Prosthetic hip replacement surgery, introduced in the second half of the last century, after an initial pioneering stage have become routine in most hospitals.
Experience gained in 50 years of clinical use have contributed to the current standards in terms of materials, instruments and surgical procedures making this type of intervention effective, reliable and durable.
Current statistics attest to 15 years, more or less, as the average life of a hip replacement. The duration of a arthroplastic implant however depends on many factors, variables in the individual, such as the physical condition and body weight, activity level, metabolic factors. In addition, surgical technique and experience of the operator play a major role in the success of the system.
Hip prostheses are generally composed of four elements:
The femoral stem: implanted into the proximal part of the femur after resection of the femoral head and the preparation of the seat by means of special rasps.
The articular head: is inserted on a conical design on the neck of the stem.
The Cup, or acetabular cup: is implanted into the acetabular cavity of the pelvis after preparation of the bone seat by means of special reamers.
The joint insert: is inserted interlocking into the acetabular cup having a concave seat in which it is housed and articulates with the joint head.
An artificial hip, even though made up of high quality materials, is not as strong and durable as a natural healthy hip and there is no guarantee that it will last for the rest of the patient’s life. Articular components however, are subject to wear and will necessarily need replacement with new components.
In particular, wear affects the acetabular cup insert, normally polyethylene: the movement of the femoral head in its interior, matched to the load, determines the wear that leads to having to “revise” the implant.
Aiming to prolong the useful life of the artificial joint as much as possible by postponing a possible revision surgery, in recent years material innovations has been introduced to minimize or avoid the phenomenon of wear:
- highly cross-linked polyethylene inserts (more wear-resistant) also added with anti-oxidant agents like vitamin E ;
- articular combinations (head / insert) with very low wear rate, like ceramic-on-ceramic (head and insert bio ceramics).