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Whats New in Knee Replacement?

Whats New in Knee Replacement?

Whats New in Knee Replacement?

By Stephen P. Makk, MD, MBA

Background

Last year, 270,000 Americans underwent knee replacement surgery. It is projected, with the graying of the population and the coming of age of the baby boomer generation, that 3.5 million will be performed by 2030. The primary indication for the surgery is arthritis pain that is unrelieved satisfactorily by non-operative measures including medicines, shots, weight loss, bracing and exercise. Arthritis is the wearing away of the cartilage in the knee and can be osteoarthritis, or wear and tear arthritis, or inflammatory arthritis, the hallmark of which is rheumatoid arthritis. Knee replacement involves removing the damaged cartilage surfaces and replacing it with metal and plastic parts which function as a new joint cushion, thus relieving pain. This operation enjoys patient satisfaction levels in the high 90 percent range and can be truly life altering for people. There have been many new developments in knee replacement surgery over the last few years and the salient points will be discussed.

Minimally Invasive Knee Replacement

Traditionally knee replacements have been done through 10 to 12 inch incisions over the knee with the same amount of dissection and splitting of the thigh muscles under the skin. This approach has worked well over time but the general rehabilitation time for this operation was 4 to 6 months or perhaps longer in some instances in part because of recovering from the trauma of the surgical exposure.

Technology and surgeon skills have produced the modern technique known as minimally invasive knee replacement. We use these techniques for hip replacements as well. Less invasive is perhaps a better term. This involves making skin incisions of about 3.5 to 6 inches, depending on patient size and anatomy, and then dividing only a portion of the underlying thigh musculature. This is a more technically demanding operation for the surgeon but the average recovery is cut in half to about 6 to 12 weeks.
Studies have shown less use of pain medication, less blood loss and quicker recoveries in about 2/3 of patients. I have found this to be true using this technique in my practice.

Studies also show that a year after a knee replacement, there is not much function difference in groups of patients that have minimally invasive joint replacements and those that have traditional, big incision surgery. This infers that the benefits derived are early on in the faster recovery that many patients enjoy.

Computer Navigated Knee Replacement

A common question that patients ask me before I replace their knees is: How long will it last? The textbook answer is about 10 years on the average. This means that half will last longer and half will last less. One factor, and perhaps the most important factor in longevity, is NOT the type of implant used; rather, it is how well aligned the implant is. Think of it like your car the better the alignment is, the better the tires wear. The same is true with knees. Experienced surgeons have a good tract record with aligning their implants, but the instrumentation used has limits because of many patient factors including size, weight and anatomy.

Computer navigated, or computer assisted, knee and hip replacement, involves utilizing a very powerful computer system during the surgery to help improve the accuracy. The technology works much like a GPS or air traffic control. During the operation, we place temporary pins that stick out of the bones with little antenna devices on them in the femur (thigh) and tibia (shin) and use a wand-like device with these antenna devices to map the patients actual bone shape and the alignment of the hip, knee and ankle.
The computer actually forms a three-dimensional model of the patients knee that is used with antenna devices in the cutting jigs to make very accurate cuts and very accurate placement of the components. The judgment of the surgeon is still paramount and the computer does not take the place of the surgeon. The learning curve of this technology is high, however, and the surgeon should have ample training prior to using computer navigation. I have found this technique to be very helpful in selected cases.

Direct to Consumer (DTC) Advertising

One of the most common issues that patients need to have clarified when they come to me for joint replacement surgery are those related to DTC advertising. The pharmaceutical companies perfected this marketing technique with commercials, infomercials, ads in print media and mailings complete with free trail offers to urge patients to directly ask for certain medical products from their doctors. Traditionally, these were at the recommendation of a trusted doctor. These techniques, however, have been show to increase the sales and the market share for drug companies.

The orthopedic companies have started this and the messages are often confusing for patients and this generates lots of questions. The bottom line is this: There are really marginal differences between the actual knee, and hip, implants on the market regardless of the shape, size, and function (they all bend and rotate to some degree) and the materials that they are made of. Longevity is thought to be largely related to alignment (see computer navigated above) and matching the proper implant to the proper type of patient and no one can do this better than an experienced joint replacement surgeon.

The next wave in all of this is going to be gender specific implants different shapes for men and women. The best advice is to find an experienced dedicated joint surgeon that YOU TRUST and let them advise you in the best implant option for you as an individual patient.

Dr. Makk, certified by the American Board of Orthopedic Surgery, joined LBJS in 2003 after practicing in the Louisville area since 1995. He received his medical degree and did his surgical internship and residency at the University of Louisville hospitals and completed his studies in 1995. He has published several medical articles, regularly gives lectures and has published a chapter in an orthopaedic textbook. In addition, he has a Masters in Business (MBA) from the Kellogg Graduate School of Management at Northwestern University. He serves as an adviser and developer for companies in the biotech and medical device industries. He is an active fellow and speaker for the American Academy of Orthopaedic Surgeons and serves on their Biomedical Engineering Committee. He is an Associate Clinical Instructor in the Department of Orthopaedic Surgery and Department of Family and Community Medicine at the University of Louisville. Dr. Makk has invented an arthroscope (fiber optic instrument for joint surgery). Dr. Makk has a special interest in minimally invasive joint replacement and computer navigated hip and knee replacement using new technology to help improve patient outcomes. Dr. Makk is an avid reader and enjoys tending his vineyard, wine making, gardening, cycling and spinning and other activities with his wife and three children. Dr. Makk can be reached at 502-897-6579.

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