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Wrist & Carpus MCQs

Practice Set 6 of 33

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

Question 101

Topic: Wrist & Carpus
A unilateral "piano key" sign indicates
. distal radioulnar joint (DRUJ) instability.
. interosseous membrane disruption.
. midcarpal instability.
. physiologic motion of hypermobility syndrome.

Correct Answer & Explanation

. distal radioulnar joint (DRUJ) instability.

Explanation

The piano key sign is a demonstration of instability at the DRUJ, typically seen after healing from a distal radius fracture with an associated ulnar styloid fracture (as in this case) or other wrist injury. The hand is pushed down against a table top, and the distal radius translates dorsally (with the distal ulna apparently moving volarly). In fact, the distal radius is the mobile segment, while the distal ulna is fixed in space. Treatment involves repair or reconstruction of the foveal insertion of the triangular fibrocartilage complex (TFCC) and distal radioulnar ligaments. This type of instability is also common in malunions of the distal radius or distal one-third of the radial shaft (Galeazzi-type fractures). In malunions, DRUJ instability can be treated with a corrective osteotomy of the distal radius to restore the anatomic relationship between the distal ulna and the distal radius at the DRUJ. Radiocarpal and midcarpal instability do not involve the DRUJ. Disruption of the interosseous membrane (in isolation, with intact distal radioulnar ligaments and an intact TFCC) does not lead to translational instability of the DRUJ. Although hypermobility syndrome may lead to ligamentous laxity, it does not lead to unilateral DRUJ instability.

Question 102

Topic: Wrist & Carpus
An otherwise healthy 26-year-old woman is involved in a high speed motor vehicle accident and sustains the injury shown in Figure 54 to her dominant right arm. Appropriate treatment of this injury complex includes
. plating of the radial shaft fracture and open repair of the triangular fibrocartilage complex.
. open reduction and internal fixation of the radius and ulna.
. plating of the radius with closed reduction and evaluation of the distal radioulnar joint (DRUJ).
. closed reduction of the radius and DRUJ.
. plating of the radius and pinning of the DRUJ in pronation.

Correct Answer & Explanation

. plating of the radius with closed reduction and evaluation of the distal radioulnar joint (DRUJ).

Explanation

DISCUSSION: This Galeazzi fracture is an injury that requires surgical treatment in an adult. The algorithm includes anatomic reduction of the radial shaft and closed reduction of the DRUJ with assessment of stability. If the DRUJ remains unstable, supination of the wrist may reduce the DRUJ. If not, either open or closed reduction with pinning is undertaken. The closer the radius fracture is to the DRUJ, the more likely it is to be unstable. REFERENCE: Rettig ME, Raskin KB: Galeazzi fracture-dislocation: A new treatment-oriented classification. J Hand Surg Am 2001;26:228-235.

Question 103

Topic: Wrist & Carpus

Video 1 depicts a 20-year-old right-hand-dominant man with a 6-month history of left wrist pain and popping that has failed nonsurgical measures. No other positive findings upon examination are noted. What is the most appropriate course of treatment?

. Triangular fibrocartilage complex (TFCC) repair
. Lunotriquetral fusion
. Distal radioulnar joint (DRUJ) tenodesis
. Extensor carpi ulnaris (ECU) tendon sheath reconstruction

Correct Answer & Explanation

. Triangular fibrocartilage complex (TFCC) repair

Explanation

EXPLANATION:Upon examination, this patient is exhibiting dislocation of the ECU tendon because of a disrupted sheath. He has failed nonsurgical measures, so surgery that would involve either direct repair or reconstruction of the tendon sheath is indicated. An option for reconstruction is to use a portion of the extensor retinaculum as a sheath substitute. Deepening of the ECU tendon groove at the distal ulna with direct repair of the sheath is another option, although a 2016 paper by Ghatan and associates did not find depth of the groove as a risk factor for subluxation. TFCC repair, lunotriquetral fusion, and DRUJ tenodesis are not appropriate because the examination clearly shows ECU tendon dislocation. TFCC and lunotriquetral ligament tears can occur along with ECU tendon dislocation, but no other examination findings suggest these conditions for this patient.

Question 104

Topic: Wrist & Carpus

A prospective randomized trial is conducted to test the efficacy of Vitamin C versus placebo in treating patients who develop chronic regional pain syndrome (CRPS) after distal radius fractures. At first follow-up, the rates of CRPS are 1% and 9% in the study and placebo group, respectively. Which statistical test is most appropriate to determine significance?

