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The Knee


A knee replacement is really a cartilage replacement. The knee itself is not replaced, only the cartilage on the ends of the bones. The replacement implants include a metal alloy on the bottom of the thighbone and polyethylene (plastic) on the top of the tibia and underneath the kneecap. The implant is designed to create a new, smoothly functioning joint that prevents painful bone-on-bone contact. Your surgeon may elect to replace all or part of your knee, depending on your condition and the extent to which your knee is affected by arthritis.

 

Total Knee Replacement Interesting Facts

 

Clinical History: Excellent Long-Term Results at 10+ Years

The appendix shows the long-term survivorship of Biomet’s AGC® knee system. Biomet also offers newer designs that have not been available for as long and thus do not have the same long-term data. All Biomet knee replacements are based on the basic design rationale of the AGC®, utilizing the same materials and concepts.

Materials: Molded Polyethylene Demonstrates Longevity

The articular surface of the knee, where the joint motion occurs, relies on polyethylene to reduce friction and allow motion. Polyethylene components for the knee are manufactured in one of two ways: direct compression molding (DCM) or machined from bar stock. The vast majority of Biomet’s polyethylene components for the knee are direct compression molded.

Unlike machining, direct compression molding does not tear at the polyethylene. The machining process can result in areas of high stress, which may over time lead to breakdown of the polyethylene. Direct compression molding greatly reduces these high stress areas, thus creating a potentially more durable component.1

What About Oxinium®?

Oxinium® is a new process, used by another company, that turns the outside of the knee’s femoral component into a ceramic compound. While laboratory results on wear resistance are promising, there are no long-term clinical data on Oxinium®, so no one really knows how well it will work over time.

In order to reduce wear in its knee products, Biomet believes an appropriate engineering step is to improve the durability of the polyethylene component. That’s why Biomet uses direct- compression molded polyethylene, which has been shown to be more durable than machined polyethylene used by most other implant manufacturers.2

1 Biomet, Inc. test data.
2 Bankston, B., Keating, M., Ranawat, C., Faris, P., Ritter, M., "Comparison of Polyethylene Wear in Machined Versus Molded Polyethylene," Clinical Orthopaedics and Related Research, 317: 37-43.


Partial Knee Replacement


In patients with only limited knee arthritis, surgeons may elect to perform a unicompartmental (partial) knee replacement. Unlike total knee replacement involving removal of all the knee joint surfaces, a unicompartmental knee replacement replaces only one side of the knee joint. Knee osteoarthritis usually occurs first in the medial (inside) compartment as this side of the knee bears most of the weight. In knees that are otherwise healthy, a unicompartmental approach allows the outer compartment and all ligaments to remain intact. By retaining all of the undamaged parts, the joint may bend better and function more naturally.

The Repicci II® - The First Minimally Invasive Knee Replacement Procedure Developed in conjunction with John Repicci, MD, the Repicci II® is a partial knee replacement designed to remove as little bone from the knee as possible. The entire surgery is performed through a very small incision, with minimal trauma to surrounding soft tissue. As a result, Dr. Repicci has reported that many patients leave the hospital on the day of, or the day after surgery, and are back to work within two weeks.1 The Repicci approach has demonstrated excellent results, with a 96% success rate after 5-8 years.2

The Oxford® Unicompartmental Knee System - Leading surgeons in Oxford, England along with engineers at Biomet, developed the Oxford® Unicompartmental Knee System. It's the only FDA-approved, free-floating meniscal partial knee system available in the United States and has been utilized throughout Europe for more than two decades.

In a healthy knee, the meniscus serves as a shock absorber between the ends of the bones. The Oxford is the first partial implant with an artificial meniscal bearing designed to glide freely throughout the knee's range of motion, more closely replicating normal movement. The free-floating nature of the device also improves durability of the implant.

Published long-term clinical results on the Oxford® Knee demonstrated a 98% success rate at 10 years, equaling the results of the most successful total knee replacements.3 Studies also show most patients experience a rapid recovery and more natural joint function.

