Wrist injuries

Anatomy

• Distal radius and ulna
  • Distal radius has three articular surfaces:
    • Radiocarpal, distal radioulnar and triangular fibrocartilage complex
  • Radiocarpal surface is concave and tilted in two planes
    • Ulnar tilt of 15-25 degrees in frontal plane
    • Volar tilt 10-15 degrees in sagittal plane
  • Distal radioulnar joint strengthened by triangular fibrocartilage + dorsal and volar radioulnar ligaments

Anatomy

• Carpal bones
  • Scaphoid is critical to wrist stability acting as a stablising strut and linking proximal and distal carpal rows at radial aspect of wrist
  • No direct tendon insertions on carpal bones (except pisiform as sesamoid of FCU)
  • Wrist motion is divided 50:50 between radiocarpal and mid-carpal joints
  • Carpal bones stabilised to one another by intrinsic ligaments and to the forearm by extrinsic ligaments

Anatomy

• Extrinsic wrist ligaments
  • Three arcades (two volar, one dorsal)
  • Two volar ligaments arranged in two inverted V-shaped arches
    • Apex of one arch inserts on the lunate supporting the proximal carpal row
    • Other arch inserts on capitate to support distal carpal row
    • Area between two palmar arches is weak = space of Poirier
      • Lies at junction of capitate and lunate and widens upon dorsiflexion of the wrist
      • Forceful dorsiflexion can tear capsule at this point causing lunate or perilunate dislocation
  • Single dorsal arcade arises off rim and styloid of radius on one side and distal ulna/triangular fibrocartilage on the other and is less important functionally

Anatomy

• Intrinsic ligaments of wrist
  • Those of the mobile proximal carpal row and particularly important
  • Scapholunate and triquetrolunate
  • Delicate balance around the lunate of opposing ligamentous tension is lost if either is disrupted, leading to volar or dorsal tilt of proximal carpal row and carpal instability

Pathophysiology

• FOOSH is most common
• Thenar eminence = Scaphoid
• Hypothenar eminence = Pisiform, triquetrum or supporting ligaments
• Children more likely to suffer injury to the immature weaker epiphyseal plate or metaphysis of radius vs. cartilagenous carpal bones
• Young adults often injure themselves with greater forces and are at risk of scaphoid, proximal row intrinsic ligaments or distal radius metaphyseal fractures
• Elderly tend to suffer distal radius metaphysis fractures (Colles’) often with intra-articular involvement

Surface anatomy

• Dorsal surface
  • Anatomical snuff box: EPL medially, EPB/APL laterally. Distal radial styloid at proximal base and scaphoid palpable in it
  • Radial tuberosity
  • Lister’s tuberosity (distal radius): Immediately distal to this is the scapholunate ligament and tenderness here suggests scapholunate disruption or lunate fracture
  • Ulnar styloid – Tenderness suggests ulnar styloid or triangulat fibrocartilage injury
  • Immediately ulnar to scapholunate ligament lies indentation where lunate and capitate reside (palpable with wrist flexion)
    • Tenderness suggests lunate or triquetrolunate disruption

Surface anatomy

• Volar surface
  • Scaphoid tuberosity at base of thenar eminence
  • Pisiform at FCU wrist crease
  • Hook of hamate deep to hypothenar eminence

Scaphoid shift test

• Place wrist in ulnar deviation and apply pressure with thumb over scaphoid tuberosity. Then move wrist to radial deviation and if ligamentous injury exists will feel clunk

Ulnocarpal stress test

• Compression load to wrist in ulnar deviation
• Pain or clicking suggest triangular fibrocartilage damage

Piano key sign

• Pain with pronation or supination of forearm may indicate distal radioulnar joint injury
• Ulnar head springing back when depressed while supporting the forearm in pronation suggests distal radioulnar injury = Piano key sign

Imaging

• Gilula lines
  • Three smooth arcs on PA view of wrist
  • 2 formed by proximal and distal surfaces of scaphoid, lunate and trigetrum
  • Third arc formed by proximal articular surface of capitate and hamate in midcarpal joint
  • Any distortion suggests fracture, dislocation or subluxation

Imaging – PA wrist

• Carpal bones should all be separated by uniform 1-2mm spacing
• Radius ulnar tilt 13-30 degrees
• Radial styloid process projects 8-18mm
• Half the lunate articulates with radius with half over ulna
• Scaphoid should appear elongated
  • Fracture or ligament disruption will make it appear shortened
• Scaphoid fat stripe
  • Linear or triangular radiolucent collection of fat distal to radial styloid and parallel to radial border of scaphoid
  • Will be obscured if scaphoid injured