. Single factor analysis of variance
. Chi-square test
. Student t-test
. Mann-Whitney rank sum test
. Wilcoxon rank sum test

Correct Answer & Explanation

. Single factor analysis of variance

Explanation

In the study provided, we need to determine whether distributions of categorical variables differ from one another. The appropriate study is the chi-square test.Data can be classified as numerical (continuous) or categorical (proportional). Responses to such questions as "What is your major?" or Do you own a car?" are categorical because they yield data such as "biology" or "no." In contrast, responses to such questions as "How tall are you?" or "What is your G.P.A.?" are numerical. When comparing two independent means from numeric data, a t-test is performed. However, if categorical data is being compared, the chi-square test will determine if the proportions are really different.Kocher et al. review basic clinical epidemiology and biostatistics relevant to orthopaedic surgery. Amongst other things, they describe that data can be summarized in terms of measures of central tendency, such as mean, median, and mode, and interms of measures of dispersion, such as range, standard deviation, and percentiles. Illustration A shows an algorithm for determining which test to use for varying data.Incorrect Answers:

Question 105

Topic: Wrist & Carpus
A 51-year-old female presents with an acute inability to extend her thumb, four months after she was treated with cast immobilization for a minimally-displaced distal radius fracture. What is the most appropriate treatment at this time?
. Occupational therapy for strengthening
. Extensor carpi radialis longus transfer to extensor pollicis longus
. Extensor pollicis brevis transfer to extensor pollicis longus
. Extensor indicis proprius transfer to extensor pollicis longus
. Primary repair of extensor pollicis longus

Correct Answer & Explanation

. Extensor indicis proprius transfer to extensor pollicis longus

Explanation

DISCUSSION: A rare complication of non-displaced or minimally displaced fractures of the distal radius treated with a cast is a delayed rupture of the extensor pollicis longus (EPL) tendon. The EPL is the primary extensor of the interphalangeal joint of the thumb and also assists with metacarpophalangeal extension. Extensor indicis proprius transfer to the EPL is the most widely used and reported treatment for this condition. Magnussen et al. reviewed results of EIP transfer following ruptures of the EPL, with 19/21 good results. None of the cases had any loss of independent index finger extension although index extensor strength reduced to half of that of the contralateral side. Hove et al. reported a similar satisfaction rate following treatment of 15 patients. In his series of 4,400 distal radius fractures treated over a 5 year period, the incidence of delayed tendon rupture following distal radius fracture was 0.3 percent.

Question 106

Topic: Wrist & Carpus
During placement of an external fixator for a distal radius fracture, the most commonly injured nerve is a branch of which of the following nerves?
. Ulnar
. Median
. Superficial radial
. Lateral antebrachial cutaneous
. Medial antebrachial cutaneous

Correct Answer & Explanation

. Superficial radial

Explanation

DISCUSSION: Pin track infections and sensory injuries are among the most common complications of external fixation for distal radius fractures. The proximal pins of most distal radius external fixators are placed in the “bare area” of the distal radius, about four finger-breadths above the radial styloid. This corresponds to the area where the dorsal sensory branch of the radial nerve penetrates the fascia dorsal to the brachioradialis tendon to become a subcutaneous structure. Injury to the superficial radial nerve may produce painful dysesthesias and neuromas. REFERENCE: Beldner S, Zlotolow DA, Melone CP, et al: Anatomy of the lateral antebrachial cutaneous and superficial radial nerves in the forearm: A cadaveric and clinical study. J Hand Surg Am 2005;30:1226-1230.

Question 107

Topic: Wrist & Carpus
An 83-year-old right-hand-dominant woman sustains a displaced right extra-articular distal radius fracture and is treated with closed reduction and casting. At her 4-week follow-up visit, radiographs demonstrate a volar tilt of -5 degrees and 4 mm of positive ulnar variance. Which treatment is recommended?
. No additional reduction and continued treatment in the cast
. Repeat closed reduction and cast application
. Closed reduction and percutaneous skeletal fixation
. Open reduction and internal fixation

Correct Answer & Explanation

. No additional reduction and continued treatment in the cast

Explanation

Studies demonstrate that surgical treatment of distal radius fractures in elderly people does not result in improved outcomes. Although nonsurgical treatment resulted in worse radiographic findings for this patient, these findings did not translate into worse functional outcomes.

