Wagner Cone Prothesis™ Hip Stem

As the Cone Prosthesis is designed for uncemented fixation, it is made of tissue friendly Protasul®-100 (Ti6Al7Nb). The surface is rough-blasted which, together with the characteristic shape, promotes osseointegration over a large area.The Cone Prosthesis is designed for difficult bone conditions at the proximal end of the femur but is also suitable for routine cases. It has also been proven reliable in deformities where implantation of standard prosthesis can be difficult, e.g. displastic or cylindrical femurs.The simple instrumentation, the straight forward operation technique and the compatibility with all articulations explain the growing popularity of this product. Since its market introduction (1992) over 25‘000 Cone Prostheses were sold worldwide.

Features and Benefits
The Cone Prosthesis is designed for uncemented fixation and is therefore made of the tissue friendly Ti6Al7Nb-titanium-alloy Protasul®–100. The fixation part is conical with the angles of core and cover both being 5º. Eight longitudinal ribs are arranged on the circumference. The height of the ribs varies between one and two and a half millimetres, depending on the diameter of the  prosthesis. The ribs are the same height over the whole length. They are constructed in a way that they penetrate several tenths of a millimetre into the bone, ideally creating contact with the bone over the whole length. The eight ribs give the prosthesis a high degree of rotational stability. Subsequent osseointegration – long-term stability- is promoted by the good primary stability, the rough blasted titanium surfaces and the ribs in contact with the bone. The rough blasted surface in the fixation part of the prosthesis offers, together with the characteristic prosthesis design, a wide area for osseointegration.

Load transfer
With continuous surface contact between the conical prosthesis and the bony interface, a uniform load transfer per unit of area can be assumed. With the conical geometry of the prosthesis, the surface per unit of length increases with the diameter. The surface area per unit of length is thus greater in the proximal area than in the distal area of the stem. The Cone Prosthesis therefore has  increased proximal loading due to the stem geometry alone.