Computer-assisted preoperative planning (CAPP) in orthopaedic surgery.

Computer-assisted preoperative planning (CAPP) is a complex approach to planning a surgical treatment. It includes computer-assisted design (CAD) principles, expert knowledge utilization and facilities for decision making process support. The CAPP system uses actual patient data and calculates instructions in real dimensions for performing a particular operation on a particular patient. Our first CAPP application was preoperative planning of corrective osteotomy of a malunited fracture at the distal end of the radius. The application was based on the construction of three-dimensional wire models from only two orthogonal projections of objects (two orthogonal X-rays of affected and healthy wrists). On these wire models, an operation of the affected hand was simulated until the best fitting of the models was achieved. The use of real dimensions in computer calculation was crucial because the numerical output was used as a surgical treatment guideline. The results obtained in a group of 33 patients were excellent when compared with the results reported in the literature.