Assemblies, systems, kits, and methods related to an endoprosthetic rotating hinge assembly. The exemplary embodiments disclosed herein can comprise a preassembled rotating hinge subassembly having a hingedly rotating femur box configured to be mechanically engaged to a femoral component via a femur fastening mechanism, the femur fastening mechanism being non-axially aligned with a tibial axis of rotation when the knee is in flexion or extension.

To provide a bioimplant capable of controlling a rate of an antibacterial agent and an antibiotic to be eluted from the coating film. An evanescent coating film made of a calcium phosphate-based material having crystallinity of 90% or less is formed at a predetermined area of the bioimplant and an antibacterial agent or an antibiotic is contained in the coating film. If necessary, a metal oxide layer made of a metal oxide having an isoelectric point of less than 7 is formed on the bioimplant thereby suppressing adhesion of bacteria.