The Replacement of Free Bone Plates in Routine Craniotomies

Abstract

E VER since 1889 when the first osteoplastic bone flap was made and described by W. Wagner, 7 it has been the customary practice of most neurosurgeons while turning a bone flap to preserve the attachment of the bone to the temporal muscle and pericranium? ,4,6 Many exceptions to this method have been made and reported, but the routine use of bone plates, completely separated from dura, pcricranium, and muscle, and their replacement in the ordinary craniotomy, has not been thoroughly evaluated. In 1935 Naffziger '~ discussed 4 cases in which bone plates containing tumor were boiled and replaced. In 1939 Grant and Norcross 3 in an extensive review of the repair of cranial defects by cranioplasty emphasized the use of osteoperiosteal grafts from the outer table of the skull. In 1941 Boldrey and Cone ~ reported the use of the free bone flap osteoplastic craniotomy in a selected series of 50 cases, and indicated that they were using it in an increasing number of cases. Several years ago we first began to replace revised bone plates in cases in which the skull was involved by tumors such as osteomas and meningiomas and in which discarded bone would have left unsightly defects. The bone was treated in the manner described by Naffziger; 5 the greater portion of the tumor was chiselled off, and the plate was boiled for periods varying from 3 to 10 minutes and immediately replaced. I t soon became apparent that there was a number of advantages to be gained by the use of the bone plate in routine craniotomies provided there were no undesirable postoperative complications, and the method was put into practice. A sufficiently long time has now elapsed to permit a reliable evaluation of the prodecure. The method has been employed in all parietal and occipital craniotomies and in a few cases in which exposure of both frontal lobes was desired. However, in the usual unilateral frontal exposures the scalp is separately reflected toward the brow and the bone plate left attached to temporal muscle as a means of anchoring the muscle when the wound is closed. In some cases, in order to enlarge the cranial opening for additional exposure, plates of bone have been used. The method has not been employed in any suboccipital operations. In outlining the scalp flap it has frequently been advantageous, particularly for obtaining exposure near the midline, to use angulated or at least only slightly curved rectangular flaps