3-D Computer-Aided Design:
Building Better Knee Replacements
An Interview with David Yasgur, MD, FAAOS
Until recently, a surgeon’s only option for customizing knee replacements was to make adjustments during the actual surgery. Once the patient was under anesthesia and incisions were made, the surgeon would fine-tune the fit of the replacement joint. If you think that sounds like a less-than-ideal way to proceed, you won’t get any argument from Dr. David Yasgur, Director of Quality and Outcomes at the Orthopedic & Spine Institute at Northern Westchester Hospital. “During surgery we needed to have a large variety of instruments out and available for making adjustments to the size and alignment of the implants—all while the patient was undergoing the procedure. This wasted time and placed additional stress on the patients.”
Now, new 3D-modeling technology enables surgeons to simulate the placement of the knee implants and design and order custom-made surgical instruments to assist in the accurate positioning of knee replacements weeks before the surgery takes place. “Essentially, all the decision-making and fitting that would happen during surgery can be done on a computer four to six weeks ahead of time,” says Dr. Yasgur.
Surgeons are able to upload magnetic-resonance images (MRIs) of the knee to a computer program that creates a three-dimensional image and allows viewing of the damaged knee from all angles. “It’s really exciting to use this software because I am able turn the image on the computer screen to see it from all angles,” Dr. Yasgur says. Once adjustments are made to the design, the manufacturer uses the surgeon-approved pre-operative plan to design and produce pin placement guides to the patient’s exact specifications. “You have tremendous control in fitting the implant to meet each patient’s unique needs—how much cartilage is left in the joint, for example, or how a previous trauma like a fracture will alter wear and tear.”
Using the custom-made positioning instruments, which serve as an intraoperative guide, knee replacements have the potential to last much longer, says Dr. Yasgur—a big advantage, though not the only one. Because the fitting is done in advance, he says, the patient spends 15 to 20 minutes less time in surgery. “That reduces the risk of infections, bleeding, and other complications.” And with a quicker, less traumatic surgery, the patient’s recovery time can be shorter as well.
“I was somewhat hesitant to use this technology at first, but once I realized the benefits, I was convinced,” Dr. Yasgur says. Interestingly, he has a history with computer-aided design. “Before medical school, I designed and developed prostheses for total joint replacement surgery at the Hospital for Special Surgery. Now I’ve come full circle and I’m using computers again to design custom-made knee replacements for my patients.” And given the results Dr. Yasgur has seen, he’s pleased to have made the journey.