In one embodiment of the invention, a method is provided including the steps of preparing an opening in the bone sized to receive a prosthesis therein and then inserting an apertured temporary implant into the opening. A fluent material is then injected into the temporary implant so that the material exudes from the apertures into contact with the bone surrounding the temporary implant. The temporary implant is then removed to make way for implanting the prosthesis into the bone opening. The fluent material can be a biological, biocompatible or bioactive material, such as a composition adapted to permanently fill voids and irregularities in the bone or a composition adapted to promote bone growth. In another embodiment, an implant assembly includes an apertured sleeve adapted to be permanently implanted within the bone opening, but providing apertures for injecting a fluent material into the opening. The sleeve defines a cavity for receiving the distal portion of a prosthetic joint element, which can be fixed to the sleeve.