Peggers’ Super Summary of Carpal Bone Injuries excluding Scaphoid

Anatomy:

JOINTS

·  DRUJ

·  Radiocarpal

·  midcarpal

WRIST LIGAMENTS
NB – volar ligaments stronger than dorsal

·  Extrinsic – connects radius to carpus

·  Intrinsic – connect carpal bone to each other

DISTAL RADIUS ANATOMY

·  11(Radial length) +12 (palmar tilt) = 23 (inclination)

·  Radial positive by 0-2mm

BLOOD SUPPLY

·  Dorsal and volar capillary network from ulnar, radial & interosseous arteries

Pain site / Cause
Anatomical snuff box / Scaphoid #
Distal to Lister’s tubercle / Scapholunate injuries
Middle of wrist / Lunate dislocation
Distal to ulna / Triquetral #
Base of hypothenar eminence / Hamate #
Dorsum of ulnar-carpal joint / TFCC injury / tears

Imaging:

1.  Standard views obtained: AP, Lat wrist in neutral and oblique (scaphoid view)

2.  If examination suggestive of carpal injury also need fist views in maximum radial and then ulnar directions and then AP clenched fist

AP VIEW:

3 radiographic arcs KNOWN AS Gilula lines

The scaphoid is bean shaped in AP shortening and squat with a circular density (cortical ring sign = #)

The lunate is always square (triangular in shape = dislocation of the lunate)

Carpal distance <2mm

Zone of vulnerability look for assc injuries

LATERALLY:

Horizontal line should run through radius-lunate-capitate-metacarpals

Scaphoid projects to horizontal line at 450 +/- 150.

Small fragments lying posterior to the proximal carpal row invariably represent triquetral fracture

Other Imaging:

CLENCHED FIST

·  Scapholunate dislocation

CARPAL TUNNEL VIEW

·  Hamate #

·  Pisiform

CT

·  Carpal fractures, non and mal union, bone loss

MRI:

·  Undisplaced fractures

·  Kienbock disease – lunate AVN

·  TFCC tear or interosseous tears

Carpal Injuries:

TRIQUETRUM

·  Dorsal ligament avulsion common – splint for a few days

·  Body fracture – plaster for 4-6 weeks

HAMATE

·  Direct blow to palm

·  Seen only on carpal tunnel views of CT/MRI

·  Body fractures may be fixed or excised

TRAPEZIUM

·  Extra-articular – Bennet’s # unstable

·  Intra-articular – Rolando’s

·  Body fracture seen on carpal tunnel view

CAPITATE

·  High force can fracture or cause rotation of distal fragment

LUNATE

·  Hyperextension injury

·  6 week for undisplaced # ++ risk of AVN

TFCC

·  Pain on supination/pronation or unstable distal ulna – piano key sign

·  Unstable ulna styloid # should be fixed

·  If no # consider arthroscopy or cast in supination for 6/52tate in supination

DISLOCATIONS

·  Lunate

o  Lunate displaces anteriorly from FOOSH

·  Perilunate

o  More common than lunate dislocation

o  Assc scaphoid and radial styloid # + DISI pattern + median nerve symptoms

o  Mx traction + flexion + palmar force of lunate +/- K wire +/- open repair

·  Scapho-lunate

o  Pain distal to Lister’s tubercle + widened gap on x-ray

o  Shortened scaphoid and DISI pattern

o  Seen < 4/52 reduce repair and k wire

o  Seen > 4/52 capsulodesis if chronic and OA for arthrodesis

·  Triquetro-lunate

o  Grip weakness with medial pain and tenderness distal to ulna

o  Gap between triquetrum and lunate with VISI pattern

·  Radiocarpal

o  Barton’s type # or reverse Barton’s

·  Midcarpal

o  Painful recurrent snap in the wrist

o  2 rows are mobile on examination

o  Mx acute repair and K wire in chronic conditions fuse

When to operate:

SCAPHOID

·  # displacement >1mm

·  Non union

·  Humpback deformity

·  Scapholunate angle (perpendicular lines through scaphoid & lunate) >600

·  Radiolunate angle >150 (VISI)

TRIQUETRUM

·  Displaced #

LUNATE

·  Displaced or angulated #

PISIFORM

·  Displaced #

TRAPEZIUM

·  Displaced or intra-articular

TRAPEZOID

·  Displaced or carpal-metacarpal articulation

CAPITATE

·  Perfect reduction and look for associated injuries in arc

HAMATE

·  Displaced

Simplified Mx options:

Non surgical

·  POP

·  MUA + POP

Surgical

·  Percutaneous

·  Open

·  Arthroscopic repair

·  Ex-fix

o  Bridging

Conservative Management of #

·  Undisplaced # circa 6 weeks in either a colles cast to prevent flexion / extension or ulnar gutter if ulnar side injury

Complications:

Early

·  Displacement

·  Median or ulnar nerve compromise

Late

·  AVN to lunate / scaphoid / capitate

·  Non union

·  OA

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