The disk of bone is removed and the conditions investigated with the dural separator. When the degree of depression and the splintering of the internal table are not excessive, the parts may be elevated into position. In most cases, however, the uncertainty that exists with regard to possible dural injury renders it necessary that the depressed fragments should be elevated and removed, or so raised as to allow of adequate inspection of the dura itself. For this purpose the craniectomy forceps may be required. The dura can now be examined. If torn, the opening may require enlargement, in order to determine whether any osseous fragments have been driven into the brain-substance; all such fragments are carefully removed. Hæmorrhage is arrested, the dura sewn up, and the scalp-flap carefully sutured. Drainage should always be avoided, the risk of infection is too great. As a prophylactic against the development of meningeal infection, the patient should undergo the routine treatment with urotropin (see p. 116). (_b_) When the depression is of such a nature that the elevation of the fragments can be carried out without preliminary trephining, the fragments are raised with the periosteal separator, and the membranes and brain examined as described above. In =simple comminuted fractures= the larger fragments of bone are to be replaced in the anticipation that they will live entire, in part, or will act as scaffolding media for the formation of dense fibrous tissue. After removal from the wound, and during the completion of the operation, the vitality of all loose fragments may be preserved by immersion in hot saline solution. All minute fragments of bone should be discarded. [Illustration: FIG. 49A. THE ELEVATION OF A DEPRESSED FRACTURE. _First stage._ The trephine circle includes the outer portion of the depressed area.] [Illustration: FIG. 49B. THE ELEVATION OF A DEPRESSED FRACTURE. _Second stage._ The trephine disk has been removed and the elevator is in position.]