Question 108

Topic: Wrist & Carpus

A 55-year-old female presents with a complex intra-articular distal radius fracture. CT imaging reveals a small, displaced volar ulnar corner (volar lunate facet) fragment. Failure to adequately reduce and stabilize this specific fragment is most likely to result in which of the following complications?

. Dorsal intercalated segment instability (DISI)
. Volar radiocarpal subluxation or dislocation
. Rupture of the extensor pollicis longus (EPL) tendon
. Nonunion of the radial styloid
. Avascular necrosis of the scaphoid

Correct Answer & Explanation

. Dorsal intercalated segment instability (DISI)

Explanation

The volar ulnar corner (volar lunate facet) of the distal radius provides critical tethering support to the lunate via the short radiolunate ligament. If this fragment (often called the critical corner or tear-drop fragment) escapes fixation, the lunate and the entire carpus are at high risk for catastrophic volar subluxation or dislocation.

Question 109

Topic: Wrist & Carpus

A 55-year-old female undergoes volar locked plating for a distal radius fracture. Six months postoperatively, she is unable to actively flex the interphalangeal joint of her thumb. Which aspect of surgical technique is most highly associated with this complication?

. Placement of the plate proximal to the watershed line
. Prominence of the plate distal to the watershed line
. Over-penetration of dorsal locking screws
. Radial-sided plate prominence
. Ulnar-sided plate prominence

Correct Answer & Explanation

. Placement of the plate proximal to the watershed line

Explanation

Iatrogenic rupture of the flexor pollicis longus (FPL) tendon is a known complication of volar plating. It is directly associated with plate prominence volar and distal to the anatomic watershed line of the distal radius.

Question 110

Topic: Wrist & Carpus
The development of complex regional pain syndrome (CRPS) following distal radius fracture is associated with what factor?
. Diabetes
. Fibromyalgia
. Nonsurgical fracture management
. Male gender

Correct Answer & Explanation

. Fibromyalgia

Explanation

CRPS is an uncommon complication following distal radius fractures; its incidence is reported to range between 1% and 37%. Two recent studies have evaluated for risk factors in the development of CRPS following distal radius fractures. Female gender, concomitant fracture of the distal ulna, and surgical treatment were all associated with an increased likelihood of CRPS, as was fibromyalgia. Older age was identified as conferring both an increased and a decreased risk for CRPS in the two studies.

Question 111

Topic: Wrist & Carpus
A 64-year-old female sustains a nondisplaced distal radius fracture and undergoes closed treatment using a cast. Three months after the fracture she reports an acute loss of her ability to extend her thumb. What is the most likely etiology of her new loss of function?
. Posterior interosseous nerve entrapment
. Extensor pollicis longus rupture
. Extensor pollicis longus entrapment
. Distal radius malunion
. Intersection syndrome

Correct Answer & Explanation

. Extensor pollicis longus rupture

Explanation

According to the referenced article by Jupiter and Fernandez, the most common scenario of extensor pollicis longus rupture after a distal radius fracture is when the fracture is non or minimally displaced. The hypothesis is that the rupture happens at an area of relative hypovascularity and healing callus can aggravate this area, leading to a degenerative tear.

Question 112

Topic: Wrist & Carpus

-A 42-year-old patient with a right distal radius fracture underwent open reduction and internal fixation. To reduce the likelihood of complex regional pain syndrome, the most appropriate medication is

. Biotin.
. Tramadol.
. vitamin A.
. vitamin C.
. vitamin E.

Correct Answer & Explanation

. Biotin.

Explanation

Question 113

Topic: Wrist & Carpus
Figures 1 through 3 are the radiographs of a 65-year-old man who sustained a fracture from a fall. The patient elects open reduction and internal fixation of the distal radius. After plating the distal radius, the distal radioulnar joint (DRUJ) is examined and found to be unstable in both pronation and supination. What is the best next step?
. Early range of motion (ROM) program with a removable short-arm splint
. Long-arm casting in pronation for 4 weeks
. Pin fixation of the DRUJ
. Fixation of the ulnar styloid fracture

