Joint-preserving tumour resection around the knee with allograft reconstruction using three-dimensional preoperative planning and patient-specific instruments

Background: The region around the knee joint is a common location of malignant bone tumours. Limb salvage procedures, whenever possible, are preferred to amputation. Allograft reconstruction is an accepted procedure to restore large bone defects. Preoperative three-dimensional (3D) planning and patient-specific instruments (PSI) have already been introduced. The purpose of this study was to provide a technical guideline for joint preserving tumour resection and allograft reconstruction around the knee using 3D planning and PSI. Material and methods: 3D triangular surface models are created based on computed tomography (CT) and magnetic resonance imaging (MRI) data, whereby tumour expansion in the bone and affection of the surrounding structures are assessed. We describe the preoperative 3D analysis and planning in tumours around the knee joint. In addition, we provide a description of different PSI as well as cutting-techniques to enlarge the toolkit and facilitate a broad range of joint preserving tumour resections with allograft reconstruction around the knee. The basic guide serves for the registration of the preoperative plan for the surgery. Reference pins facilitate the application of further guides. Different additional guide designs can be applied, such as "safety guides," "osteotomy guides," and "allograft adjustment guides." Discussion: The use of 3D planning and generation of PSI offers valuable tools in tumour resection and allograft reconstruction around the knee joint. To perform complex osteotomies and to preserve vital structures PSI seems to be helpful tools. A step-by-step guideline is provided for the use of 3D preoperative planning and sequentially applied patient-specific guides. (C) 2019 Elsevier B.V. All rights reserved.