Hip and knee arthroplasty: What prosthesis did you say I would get? (part two)

1 Feb
Olga Martínez, Xavier Mora

We continue the interview with Olga Martínez expert at the Catalan Arthroplasty Register (RACat) and Xaxier Mora, specialist in traumatology and orthopaedic surgery with a Master in biomaterials.

The aim of today’s post is to know a little more about prostheses and the biomaterials used in arthroplasties.

With this post and the previous one, we have wanted to present the opinions of these two professionals.

Are all prostheses the same?

Xavier: No, because each patient is different. Therefore, the orthopaedic surgeon will recommend one type of prosthesis or another, depending on the extent to which the bone is affected, the patients’ age, associated diseases and the daily activity of a the patient.

Olga: At present, there are different types of prosthesis on the market in terms of design, materials used in their manufacture and the way they are anchored to the bone. There are prostheses that range from replacing only a part of the joint to more complex joint replacements in situations where bone damage is extensive.

As a user of the health system, to which hospital should I go to receive the best prosthesis?

Xavier: One cannot talk about better or worse prostheses because all prostheses used for implants have to follow a standardised procedure according to specific international standards, such as those of the American FDA and the European CE seal of approval, for materials that will be implanted in humans. In the same way, hospitals in Catalonia are certified to be able to carry out this type of surgery.

Olga: The prostheses which are commercialised in Catalonia meet the international standards of quality and public hospitals base their choices of prostheses on the scientific evidence available. This is allows them to select those with the best results according to arthroplasty registries, using recommendations from different institutions such as the NICE (National Institute of Healthcare and Clinical Excellence) and the ODEP (Orthopaedic Data Evaluation Panel).

Olga: In addition, the new European legislation passed in 2016, regarding implants used in health, aims to increase the supervision of the industry by implementing stricter norms and regulations including the obligation of clinical assessment, while at the same time fostering innovation in this field.

Who does the research into the best materials available and what factors are taken into account?

Olga: These days, the research of new materials and manufacturing techniques as well as the design and improvement of new prosthetic implants is a multidisciplinary process. The contributions of orthopaedic surgeons are especially important together with studies in joint biomechanics and surgical technique. In Catalonia there are research centres in biomaterials such as Leitat and the Technical University of Catalonia (UPC).

Olga: From the AQuAS we have written up and published short reports on biomaterials (polyethylene, cements and ceramics and metals) aimed at professionals that work in services of orthopaedic surgery and traumatology, with the aim of updating their knowledge.

Reports available in Catalan:

Xavier: Nowadays, when manufacturing new materials, the interaction between the surface of a biomaterial and the bone is taken into account more and more often, so that bone cells can consider an implant as part of its own structure and thereby avoid the prosthesis from moving about because this is one of the biggest problems in getting an implant to function well.

How have materials evolved since the first prostheses to the present day?

Olga: The discovery of new materials and/or the progress made both in terms of manufacturing techniques and the knowledge gained in the biomechanics of the human body have influenced the design of prostheses over time.

Xavier: The first experiences in joint implants date back to the 20s of last century. One of the first attempts at replacing the surface of the head of the hip was done by manufacturing a metal socket or dome (Smith-Petersen).

Xavier: In the last 20 years, many important advances have been made regarding the use of new biomaterials, much safer and of greater resistance to wear, thus extending the life of an implant in a biological environment such as the human body. Together with metallic biomaterials, these days ceramic biomaterials are used with good results in relation to their integration in bone tissue.

Xavier: On the other hand, research in 3D technology has paved the way for a more precise surgery, and in the future it will be possible to manufacture more personalised implants.

Xavier and Olga: We both agree that we are getting closer and closer to having a prosthesis that is for life.