Correct Answer & Explanation

. Fixation of the ulnar styloid fracture

Explanation

EXPLANATION: The initial radiographs show a comminuted displaced distal radius fracture, along with a displaced fracture of the base of the ulnar styloid. The displacement is best seen on the oblique view. After reduction and fixation of the radius, DRUJ stability should be assessed. The majority of scenarios that involve this injury pattern will not be unstable because of the oblique band of the interosseous ligament. When DRUJ instability is present after fixation of the radius, reduction and fixation of the ulnar styloid fracture is the best option to provide stability of the distal radioulnar joint (DRUJ). A study by Lawton and associates revealed that all distal radius fractures complicated by DRUJ instability were accompanied by an ulnar styloid fracture. A fracture at the ulnar styloid’s base and substantial displacement of an ulnar styloid fracture were found to increase risk for DRUJ instability. An ulnar styloid base fracture involves the insertion of the radioulnar ligaments and can cause DRUJ instability if displaced. If persistent instability is present after fixation of the ulnar styloid, DRUJ pinning is a reasonable option. Early ROM with splinting would not allow reduction or healing of the ulnar styloid and would result in persistent instability. Short-arm casting also would not allow stability of the DRUJ and would be a less reliable method with which to achieve healing of the ulnar styloid.

Question 114

Topic: Wrist & Carpus
A 26-year-old man falls off a motorcycle and injures his left wrist. There are no open wounds and the neurovascular examination is normal. Radiographs are shown in Figures 10a and 10b. Definitive management should consist of
. closed reduction and casting.
. external fixation and percutaneous pinning of the distal radius.
. open reduction and internal fixation of the distal radius.
. open reduction and internal fixation of the distal radius and open repair of the ulnar styloid.
. nonbridging external fixation of the distal radius.

Correct Answer & Explanation

. open reduction and internal fixation of the distal radius.

Explanation

DISCUSSION: The patient has a high-energy injury with resultant comminution of the distal radius metaphysis. Cast immobilization is likely to lead to radial shortening and angulation due to the comminution. Similarly, while external fixation and pinning has been successful in the past, some loss of radial length and volar angulation is typically noted. Present plate fixation devices for the distal radius employing locking screw technology have a superior ability to resist radial shortening and dorsal angulation. Fixation of the ulnar styloid is warranted when there is distal radioulnar joint instability or significant displacement of the styloid. This is more likely to occur with a fracture at the base of the styloid. In this instance, the distal radioulnar joint does not appear to be disrupted. REFERENCES: May MM, Lawton JN, Blazar PE: Ulnar styloid fractures associated with distal radius fractures: Incidence and implications for distal radioulnar joint instability. J Hand Surg Am 2002;27:965-971. Nana AD, Joshi A, Lichtman DM: Plating of the distal radius. J Am Acad Orthop Surg 2005;13:159-171.

Question 115

Topic: Wrist & Carpus

A 65-year-old female presents with the sudden inability to actively extend her thumb interphalangeal joint 6 weeks after nonoperative treatment of a nondisplaced distal radius fracture. Radiographs show a healing fracture. What is the most appropriate definitive management?

. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Primary end-to-end repair of the EPL tendon
. Extensor carpi radialis longus (ECRL) to EPL tendon transfer
. Cortisone injection into the third dorsal compartment
. Observation and passive range of motion therapy

Correct Answer & Explanation

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

Explanation

The patient has experienced a spontaneous rupture of the extensor pollicis longus (EPL) tendon, a known complication of nondisplaced distal radius fractures due to ischemia or mechanical attrition at Lister's tubercle. Because the tendon ends typically retract and undergo degeneration, primary repair is rarely possible. An EIP to EPL tendon transfer is the standard of care.

Question 116

Topic: Wrist & Carpus
According to Mayfield's stages of progressive perilunate instability, what structural disruption defines Stage III of the cascade?
. Disruption of the scapholunate interosseous ligament
. Disruption of the lunotriquetral interosseous ligament
. Disruption of the radioscaphocapitate ligament
. Complete palmar dislocation of the lunate
. Dislocation of the capitate from the lunate without interosseous disruption

Correct Answer & Explanation

. Disruption of the lunotriquetral interosseous ligament

Explanation

The Mayfield classification describes the progressive perilunate instability cascade resulting from wrist hyperextension, ulnar deviation, and intercarpal supination. Stage I: Scapholunate interosseous ligament disruption. Stage II: Disruption of the capitolunate articulation. Stage III: Disruption of the lunotriquetral interosseous ligament (resulting in a perilunate dislocation). Stage IV: Failure of the dorsal radiocarpal ligament allowing the lunate to dislocate completely (usually volarly).

Question 117

Topic: Wrist & Carpus

A 24-year-old male sustains an isolated distal-third radial shaft fracture (Galeazzi variant) and undergoes open reduction and internal fixation with a rigid compression plate. Intraoperatively, after anatomic fixation of the radius, the distal radioulnar joint (DRUJ) is tested. It remains grossly unstable in neutral and full pronation, but reliably reduces and remains perfectly stable in full supination. What is the most appropriate next step in management?

