by Dr. John Burrow
Knee pain. It’s what drives thousands of people to seek a physician’s opinion every year. Many will be prescribed anti-inflammatory medications, physical therapy, or given a steroid injection to reduce inflammation. Some will have a clear diagnosis of arthritis, which can be seen on x-ray or MRI. Some patients have been managing their pain for years, but are thinking now is the time for the Total Knee Replacement they’ve been contemplating. Many of the people in that group will have hesitation because they have heard a horror story about someone they know and how the person “was never the same again”. Here at OSC, we have many years of experience in treating knee pain and doing knee replacements. This experience serves our patients well as we determine the course of treatment, with the goal of improving our patient’s lives.
OSC physicians care for patients with a wide variety of musculoskeletal and pain management issues, but by far, we see more patients with knee problems than any other problem. Barring an acute condition or injury, we always start with conservative treatment, such as medication and physical therapy. Many people manage their knee pain well with these options, but others do not. Most people who will require a knee replacement are dealing with osteoarthritis (OA). OA is a degenerative condition, and at this time, we have not figured out how to reverse it. Patients whose knee cartilage has worn away and who experience “bone on bone” arthritis, are often in a great deal of pain, and a joint replacement (partial or total, depending on the extent of the arthritis) may be their only option for feeling better.
According to the American Academy of Orthopaedic Surgeons, the number of Total Knee Replacements (TKR) per year has more than tripled in the past 20 years. A recent study cites many reasons for that, however, the most prevalent is the aging population in this country. TKR has become more desirable for people who need it because of technological advances made in the past several years, such as:
• Implant companies are continually improving their prosthetic knee implants. There are knee implants now that are patient specific, and most implants now require a less-invasive approach than in the past, meaning smaller incisions, less blood loss, and less cutting.
• Many orthopaedic surgeons are now doing total joint replacements as an outpatient procedure, meaning the patient goes home from the hospital the same day as their procedure. Patient selection for an outpatient joint replacement is very important, but the reality is that people would rather recover in their own homes. We are pleased we are able to allow appropriate patients this opportunity.
• We are also able to do partial knee replacements for people who have arthritis in only one or 2 compartments of their knee. This preserves the ligaments of the knee and reduces the amount of bone lost, which gives the surgeon more options in the event the patient needs surgery later in life on the same knee.
Today’s implants are designed to last many years – typically 15-20 years, or sometimes longer. If a patient has their first knee replacement at a relatively young age, there is a distinct possibility that the prosthetic will need to be replaced a second time. When this happens, the procedure is called a Total Knee Revision. Joint revision is a complex procedure, during which the old implant is replaced with a new one. A knee implant revision surgery requires extensive planning, specialized tools, and specific surgical skills. Revision is typically more complicated than a primary knee replacement, because tissue and bone often grow around the implant, making it a challenge to remove. Also, once the implant is removed during surgery, there is less bone remaining with which the surgeon can work. A bone graft might be required for the purpose of supporting and encouraging new bone growth around the prosthesis.
Approximately 50% of total knee revisions in the U.S. take place within two years of the initial replacement. There are a few major reasons for replacement so quickly:
• Surgeon error – The surgeon may have placed the prosthesis poorly, so alignment is not correct. This causes discomfort and pain which does not improve over time. This can cause ligament instability, joint stiffness, knee cap dislocation, and excessive scar tissue. All of these need to be addressed as soon as possible, giving the highest probability that the patient’s problem can be fixed.
• Device Failure – This could be due to a manufacturer’s defect or patient’s lifestyle. People who are overweight may have to replace their knee sooner. High impact activities can also cause an implant to fail early.
• Other reasons for immediate revision might be surgical site infection or nerve or blood vessel damage.
Every device has a lifespan, and toward the end of its lifespan, it stops working properly. There are many other reasons that require a patient to have a revision.
• Loosening, caused by osteolysis. Osteolysis is the auto-immune resorption of your bones, causing them to become thin and weak. There are other causes of osteolysis (cysts, arthritis, infection), but in this case, the friction of the natural joint rubbing against the implant creates small particles, which then accumulate around the joint. The bonds are destroyed by your body’s attempt to digest these particles. The body attempts to digest these particles, and in turn, will digest your own bone. This can weaken or even fracture the bone.
Often implants will prevent your body from making new bone, so this can be a major problem. By the time the pain sets in, the bones are already affected and the problem needs to be addressed.
• Patient-Related Factors – These can include age, weight, level of activity, and any health conditions that might affect the joint.
o Younger, more active patients have a higher rate of revision because of the wear and tear they impose on the implant.
o Carrying excess weight also contributes to loosening of the implant, so these patients have a higher rate of revision.
o Patients who have rheumatoid arthritis, previous bone fractures, or avascular necrosis (death of bone tissue due to lack of blood supply) also have more revisions.
• Infection – The purpose of a knee replacement is to provide the patient with a new knee. Unfortunately, the large foreign metal and plastic implant that has improved the patient’s life can serve as a breeding ground for bacteria. The tissue surrounding the implant has an altered blood supply since the operation, so it might not have the ability to fight the infection very well. Often the implant will remain intact when a patient has an infection, but they experience significant pain, swelling and drainage, so a revision is necessary to remove the infected device and tissue.
• Dislocation – Dislocation is the sudden “popping out” of the implant from its normal position. This is much more common after hip replacement surgery. It can happen with a knee replacement, but it is uncommon. The dislocation can be caused by some of the previously mentioned issues, such as loosening, scar tissue, and poor device positioning during the initial operation.
