New Implant Technology, A New Twist On Knee Replacement

by Jennifer Sexton-Riley

Favorite pastimes come and go. From long hikes to softball or cycling, it’s common to switch from one interest to another over the years. To be forced to leave favorite activities behind entirely due to knee pain, however, can be a heartbreaker. Unfortunately, this scenario plays out all too often as knee pain due to various forms of arthritis, degenerative joint disease or injury strands formerly active individuals on the sidelines. Stephanie McHale Donvan was one of the sidelined until she found out about a Massachusetts-based company with the power to give back her favorite activities.

“Hi, my name is Stephanie. I’m 60 years old, I’m from Arlington Massachusetts, and I had my right knee replaced with a Conformis custom‑made knee in 2016. Now I’m back to riding my bike, hiking in the woods, and taking my dog for very, very long walks”

“I was about 51 when the pain started,” she recalled. “The first twinge happened on Harding’s Beach one summer, playing in the waves with my daughter. The pain in my knee became like a giant, gnawing toothache. I felt like I was dragging around a tree trunk of a leg. I couldn’t go sledding with my daughter, I couldn’t even walk up stairs without pulling myself up by the railing. I went through five years of constant pain, cortisone shots, expensive knee braces, daily ibuprofen and Tylenol, swelling, elevating my leg and telling my daughter constantly, ‘No. Mommy can’t do that.’ I was probably a real drag to be around.”

That all changed one day as Donvan sat in a doctor’s waiting room and met three women, all walking and in very little pain while recovering from total knee replacements.

“I was stunned! I had been dreading knee replacement for years, after reading that up to 25 percent of patients are unsatisfied post-op. Meeting these women gave me hope. I asked for their doctor’s name and soon I learned all about ConforMIS.”

About 700,000 knee replacement surgeries are performed annually in the United States, and that number is only expected to grow. ConforMIS, based in nearby Billerica, is breaking new ground in the field of knee replacements by offering something never seen before: customized knee implants designed and manufactured for each individual patient, with no two quite alike. With each implant created specifically to fit each patient’s unique anatomy, a knee replacement has never before been so perfectly shaped, placed and aligned.

Knee replacement has come a long was since German surgeon Themistocles Gluck imagined crafting hinge joints of ivory back in the mid 1800s. The unique ConforMIS process starts with a CT scan of the patient’s leg, all the way from the hip to the ankle. Imaging software then converts the two-dimensional information from the scan into a three-dimensional model of the patient’s unique bone structure. A model can then be created that perfectly replicates the curves and shapes of the patient’s bones, corrected for any malformation. Unique femoral and tibial implants are then created to fit only that patient. Even more fascinating, ConforMIS uses 3D printing to create pre-sterilized instruments to be used on only one patient, eliminating the need for re-sterilizing multi-use instruments.

Why are customized knee replacements such an important breakthrough? The answer is simple. Just as all human beings are unique, all knee structures are also unique, with subtle variations in

size and shape. Standard knee replacement implants are available in a range of standard sizes, from which a surgeon must choose the best fit. A nearly-right knee joint, however, is not quite as minor an annoyance as a nearly-right pair of shoes or almost-the-right-size hat. With the off-the-shelf knee implant, there may be a slight overhang if the implant is just slightly too large for the bone, or an underhang if the implant is just slightly too small.  This imperfect sizing may in turn cause imperfect alignment, leading to residual long-term pain post-surgery as well as an unnatural feeling within the joint. A customized knee replacement implant, created to replicate the size, shape and contour of the natural bone, provides the potential for a more natural feeling, and a pain-free life post-surgery.

How does Donvan feel about her ConforMIS implant today?

“I feel like the luckiest person on the planet, and I am happy to talk to anyone who will listen,” she said. “Dr. Wolfgang Fitz at Brigham and Women’s Faulkner Hospital in Boston performed my surgery, and I was walking in my back yard and throwing tennis balls for my yellow lab, Bella, on day five post-op. I was so happy I sent Dr. Fitz a Valentine’s Day card on the first Valentine’s Day after my surgery! My ConforMIS knee has changed my life. By three or four months post-op, I could hike four to five miles with Bella. Now we go every day, up and down hills and mountain trails. I can do anything. I have complete range of motion. I even started paddle boarding, and I can sit cross-legged on the paddle board, which is something most off-the-shelf knee replacement patients can never do. I can kneel, ride my bike, go up and down stairs a million times, and I have no pain, zero. Sometimes I almost forget which knee was done!”

A little knee discomfort can be, well, a big pain. If you find your everyday activities becoming difficult or impossible due to knee pain, if you have trouble falling asleep or even find your sleep interrupted by discomfort in one or both knees, it may be time to consider an examination. Changes in the appearance of the knee, including swelling or change in shape, may be another warning sign. A catching feeling in the motion of the knee while bending or straightening the leg may be worth an appointment. Don’t secondguess or try to tough it out. Visit your doctor and ask about seeing a specialist to address the cause of any discomfort or changes.


Sexton-Riley, J. (2018, March 8). Cape Cod Chronicle. Take A Knee: New Implant Technology A New Twist On Knee Replacement, 6-6.

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