Cranioplasty performed with a new osteoconductive osteoinducing hydroxyapatite-derived material

Cranioplasty is required to protect underlying brain, correct major aesthetic deformities, or both. The ideal material for this purpose is autogenous bone. When this is not available, alloplastic or artificial materials may be used. These materials should be malleable, strong, lightweight, inert, noncarcinogenic, nonferromagnetic, and, if possible, inexpensive. The authors reviewed their surgical experience with a new bone substitute and discuss outcomes in patients in whom it was used.

The 11 patients presented in this series had bone defects resulting from bone-involving tumor (eight cases), trauma (two cases), or aesthetic deformity due to repeated craniotomies (one case). The defects were repaired using Osprogel, a bone substitute that consists of calcium hydroxyapatite combined with synthetic, human bone-derived gelatin, glycerol, and water. Osprogel is not only a bioinert material but also an osteoconductive and osteoinducing substrate; when it is placed in contact with healthy cancellous bone, it induces osteogenesis and angiogenesis, thus permitting the regrowth of nearly normal bone. The sheet of Osprogel was modeled onto the cranial defect intraoperatively and was kept in place either by using a titanium micronet secured to surrounding bone with microscrews (first two cases) or by using a single- or double-layer titanium mesh secured with stitches. No complications due to the procedure were observed. The results, evaluated at least 6 months after surgery by using three-dimensional (3-D) reconstructed computerized tomography scans, were excellent in seven patients, good in three, and fair in one. In the patient with a fair result, the repair was unsatisfactory because there was lack of experience in using the material. In part of the area to be repaired, the Osprogel was used as filler; here it was washed out and resorbed. The cases deemed as having a good result had good bone replacement; however, the curvature was faulty.

In the near future, this technique may be refined to achieve good or excellent results either without the use of supporting material or with the use of individual, computer-designed 3-D prostheses.