How do I know if I need a revision? You will experience specific signs and symptoms that will alert you that something is wrong and that it is time to visit with your orthopaedic physician:
o Decreased stability or reduced function in the knee
o Increased pain
o Outright device failure, such as dislocation or metal fatigue
o Bone fracture
If a patient has these issues, we will perform an assessment, including the following:
o Physical Examination – the goal is to look at the problem and assess it. We will also ask a series of questions, including patient’s activity level, swelling, pain, etc.
o X-Rays – These provide important insight into what is happening on the inside of the knee. Mechanical failure, loosening, and severe wear are all detectable on X-ray.
o Laboratory Tests – This will enable us to test for infection by checking the patient’s complete blood count, a protein test, and other tests.
o Additional tests – We may remove some joint fluid to be analyzed to determine the cause of infection
What are risks and complications? A Total Knee Revision is more complicated than initial surgery. It is typically more complex and invasive, so it is important that your physician reviews these complications with you to fully make you aware of any potential issues. Any type of surgery presents the potential for complications, such as infection, bleeding, and trauma to the nerves. To minimize the chances of infection, antibiotics are given to patients before and after their surgery. Also, many hospitals and surgery centers have pre-surgical measures they encourage patients to take, including very specific personal hygiene recommendations beginning a few days prior to surgery.
Other complications that may follow total knee revision surgery:
• Deep Vein Thrombosis/pulmonary embolism – blood clots in the lungs or legs can occur. Revision surgery requires extensive twisting of blood vessels and can create clotting. Your physician should prescribe an anti-coagulant to help counteract this.
• Loosening or dislocation of the implant. Dislocation is about two times more likely to occur after revision than after a primary replacement
• Additional or more rapid loss of bone tissue after the surgery
• Other medical conditions, unrelated to the reason for surgery, can be aggravated following this surgery. Your orthopaedic surgery will obtain surgical clearances from other specialists if necessary. We want to be sure that your body will be able to handle this invasive procedure.
Are there any alternatives to revision surgery? The manner in which revision surgeries are done has improved greatly over the past several years. More than 90% of patients who have a knee revision will have good results. There are surgical alternatives to having a revision, but those methods are rarely used because they are more complex and can lead to an even worse situation in the knee.
• Surgical alternatives: One alternative to a total knee revision is a fusion. This would alleviate the pain, but the fusion would cause the knee to be kept in a non-bending position. Obviously, this is not a desirable state in which to live, so this method is typically only used in a case of severe infection that has not been eradicated with treatment.
• Non-surgical alternatives: Often when a patient presents with problems that signify the possible need for a revision, we will spend time determining if any non-surgical options might work. A total knee revision is a major procedure that has a higher complication rate than the initial surgery, so if we can alleviate the issues with non-surgical techniques, we would like to be able to do so.
• Amputation: This is reserved for extreme cases and major infections that do not clear after multiple attempts.
What do I need to do prior to surgery? Please follow any pre-op recommendations from your surgeon and the facility where you are having the procedure. This may include a class at the surgery center on what to expect from your surgery, a series of blood work and a physical exam if necessary. It may also include antibiotics and pre-surgical hygiene suggestions. We also recommend that you prepare your home and family as best you can, just like you did prior to your initial knee replacement. Make sure you have support you need and any additional items that will make your recovery a bit more enjoyable.
What happens during surgery? Revision surgery typically takes about 2-3 hours to perform, while a primary knee replacement usually takes 1-2 hours. During a revision, your surgeon may follow the line of incision of your initial procedure, or another entrance location may be chosen. The revision incision may be longer to allow for removal of old components and placement of the new prosthesis.
Once the incision has been made, the surgeon will remove all old implants, hardware, cement, and abnormal scar and bone tissue. This is done very carefully because the goal is to preserve as much healthy bone as possible to help aid in recovery. Some patients will have the same amount of intact bone as their initial procedure. Others will have more significant bone loss, which may require the use of bone grafts, plates, cages, and screws to piece the knee together to be as strong as possible.
After removing all components (and cement, if used), the surgeon prepares the bone for new implant by cleaning it, removing any unnecessary spurs, particles, etc. The prosthesis is placed and fixed to the bone using cement, screws, additional bone, plates to improve bone strength. Tissue around the joint is repaired, the surgeon carefully tests the motion of the knee, then repairs surrounding tendons and muscles before closing the site. We give the patient three doses of antibiotics and anti-coagulation to keep infection and blood clots at bay. The surgical site is monitored, as is the overall general medical condition of the patient.
What should I expect after surgery (recovery, etc.)? As with anything, recovery time is very individualized. Recovery from a revision typically takes longer than an initial replacement, so we encourage patients to be mentally prepared for that. Rehabilitation is also more aggressive. Physical therapy will begin within 24 hours of the surgery, and may continue up to 3 months depending on how it progresses. The stakes are higher now to be very diligent about doing the proper exercises to maintain mobility and flexibility. Regaining motion is crucial. Crutches or a walker will be used in the beginning of the rehabilitation period and will progress to a cane or no assisted device. Some patients choose to convalesce at home, while others go to rehab facilities.
If you have had a total knee replacement and are experiencing some of the symptoms mentioned in this article, we encourage you to see an orthopaedic specialist. You may be able to address the problem with non-surgical care. If non-surgical options have not worked for you, your physician may recommend you have a revision due to pain, discomfort, stiffness or instability due to a prosthesis problem. Modern techniques and surgical equipment have helped increase success rates of total joint revision procedures.
John D. Burrow, DO is a Joint Revision and Reconstruction Fellow who practices at Orthopaedic & Spine Center in Newport News, VA. To make an appointment with Dr. Burrow or OSC, go call us for an appointment at 757-596-1900.
by Dr. John Burrow