Injuries in the Region of the Wrist
These include fractures of the lower ends of the bones of the forearm and separation of their epiphyses; sprains and dislocations of the inferior radio-ulnar, and of the radio-carpal articulations; and fractures and dislocations of the carpus.
Surgical Anatomy.—The most important landmarks in the region of the wrist are the styloid processes of the radius and ulna. The tip of the radial styloid is palpable in the “anatomical snuff-box” between the tendons of the long and short extensors of the thumb, and it lies about half an inch lower than the ulnar styloid. The ulnar styloid is best recognised on making deep pressure a little below and in front of the head of the ulna, which forms the rounded subcutaneous prominence seen on the back of the wrist when the hand is pronated.
The tubercle of the navicular (scaphoid) and the greater multangular (trapezium) can be felt between the radial styloid and the ball of the thumb, a little below the radial styloid; and the pisiform and hook of the hamatum (unciform) are palpable, slightly below and in front of the ulnar styloid.
In examining an injured wrist, the different bony points should be located, and their relative positions to one another and to the adjacent joints noted; and the shape, position, and relations of any unnatural projection or depression observed, using the wrist on the other side as the normal standard for comparison. The power and range of movement—active and passive—at the various joints should also be tested.
Fracture of the Lower End of the Radius
Colles' Fracture.—This injury, which was described by Colles of Dublin in 1814, is one of the commonest fractures in the body, and is especially frequent in women beyond middle age. It is almost invariably the result of a fall on the palm of the hand, in the three-quarters pronated position, the force being received on the ball of the thumb, and transmitted through the carpus to the lower end of the radius which is broken off, the lower fragment being driven backwards.
The fracture takes place through the cancellated extremity of the bone, within a half to three-quarters of an inch of its articular surface ([Fig. 45]). It is usually transverse, but may be slightly oblique from above downwards and from the radial to the ulnar side. In a considerable proportion of cases it is impacted, and not infrequently the lower fragment is comminuted, the fracture extending into the radio-carpal joint.
| Fig. 43.—Colles' Fracture showing radial deviation of hand. | Fig. 44.—Colles' Fracture showing undue prominence of ulnar styloid. |
When impaction takes place, it is usually reciprocal, the dorsal edge of the proximal fragment piercing the distal fragment, and the palmar edge of the distal fragment piercing the proximal. The periosteum is usually torn and stripped from the palmar aspect of the fragments, while it remains intact on the dorsum.