skier's Thumb. After incising the adductor aponeurosis and exposing the joint, the torn ulnar collateral ligament stump is mobilized. The surgeon then uses a small curette and burr to decorticate the bony footprint at the volar-ulnar aspect of the proximal phalanx base. What is the primary purpose of this crucial step?

. A. To create a larger surface area for suture anchor placement, improving pullout strength.
. B. To remove any remaining ligamentous tissue that could impede healing.
. C. To stimulate the local inflammatory cascade and provide marrow-derived osteoprogenitor cells for enhanced ligament-to-bone healing.
. D. To decompress the joint space and prevent postoperative stiffness.
. E. To facilitate easier passage of sutures through the bone for direct repair.

Correct Answer & Explanation

. C. To stimulate the local inflammatory cascade and provide marrow-derived osteoprogenitor cells for enhanced ligament-to-bone healing.

Explanation

Correct Answer: CThe case describes this step: 'Using a small curette and a fine surgical burr, the cortical bone at the footprint was decorticated to expose bleeding cancellous bone. This crucial step stimulates the local inflammatory cascade and provides marrow-derived osteoprogenitor cells to enhance ligament-to-bone healing.' This is a fundamental principle in orthopedic surgery to promote robust soft tissue-to-bone healing.Option A is incorrectbecause while anchor placement is important, decortication's primary role is biological, not purely mechanical for anchor purchase, which is achieved by proper anchor design and insertion technique.Option B is incorrectbecause debridement of frayed ligament edges is done on the ligament itself, not by decorticating the bone. Decortication is about preparing the bone for healing, not removing tissue.Option D is incorrectbecause decortication does not primarily decompress the joint space; that is achieved by proper reduction and irrigation. It also doesn't directly prevent stiffness.Option E is incorrectbecause suture anchors are used for fixation, not direct suture passage through the bone in this context. Decortication is not for easier suture passage.

Question 1038

Topic: 7. Hand and Wrist

A 31-year-old male presents with a painful, swollen thumb 3 days after a fall onto an outstretched hand. Clinical examination raises suspicion for a complete ulnar collateral ligament (UCL) tear. MRI demonstrates a complete rupture of the UCL with the torn end retracted and resting superficial to a distinct anatomical structure, preventing anatomical reduction. Which structure is interposing between the torn UCL and its insertion site in this classic lesion?

. Extensor pollicis longus tendon
. Abductor pollicis brevis tendon
. Adductor aponeurosis
. Flexor pollicis longus tendon
. Volar plate

Correct Answer & Explanation

. Adductor aponeurosis

Explanation

This describes a Stener lesion, where the torn UCL flips superficially and becomes trapped proximal to the adductor aponeurosis. This interposition prevents spontaneous healing and is an absolute indication for surgical repair.

Question 1039

Topic: 7. Hand and Wrist

A 25-year-old man presents to the emergency department after being struck on the tip of his right long finger by a baseball.

Assuming the provided radiograph demonstrates a dorsal avulsion fracture of the distal phalanx involving 60% of the articular surface with associated volar subluxation of the remaining distal phalanx, what is the most appropriate definitive management?

. Continuous splinting of the DIP joint in full extension for 8 weeks
. Splinting of the DIP and PIP joints in full extension for 6 weeks
. Open reduction and internal fixation with a dorsal plating system
. Closed reduction and extension block pinning
. Primary arthrodesis of the DIP joint

Correct Answer & Explanation

. Closed reduction and extension block pinning

Explanation

Bony mallet injuries with >50% articular involvement or volar subluxation of the distal phalanx are generally unstable and require surgical stabilization. Closed reduction with extension block pinning (Ishiguro technique) is the most established and appropriate management.

Question 1040

Topic: 7. Hand and Wrist

During the surgical repair of an acute, retracted ulnar collateral ligament (UCL) tear of the thumb (Skier's thumb), the surgeon makes a lazy-S incision over the ulnar aspect of the MCP joint. Which of the following nerve branches is at greatest risk of injury during this surgical exposure?

. Palmar cutaneous branch of the median nerve
. Superficial sensory branches of the radial nerve
. Dorsal sensory branch of the ulnar nerve
. Recurrent motor branch of the median nerve
. Deep branch of the ulnar nerve

Correct Answer & Explanation

. Superficial sensory branches of the radial nerve

Explanation

The superficial sensory branches of the radial nerve cross the ulnar aspect of the thumb MCP joint. They must be carefully identified and retracted to avoid painful neuromas during UCL repair.

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