Developing a novel custom cutting guide for curved peri-acetabular osteotomy

Curved peri-acetabular osteotomy (CPO) produces excellent clinical results, but the surgical procedure is technically demanding, and severe complications related to the osteotomy have been reported. To provide a safe, accurate surgical procedure, we have developed a novel method for setting the cutting line and direction. We have designed and made a custom cutting guide for individual patients. The purpose of the study was to evaluate the efficacy of this new method and cutting guide. The cutting line was designed on a full-scale three-dimensional plaster model made from computed tomography (CT) data for each case. The surface of each plaster model was colour-coded according to the distance from the centre of the femoral head. A custom cutting guide was designed based on this cutting line on the workstation. A titanium custom cutting guide was fabricated using rapid prototyping technology. The cutting guide directed the cutting direction of the osteotome. We evaluated the outcomes for seven consecutive hips in seven patients who underwent CPO using the system between April and December 2011. All peri-operative complications were recorded. The accuracy of the cutting line was evaluated using CT data obtained two weeks after the operation. There were no major complications related to the osteotomy such as posterior column fracture or intra-articular osteotomy. The actual cutting line corresponded almost exactly to the planned cutting line in all cases. The colour-coded plaster model and the custom cutting guide were effective for avoiding severe complications associated with a CPO.