The use of CT derived solid modelling of the pelvis in planning cancer resections.

Resection of malignant tumors of the pelvis is demanding. To avoid disabling hemipelvectomies, years ago internal hemipelvectomy combined with partial pelvic replacements had become a surgical procedure. To achieve adequate reconstructions custom-made replacements were recommended. In early stages of the surgical procedure using megaprostheses, individual pelvic models were manufactured.Since little is known about the accuracy of such models we analysed the charts of 24 patients (25 models) for whom an individual model of the osseous pelvis had been manufactured.Two patients refused surgery. In 23 patients partial resection of the bony pelvis was performed followed by a partial pelvic replacement (13x), hip transposition procedure (5x), ilio-sacral resection (4x), or revision surgery. In all patients who received a partial pelvic replacement, the fit of the replacement was optimal. No major unplanned resection was necessary. The same was observed in patients who received a hip transposition procedure or an ilio-sacral resection. Oncologically, in most of the patients we achieved wide resection margins (14x). In 5 patients the margins were marginal (4x) or intralesional (1x). In two cases the aim was a palliative resection because of a metastatic disease (1x) or benign entity (1x).Pelvic models are helpful tools to planning the manufacture of partial pelvic replacements and ensuring optimal osseous resection of the involved bone. Further attempts have to be made to evaluate the aim of navigational techniques regarding the accuracy of the osseous and soft-tissue resection.