Issue link: https://viewer.e-digitaledition.com/i/86594
+++++++++++++++++++++++++++++ + + +++++++++++++++++++++++++++++ ORTHOPEDIC UPDATE +++ +++ Engineering More Efficient Knee Replacement Surgery David Yasgur, M.D., FAAOS AFTER EARNING BACHELOR'S AND MASTER'S DEGREES IN MECHANICAL ENGINEERING, DAVID YASGUR, M.D., FAAOS, WORKED AS AN ORTHOPEDIC ENGINEER FOR THE HOSPITAL FOR SPECIAL SURGERY. HE THEN COMPLETED HIS ORTHOPEDIC RESIDENCY AT THE HOSPITAL FOR JOINT DISEASES AND A FELLOWSHIP AT THE INSALL-SCOTT-KELLY INSTITUTE IN KNEE RECONSTRUCTION. HE IS NOW THE DIRECTOR OF QUALITY AND OUTCOMES AT THE ORTHOPEDIC AND SPINE INSTITUTE AT NORTHERN WESTCHESTER HOSPITAL AND ATTENDING ORTHOPEDIC SURGEON AT MOUNT KISCO MEDICAL GROUP. IN THE LAST SIX MONTHS, INNOVATIONS IN COMPUTER-NAVIGATED TOTAL KNEE ARTHROPLASTY HAVE BROUGHT DR. YASGUR'S CAREER FULL-CIRCLE, FROM ENGINEERING DESIGNER TO SURGICAL SPECIALIST OF CUSTOM-ENGINEERED DEVICES. S TANDARD COMPUTER-NAVIGATED SURGERY, accord- ing to Dr. Yasgur, can be a slow and tedious process. Essentially, the computer conducts a process similar to global positioning system mapping on the affected limb. Should the computer crash, the entire navigational process must be restarted from the beginning. Now, Dr. Yasgur says, removing the computer from the operating room altogether has made the procedure more swift and accurate. Modeling Perfect Alignment Before a patient undergoes computer-navigated knee arthro- plasty, he or she undergoes a magnetic resonance imaging (MRI) scan. The resulting images are sent to engineers at the manufacturer to create a 3-D model of the patient's hip, knee and ankle. The 3-D software realigns the limb perfectly, linking the hip and the lower end of the femur as one segment, and the tibial components of the leg as another segment. It eliminates any deformities that may exist in the patient's leg or knee and also assists in planning preliminary bone cuts, as well as initial prosthetic sizing and orientation. Dr. Yasgur then perfects the 3-D model four to six weeks before the total knee replacement surgery using computer software that allows visualization and rotation of about three axes, including a posterior view, which was not available in previous technologies. "The model gives me a great deal of confidence that the prosthesis will fit properly," says Dr. Yasgur. "This approach is groundbreaking, as I can view angles with the 3-D model that I could never see in the patient's body. When done without visualization technologies, we used to make certain assumptions 12 | Mid Hudson MD NEWS ■ MDNEWS.COM about proper fit without a way to see it. Now, I can use the design software to rotate the model in every direction on the computer screen, to ensure the prosthesis is going to fit correctly." A Faster Procedure After Dr. Yasgur receives the model, he makes adjustments to the size and orientation of the prosthesis, accepts the changes in the 3-D model and sends revisions back to the manufacturer for production. Customized instrumentation that is specific to each patient is then developed. These instruments, says Dr. Yasgur, "speed the plow" because they do not require any intraoperative adjustment. Compared to conventional knee arthroplasty, 15-20 minutes are shaved off of each computer-navigated procedure, resulting in less blood loss, time under anesthesia and postsurgical swelling. The customized instruments essentially act as a drill guide, notes Dr. Yasgur. The four drill pins are keyed into the standard instrumentation used in total knee replacement. The patient-specific instrumentation allowed by the computer guidance enables physicians to avoid drilling a large hole into the medullary space of the femur for proper alignment, as they would in standard knee replacement procedures. Avoiding these steps, Dr. Yasgur says, reduces the risks of pulmonary or fat emboli and leads to better alignment and fit. A better aligned and fitting prosthesis has the potential to improve long-term outcomes and durability. For more information about the Orthopedic and Spine Institute at Northern Westchester Hospital, visit www.nwhorthoandspine.org. ■