For decades, Knee-replacement surgery has been allowing people with extreme pain and joint deterioration to return to an active life. Recently, the procedure itself has undergone an evolution, leading to even greater benefits. What’s making the difference? Three-dimensional (3D) technology that personalizes the surgery for each individual’s anatomy.
This is key because your gait (how you walk or run) is unique like a fingerprint. How your knee bends is different from how someone else’s knee bends. This means that the shape of your bones also will be different from another person’s.
With the use of 3D technology, surgeons now can “see” the precise uniqueness of your anatomy—and adjust the replacement accordingly—long before the first incision. What you need to know about this high-tech breakthrough…
How It Works
The first step of 3D knee replacement, as with the traditional approach, is to get high-resolution images of your knee, usually with a CT scan or an MRI. With the new technique, a computerized 3D replica of your joint then is created from the scan using specialized software. Your surgeon reviews this replica to evaluate your bone structure, surrounding tissues, joint alignment and the extent of joint damage, noting the subtleties of your anatomy.
Because the 3D images are so precise, your surgeon can generate a computerized model of exactly how the bones glide against one another as the joint connects with other bones, which helps in selecting the best size and shape of implant for you…and in determining the best placement and alignment of that implant. The 3D replica also shows whether modifications are needed, such as compensating for loose or injured ligaments with an implant that provides a tighter fit.
Many different versions of personalized knee replacement rely on the 3D model. For example, some surgeons who perform knee replacements have received specialized training in the use of robotic surgery. In other cases, the surgeon will use the computerized 3D model to formulate navigation guides for making incisions and choosing the optimal placement of the joint, sometimes using specially created 3D-printed instruments that will help align implant components during the surgery.
The 3D Advantages
Compared with traditional knee replacement, 3D-based knee replacement offers a variety of benefits for patients such as…
More precise positioning for a better fit. Research shows that a customized pre-op plan means fewer errors in positioning the implant and reduces your chance of needing a revision, which involves replacing some parts of the original implant. Without 3D imaging, even the best surgeons have to do a bit of educated guessing to try to place the replacement knee as perfectly as possible. If the placement is even a little bit off, you could have extra pain and stiffness, and your recovery could take longer.
Smaller incision, less pain. Because the surgeon uses 3D technology to model where the replacement joint will be positioned, clinical practice has shown that the incisions used for 3D-based knee replacement can be up to 20% smaller than with the traditional approach. There also is less stretching of ligaments and soft tissue, so there is less pain—and less need for narcotic medication, which can be addictive.
Safer procedure. With 3D-based knee replacement, there is less blood loss and a far lower likelihood of needing a blood transfusion, which carries potential side effects, ranging from fever and chills to suppression of your immune system.
With better pre-op planning, the surgery also takes about 15 minutes less to perform than traditional knee replacement. Less time spent in the operating room means less time under anesthesia, which, in turn, reduces its associated risks, such as heart attack, stroke and infection.
Less need for hospital re-admission. You’re less likely to be readmitted to the hospital after getting a 3D-based knee replacement because there are fewer postsurgery problems, such as blood clots, infection and loose components.
Better recovery. 3D technology leads to better biomechanics, too. By replicating your own anatomy as much as possible, the better-fitting implant you’ll receive feels more natural, allowing you to resume normal activities sooner—usually in about six weeks versus roughly three months for traditional knee replacement. This is because 3D-based knee replacement causes less inflammation. Bonus: There is less need for pain medication.
While participation in a rehab program is still essential, you should be able to bend your knee properly soon after surgery, and that will make it easier for you to build up strength and overcome the weaknesses caused by years of arthritis.
Longer-lasting implant. When the implant fits better, there’s less daily friction, so its life span may extend beyond the 20-year average for traditional implants (right now, 3D hasn’t been used long enough to know for sure). A better fit means less loading and stressing being placed on the joint, which lengthens the life span of the implant.
Availability of 3D
3D-based knee replacement is increasingly available at most major academic centers but is conducted by only a few surgeons because it requires specialized training. Before scheduling a 3D-based knee replacement, make sure your surgeon has proper training and experience. Best approach: Ask the surgeon whether he/she has completed an orthopedic total-joint-replacement fellowship, a one-year program that now routinely includes training in the use of 3D technology.
Nearly all insurance companies cover 3D-based knee replacement. Some may not cover the pre-op CT or MRI imaging (about $150), but that could be a small price to pay for the advantages of this type of knee replacement. All of the increased cost of 3D-based knee replacement is covered by insurance (including the costs of the robotic technology, computer navigation technology, 3D-printed cutting guides and 3D-printed implants).
Note: 3D technology also is available for hip replacements, using a 3D model of the femoral head (the ball at the top of the thighbone) and socket joint.
3D Boosts Implant Durability
With the use of 3D technology, manufacturing practices have become more advanced, improving the durability of knee implants. Most knee implants are made of metal (such as cobalt chromium or titanium) or ceramic, often in combination with polyethylene (a plastic). Ceramic is becoming the leader for longest-lasting material, with an average life span of 25 to 30 years.
One material-based innovation is oxidized zirconium (a proprietary material called Oxinium and developed by medical-device-maker Smith & Nephew), which starts as a metal but is processed in a way that turns it into a ceramic. Instead of polished cobalt chrome connecting with the polyethylene liner, the oxidized zirconium, which is a very smooth, wear-resistant surface, connects with the polyethylene, resulting in less wear and a longer life span.
Important: With so many implant options available, be sure to discuss your lifestyle and goals with your doctor so the best one for you can be chosen.
