Fractures, joint injuries & instability

Question 1

What happens to external fixator rigidity if you increase the distance between rods and bone in distal radius fractures?

Answer 1

Rigidity decreases.

Increasing distance reduces mechanical stability.

Question 2

Optimal position for distal pin placement in external fixation of index metacarpal?

Answer 2

Insert pins with MCP joint flexed at 90° to avoid extensor tendon tethering.

Optimal positioning prevents tendon injury during fixation.

Question 3

Where should proximal pins in radial shaft be placed during external fixation?

Answer 3

Between ECRB and ECRL or between ECRB and EDC, avoiding the superficial radial nerve.

Precise placement prevents nerve irritation or injury.

Question 4

According to Lafontaine criteria, which radiographic feature indicates instability of distal radius fractures?

Answer 4

Dorsal comminution.

Predictive of secondary displacement post-reduction.

Question 5

Does radial shortening greater than 5mm define instability according to Lafontaine criteria?

Answer 5

No, radial shortening is not a criterion defined by Lafontaine.

It is considered by some authors, but not by Lafontaine.

Question 6

List 3 features from Lafontaine criteria that indicate an unstable distal radius fracture.

Answer 6

1. Age >60
2. Dorsal angulation >20°
3. Intra-articular radiocarpal fracture

Presence of 3+ indicates instability.

Question 7

Which distal radius fracture type most commonly associates with scapholunate ligament injuries?

Answer 7

Chauffeur fracture (radial styloid fracture).

Injury extends distally into ligament insertion.

Question 8

What defines a Barton fracture of distal radius?

Answer 8

Intra-articular fracture with dorsal or volar subluxation of the carpus.

Associated carpal instability differentiates Barton fractures.

Question 9

Which fracture historically described as a “reverse Colles” fracture?

Answer 9

Smith fracture (volar angulation fracture).

Contrasts the dorsal displacement typical of Colles fracture.

Question 10

True or false: Non-displaced distal radius fractures have lower EPL tendon rupture risk compared to displaced fractures.

Answer 10

False, non-displaced fractures have a higher EPL rupture risk.

Non-displaced fractures increase pressure at EPL watershed zone.

Question 11

Does wrist immobilization in full palmar flexion decrease risk of carpal tunnel syndrome after distal radius fracture?

Answer 11

No, it increases risk due to higher intracarpal pressure.

Extended wrist positions are preferred to reduce pressure.

Question 12

Which distal radius fracture classification is based on the mechanism of injury?

Answer 12

Fernandez classification.

Question 13

What is the key feature distinguishing the Melone classification for distal radius fractures?

Answer 13

It classifies fractures based on four major fragments: radial styloid, dorso-ulnar, volar-ulnar, radial shaft.

Emphasizes fragment-specific management.

Question 14

What does Frykman classification primarily focus on in distal radius fractures?

Answer 14

Radiocarpal and distal radioulnar joint involvement, and ulnar styloid presence or absence.

Highlights joint involvement and ulnar injury.

Question 15

Through which anatomical space does the lunate displace volarly in perilunate dislocations?

Answer 15

Space of Poirier (weak volar area of capsule between radiocapitate and long radiolunate ligaments).

Question 16

Describe Stage 2 of the Mayfield classification for perilunate injuries.

Answer 16

Stage 2 involves disruption of the lunocapitate articulation (progression from radial to ulnar side).

Question 17

What differentiates greater arc from lesser arc perilunate injuries?

Answer 17

Greater arc injuries involve fractures of radius, carpus, or ulna; lesser arc injuries involve purely ligamentous disruptions.

Question 18

Which ligament is the primary stabilizer of the scapholunate joint?

Answer 18

Dorsal component of the scapholunate ligament.

Question 19

Is the dorsal or volar component of the lunotriquetral ligament stronger?

Answer 19

The volar component of the lunotriquetral ligament is stronger (300N strength vs. dorsal component).

Question 20

Name two secondary stabilizers of the scapholunate joint.

Answer 20

Dorsal radiocarpal ligament and scaphotrapezial ligament.

Question 21

At what displacement (in mm) is a scaphoid fracture considered unstable?

Answer 21

Displacement greater than 1mm.

Question 22

How does delay in treatment (>4 weeks) influence scaphoid non-union risk?

