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DR.JAMAL AL-SAIDY
M.B.CH.B…F.I.C.M.S
CARPAL INJURIES
Fractures and dislocations of the carpal bones are common.
They vary greatly in type and severity.
These should never be regarded as isolated injuries; the entire carpus suffers, and
sometimes, long after the fracture has healed, the patient still complains of pain and
weakness in the wrist.
The commonest wrist injuries are:
o sprains of the capsule and ligaments;
o fracture of a carpal bone (usually the scaphoid);
o injury of the triangular fibrocartilage complex (TFCC) and distal radio-ulnar
joint;
o dislocations of the lunate or the bones around it;
o subluxations and ‘carpal collapse’, which may be acute or chronic.
Clinical assessment
Following a fall, the patient complains of pain in the wrist.
There may be swelling or well-marked deformity of the joint.
Tenderness should be carefully localized; undirected prodding will confuse both the
patient and the examiner. The blunt end of a pencil is helpful in testing for point
tenderness. For :
o scaphoid fractures, the ‘jump spot’ is in the anatomical snuffbox;
o scapho-lunate injuries, just beyond Lister’s tubercle;
o lunate dislocation, in the middle of the wrist;
o triquetral injuries, beyond the head of the ulna;
o hamate fractures, at the base of the hypothenar eminence;
o triangular fibrocartilage complex injuries, over the dorsum of the ulnocarpal
joint.
Movements are often limited (more by pain than by stiffness) and they may be
accompanied by a palpable catch or an audible clunk.
Imaging
X-rays are the key to diagnosis. There are three golden rules:
• Accept only high-quality films
• If the initial x-rays are ‘normal’, treat the clinical diagnosis
• Repeat the x-ray examination 2 weeks later.
Initially three standard views are obtained: anteroposterior and lateral with the wrist
neutral, and an oblique ‘scaphoid’ view. If these are normal and clinical features suggest
a carpal injury, further views are obtained: anteroposterior x-rays with the wrist first in
maximum ulnar and then in maximum radial deviation, and an anteroposterior view with
the fist clenched.
The examiner should be familiar with the normal x-ray anatomy of the carpus in all the
standard views :
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DR.JAMAL AL-SAIDY
M.B.CH.B…F.I.C.M.S
o In the anteroposterior x-rays note the shape of the carpus, whether the individual
bones are clearly outlined and whether there are any abnormally large gaps
suggesting disruption of the ligaments.
o The scaphoid may be fractured; or it may have lost its normal bean shape and
look squat and foreshortened, sometimes with an inner circular density (the
cortical ring sign) –
o The lunate is normally quadrilateral in shape, but if it is dislocated it looks
triangular.
o In the lateral x-ray the axes of the radius, lunate, capitate and third metacarpal are
co-linear, and the scaphoid projects at an angle of about 45 degrees to this line.
With traumatic instability the linked carpal segments collapse (like the buckled
carriages of a derailed train). Two patterns are recognized:
dorsal intercalated segment instability (DISI), in which the lunate
is torn from the scaphoid and tilted backwards;
volar intercalated segment instability (VISI), in which the lunate
is torn from the triquetrum and turns towards the palm; the
capitate shows a complementary dorsal tilt.
A radioisotope scan will confirm a wrist injury although it may not precisely localize it.
MRI is sensitive and specific (especially for detecting undisclosed fractures or
Kienböck’s disease), but unless very fine cuts are taken it may miss TFCC and
interosseous ligament tears.
Arthroscopy Wrist arthroscopy is the best way of demonstrating TFCC or interosseous
ligament tears.
Principles of management
‘Wrist sprain’ should not be diagnosed unless a more serious injury has been excluded
with certainty.
Even with apparently trivial injuries, ligaments are sometimes torn and the patient may
later develop carpal instability.
If the x-rays are normal but the clinical signs strongly suggest a carpal injury, a splint or
plaster should be applied for 2 weeks, after which time the x-rays are repeated.
A fracture or dislocation may become more obvious after a few weeks, but a second
negative x-ray still does not exclude a serious injury. A bone scan or MRI at this stage
will confirm the diagnosis and avoid an unnecessary period of immobilization and time
from work.
If these tests are not readily available, then the patient should be re-examined repeatedly
until the symptoms settle or a firm diagnosis is made.
THANK YOU
DR.JAMAL AL-SAIDY
M.B.CH.B..…… F.I.C.M.S