DISLOCATIONS OF THE THUMB AND FING ERS.—Metacarpo-Phalangea 1 Dislo cations of the Thumb.—Lateral (one case) and forward dislocations present no es , peeial points of interest. The latter are easily reduced by hyperflexion and trac ! tion. Backward dislocations of this joint, however, have long been the sub ject of controversy, and are treated in some of our latest text-books in a manner none too accurate. This dislocation may be incomplete, complete, or complex. In complete backward dislocations may be produced voluntarily by many young persons. It is reduced at will. In the complete form the phalanx is carried backward and upward on the dorsum of the metacarpal, usually by forced exten sion, the anterior ligament is torn away from the metacarpal bone and drawn backward with its sesamoid bones along, and even past, the articular surfaee of the head of the metacarpal, while the tendon of the long flexor slips to one side of the head, -usually the inner, al though it may exceptionally remain in place. The first phalanx is in extension at a right angle, the terrainal phalanx in flexion, and the head of the metacarpal prominent in the thenar eminence (Fig. 11).
In the complex form (produced from the complete by forced flexion of the thumb) the glenoid ligament, and the two sesamoid bones with it, are turned upward so as to lie between the phalanx and the head or dorsurn of the meta carpal. The thumb is in straight exten sion, parallel and posterior to the meta carpal; its base can be felt as a promi nence behind, and the head of the meta carpal protrudes in front. The sesamoid bones stand at a right angle to the ar ticular surface of the phalanx, and can not be folded under it, thus offering a great—often insurmountable--obstacle to reduction. The essential point of re
duction, therefore, is to avoid the trans formation of the complete into the com plex form. The extension must be main tained or even increased and the thumb pressed bodily downward until the an terior edge of its base, following the glenoid ligament, overlaps the articular surface of the metacarpal, when it can be turned into place by flexion. If this fail, a combination of rotation with the downward pressure may succeed: a sort of unbuttoning of the head of the meta carpal from the grasp of the glenoid liga , ment and the attached. heads of the short flexor. If, however, the dislocation has become complex by the interposition of the glenoid ligament, the same method may yet succeed; but much more for cible downward traction is necessary to carry the edge of the ligament over the end of the metacarpal bone ahead of the phalanx before instituting flexion. If all manipulations fail, the joint must be opened through a longitudinal anterior incision, and the centre of tbe glenoid ligament nicked deeply enough to allow it to be drawn over tbe bead of the meta carpal, after. which the dislocation may be readily reduced.
Melacarpo-phalanyeal dislocations of toms and treatment of which it does not materially complicate.
The coccyx may be dislocated forward or backward. The pain is usually in tense. Diagnosis and reduction are ef fected by rectal touch. The tendency to recurrence can only be remedied.by exci sion of the bone.