Answer 22

Increases non-union rate significantly, from ~5% up to 45%.

Question 23

Recommended definitive treatment for a Gustilo-Anderson type II open distal radius fracture with a 2mm intra-articular step-off?

Answer 23

Internal fixation using a volar locking plate.

Question 24

Why is K-wire fixation insufficient for an intra-articular step-off in an open distal radius fracture?

Answer 24

K-wire fixation doesn’t reliably maintain reduction of intra-articular fragments, leading to poor outcomes.

Question 25

What advantage does volar locking plate fixation offer in open distal radius fractures?

Answer 25

Stable internal fixation, better fracture alignment, and lower infection risk after adequate debridement.

Question 26

Optimal management of a displaced fracture-dislocation of ring and little finger CMCJs diagnosed at 5 weeks post-injury?

Answer 26

Open reduction and internal fixation (due to chronicity and complexity of injury).

Question 27

Why is buddy-splinting insufficient at 5 weeks for CMCJ fracture-dislocation?

Answer 27

Because malalignment is already established, closed techniques are unlikely to restore proper anatomy.

Question 28

When might arthrodesis of ring and little finger CMCJs be considered after a fracture-dislocation?

Answer 28

If severe articular cartilage damage is present, making functional restoration impossible.

Question 29

Why is remanipulation with casting alone insufficient for re-displaced intra-articular distal radius fractures?

Answer 29

High risk of further displacement and poor anatomical restoration.

Question 30

When is open reduction with a volar locking plate indicated in distal radius fractures?

Answer 30

For severely displaced fractures or those failing closed reduction or pinning.

Question 31

Typical MRI appearance of occult scaphoid fracture on T1-weighted sequences?

Answer 31

Low signal (dark) on T1 images.

Question 32

On STIR MRI sequences, how does an acute scaphoid fracture typically appear?

Answer 32

High signal (bright) on STIR due to bone marrow edema.

Question 33

Why is MRI superior to X-ray in early scaphoid fracture detection?

Answer 33

MRI has higher sensitivity (>90%) detecting fractures invisible on X-rays.

Question 34

What is the primary purpose of pre-bending a compression plate before fixation?

Answer 34

To prevent volar gapping at the fracture site.

Question 35

What happens if a straight compression plate is applied without pre-bending?

Answer 35

Tension develops on the far cortex, leading to asymmetric compression and instability.

Question 36

How does pre-bending the plate enhance stability in transverse fractures?

Answer 36

It creates uniform compression across the entire fracture site, minimizing gapping.

Question 37

Which cells predominate early in the inflammatory stage of fracture healing?

Answer 37

Monocytes (which differentiate into macrophages).

Question 38

Name two cytokines crucial for early inflammatory response in fracture healing.

Answer 38

TNF-α and IL-1.

Question 39

During secondary bone healing, what is the role of the fibrin matrix?

Answer 39

Acts as a scaffold for inflammatory cell influx and subsequent cell differentiation.

Question 40

How does a lag screw fixation promote fracture healing?

Answer 40

It achieves interfragmentary compression, facilitating primary bone healing without callus.

Question 41

Why is a countersink used during lag screw fixation?

Answer 41

To ensure even load distribution, preventing stress concentration and screw head prominence.

Question 42

What happens to the proximal phalanx in an ulnar collateral ligament (UCL) tear of the thumb MCP joint?

Answer 42

It rotates by volar supination on the side of the UCL tear.

Question 43

In a Stener lesion, what prevents the UCL from healing spontaneously?

Answer 43

The torn UCL lies superficial to (trapped above) the adductor aponeurosis.

Question 44

What is the most common site for avulsion fractures associated with thumb MCP UCL injuries?

Answer 44

At the proximal phalanx insertion of the UCL.

Question 45

What intra-operative maneuver determines the need to fix an ulnar styloid fracture associated with distal radius fractures?

Answer 45

Ballottement test for DRUJ instability.

Question 46

When does an ulnar styloid fracture require fixation during distal radius fracture surgery?

Answer 46

Only if the DRUJ is unstable after distal radius fixation.

Question 47

Does ulnar styloid fracture size correlate with DRUJ instability in distal radius fractures?