Scaphoid fat pad

Lateral wrist view

• Axis of radius, lunate and capitate should be straight on true lateral
• Axes of lunate and capitate should be <10 degrees angulated
• Scaphoid is normally plantarflexed and scapholunate axis should be 30-60 degrees
• Volar radial tilt 10-15 degrees is normal

Ligamentous injuries

• Scapholunate ligament instability
  • Bridges the proximal and distal carpal rows and thus propensity for injury and the most commonly injured ligament in the wrist
  • Often complain of radial side of wrist pain, clicking sensation with wrist movement, localised tenderness immediately distal to Lister’s tubercle

Ligamentous injuries

• Scapholunate ligament instability
  • 3 radiographic signs
    • Scapholunate dissociation: Widening of scapholunate joint space >3mm on PA view (more obvious if clenched fist view) = Terry-Thomas sign
    • Rotary subluxation of scaphoid: Scaphoid appears short on PA with cortical ring sign (circular cortex of bone becomes more prominent due to palmar tilt) and >60 degree scapholunate angle on lateral view
    • Dorsal intercalated segment instability: Lunate tilts dorsally due to unopposed extension torque from triquetrum and scaphoid tilts more palmar. Get zig-zag pattern on lateral instead of radio-lunate-capitate axes all aligned

Ligamentous injuries

• Scapholunate ligament instability
  • If unsure, arthroscopy is gold standard (even MRI has sensitivity of only 63%)
  • ED Rx: radial gutter slab and orthopaedic referral for repair
  • Risk of Kienbock disease (ischaemic necrosis of lunate)

Ligamentous injuries

Ligamentous injuries

Ligamentous injuries

• Triquetrolunate ligament instability
  • Bind triquetrum and lunate on ulnar aspect of wrist
  • Ulnar equivalent of scapholunate disruption
  • Must less often seen, more stable and easily misdiagnosed as triangular fibrocartilage complex injury or distal radioulnar joint injury
  • Localised tenderness on ulnar aspect of wrist

Ligamentous injury

• Triquetrolunate ligament instability
  • On X-ray
    • Lunate tilts palmar and capitate extends slightly with zigzag pattern on lateral = volar intercalated segment instability
    • Capitolunate angle >10-20 degrees
    • Scapholunate angle unaffected
    • PA view may show widening of triquetro-lunate joint space and obliteration of capitolunate joint space +- loss of Gilula lines
  • Rx – Ulnar gutter splint and referral to fracture clinic

Ligamentous injuries

• Perilunate dislocation
  • Posterior dislocation of carpal bones while lunate maintains position relative to radius
• Lunate dislocation
  • Involves posterior dislocation of carpal bones with concavity of lunate facing anteriorly

Ligamentous injuries

• Perilunate/lunate dislocation
  • Injury typically begins with scapholunate ligament disruption or scaphoid fracture
  • Injury progresses around the lunate in a semicircular fashion with increasing forces, tearing the volar ligament arcade at the radiocapitate ligament
  • Space of Poirier open further as heavy loading disrupts the lunatotriquetral ligament
  • Any number of carpal bones may fracture around the lunate
  • If sufficient force is applied, results in perilunate dislocation
  • If capitate rebounds with sufficient force, it can push the lunate off the radius and into the palm causing a lunate dislocation

Ligamentous injury

• Perilunate/lunate dislocation
  • Often gross deformity is absent clinically with just swelling, pain and tenderness of wrist
• Perilunate X-ray
  • Lateral: Capitate dorsally displaced with lunate still in line with radius. Scapholunate and capitolunate angles are increased
  • PA: Loss of lines of Gulil
  • Scaphoid and capitate often fractured also = trans-scaphoid perilunate dislocation
  • Need CT
• Lunate dislocation X-ray
  • Lateral: Lunate pushed into palm but radiocapitate line intact. Spilled teacup sign
  • PA: Lunate has –piece-of-pie’ sign (triangular shape)
• Need closed reduction if possible (traction + pressure over displaced lunate/capitate) and orthopaedic consult

Scaphoid fracture

• Most common carpal bone fracture and most commonly missed
• Tender radial aspect of wrist, eliciting pain while patient resists supination/pronation of hand or pain with axial load on thumb metacarpal
• Clasp sign (clasps around scaphoid when asked where pain is)
• Scaphoid tubercle test
• X-ray
  • Standard + scaphoid views
  • Loss of scaphoid fat stripe
  • 2/3 at waist or middle third
  • 16-28% in proximal third and 10% distal third

Scaphoid fracture

• Associated injuries in 12%: Radius, other carpal bones, carpal instability pattern or dislocation
• If initial plain films normal but high index of suspicion:
  • Cast and return for repeat X-ray
    • Only 2-12% of these patients will actually have fractures though
    • If high index of suspicion – get CT or MRI (usually 2 or more positive exam findings)
      • Will result in 25 CT scans to find one fracture requiring treatment
  • CT: 85-90% sensitive, 85-100% specific and 98% NPV
  • MRI is gold standard (98% sensitive)

