Titanium in Cranioplasty

Abstract

The substances most commonly used in the repair of defects of the skull are autogenous bone, sheet tantalum, and plastics of various kinds. All have certain disadvantages. Bone, whether from rib or iliac crest, is difficult to shape into the proper contours; moreover, even autogenous bone grafts sometimes fail to unite, and may then be absorbed. Tantalum, in many ways a satisfactory alloplastic material, is impervious to diagnostic roentgen rays and this can be inconvenient when neuroradiological investigation is needed later. Zirconium, which was recommended for cranioplasty and other purposes by Bates et al., 1 apparently has the same disadvantage, although it is considerably lighter than tantalum. The plastics now in use in this country are chiefly of the acrylic group, and with careful technique these substances give good cosmetic results. However, there has been at least one report of traumatic fracture of a plastic insert, 4 and experiment has shown that an acrylic plate must be at least as thick as the skull if it is to give comparable protection; when the skull is thin, it is indeed quite difficult to mould a plate that will be strong enough, yet not palpable subcutaneously. Titanium, a light (atomic No. ~) metal, is frequently used for implants in orthopaedic surgery. As a material for cranioplasty, it has certain advantages which have appeared to justify its use, though it is by no means an ideal substance. It is well tolerated by the tissues; 3 recent spectrographic studies 2 show that, like vitaltium, a titanium implant undergoes very slight electro