Answer 47

No, stability is related to the integrity of the foveal attachment, not fracture size.

Question 48

What indicates surgical treatment for collateral ligament avulsion fractures of the proximal phalanx base in fingers?

Answer 48

Fragment involving ≥25% of articular surface with joint instability.

Question 49

Preferred surgical approach for unstable avulsion fractures at the proximal phalanx base?

Answer 49

Volar approach (avoids violating extensor mechanisms).

Question 50

When is ligament reconstruction required for proximal phalanx collateral ligament injuries?

Answer 50

Rarely, typically only in chronic injuries with persistent instability.

Question 51

First-line treatment for a type 1A TFCC tear presenting with clicking and ulnar wrist pain?

Answer 51

Arthroscopic synovectomy and TFCC debridement.

Question 52

Which TFCC tear type involves central perforation of the disc?

Answer 52

Palmer type 1A.

Question 53

What clinical test is most sensitive for DRUJ instability assessment in TFCC injuries?

Answer 53

Ballottement test.

Question 54

In Mayfield classification of perilunate injuries, what causes lunotriquetral dissociation in stage III?

Answer 54

Ulnar arcuate ligament pulling the triquetrum dorsally.

Question 55

In which stage of Mayfield classification do you see disruption of the lunocapitate articulation?

Answer 55

Stage III.

Question 56

What ligament remains intact until Mayfield stage IV perilunate dislocation?

Answer 56

Radioscaphocapitate (RSC) ligament.

Question 57

What type of carpal instability involves ligament injury within a single carpal row?

Answer 57

Carpal instability dissociative (CID)

Question 58

How is carpal instability non-dissociative (CIND) defined?

Answer 58

Instability due to injury of extrinsic ligaments, affecting stability between carpal rows.

Question 59

What best describes a radiocarpal joint dislocation in terms of carpal instability patterns?

Answer 59

Carpal instability non-dissociative (CIND)

Question 60

What is the Eaton-Belsky technique?

Answer 60

Transarticular fixation using antegrade k-wires through the MCP joint into the proximal phalanx.

Question 61

What is the advantage of lateral plating via mid-axial approach for proximal phalangeal fractures?

Answer 61

It avoids plate irritation and tendon adherence compared to dorsal plating.

Question 62

What deformity occurs commonly with proximal phalangeal base fractures due to intrinsic muscle pull?

Answer 62

Apex angulation deformity.

Question 63

What imaging is the gold standard to assess scaphoid vascularity intra-operatively?

Answer 63

Punctate bleeding assessment during surgery.

Question 64

Describe a Zaidemberg graft.

Answer 64

Vascularized graft from dorsal distal radius using the 1,2 intercompartmental supraretinacular artery.

Question 65

How is stage I SNAC wrist treated?

Answer 65

Cancellous bone grafting and radial styloidectomy.

Question 66

What factor determines surgical indication for a bony mallet injury?

Answer 66

Volar subluxation of DIP joint rather than fracture fragment size alone.

Question 67

Describe the Ishiguro extension-blocking technique.

Answer 67

The DIP joint is hyperflexed; k-wire blocks dorsal fragment migration and stabilizes the joint.

Question 68

What is the standard non-operative treatment duration for bony mallet injuries?

Answer 68

Mallet splint for 6-8 weeks, followed by 2 weeks night splinting.

Question 69

Which method is preferred for a dorsal fracture-dislocation involving 30% of the volar articular surface?

Answer 69

Extension-block pinning.

Question 70

When is hemi-hamate arthroplasty indicated for PIP fracture-dislocations?

Answer 70

For unstable injuries involving 30–50% of joint surface with non-reconstructable fragments.

Question 71

Why is static external fixation less desirable in PIP fracture-dislocations?

Answer 71

It does not allow early mobilization, increasing stiffness risk.

Question 72

Identify the fracture type described: “Intra-articular dorsal shear fracture of distal radius with dorsal subluxation of the carpus.”

Answer 72

Barton fracture ## Footnote • Involves dorsal or volar rim of radius • Associated with carpal subluxation • Often requires buttress plate fixation

Question 73

Identify the fracture type described: “Fracture of distal third of radius with distal radio-ulnar joint (DRUJ) dislocation.”

