A total hip replacement is one of the surgical procedures which provide greatest satisfaction among patients due to the significant improvement in the quality of life they experience.
So much so, that it has been defined by some authors as the surgery of the 20th Century. It is a procedure which consists in substituting the hip joint with an artificial joint or prosthesis.
The most common reason for surgical intervention is arthrosis, a disease caused by the wear-and-tear of the cartilage which leads to a malfunction of the joint. It is especially common in older people, older than 65, who live with pain and which can limit their day-to-day activities considerably.
In today’s context of continuous technological innovations and advances and facing the enormous pressure from manufacturers, the range of prosthesis available to orthopaedic surgeons is wider than ever. This situation demands that the prostheses used have supporting scientific evidence based on clinical studies or on data from arthroplasty registries.
The legislation which regulates the commercialisation of medical devices, such as prostheses, is more lax than that which regulates drugs which means that not the same type of studies are required for their approval and in consequence, neither is the scientific evidence. In fact, this precise legislation is undergoing a review at present and a new one on this matter will soon be made available.
Several years ago, the prestigious journal BMJ (British Medical Journal) published an article in which it was highlighted that in the UK, 24% of hip prostheses used had no scientific evidence to demonstrate their clinical effectiveness.
As a consequence of that publication and applying the same methodology, at the Hospital Sant Rafael and in collaboration with the Catalan Arthroplasty Registry (RACat) of the Agency for Health Quality and Assessment of Catalonia (AQuAS), we embarked on the task of analysing what the scientific evidence was on hip prostheses used in public hospitals in Catalonia which had sent their data in to the RACat during the period 2005-2013.
We did this via a search on different platforms putting the spotlight on Orthopaedic Data Evaluation Panel (ODEP), as well as Tripdatabase, PubMed and Google acadèmic.
Following the analysis of the 18,816 acetabular or hip cups and 19,546 femoral stems (the main components of the hip prosthesis) collected in the registry, our first surprise was to observe that 123 different models of cups had been used and 138 different models of stems. In the group of participating hospitals in the RACat during the period of the study, it was seen that with many of these models less than 10 units in number of each had been used.
As these models only represent 1% of implants used, they were excluded from the study and in the end 74 models of hip cups and 75 models of femoral stems were studied.
The results of the analysis, either recently published or not yet published, now at a pre-publication stage, show that less than 50% of components used had the highest level of scientific evidence in accordance with the ODEP. This top level is achieved when there are studies having 10 years at least of monitoring with a number of prostheses evaluated exceeding 500 units.
What also caught our attention was not finding any evidence for 18 hip cups or 16 femoral stems which represented, respectively, 13.56% and 9.53% of all implants carried out during this period.
All scientific studies show limitations and it is not always possible to offer exhaustive results. Aware of this, and of the fact that the data in our study are the results of a research project which might not be able to reflect what the reality of public hospitals in Catalonia is in absolute terms.
We do want to stress that the task of the orthopaedic surgeon needs to be more and more regulated by evidence based medicine and this is, precisely, one of main purposes of arthroplasty registers: to carry out studies like the one we have been able to do at Hospital Sant Rafael with the aim of improving the health care of people.
Post written by Miquel Pons, Danieol Chaverri and Luis Lobo, Hospital Sant Rafael, Barcelona.