. Open repair of the triangular fibrocartilage complex (TFCC) through a dorsal approach
. Immobilization of the forearm in a long-arm splint or cast in full supination for 4 to 6 weeks
. Placement of a trans-articular radioulnar Kirschner wire followed by pronation casting
. Immediate ulnar shortening osteotomy to decompress the DRUJ
. Immobilization in a short-arm cast in neutral rotation

Correct Answer & Explanation

. Open repair of the triangular fibrocartilage complex (TFCC) through a dorsal approach

Explanation

A Galeazzi fracture involves a distal radius shaft fracture with disruption of the distal radioulnar joint (DRUJ). The primary treatment is rigid anatomic internal fixation of the radius. If the DRUJ is unstable post-fixation, its stability should be assessed in supination. Supination functionally closes the DRUJ by tightening the palmar radioulnar ligaments and reducing the ulna dorsally into the sigmoid notch. If the DRUJ is stable in full supination, the standard of care is nonoperative management of the DRUJ using a long-arm cast or splint in supination for 4-6 weeks. Operative intervention (pinning or TFCC repair) is reserved for DRUJ instability that persists even in full supination.

Question 118

Topic: Wrist & Carpus

A 65-year-old female sustains a dorsally displaced distal radius fracture (Colles type). A volar approach (modified Henry) is planned for open reduction and internal fixation. During the approach, the interval is developed between the flexor carpi radialis (FCR) and the radial artery. Which muscle must be incised and elevated from the radius to expose the fracture site?

. Pronator teres
. Pronator quadratus
. Flexor pollicis longus
. Brachioradialis
. Flexor digitorum superficialis

Correct Answer & Explanation

. Pronator teres

Explanation

In the modified Henry approach to the distal radius, the superficial interval is between the FCR tendon and the radial artery. In the deep dissection, the pronator quadratus muscle is encountered overlying the volar surface of the distal radius. It is incised along its radial border and elevated ulnarly (often as an L-shaped flap) to expose the fracture site.

Question 119

Topic: Wrist & Carpus

A 45-year-old man falls from a height and sustains a comminuted radial head fracture. During surgery, the radial head is deemed unsalvageable and excised. Postoperatively, the patient develops progressive wrist pain and ulnar-sided prominence.

What is the primary pathomechanical cause of this complication?

. Undiagnosed scaphoid fracture
. Disruption of the triangular fibrocartilage complex (TFCC) alone
. Unrecognized interosseous membrane (IOM) disruption
. Radial nerve palsy
. Proximal radioulnar joint instability

Correct Answer & Explanation

. Unrecognized interosseous membrane (IOM) disruption

Explanation

The clinical presentation is classic for an Essex-Lopresti injury, which consists of a radial head fracture, disruption of the interosseous membrane (IOM), and injury to the distal radioulnar joint (DRUJ). Excision of the radial head in the presence of an IOM injury leads to proximal migration of the radius, causing ulnar impaction syndrome and DRUJ instability. The primary stabilizer against proximal radial migration is the radial head, and the secondary stabilizer is the central band of the IOM.

Question 120

Topic: Wrist & Carpus
A 42-year-old male sustains a high-energy fall onto an outstretched hand. He is diagnosed with a comminuted, unsalvageable radial head fracture, an interosseous membrane tear, and distal radioulnar joint (DRUJ) disruption. What is the most appropriate surgical management strategy?
. Radial head resection and casting in supination
. Radial head replacement, followed by assessment of DRUJ stability, and pinning of the DRUJ if unstable
. Radial head resection and immediate DRUJ pinning
. Open reduction internal fixation of the radial head and Darrach procedure
. Radial head replacement and immediate Sauvé-Kapandji procedure

Correct Answer & Explanation

. Radial head replacement, followed by assessment of DRUJ stability, and pinning of the DRUJ if unstable

Explanation

This is an Essex-Lopresti injury. The interosseous membrane (IOM) and DRUJ are disrupted, leading to longitudinal radioulnar dissociation. Radial head resection alone is contraindicated, as it will lead to proximal migration of the radius, ulnar positive variance, and chronic wrist pain. The correct management is radial head replacement to restore the primary stabilizer against proximal radial migration, followed by assessment of the DRUJ. If the DRUJ is unstable, it should be pinned (typically in supination) or the TFCC repaired.

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