A fall on the out-stretched hand
(FOOSH) tends to result in specific injuries depending on the general
age of the patient:
4-10years – Torus fracture of the distal radial metaphysis.
11-16years – Salter-Harris II fracture involving the physeal plate.
17-40years – Scaphoid fracture.
Over 40years – Colles-type fracture.
Normal anatomy - PA film
Distal radial articular surface tilts 17 degrees towards
the radius articulates with the head of the ulna at the ulnar notch.
The head of the ulna is usually 2mm shorter than the radius and either
touches or slightly overlaps the radius at the distal radioulnar joint.
The width of the intercarpal joints is uniform,
Three carpal arcs should be traced:
along the proximal row of carpal bones; proximal aspect.
along the proximal row of carpal bones; distal aspect.
along the capitate and hamate proximally.
These three lines should remain
distal radial epiphyseal line may remain as a linear density, with a
spur-like projection laterally, simulating a fracture due to the break
in the cortex. However, this is a normal variant.
Normal anatomy - Lateral film
distal articular surface is angled 10-15 degrees anteriorly. This is
useful when identifying subtle fractures at the distal radius with
flattening of this angle.
Articular surfaces of radius, lunate
and capitate should be in a straight line and be congruent (parallel).
The “apple” (capitate) should sit in the “cup” (lunate), which should
sit in the “saucer” (radius):
Colles / Smiths fracture
of the distal radius are classified depending on which direction the distal fragment
is displaced. If displaced posteriorly, it is refered to as a Colles fracture. The term
“Colles” was originally used to describe a very specific injury, but
the term is now used more generally.
If the distal fragment is displaced anteriorly, the fracture is classified as a Smith's fracture:
If a shearing fracture is
intra-articular with posterior displacement of the distal fragment,
along with the carpus, then it is termed a Bartons. A reverse Bartons
refers to anterior displacement of the fragment along with the carpus.
the distal radius fracture is displaced, the attachment of the
triangular fibrocartilage tends to result in an avulsion fracture of
the ulnar styloid process:
Radial Styloid Fracture
Fractures are common due to blunt trauma directly to the radial styloid process. Fractures are oblique, intra-articular and are usually minimally displaced:
common, but often subtle, are torus fractures of the distal radial
metaphysis, usually dorsally (due to a FOOSH). The torus fracture will
be evident by a buckling of the cortex with little displacement:
fractures of the radial and ulna shaft are demonstrated by a break in
one cortex only (incomplete), with displacement/angulation. An increase
in the force will result in a complete fracture.
fractures involving the physeal growth plate are common, particularly
Salter-Harris type II through the dorsal aspect of the distal radial
metaphysis (again due to FOOSH):
of fractures are at the waist and are non-displaced. Can be difficult
to see initially, therefore if clinically suspected repeat films are
taken at 10-14 days to demonstrate sclerosis or resorption at the
Fractures at the distal pole are usually
avulsion injuries caused by the radial collateral ligament. The distal
pole has its own blood supply, so healing is quick.
supply to the proximal pole enters at the waist. This supply may be cut
off by a fracture through the waist. The proximal pole is consequently
at risk from delayed union or avascular necrosis, where the
proximal fragment collapses and becomes radiographically denser:
Clinical assessment of the injured scaphoid includes compression by axial loading which causes pain to the anatomical snuff-box. However, fractures to both the base of the 1st metacarpal and to the radial styloid will also produce pain to the anatomical snuff-box with this clinical assessment. It is therefore important to assess these areas carefully on the scaphoid views:
This is the second most common carpal bone to be fractured.
An avulsed bony fragment will be demonstrated on the
lateral film, dorsal to the proximal row of carpal bones:
Associated with fracture-dislocations at the base of the
4th and 5th metacarpals. Important to spot but often subtle.
Scrutinise the cortex of the hamate, particularly on an
Ensure there is a 2mm joint space with the adjacent
metacarpals on the DP view:
Fractures are rare. Lunate dislocations may occur following high impact trauma. A sclerotic lunate is sometimes seen. This is due to Keinbock's disease which refers to osteochondritis of the lunate due to avascular necrosis (decreased blood supply). The lunate becomes denser radiographically, fragments and collapses:
Fractures very occasionally seen due to direct trauma to the antero-medial aspect of the carpus:
Isolated fractures are rare, but as part of complex lunate/perilunate fracture-dislocations, a transverse fracture of the capitate may be seen.
Fractures are rare. The 1st carpo-metacarpal joint is a very common site for arthritic changes.
Fractures are rare.
dislocation - Lunate loses its articulation with both the capitate and
the radius and is displaced volarly with up to 90 degrees rotation. The
capitate remains aligned with the radius but sinks proximally:
dislocation - The lunate maintains its normal articulation with the
radius, but the capitate articular surface is dislocated from the
lunate, normally dorsally:
Midcarpal dislocation - The lunate
tilts volarly but is not dislocated from the radius. The capitate is
dislocated from the lunate but not as dorsally as seen in a perilunate
Zone of vulnerability
Most fracture-dislocations fall within the “zone of
identifying a fracture or dislocation, it is helpful to understand that
likely associated fractures will be within this zone, i.e., radial
styloid, waist of the scaphoid or capitate, proximal pole of the
hamate, triquetrum or ulnar styloid.
With progression from the
radial to the ulnar side of the arch, the severity of the injury
increases and the frequency of the injury decreases:
Refers to ligament rupture within the carpal bones, most
commonly at the scapho-lunate joint.
dissociation is demonstrated by the gap between the scaphoid and lunate
increasing in size more than 2mm. It may also become triangular in
appearance on the PA film.
There is foreshortening of the scaphoid and a cortical
“ring sign” is seen at the distal pole:
A 'clenched fist' view is sometimes helpful to demonstrate
the widening at the joint:
Refers to a displaced fracture of the distal radial shaft
accompanied by a dislocation to the distal radio-ulnar joint:
pattern seen at the elbow where a displaced fracture to the proximal
ulna is accompanied by a dislocation of the radial head. This is termed
the Monteggia fracture-dislocation.