Knee Replacement FAQs
Who is a candidate for a knee replacement?
The primary criterion we use to evaluate total knee replacement patients is the diagnosis of arthritis, primarily diagnosed by history, physical exam, and Xray. The primary indication for a knee replacement with a diagnosis of arthritis is the severity and chronicity of the pain and disability. Additionally, various non-surgical methods such as medications, activity modifications, and injections need to have been tried and failed. Knee replacement should be done as a last resort, and only after careful consideration. Overall health factors need to be evaluated as well, and any medical conditions optimized, to insure a safe procedure.
Who is a candidate for a partial knee replacement?
There are 3 compartments to the knee – medial, lateral, and anterior. Each can have isolated degeneration in osteoarthritis. Most patients have involvement of all three compartments by the time they seek surgical treatment, and they need a total knee replacement. If the pathology is truly isolated to one compartment, then a partial replacement can be considered. The decision is based on a careful history, physical exam and Xrays. If a patient wants to consider a partial knee replacement, they should inquire as to the surgeon’s personal experience with it, as it can influence their opinions, and their surgical results.
What are the advantages of a partial knee replacement?
In a partial knee, you essentially keep 2/3 of your own knee, including the anterior cruciate ligament. There is a smaller incision, less bleeding, and overall less tissue trauma. In general, the recovery is therefore quicker, and the feel of the knee is more natural with a partial versus a total knee. This leads to improved functional activities. In general, the recovery is quicker, and the feel of the knee is more natural with a partial versus a total knee. Additionally, in a young, active patient, there is an assumption that the knee will eventually fail mechanically, like a car that has too many miles on it. If the partial fails, it is easier to revise than if a total knee fails.
What are the disadvantages of a partial knee replacement?
Statistically, at ten years, the partials have a somewhat higher revision rate than the totals. The partials often fail not from prosthetic wear, but from the rest of the knee wearing out. Hence the double edged sword: the knee is likely to function better because you retain 2/3 of the knee, but is more likely to eventually fail by ten years because you retain 2/3 of the knee. Also, the partial knee replacement implants are less time-tested, and surgeons are less experienced with the techniques. Therefore, some patients choose a total knee replacement even if they are a candidate for a partial.
Why do you use a robotic arm in the Operating Room for partial knee replacements?
There are many partial knee replacements on the market, and Dr. Hanson has used several of them over the years. He has found that use of the MAKOplasty robotic arm system gives him the best control over the precision of the operation with regards to ideal positioning of the implant and soft-tissue balancing of the knee. It is well known that these factors play an important role in the early function and the long-term survival of implants. It has only been used for a few years, and only time will tell if this implant is indeed the best.
The Oxford prosthesis is another implant Dr. Hanson has used extensively. They have the longest-term data on survival, since they have been around for many more years. He still utilizes this as well. A third implant system that is relatively new and with which Dr. Hanson has experience is Arthrosurface, perhaps the least invasive of the partial knee replacements, and smaller lesions can be treated with smaller implants. Again, it is new, and therefore does not have the long-term outcome data. It is great for outpatient use.
Why do patients recover faster with this approach?
All partial knee replacements use smaller incisions, lose less blood and retain a “more natural feel” with their knee, i.e. patients trust their new knee more in the rehabilitation process as well as later in the recovery and function. So, they recover faster, spending less time in the hospital, less time in rehab, and less time in pain.
Does everyone get a good result from a partial or total knee replacement?
NO. With total knee replacements, studies suggest that fully 18% of patients are not pleased with the outcome of their procedure. Approximately 8% of patients have some sort of complication, some of which can be potentially life or limb threatening such as blood clots, infections, and anesthesia complications. No one should go into a knee replacement thinking that it will be easy, or that there are any guarantees.
What is a “minimally invasive” knee replacement?
I don’t like the term “minimally invasive”. In my opinion, there is nothing minimally invasive about a procedure that has potential complications like those listed above, and these complications exist no matter how big the incision, or what implant is used. Having said that, be sure to have your surgery performed by a surgeon who has years of experience and who has sub-specialty training. You should also look for a surgeon who has a good track record with knee replacements using modern pain control methods, “less invasive” incisions and approaches, with partial knees when indicated, and who does them in an institution that has a low complication rate.
Knee replacement is a surgical procedure in which a diseased or damaged joint is replaced with an artificial joint called a prosthesis. Made of metal alloys and high-grade plastics (to better match the function of bone and cartilage, respectively), the prosthesis is designed to move just like a human joint.
The knee joint is the largest and most complex and therefore the most stressed joint in the body. It is this complexity and stress, which can cause arthritis. Although there are several conditions which may lead to the need for knee replacement, arthritis (whether it be osteoarthritis, rheumatoid arthritis or traumatic arthritis) is the most common reason. A number of other factors contribute to joint disease including genetics, developmental abnormalities, repetitive injuries and obesity.
Just like any joint replacement the success of the surgery depends on many factors including the advanced state of the arthritic joint at the time of surgery, the precision of the surgery, the overall health of the patient and the dedication to the physical therapy required after the surgery.
Knee replacement surgery can performed as a partial or total knee replacement. A vast majority of patients needing their knees replaced require a total knee replacement. However, for some patients a partial knee replacement offers new treatment options for those living with painful osteoarthritis of the knee, affecting only one or two components of the three compartments of the knee, and who prefer a less invasive surgery and more rapid recovery than total knee arthroplasty.
Only with a complete history and physical along with Xray analysis with an orthopaedic surgeon who understands all of the issues and who is trained in the latest joint replacement techniques can the decision be made.
Dr. Hanson has dedicated his practice to joint replacement surgery, and helps people make decisions every day about the treatment of their injured and arthritic knees. Sometimes a person really doesn’t need surgery, and it is as simple as changing a medication, doing some physical therapy, taking supplements, or doing injections of cortisone or viscosupplementation. Other times it is suggesting treatments that are considered “alternative medicine” like acupuncture, prolotherapy, PRP injections, or stem cell injections. Sometimes an arthroscopy is indicated, a less invasive procedure that is very routine. When these alternatives fail to relieve the pain and dysfunction a patient is experiencing, a joint replacement may be necessary, and he can help you with those issues and decisions.
For those who need a knee replacement, Dr. Hanson performs both total knee replacements and partial, or unicompartmental, knee replacements. For those who are candidates for partial knee replacements, he uses primarily the MAKO robotic arm system, though he occasionally uses other implants as well, such as the Oxford and the Arthrosurface. If you have questions, they may be answered in the FAQ section. For further technical information about the implants Dr. Hanson routinely utilizes for his knee replacements, please refer to the Useful Links section.