1 Personal correspondence, John Repicci, MD.
2 Romanowski, M.R., Repicci, J.A., "Minimally Invasive Unicondylar Arthroplasty: Eight Year Follow-Up," Journal of Knee Surgery, Vol. 15, No. 1, 2002, pp. 17-22.
3 Murray, D.W.; O'Connor, J.J.; and Goodfellow, J.W.: "The Oxford Medial Unicompartmental Arthroplasty. A Ten Year Survival Study." JBJS (Br), No. 6, 80-B: 983-989, 1988.


Patellofemoral Knee Replacement with the Vanguard™ PFR

Designed by Walter F. Abendschein, M.D., the Vanguard™ PFR represents a unique and effective treatment for patients with severe pain in the front or middle of the knee from cartilage degeneration of the patellofemoral compartment (beneath the kneecap).

The advantage over a total knee replacement is that the healthy cartilage is not removed, making future total knee replacement easier to perform, if necessary. Another advantage is that the Vanguard™ PFR may be implanted utilizing a minimally invasive technique. Minimally invasive knee replacement patients typically recover more quickly than traditional joint replacement patients.


Not all patients are candidates for partial knee replacement. You should discuss your condition and treatment options with your surgeon. Biomet offers the broadest range of partial knee replacements available, providing your surgeon with unparalleled flexibility to address your condition. All provide the option of minimally invasive surgery.

Complications

While uncommon, complications can occur during and after surgery. Some complications include infection, blood clots, implant breakage, mal-alignment, and premature wear. Although implant surgery is extremely successful in most cases, some patients still experience pain and stiffness. No implant will last forever and factors such as the patient's post-surgical activities and weight can affect longevity of the implant. Be sure to discuss these and other risks with your surgeon.

There are many things that your surgeon may do to minimize the potential for complications. Your surgeon may have you see a medical physician before surgery to obtain tests. You may also need to have your dental work up to date and may be shown how to prepare your home to avoid falls.

After Surgery

After surgery you will receive pain medication and start with physiotherapy. It is important to start moving your new knee as soon as possible after surgery to promote blood flow to regain knee motion and to facilitate the recovery process.

You will most likely be out of bed and walking with crutches or a walker within 24 hours of your surgery.

You will be shown how to safely climb and descend stairs, how to get into and out of a seated position and how to care for your knee once you return home. It is a good idea to enlist the help of friends or family to help you once you do return home.

Before you leave the hospital your physiotherapist will show you a variety of exercises designed to help you regain mobility and strength in your knee. You should be able to perform these exercises at home.

Most people are ready to go home between 3-5 days after surgery, however some people may go to a separate rehabilitation facility, an option your surgeon should discuss with you before surgery. Many will directly go home and begin supervised therapy either at home or as an outpatient. When at home, it is important to continue with your exercises as your doctor has instructed.

What type of rehabilitation can I expect following surgery?

Exercise is necessary for proper healing. Your surgeon may recommend physiotherapy to assist with gentle leg movement, strengthening and mobility exercises between 24-48 hours after surgery. Physiotherapy will begin in the hospital and usually continues after discharge for (approximately) six weeks.

What activity range can be expected after this surgical procedure?

Diligent physiotherapy, proper diet and a willingness to follow all of your surgeon's recommendations will contribute to a more successful recovery after surgery. Most patients are able to walk without support and drive a car 3-6 weeks after surgery. Activities such as golf, doubles tennis, and swimming can usually be resumed but only after a thorough evaluation by your physician. Always follow your doctor's recommendations as recovery time will vary for each patient.

You will typically not be allowed to participate in high-impact activities or contact sports. These types of activities place extreme amounts of pressure on the joints, which could lead to complications. Ask your surgeon which activities you should avoid after surgery.

Will I need to see my surgeon after surgery?

Your surgeon will set a follow-up schedule for the first year after surgery to evaluate your progress. You will be seen every year or two thereafter. Complications can occur with implants, so seeing your surgeon when you notice a change in symptoms can assist in evaluating any changes that may occur with your new joint.

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