Scaphoid fracture

• AVN of proximal segment can occur
• The more proximal, oblique or displaced = greater risk of AVN
• Unstable if oblique, 1mm of displacement, rotation, comminution or if carpal instability pattern exists
• 2/3 of surface is articular

Scaphoid fracture

• Main complications are AVN, delayed union, non-union, mal-union and subsequent early degenerative arthritis
• Non-union 5-10% overall (close to zero for non-displaced fractures)
  • Delayed immobilisation <4 weeks for undisplaced fractures does not increase the risk of non-union or time to union
• AVN 50% incidence if >1mm displacement
• 10% of initial X-rays do not show fracture
• Initial treatment should be based on clinical suspicion – short-arm thumb spica in dorsiflexion and radial deviation to compress fracture site
• If unstable fractures (see above), place in long-arm thumb spica and ortho consult

Triquetrum fracture

• Second-most common carpal bone injury
• Avulsion or fracture through body
• Avulsion with twisting motion of hand suddenly resisted or hyperextension stress pushes hamate or ulnar styloid against triquetrum
• Fractures of body with direct blow and seen with perilunate and lunate dislocations (part of the arc fractures)
• Localised tenderness over dorsum of wrist in area distal to ulnar styloid
• Dorsal avulsion best seen on lateral view with tiny flake of bone
• Body fractures usually non-displaced due to ligamentous encasing

Triquetrum fracture

• Non-union is possible however AVN has not been described
• Avulsion fractures can be splinted for 1-2 weeks + EROM if comfortable
• Stable body fractures in cast for 6 weeks
• Refer stable and avulsion fractures for follow-up in fracture clinic
• Unstable body fractures (>1mm displacement) and those with associated perilunate/lunate dislocations requires internal fixation and consult

Carpal bone fracture

• Triquetrum avulsion and body

Lunate fracture

• Isolated injuries are rare
• Tenderness in shallow indentation on dorsum of hand – rises with palmar flexion
• Axial load on 3^rd digit also elicits pain
• Lunate’s blood supply enters distally like the scaphoid and thus carries risk of AVN of proximal portion
• If clinical suspicion exists but X-ray okay, CT
• Short arm thumb spica with f/u if diagnosis unclear
• Main complication is Kienbock’s disease: AVN with lunate collapse, OA, chronic pain and reduced grip strength

Trapezium fracture

• Tender base of anatomical snuff box and base of thenar eminence
• Typically intra-articular
• Non-displaced: Short-arm thumb spica
• Displaced 1mm or diastases >2mm require surgery

Pisiform fracture

• Localised tenderness over FCU tendon at hypothenar eminence
• Flex wrist and grasp pisiform between thumb and forefinger to elicit tenderness
• Forms bony wall of Guyon’s canal (ulnar nerve and artery) so must exclude injury to them
• Carpal tunnel view is ideal on X-ray
• Last carpal bone to ossify (usually complete by age 12)
• After age 12, any line is considered a fracture
• Refer to fracture clinic – compression dressing or splint in 30 degrees of flexion with ulnar deviation to relax tension from FCU
• Excellent prognosis

Hamate fracture

• Body fractures are rare and usually involved with 4^th/5^th metacarpal fracture dislocations
• Mostly hamate hook fractures classically from interrupted swing of bat
• Localised tenderness over hook of hamate in hypothenar eminence
• Standard and carpal tunnel views are required to identify +- CT
• Assess for injury to Guyon’s canal
• Hamate hook – Compression dressing or splint with fracture clinic f/u
• Non-displaced hamate body – Splint immobilisation
• Displaced hamate body – ORIF

Capitate fracture

• Large proximal head, mid-portion neck and distal body
• Mostly neck +- scaphoid fracture (Scaphocapitate syndrome)
• Fracture can continue around the lunate resulting in perilunate or lunate dislocation
• Typically tender proximal to 3^rd metacarpal with diffuse swelling
• Blood supply enters from distal end so same potential for proximal AVN
• Mostly displaced and required ORIF
• Easily missed

Trapezoid fracture

• Extremely rare
• Axial load onto index metacarpal and can test axial loading this way
• CT or MRI may be necessary as easily missed on standard views
• Thumb spica and fracture-clinic if non-displaced

Distal radius and ulna fractures

• Younger patients tend to suffer intra-articular fractures vs. older patients

• Most common orthopaedic injury
• 50% intra-articular
• Associated injuries
  • Distal radio-ulnar joint injuries
  • Radial styloid fracture (suggests high energy)
  • Triangular Fibrocartilage Complex (TFCC) injuries (40%)
  • Scapholunate ligament injury (30%)
  • Lunotriquetral ligament injury (15%)
  • Risk of osteoporosis

