EFORT ExMEx Forum Athens, Greece, April 20-21, 2012
The term “primary osteoarthritis”, utilized for years to characterize hip arthrosis of unknown origin, has tended to disappear now that we know a lot more about the mechanisms of joint destruction in the hip. Understanding hip pathology led the way to developing new treatment methods that may in some cases prolong the lifespan of hips and, thus, avoid prosthetic surgery in young patients. Open surgical dislocation, osteotomies and hip arthroscopy are useful tools and offer treatment options for early hip arthrosis. Though they are not yet routine procedures for most orthopaedic surgeons, their usefulness has been discussed in the recent literature. Also, much progress has been made in the materials and methods used in prosthetic surgery and important lessons have been learned from past mistakes in the choice of materials. These achievements were mainly possible thanks to consistent patient follow-up provided by registries.
Professor George Macheras from the KAT Hospital in Athens, Greece addresses these topics as well as the reduction of post-operative implant problems, the expansion of the European Arthroplasty Registry and a number of other topical issues at the April 2012 ExMEx Forum Athens which he will chair.
EFORT, together with the European Hip Society (EHS), will soon offer an ExMEx Forum on the “science and art” of hip arthroscopy and arthroplasty. Why this topic right now?
Prof. Macheras: Conservative hip surgery, coupled with the development of new treatment tools such as hip arthroscopy, is a brand new field, and relatively few orthopaedic surgeons are dealing with arthroscopic methods on a routine basis. Yet, this is an especially useful option in dealing with pathologies of the hip in young and active patients. Instead of operating on joints destroyed by arthrosis, we can now intervene early on in the destruction process and correct the anatomic variations that cause it. In a case of femoro-acetabular impingement, for example, the surgeon can correct the bony irregularities leading to it, and in some cases even reattach the labrum, thus delaying failure of the hip.
Despite the huge success of total hip arthroplasty, some patients still suffer pain and discomfort after surgery that is difficult to diagnose and treat. What are the primary causes for such post-surgical problems?
Prof. Macheras: Among the persisting difficulties are post-surgical infections, especially the less obvious, low-grade infections. With a decent surgical technique and modern materials, a prosthesis should prove pain-free for at least 15 years, unless there are complications due to infection. But infection is still part of the game. It occurs in 0.5 to 1 % of the cases, even in the world’s best orthopaedic clinics.
A second problem is mechanical loosening, which usually means that the implants were not well incorporated in the bone. The more bone-friendly, increased porosity of the outer surface of modern materials represents the latest advance in the technology for tackling the problem. Titanium is one of the preferred materials, but there are even more modern ones such as porous tantalum, a titanium-like substance with 80% porosity on the outer surface. This is yet another step forward compared to the porosity of about 40% in the older materials. This porosity enables the bone to grow both onto and into the prosthetic material.
A third post-operative problem is the risk of damage from periprosthetic fractures. Dealing with such complications requires a lot of expertise. The Forum will offer an opportunity to discuss the latest innovative solutions to these problems.
Hip registry data is becoming the standard by which all hip implants are evaluated. What kind of information can ExMEx participants expect here?
Prof. Macheras: The latest information from the European registries will be presented. EFORT’s European Arthroplasty Registry (the “EAR”) tries to register all different approaches and types of implants used. The practice originated in Scandinavia, which to this day has the most successful, comprehensive and widely recognized registries of operated patients and follow-up data. We are trying to extend the project to all European countries. This will give us a better idea of the distribution of different implants and, ideally, of their outcomes. So if it seems that one type of implant has a higher failure rate than another, we look more closely at the two implant designs, modes of sterilization, material properties etc. to better assess what might be the underlying cause of the higher failure rate.
Could you summarize other highlights of the Forum?
Prof. Macheras: Most major problems and complications of hip surgery will be discussed. An important focus will be on femoral and acetabular revisions. Some of the prostheses implanted roughly 10 or 15 years ago were made of materials that led to osteolysis – painful bone lesions resulting from debris at the bearing surfaces. The implants must be removed and changed. But how to deal with the bone defects and what type of revision implants to use are burning questions for the surgeons.
A young surgeon has to know – and to learn the lessons from the past – about bearing surfaces and special approaches and techniques in femoral or acetabular revision. Special strategies are also needed to manage patient-induced complications, e.g. missing follow-up treatments or showing up ten or fifteen years after the bone stock has been destroyed. Serious difficulties arise when dealing with these bone defects. The ExMex Forum will discuss and identify possible solutions.
Another highlight will be classification issues and treatment options of patients with congenital hip disease.
Who should participate in this Forum?
Prof. Macheras: This Forum targets younger, trained orthopaedic surgeons as well as some of the more experienced hip surgeons. We expect that both groups will be able to update their knowledge and broaden their skills through the exchange with experienced lecturers and participants.
Do you have a personal vision about future developments in hip joint replacement?
Prof. Macheras: I think we have a clearer understanding today of what went wrong in the past and have more experience with bearing surfaces. We also know more about the behavior of materials used for the outer surface of prostheses that are in contact with bone, as well as about the biomechanics and elasticity of the devices. We now have modern materials with good bearing surfaces such as the ceramics-on-ceramics, highly cross-linked polyethylene, ceramics-on-metal, or titanium with grid-blasting for the femoral and acetabular component. Finally, porous tantalum implants and augments are a great improvement. This material offers huge advantages in primary and revision hip surgery.