Hip and knee arthroplasty: What prosthesis did you say I would get? (part one)

25 Jan
Olga Martínez, Xavier Mora

Today, we interview Olga Martínez expert at the Catalan Arthroplasty Register (RACat) and Xavier Mora, specialist in traumatology and orthopaedic surgery with a Master in biomaterials. They are two professionals involved in arthroplasties, a subject of great impact among a large sector of the population. We focus on aspects of recommendation and prognosis related to the pathology and on the value of registries for quality care.

In what cases is an arthroplasty intervention recommended?

Xavier: The most important surgical indication to carry out a knee or hip arthroplasty is arthrosis. Advanced arthrosis has a considerable social impact with a loss of life quality for the person affected due to pain, a loss of personal autonomy and an increase in dependency. In addition, the loss or reduction in mobility can worsen existing diseases such as diabetes or heart diseases. It is in these situations when an arthroplasty is recommended which will reduce pain and improve joint mobility.

Olga: In our field, according to the data from the Conjunt Mínim de Dades dels Hospitals d’Aguts (Minimum Set of Data from Acute Care Hospitals) and the Catalan Arthroplasty Register (RACat), the main reason for an intervention in knee and also hip arthroplasties is arthrosis. In the case of the hip, femoral neck fractures are the second cause for arthroplasty recommendation.

It seems that there are more and more people who undergo arthroplastic surgery each day to implant a prosthesis. Is this a fact?

Xavier: Yes, around 9,6% of the Spanish population suffer from this disease to some degree, a percentage that increases up to 33,7% among people aged between 70 and 80. With the ageing of the population, it is evident that there will be an increase in the number of people who could be candidates for arthroplastic surgery in the future. In the context of Catalonia, if we do a simulation with 2026 as the time horizon, based on data from the Idescat, the population aged between 15 and 39 will decrease while the population of 40 to 64 will increase (227,000 people and 330,000 people respectively).

Olga: At present, knee arthrosis has a prevalence of 10,2% and that of the hip is around 5%, more frequent among women, even though the data vary between one study and another.

The AQuAS, the Agency for Quality and Health Assessment of Catalonia, has been managing the Catalan knee and hip arthroplasty registry (prosthesis) for many years. What purpose does a registry like this have?

Xavier: The aim of all orthopaedic surgery is the survival and good functioning of a prosthesis and in consequence, the improvement in the quality of life of patients. Although a prosthetic implant undergoes strict manufacturing procedures before being used and follows a rigorous surgical technique during surgery, the functional results in a patient need to be assessed via follow up sessions from the time they receive an implant. To this effect, arthroplasty registries can help detect models of prosthesis with a malfunction, both in the short and long term, and identify the patients who have received these implants.

Olga: This is what happened a few years ago with the ASR model, a hip prosthesis that some publications and registries, such as the National Joint Registry, pointed out due to an unusual increase in the rate of revisions. This motivated an international health alert and a protocol was adopted to monitor patients.

Olga: One of the first prosthetic failures that prompted the creation of registries was that of the 3M Capital Hip, a hip prosthesis introduced in 1991 in the United Kingdom as an inexpensive prosthesis. After six years and more than 4,600 prosthesis implants, the risk of undergoing a revision was considered to be 4 times higher than that expected with the added difficulty of the traceability of the implants as no registry existed at a national level.

Olga: The Registry for Arthroplasties of Catalonia created in 2005, an epidemiological tool of surveillance in the Catalan Health System, stemmed from the collaboration between the AQuAS, CatSalut and the Catalan Society of Orthopaedic Surgery and Traumatology.

Are there other similar experiences of registries of this type in other countries?

Olga: Sweden (1975) and Finland (1980) were the first countries to push for a national registry of arthroplasties of a demographic nature.

Olga: At present, many countries have implemented this tool, be it in Europe, America, Oceania, etc… with different territorial coverage, but with a common aim: to be a valid instrument in assessing arthroplasty procedures and implants used.

As a patient or as a family member of a person that suffers from joint arthrosis, what is the message that you would like to get across based on your experience?