Distal radius and ulna fractures

• Colles’ fracture
  • Dorsal angulation of distal radius (dinner-fork deformity)
  • Distal radius fragment displaced proximally and dorsally
  • Radial displacement of carpus
  • Ulnar styloid may be fractured and suggests triangular fibrocartilage complex injury
  • Palmar paraesthesia suggests median nerve pressure
  • Unstable fractures = >20 degrees dorsal angulation, intra-articular involvement, marked comminution or >1cm of shortening, >2mm step-off -> Orthopaedic referral
  • More likely to develop loss of reduction, distal radioulnar joint instability, radiocarpal instability and arthritis
    • Volar tilt should be restored if possible, but minimum of zero degrees angulation is acceptable
    • All open and neurovascularly compromised fractures require ortho consult
  • Slight ulnar deviation and palmar flexion in below-elbow backslab
  • High-arm in mid-supination if RUJ or ulnar styloid involved

Distal radius – Acceptable healed position

• Dorsal tilt <5 degrees or within 20 degrees of contralateral wrist
  • Normal volar tilt 0-28 degrees (average 11)
• <2mm radial shortening (coreEM <5mm)
  • Radial styloid normally 9-12mm beyond articular surface of ulna
• No radial shift
• Radial inclination 15-25 degrees
• Intraarticular step <1mm
• No dorsal displacement

Dorsal comminution and die-punch lunate impaction are most critical factors in subsequent arthritis development

Distal radius and ulna fractures

• Smith’s fracture
  • Volar angulation of distal radius
  • Distal radius fragment displaced proximally and volarly
  • Radial displacement of carpus
  • Fracture line extends obliquely from dorsal surface to volar surface 1-2cm proximal to articular surface
  • Same treatment but opposite forces for reduction
  • Cast should be above elbow as more unstable with supination/pronation and in supination (begger’s slab)
  • Most authors state just volar backslab in slight dorsiflexion

Distal radius and ulna fractures

• Barton’s fracture
  • Dorsal or volar rim fractures of the distal radius
  • Often fracture-dislocations as carpus is displaced in direction of fracture
  • Radiocarpal instability is common due to ligamentous involvement
  • PA often shows comminuted fracture of distal radius metaphysis
  • Lateral view shows intra-articular fracture at rim of radius +- carpal subluxation in same direction
  • Minimally displaced – Sugar tong with inpatient ortho consult (highly unstable)
  • Unstable fractures = >50% articular surface involvement or accompany carpal subluxation require ORIF

Distal radius and ulna fractures

• Radial styloid fracture (Chauffer’s fracture)
  • Force along radial aspect of hand produces fracture extending from scaphoid fossa to metaphysis of radius
  • Often associated scapholunate dissocation, trans-scaphoid perilunate dislocation or ulnar styloid fracture
  • Major carpal ligaments insert onto radial styloid, thus displacement of styloid leads to radiocarpal instability
  • Displaced fractures need ORIF
  • >3mm displacement associated with scapholunate dissociation
  • Refer to fracture-clinic and place in short-arm splint in mild flexion and ulnar deviation

Chauffer’s fracture

Distal radius and ulna fractures

• Die-punch fracture
  • Depressed lunate fossa of distal radius

Distal radius and ulna fractures

• Ulnar styloid fractures
  • May be isolated or in association with Colles’
  • Can be associated with triangular fibrocartilage complex injury
  • If distal radioulnar joint is stable – place in ulnar gutter splint in slight ulnar deviation and neutral wrist positioning
  • If any question of instability – ortho consult in ED

Distal radial and ulna fractures

• Distal radioulnar joint disruption
  • Generally seen with intra-articular or distal radial shaft fractures = Galleazi fracture-dislocation
  • Often missed due to other fractures taking attention
  • Isolated joint injuries often under-appreciated and missed
  • Ulnar head often dorsally displaced and may appear more prominent
  • Pain with supination/pronation, weak grip
  • PA shows narrowing and overlap of distal RUJ
  • Lateral shows volar or dorsal displacement of ulna
  • May require CT
  • Refer for Ortho consult in ED as high recurrence rate and reconstructive rate if missed/not treated adequately

Distal radius and ulna injuries

• DRUJ injuries

• TFCC tears
  • MOI: Wrist extension and forearm pronation
  • Immobilise all acute tears
  • Debridement or repairs for failed conservative Rx
• Ulnar impaction syndrome
  • Radial shortening leads to positive ulnar variance and latered mechanics
• Essex-Lopresti injuries
  • Radial head fracture with interosseous membrane injury extending to DRUJ
  • Leads to proximal migration of radius and secondary DRUJ pathology + ulnocarpal abutment

Last Updated on October 28, 2020 by Andrew Crofton