The treatment of major osseous defects in orthopedic oncology is dominated by surgical techniques which focus on preserving the affected limb. Ablative measures (amputations and reverse plastics) as well as arthrodeses of major joints are avoided as far as possible, if reasonable from an oncologic point of view. Surgeons may choose between different standard procedures: Besides the option of using allogene and autologous graft material, tumor prostheses present a proven solution for the reconstruction of osseous defects. A combined use of allograft and prosthesis is often chosen. During the past few years, modular replacement systems have become more and more popular, since they offer the opportunity to fill defects of varying extents with respect to each individual case. Since 1992, (MUTARS^® Modular Universal Tumor And Revision System) has been successfully used for the treatment of major osseous defects of the lower and upper extremities. Its modular design was developed in co-operation with Prof. Dr. med. W.Winkelmann and Prof. Dr. med. Georg Gosheger^[1], The system shows good functional results and allows for an individual solution for major osseous defects, including hip and/or knee arthroplasties. Up to 2005 more than 4,000 MUTARS® prostheses have been implanted successfully. Co-operation with leading European clinics has enhanced continuous further development of the implants and instruments, resulting in the proven instrumentation available today. This good collaboration enables us to always remain up-to-date and continue further development by using the latest experience in the tumor prosthesis sector and modify our products according to this latest standard of knowledge. Since March 2003 the new PEEK-Optima® lock became available. This material shows excellent properties for the femorotibial locking of the Total and Distal Femoral Replacement . The fatigue strength of PEEK-Optima^® is 5 times higher than fatique strength of polyethylene. The use of PEEK-Optima^® is recommended in those cases where extraordinary forces occur. Actually the development of MUTARS^® is going on with the trial use of an inverse proximal humeral replacement and the investigation of a special silver-coating which reduces the infection risk because of the antibacterial effect of the silver ions.

^[1] Univ.-Prof. Dr. med. Georg Gosheger, Direktor Klinik für Allgemeine Orthopädie und Tumororthopädie, der Facharzt  für Orthopädie, Sportmedizin, phys. Therapie,  Universitätsklinikum Münster.
     Prof. Dr. med. W. Winkelmann, Klinik und Poliklinik für Allgemeine Orthopädie, Universitätsklinikum Münster.