Hip Unit
Established alongside the creation of the Department of Locomotor System Pathology and Sports Medicine.
What is prosthesis loosening?
Although the survival rate of total hip prostheses is very high, an implant that is loose can always be replaced. A patient with a prosthesis experiences pain while walking, which limits their walking distance. They may also feel pain when sitting, getting up from a chair, or starting to walk. It is also crucial for patients with a hip prosthesis to regularly follow up with their specialist in order to minimize bone wear in case the prosthesis begins to loosen.
Causes of Loosening
The causes of loosening are multifactorial, although it is classically attributed to the reaction caused by polyethylene particles that detach from the polyethylene cup of the acetabular component; this is known as periprosthetic osteolysis. Modern high cross-linked polyethylene cups present less wear, so it is expected that in the coming years this phenomenon will occur with decreasing frequency.
However, we have replacement implants for every situation, so it does not make sense to think that a person has a limited number of possibilities for hip prosthesis replacement in the worst-case scenario. Additionally, the availability of a bone bank allows for the anatomical reconstruction of any bone portions that may be needed. Moreover, besides radiographic exams, scans, and bone scans, we perform helical CT scans with three-dimensional representation that allow us to precisely identify the bone defect and the situation of the loosened prosthesis with great accuracy.
Our center, with a bone bank linked to the Transplant Services Foundation of the Hospital Clínic of Barcelona, is one of the most experienced centers in bone transplantation worldwide, having carried out over 1,500 transplants since 1986.
Treatment of Prosthesis Loosening
The objectives of total hip prosthesis replacement are several:
- To restore joint function to its anatomically most appropriate position.
- To restore the bone loss caused by loosening – osteolysis.
- The implants used must ensure the maximum survival rate.
To achieve this, we use revision implants depending on the degree of wear, both at the acetabular level and at the femoral level. Likewise, we use allografts or bone transplants based on each case and according to a predetermined classification. For example, at the acetabulum, we use the modified Icatme classification of Gross with four grades, as illustrated in the diagram on the right.
The most common cases correspond to grades I and II. Generally, we use tantalum cups (titanium with 80% more porosity) and, in some cases, graft-transplantation with fragmented-impacted grafts according to the Sloof technique. In grades III and IV, where there is a lack of a column, generally the posterior column, or when a floating hip remains, we use massive acetabular transplantation from the bone bank. Along with Mount Sinai Hospitals in Toronto and Rush Presbyterian Hospital in Chicago, we have the greatest experience in the world in this type of transplant.
