Treatment of stem fractures in tumor prostheses by connecting different systems with a special adapter

In long-term survivors, oncologic surgeons are regularly faced with the problem of revising stem breakage of first generation Kotz modular femoral and tibial reconstruction system (KMFTR) prostheses. To avoid a whole prosthesis-exchange, we invented an adapter which allows connecting original KMFTR devices to new modular universal tumor and revision system (MUTARS) components. The adapter was used in 10 patients after a mean time span of 16.6 years after primary implantation of KMFTR prostheses. Reasons for revision included femoral stem breakage in five cases, breakage of tibial component in three cases and periprosthetic fracture in two cases (one femoral, one tibial). The femoral stem (three cases), the tibial stem (two cases) or the tibial plateau and body (two cases) were exchanged to MUTARS and connected to the remaining KMFTR parts. Three cases were converted to a total femur. Postoperative complications included one cone-dislocation and one aseptic loosening. In all patients, the pre-incidence function could be restored. The mean Musculoskeletal Tumor Society score was 81.7% of normal function. The presented adapter enables restoration of the long-term extremity function with relatively minor revision.