Replacing knees with 3-D

Every year knee replacements can put half a million Americans out of commission for a month or more. Now, without cutting any muscles, a new option is cutting recovery time.

A total knee replacement can take place using Shapematch technology. MRI images are used to create a 3-D image of your knee. Then a custom fit knee is made and precisely placed.

One of the hundreds of thousands of Americans who suffered from knee pain is Joyce Horowitz. Horowitz’ knee began to bother her four years ago. Even simple things such as standing while making a cup of coffee became a struggle. “My daily routine became an effort…it was a 24-hour feeling of just being in pain,” says Horowitz.

When the constant ache wouldn't go away, she knew it was time to do something about it.

Dr. Robery Zann, orthopedic surgeon at Delray Medical Center recommended the Shapematch technology treatment for Horowitz.

After recovering from the replacement, Horowitz is thrilled with the results. Dr. Zann is also pleased with the procedure. "It’s a tremendous, tremendous feeling that I can go home every day and feel very comfortable that my knee was done perfectly," says Zann.

Dr. Zann says, "There's no guesswork anymore. We can place the knee exactly where it's supposed to be. When we're done, the x-rays show they are in perfect position.”

About 85 percent of knee implants last 20 years. But with better alignment, patients can expect longer-lasting results.

"A knee that's done well and lines up perfectly has every potential to last a patient's lifetime,” explains Dr. Zann.

Getting back to normal activity is also improved. With traditional surgery, it takes patients 4 to 6 weeks to walk unaided. Horowitz was on her feet the same day and walking without a cane in two weeks. Just four weeks later Horowitz says, "It's been remarkable. I never thought that it would have healed and I’d be able to resume the things I am doing in such a short period of time."

Right now, about a dozen surgeons across the US are using the Shapematch cutting guides for total knee replacements.

While about a half a million people a year get knee replacements now, that number is expected to jump to 3.5 million by 2030.


BACKGROUND: Knee replacement surgery, also known as knee arthroplasty, is a surgical procedure used to replace a damaged knee joint, usually due to arthritis, with an artificial knee. Artificial joints are designed to mimic the knee's natural rolling; gliding motion and a wide variety of options allows the surgeon to customize the joint according to one's body, age and activity level. The most common cause of knee joint replacement is to repair joint damage caused by osteoarthritis and rheumatoid arthritis. Candidates for knee replacement surgery are people who have trouble walking, climbing stairs, and getting in and out of chairs. They may also experience sever knee pain at rest. A knee deformity is also another good reason for knee surgery. This surgery is also typical for people who are 55 or older. (

SHAPEMATCH: Shapematch technology used by Stryker was created to help orthopedic surgeons fit and position knee implants based on the individual's anatomy. The procedure is achieved by first having an MRI, Magnetic Resonance Imaging, that scans and records detailed images of the knee. Second, the proprietary software utilizes the MRI images to create a three-dimensional knee model. Then the implant size and positioning is determined using the 3D model of the knee. With the pre-surgical model completed, the surgeon reviews the specifications based on Shapematch Technology. Following approval, customized guides are then used in the operating room. (

APPLICATION: Stryker knee replacements are designed to work with the body to promote easier motion. The knee replacements are designed with a single radius, which means that as the knee flexes, the radius is the same, similar to a circle, requiring less effort from the thigh muscle. Since the thigh muscle, or quadriceps, is attached to the knee it is unavoidably involved in the surgery. Therefore, the quadriceps muscle can become a source of pain or discomfort post surgery. The durability of the knee implants depends on many things including the patient's weight and activity level, as well as the implants bearing surface technology. The bearing surface is defined as the two parts of the knee that glide together throughout motion. However, Stryker developed the Triathlon Knee System with X3 Advanced Bearing technology and based on laboratory testing, the technology only offered by Stryker has had a lower wear rate which may result in a longer lasting implant. (

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