Validation of computer-assisted manufacture of titanium plates for cranioplasty

We have constructed 300 titanium cranioplasty plates, over 150 cases using a computerised technique, the remainder by external impression. The clinica l follow-up of these cases over 8 years has shown consistently good results that justify our simple low-cost method of manufacturing these plates. Bot h techniques require the provision of a model on which to construct the pla te. In the traditional technique, an approximate model is derived from the resected bone or a direct impression of the defect over the patient's scalp . Using the computerised technique, a more accurate model of the defect and the surrounding bone is milled in polyurethane foam from cross-sectional c omputerised tomographic (CT) scans. Sheet titanium is pressed to shape from a design outlined on a counterdie. The subsequent stages of the plate cons truction are then the same for both methods. This study describes the stage s of the :model manufacture, the validation of its accuracy and the plate c onstruction that follows. Use of the computerised method has resulted in a reduction of errors, enabling the manufacture of a smaller plate than was p ossible previously. It has also enabled design changes through the achievem ent of greater accuracy in fit.