Introduction. The use of computer navigation has a potential to allow precise tumour resection and accurate reconstruction of the resultant defect. This can be useful in difficult areas such as pelvis, diaphyseal (intercalary) resections and geometric bony resections. Methods. We have carried out resections of musculoskeletal tumours in 7 patients using an existing commercial computer navigation system (Orthomap 3D). CT & MRI scans of each patient were fused preoperatively using navigation software and the tumour margins were marked. The planes of tumour resection were defined on the 3D image generated. During surgery, trackers were attached to bone with tumour and registration performed. Instruments attached to navigation tracker were then used to identify the predetermined resection points. Of the 4 pelvic tumours, 1 had biological reconstruction with extra corporeal irradiation, 3 had endoprosthetic replacement & 1 did not need any bony reconstruction. 1 patient with proximal femur tumour needing extraarticular resection had endoprosthetic replacement. The 2 tibial diaphyseal tumours had biological reconstruction. Results. Examination of the resected specimens revealed tumour free margins. Postoperative radiographs showed resection and reconstruction as planned in all cases. In the patient with extraarticular proximal femur resection the hip joint was inadvertently exposed whilst making the acetabular osteotomy & in one patient with pelvic tumour the intra-operative registration could not be accurately performed as she was overweight and a real time matching of anatomy & virtual images was not achieved. Discussion and Conclusion. The use of computer navigation in musculoskeletal oncology allows integration of local anatomy and tumour extent and thus resection margins can be identified accurately. Our experience so far has been encouraging. Further clinical trials (multicentre) are required to evaluate its long term impact including functional & oncological outcomes

Aims

Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model.