Xavier: The first consultation that a patient has is always because of the pain they are experiencing in the hip or knee joint when walking, going up or down stairs, getting up from a sitting position in a chair, having difficulty to put on shoes, etc. The aim of treatment should be to eliminate pain by using medication, doing physical exercise and physiotherapy that help improve 95% of patients. An arthroplasty intervention should only be considered as a last therapeutic resort. In this context, shared decisions between professionals and patients are very important too when talking about arthroplasties. We should all ask ourselves whether the best option to reduce this pain is to implant a prosthesis.

Does a patient go back to normal routine life after an arthroplasty intervention?

Xavier: After a surgical intervention and once the period of functional recovery has come to an end, a normal lifestyle can begin, due to the disappearance of pain and an improvement in joint mobility. In certain cases, constraints will be limited to intense activity that could overburden the joint.

(To be continued …)

Preference sensitive health care: the causes of variations

19 Feb

Jordi VarelaJordi Varela. Editor of the blog “Advances in Clinical Management

There is a case-mix part (25% according to Wennberg) such as inguinal hernia, cataracts, metrorrhagia or knee osteoarthritis, for which modern medicine has an effective surgical response, although in the application of the technique there is often a margin for the doctor’s interpretation, another margin for the subjectivity of the patient, such as pain perception or adaptation to the lack of visual acuity, as well as a very important factor: the decision of the patient himself. There are men who prefer to wear a brace to hernia surgery and women who prefer to live with their uterus, provided that the degree of the discomfort and metrorrhagy allows them to.

After this introduction, let’s see the Variations in Health Care, the good, the bad and the inexplicable report by John Appleby and his collaborators, published by King’s Fund in 2011, which states that variations in hospitalization rates are pervasive and persistent, and even affect common interventions known to be effective such as hip replacement for advanced osteoarthritis cases.

Distribution rates of hip replacement in England 2009/10

Note that although adjusted for age and sex, the rate of hospitalization for hip replacement (with lighter blue line) in the graphic, are observed in 18 PCT (Primary Care Trust) that show a value of 60 interventions per 100,000 inhabitants per year, while at the other extreme, there are 20 showing a rate of 140. That is, citizens of the latter communities have a 2.3 times higher probability of being operated on for prosthetic hip replacement than the citizens of the former. The same report shows that these regional differences are extended to other elective procedures such as knee, cholecystectomies or coronary angioplasty.

Whichever way you look, this type of variation in the use of health care resources for procedures seemingly well identified and standardized, is universal, and this is seen when comparisons between systems (countries) are being made, but don’t disappear when, as in the English case, intra-communities and intersystem analysis are being made. If I may, I’ll next show a Spanish example from the Variaciones de la Práctica Médica (VPM) initiative that has the support of all autonomous regions. I have in hand the final report of the VPM research project: Variations in the use of knee arthroplasty in the National Health System, from which I have chosen this graph:


I think in the above graph it should be noted that, excluding outliers health areas (in light blue), there are Spanish territories where inhabitants have a probability of knee prosthesis intervention 6.4 times higher than inhabitants from the areas with the lowest rates. And this occurs in a health system that is considered one of the most fair and accessible in the world.

Where is the problem? What explains these extraordinary variations?

To answer these questions, there’s nothing better that to resort to a 1977 investigation led by a young Wennberg. The following table, published in Tracking Medicine by the same author (Oxford University Press 2010), there is a summary of the results of this work. It’s the comparison of two small communities: Middlebury in Vermont vs. Randolph in New Hampshire. As seen in the table, the two communities have the same socioeconomic characteristics, the same prevalence of chronic diseases, and the same doctor accessibility. However, the Middlebury citizens are hospitalized 67% more than those of Randolph, and undergo surgery 63% more.

This work is a benchmark for questions about the causes of variations in the use of health resources. According to Wennberg, if when demographic, socioeconomic and accessibility factors have been adjusted, such overwhelming differences still remain, one must draw the attention of the variations towards the medical practice and the availability of healthcare resources provided by doctors in each area.