Abstract: An osteal prosthesis having an outer surface splined in a direction generally parallel to its mean axis is capable of being secured in the bone without cement, the bone tissue developing so as to at least partly occupy the interior or hollow between the splines.The cross-sectional profile of the splines is such that it imparts a bone tissue retaining capability, and the longitudinal interior surface or hollow of the splines, which are non-cylindrical, has a shape which tapers from the end of the prosthesis (lower end) which is the most deeply embedded in the bone to the other end (upper end), the prosthesis being thus capable of being extracted from the bone tissue by a tractive movement.