Biomechanical analysis of use of porous meta-diaphyseal custom-made cones in knee revision surgery

In many cases, traditional revision (TR) implant may be an effective solution to be used after primary TKA. However, it does not cover the full range of clinical possibilities, especially in patients with multiple revisions presenting an extremely weak bone and a variable geometry. Therefore, custom-made metaphyseal titanium porous cones were developed as an alternative to amputation in patients with severely pathological bone conditions. The aim of the study is to evaluate whether this innovative implant is able to restore patient’s ability to perform simple daily activities, in comparison with TR. The performances of implant were compared with TKA with cementless press-fit stems and cemented stems, and using a large resection prosthesis with cemented stems. These techniques were simulated by FEA and daily activities as full-extension and chair-rise configuration were analyzed with applied static force. Stress patterns in the interface regions between prosthesis and bone and risk of fracture in the bone were extracted and compared. Biomechanical results demonstrate that the use of custom-made devices can be considered a viable option to manage the patient's bone loss because the bone stress is more homogeneously distributed than stress induced by the other three techniques, where is more concentrated in specific regions.