Dislocations, like fractures, may be _complicated_ by injuries to large blood vessels or nerve-trunks, by injuries to internal organs, or by a wound of the soft tissues which does not communicate with the joint. Further, a fracture may coexist with a dislocation--a most important complication. _Clinical Features._--The most characteristic signs of dislocation are _preternatural rigidity_, or want of movement where movement should naturally take place; _mobility in abnormal directions_; and _deformity_, the part being "out of drawing" as compared with the uninjured side (Fig. 18). The bony landmarks lose their normal relationship to one another; and the deformity is characteristic, and is common to all examples of the same dislocation. Although any of the subsidiary signs may occur in lesions other than dislocations, due weight must be given to them in making a diagnosis. _Loss of function_ is complete as a rule. _Pain_ is much more intense than in fracture, usually because the displaced bone presses upon nerve-trunks, and from the same cause there is often numbness and partial paralysis of the limb beyond. _Swelling_ of the soft parts due to effused blood is usually less marked in dislocation than in fracture, but is often sufficiently great to interfere with diagnostic manipulations. The displaced bone, and sometimes the empty socket, may be palpable. _Discoloration_ is usually later of appearing than in fractures. _Alteration in the length_ of the injured limb--usually in the direction of shortening--is a common feature; while girth measurements usually show an increase. A peculiar soft _grating_ or _creaking sensation_ is often felt on attempting to move the joint; this is due to cartilaginous or ligamentous structures rubbing on one another, and must not be mistaken for the crepitus of fracture. In the majority of cases, although not in all, after reduction has been effected, the bones retain their proper relations without external support, a point in which a dislocation differs from a fracture. A careful investigation of the kind of force which produced the injury, particularly as regards its intensity and direction of action, may aid in the diagnosis. The diagnosis can always be verified by the use of the Röntgen rays, and this should be had recourse to whenever possible, as a fracture may be shown that otherwise would escape recognition. _Prognosis._--After having once been dislocated, a joint is seldom as strong as it was formerly, although for all practical purposes the limb may be as useful as ever. Some degree of stiffness, of limited movement, or of muscular weakness, and occasional arthritic changes and a liability to re-dislocation, are the commonest sequelæ. Prolonged immobilisation is liable to lead to stiffness by permitting of the formation of adhesions; while too early movement tends to produce a laxity of the ligaments which favours re-displacement from slight causes.