Revision Joint Replacement

Revision Joint Replacement

Revision joint replacement is a procedure done to fix a problem with a previously implanted joint replacement. This can be done for any problem with an existing joint replacement, from the most simple up to the most complex. Revision surgery is always more complicated than first time surgery. There are a number of reasons for this, but one of the biggest is scar formation. Once an area has been operated on previously, there is a lot of scar tissue that forms. This makes future surgery in the area much more difficult. When we are taught the basics of surgery, surgeons learn how to find spaces between structures, called “planes” that are safe to operate through. These safe planes don’t contain nerves or blood vessels and we can work in these areas without damage to these important structures. The problem with scar tissue is that  it obliterates these planes, making them either stuck together to impossible to find, or behave differently so that they can’t be followed with standard techniques. Therefore, a revision surgeon needs to be a master of advanced techniques that help deal with scar and compromised anatomy. These techniques involve knowing how to find nerves and blood vessels outside of a scarred area, and how to dissect these out of scar if necessary. These techniques are very technically demanding and require constant practice and refinement, so revision surgery is best carried out by someone who does it all the time, rather than someone who does a few revisions here and there. Incidentally these techniques are the ones that are mastered by oncologic surgeons, who deal with these challenges frequently in the setting of cancer surgery. Additional difficulties with revision surgery are that blood loss is a major issue, infection rates are higher, patients are usually older because they have already worn out one joint replacement, and decision making is tougher, because there isn’t a “textbook answer” for every problem. Primary, or first time, joint replacement happens according to a very straightforward algorithm: If patient has a certain issue, then the surgeon does a certain fix in surgery. So as long as a surgeon knows the algorithm, they can reliably perform a good joint replacement. Revision surgery is different: rather than an algorithm, the surgeon needs an arsenal of tools and experience to know when and how to use them for whatever they find when they open up a failed joint, as the cause of failure is often unknown until the joint is actually opened. Combine this with the potentially extensive surgery times, increased risk of surgical damage, potentially sicker patients, more technically difficult procedures, and compromised anatomy from scar, and it becomes clear why revision joint surgery is a totally different “ballgame” than primary surgery.

All that being said, not every revision is extremely complex. For instance, one frequent cause for revision surgery is wearing out of the prior joint replacement. When a joint replacement wears out, it is the polyethylene (or plastic) part of the joint replacement that wears out. Joint replacements are designed with metal parts that fix to the bone, and plastic parts that attach to the metal that actually form the “cushion” part of the joint replacement. These are the parts that are designed to bear the weight and do wear out over time.The newer plastics have been improved over older versions such that when they wear out, they do little if any damage to the rest of the pieces of the joint replacement, or the bone. Since they are designed to be exchanged easily, the operation that is needed to fix a worn-out plastic is very straightforward: The surgeon opens up the joint, “pops out” the worn plastic piece usually with a special tool provided by the company that makes the joint replacement, and then inserts in a brand new one. The joint is then closed and the operation is completed. These operations can be done in as little as 20 minutes in some cases. A slightly more complicated revision would be one in which the metal portion of the implant has loosened and is no longer fixed firmly to the bone. This causes pain and instability. In some cases, this can be due to infection, which becomes more complicated, but in many cases, this is just due to mechanical loosening over time. In these cases, the joint may be opened up and the loose piece removed, and then a new replacement piece re-fixed to the bone. In many cases, only the loose piece will need to be exchanged and the remaining parts of the joint can be left alone.

Although some revisions like the ones described above can be straightforward, in many cases, revision operations can be quite complex and require specialty training and techniques. Examples of these are in cases where there is infection, extensive bone loss, or in complex anatomical areas. In the past, before some important discoveries were made, the older plastics used in joint replacements had a tendency to release tiny particles of plastic into the joint when they started to wear out. As this process continued, there could be millions and millions of tiny particles left to float around the joint. These particles are recognized a foreign material by the body, which sends out specialty cells to “scoop” them up..however in the process of doing this, a small bit of bone is scooped up as well. When millions of tiny particles are scooped up, each one taking with it a tiny piece of bone, eventually large holes or cavities will appear in the bone where bone is lost to this mechanism. This is called “osteolysis”, and although this is a simplification of what actually happens, it explains why older joint replacements can have large areas of bone loss when the patient comes in for a revision. These cases can be very complex and the remaining bone is thin and can fracture, and removal of the implants can be risky and technically challenging as the have to be removed extremely carefully to avoid destruction of the remaining intact bone. Furthermore, once the implants are removed, all the missing bone has to be rebuilt using special metal augments, which can be difficult to do. To make matters even more complicated, the normal bone contains the landmarks that surgeons use to make sure they are putting the joint replacement in the exact correct position in the body, as in some cases even one or two degrees of malalignment can cause failure of the joint. When large areas of bone are missing, it can be extremely challenging to position the new joint replacement in the exact right place in the body to make sure it functions properly, because the normal landmarks are missing as a result of osteolysis bone loss. This often comes down to experience and expertise of the surgeon performing the procedure, and makes these operations generally performed by expert revision surgeons. Dr. John Abraham not only has extensive experience with these difficult operations, but has also served as a teaching faculty for joint revision operations, teaching less experienced joint replacement specialists how to deal with these issues. 

