The prosthesis models

What are the different types of prostheses? The goal is always to restore undisturbed, pain-free and above all permanent function of the hip joint. Consequently, there are three different types of prosthesis, which differ in the way the prosthesis is anchored in the body’s own bone.

These are: The advantage that there are different ways of anchoring the prosthesis in the body’s own bone is that the patient can be fitted with a total of three – possibly even more – HTEPs. Despite all the requirements that a prosthesis model must meet, replacement operations cannot be ruled out and are due within a certain period of time (see below). In the following, the different types of prostheses will be presented and their characteristics described.

In contrast to a cemented prosthesis, the prosthesis stem and the artificial acetabulum are either screwed to the bone or clamped into the bone in the case of a cementless prosthesis. In the former case, one speaks of a so-called screw cup, in the latter case of a “press fit prosthesis”. A fixation of cementless prostheses, which are usually made of titanium, is achieved in a special way by the special surface coating, which consists of a basic bone substance, hydroxyapatite.

The surrounding bone grows up to the prosthesis so that a close connection is established between the two substances. Above all, this ensures the direct transfer of the load forces. Cemented prostheses differ from uncemented prostheses in that both the acetabular cup and the prosthesis stem are inserted with the aid of a fast-hardening, antibiotic-containing bone cement.

Accordingly, they do not have a roughened surface that is supposed to cause ingrowth. With cemented prostheses, it is important to avoid any gaps that may occur between the cement and the prosthesis, which could possibly be responsible for the loosening of the prosthesis. A hybrid prosthesis is the combination of a cementless and a cemented prosthesis.

Here, either the prosthesis stem is fixed with the help of a fast hardening and – to prevent infection – usually antibitotic cement, while the socket is anchored without cement, or vice versa. Different model variants exist for all types of prostheses. Determining the correct model requires determining the patient’s size, weight and bone shape, as well as the requirements of his new hip joint.

In the run-up to the operation, the surgeon usually prepares a drawing of the hip to be operated on using the imaging techniques, which he or she can then use to determine the exact size and model of the hip prosthesis. Below are shown divergent components of hip joint endoprosthetics. It can be seen that – depending on the model variants and the manufacturing companies – there are different models on the market whose advantages and disadvantages can only be determined after many years and always depend on individual circumstances.

The following pictures are intended to illustrate the differences between cemented and cementless acetabular cups. As already mentioned, cementless prostheses always imply the use of a metal alloy acetabulum (for example in the form of titanium).

The cementless prosthesis
The cemented prosthesis
The hybrid prosthesis,which consists of cemented and uncemented prosthesis parts.

Analogous to the large number of different cup types, there is also a large selection of prosthetic shafts. Here, too, a distinction is made between: In particular, the uncemented cups are again distinguished with regard to their main anchoring zones.

Cemented ladles and
Uncemented pans