How is the hip prosthesis secured?

Cemented or cementless?

An artificial hip joint can be secured into the bone in a number of different ways. In essence, there are two main types of fixation – with cement or cementless:

If the bone structure lacks stability, the hip joint replacement is secured using bone cement. Immediately after the operation, the hip endoprosthesis and bone are thus securely bonded.

If the patient’s bone is of good quality, the artificial hip joint can be secured using a cementless technique. With such methods, the bone slowly grows into the hip endoprosthesis to form a strong joint after some time.

The correct choice therefore not only depends on the patient’s age but also on the nature of the bone. The surgeon decides upon the appropriate method together with the patient during the preoperative discussion.

→ What happens before the operation?

Cemented hip endoprosthesis

With this method, the artificial acetabular cup and the prosthesis stem are bonded to the bone using so-called bone cement.

Question: What is bone cement?: Bone cement is not actually cement but rather a fixation material comprising two components. The liquid and powder are mixed together immediately before the artificial joint is placed, the cement cures completely within a few minutes. The prosthesis elements are thus securely bonded to the bone. Bone cements often contain an antibiotic in order to prevent infections. Bone cement has been successfully used for over 50 years in order to anchor artificial joints.

In particular for older patients, the use of bone cement for securing hip endoprostheses is often advisable. The slow bony ingrowth process of the artificial hip joint is avoided and the patient is able to load the leg again soon after the operation.

Furthermore, major studies have shown that cemented hip endoprostheses are particularly durable. This may prevent the necessity of a second operation to change the prosthesis, or at the least postpone it.

Cementless hip endoprosthesis

As opposed to cemented techniques, here the prosthesis components are wedged or, in part, screwed into the bone. To this end, the surgeon has to fit the artificial acetabular cup and the prosthesis stem into bone accurately. Consequently, the metal surfaces of the prosthesis components are in direct contact with the bone. The latter slowly grows into the prosthesis to form a secure attachment for the artificial hip joint.

Hybrid prosthesis

Hybrid prostheses combine both cemented and cementless fixation methods; the acetabular cup is placed without cement whilst the prosthesis stem is cemented.