Another complicated revision situation is in the setting of infections. Joint replacements are inorganic, or “dead”, foreign materials existing inside a living body. Human bodies have immune systems, but joint replacements do not. So the safest place inside a human body for a infection-causing bacteria to hide out is in an area that is not protected by an immune system: a joint replacement. For this reason, when a person with a joint replacement develops an infection in another part of the body, like a pneumonia, or a urinary tract infection or tooth infection, there is a risk that those bacteria will work their way to the joint replacement and settle in there. To make matters worse, the bacteria that do this have figured out how to build a wall or shield that is impenetrable, and protects them from the immune system attack while they are living on the metal surface of the joint replacement. Once that wall, called a “glycocalyx” or “biofilm” is made, there is no known way to remove it from metal. The only solution is to physically remove all the metal from the body. This means a joint replacement which is securely fixed to the bone and functioning well for years may suddenly need to be removed completely because of an infection. These operations are very risky and cause a lot of damage to remaining bone if not done properly. In addition, the surgeon needs to be aware of all the techniques of removing infection from the surrounding soft tissues as well, called “debridement”. In many cases, the patient may have to be treated for several months with antibiotics, without a joint replacement in place, using a temporary “spacer” which they cannot walk fully on or bend, until the infection is fully cleared. After that, another complex operation called a “reimplantation” is performed in which a new joint replacement is put in, again often utilizing augments and requiring difficult placement decisions without normal bony landmarks. Like other complex operations, treating infections of joint replacements is best left to experienced and highly skilled surgeons who have familiarity with these techniques and perform these operations frequently. Dr. Abraham has extensive expertise in managing infections of joint replacements, and has served as one of the primary surgeons handling joint infections in two of the largest joint replacement centers in the country.

Another category of complex revision operations is when complex anatomical areas are involved. The best example of this is the hip socket. The hip socket, or “acetabulum”, is part of a larger bone called the pelvis, which is often referred to as the “foundation” of the skeleton. Much like the foundation of a house, the pelvis is the “bedrock” where many important structures in the body are contained, or pass through. The entire bowel, the urinary system, sexual organs, as well as nerves and large blood vessels are contained in the pelvis, much like in a house where the electrical, plumbing, HVAC and mechanical systems are all located in the foundation. When the hip socket of a joint replacement fails, and especially in cases where there is severe bone loss, the operation to fix this problem can be extraordinarily complex. The surgeon has to deal with nerves, blood vessels, urinary and bowel organs, as well as mechanical issues in a weight bearing bone, as well as limited real estate to work with and high risk structures nearby. This is why very few surgeons routinely tackle acetabular revisions. In some of the cases of extreme bone loss, highly specialized techniques need to be used, like the creation of a custom-made implants specifically for that patient, because there is no readily available off-the-shelf implant that can make up for an extreme level of bone loss. This requires a specialty knowledge of implant design, engineering, Computer-Aided Design and pelvis anatomy well beyond what most joint replacement surgeons have. These cases are extremely challenging and are only handled by surgeons with the highest levels of experience and comfort in the “tiger country” of the pelvis. Dr. Abraham has particular expertise in pelvis surgery including acetabular revisions, and has published articles on pelvis surgery. He is one of the leading users of custom-made acetabular revision components in the country. 

Other examples of complex joint replacement and revision surgery are patients with abnormally shaped, or deformed, bones. These can be patients with a problem called “dysplasia” in which the bones never formed the proper way while the child was developing, or in patients that have other issues, like tumors that press on the bones over time and change their shape. Also, patients who have a condition known as “achondroplasia” or “dwarfism” have bodies of smaller stature, sometimes informally called “little people”, and have abnormally shaped bones that also have the additional challenge of being much smaller than usual. In many cases these patients also require custom made implants in order to successfully perform a joint replacement. Dr. Abraham also has significant expertise in managing patients with dwarfism and other forms of bone dysplasia.

For patients with a failed joint replacement for any reason, it makes sense to consult a surgeon with vast expertise in this type of surgery, who has detailed anatomic knowledge and is an expert in the entire gamut of surgical techniques and implants, and can put that knowledge to use for dealing with whatever situation may arise during these difficult undertakings. If you have a joint replacement that you have concerns about, or is painful and may be failing, Dr. Abraham and the joint revision team at Abraham Orthopaedics is the team to see. Dr. Abraham has consistently been ranked as one of the top doctors in Philadelphia for over a decade, and his reputation for excellence has now earned him a spot on the list of Top Doctors in New York City as well. If your joint replacement is failing, insist on the best, at Abraham Orthopaedics.