Answer 73

Galeazzi fracture ## Footnote • Needs ORIF of radius and stabilization of DRUJ

Question 74

Identify the fracture type described: “Fracture of ulna shaft with proximal radial head dislocation.”

Answer 74

Monteggia fracture ## Footnote • Typically requires ORIF of ulna

Question 75

Identify the fracture type described: “Extra-articular distal radius fracture with volar angulation.”

Answer 75

Smith fracture ## Footnote • Reverse deformity of Colles • Usually treated with volar plating if unstable

Question 76

Identify the fracture type described: “Isolated intra-articular radial styloid fracture.”

Answer 76

Chauffeur fracture ## Footnote • From rotational or shear trauma (historically crank handle injuries) • May require surgical fixation

Question 77

Which fixation method is described by: “Converts tensile forces into compression at fracture site.”

Answer 77

Tension band wiring ## Footnote • Common in olecranon and phalangeal avulsion fractures

Question 78

Which fixation principle is defined by: “Achieving fracture stability through three cortical points of fixation?”

Answer 78

Intramedullary wiring (three-point fixation) ## Footnote • Common in metacarpal fractures

Question 79

Which fixation type is ideal for: “Providing stability against shear forces at metaphyseal fractures, e.g., volar Barton fracture?”

Answer 79

Buttress plate fixation ## Footnote • Prevents fragment displacement under axial/shear loads

Question 80

Which fixation device achieves maximal compression when placed perpendicular to the fracture line?

Answer 80

Lag screw fixation ## Footnote • Ideal for oblique/spiral fractures

Question 81

Which fixation method bridges comminuted fracture segments without directly fixing intermediate fragments?

Answer 81

Bridging plate ## Footnote • Maintains alignment and length

Question 82

Which hand radiograph view best demonstrates thumb CMC arthritis?

Answer 82

Robert view ## Footnote • True AP projection of thumb

Question 83

Which radiographic view demonstrates proximal migration of the capitate and scapholunate diastasis?

Answer 83

Clenched fist view ## Footnote • Highlights subtle instability

Question 84

Which radiographic view identifies subtle impaction fractures at metacarpal heads (fight-bite injuries)?

Answer 84

Brewerton view ## Footnote • Tangential view of metacarpal heads

Question 85

Which wrist view clearly identifies scaphoid fractures?

Answer 85

Ziter view ## Footnote • PA, ulnar deviation, angled 20° towards elbow

Question 86

Which view is best for identifying fractures of the trapezial ridge or hook of hamate?

Answer 86

Carpal tunnel view ## Footnote • Axial view with maximal wrist dorsiflexion

Question 87

Which wrist test is used to detect scapholunate ligament instability?

Answer 87

Watson’s scaphoid shift test ## Footnote • Positive if painful clunk occurs

Question 88

Which wrist maneuver identifies midcarpal instability through a “catch-up” clunk?

Answer 88

Lichtman pivot shift test

Question 89

Which test assesses lunotriquetral joint instability?

Answer 89

Kleinman shear test ## Footnote • Radially/ulnarly deviates wrist

Question 90

Which test helps identify ulnar-sided wrist pathology (e.g., TFCC injury)?

Answer 90

Ulnocarpal stress test ## Footnote • Pain indicates positive test

Question 91

Which clinical test identifies lunotriquetral ligament instability?

Answer 91

Reagan shuck test ## Footnote • Positive if painful click or laxity present

Question 92

What surgical technique is ideal for irreparable scapholunate ligament injury with reducible malalignment and no arthritis?

Answer 92

3-ligament tenodesis (Brunelli) ## Footnote • Stabilizes scapholunate dissociation

Question 93

What treatment is best for complete yet reparable scapholunate ligament injury with normal alignment?

Answer 93

Open repair + K-wire stabilization ## Footnote • Direct ligament repair, healing potential intact

Question 94

Which surgical procedure addresses incomplete scapholunate ligament injuries?

Answer 94

Blatt capsulodesis/Berger ## Footnote * Uses dorsal capsule for wrist stabilization

Question 95

Which fusion is optimal for irreparable scapholunate ligament injury with irreducible malalignment but intact cartilage?

Answer 95

Scapho-trapezium-trapezoid (STT) arthrodesis ## Footnote • Stabilizes scaphoid; preserves wrist function