Computer-assisted navigation positioning systems help orthopaedic surgeons perfect minimally invasive joint replacement surgery

Chicago 23 June 2004Rush University Medical Center, USA, is among the first hospitals in the country to use a computer-assisted navigation system in orthopaedic joint replacement surgery. The image-guided navigation system is similar to the location and directional tracking systems used for cars and ships today. It is, in effect, a global positioning system (GPS) for the surgeon. Informative positioning calculations are displayed on a graphically intuitive screen, which dynamically changes with the individual patient's anatomy.


Orthopaedic implant developer, Zimmer Inc. and navigation technologies developer, Medtronic Surgical Navigation Technologies have teamed up to offer this solution in the United States at Rush. Orthopaedic surgeons at Rush have been leaders in the introduction of minimally-invasive surgical (MIS) joint replacement in the United States and plan to adopt surgical navigation into their MIS procedures in the near future.

This technology superimposes the position of the instruments as they are used in surgery onto images of the anatomy displayed on a monitor. Much as the driver of a car uses the GPS system to find the way on the road, the surgeon depends on these images to confirm the position of their instruments in relation to the patient's anatomy.

The image-guided surgery (IGS) camera works like the satellite that detects signals from cars, boats, and other vehicles equipped with special tracking devices. As the surgeon moves an instrument within the patient's joint, the IGS camera, like the GPS satellite, calculates its position, and then transfers that data to a computer in the operating room. The computer then shows the direction and location of the instrument.

Rush orthopaedic surgeon Dr. Mitchell Sheinkop has introduced a universal navigation system in conventional knee replacement surgeries, and will train other orthopaedic surgeons using this new computer-assisted navigation system. Dr. Sheinkop did the first minimally invasive surgical unicompartmental (partial) Zimmer knee replacement in the United States in 2001. Since then, Dr. Sheinkop and his colleagues at Rush has have pioneered the minimally invasive hip and total knee replacement surgeries, without navigation.

Minimally invasive surgery orthopaedic surgery involves the use of specially developed instrumentation and new surgical techniques. Because MIS surgery uses small punctures in the skin compared to long incisions that cut muscle tissue, blood loss during surgery is minimized, the hospital stay is shortened, pain is reduced and patients can return to a normal lifestyle much more quickly.

"For the surgeon, minimally invasive joint replacement surgery is difficult and time consuming to learn, even for surgeons who do 200 or more joint replacements a year", stated Dr. Sheinkop. "MI surgery has unique demands of component alignment, positioning and soft tissue balance. This navigation system can allow more orthopaedic surgeons to learn MI joint replacement surgical techniques and have excellent patient outcomes. Computer-assisted surgery provides a visual confirmation and verification for the surgeon and enables a more precise implantation. This will help make true minimally invasive surgical joint replacement available to patients throughout the country."

While other navigation systems exist for orthopaedic surgery, Dr. Sheinkop prefers the Zimmer-specific solution for minimally invasive surgery because it is customized to measure implant size, as well as detail the shape, fit, and fill of the patient's joint location. Implant-specific navigation solutions are tailored and customized to meet the needs of a particular prosthesis or system, in this case, Zimmer orthopaedic implants.

The implant-specific platform allows elimination of instrumentation. It reduces costs, inventory, and complications, according to Dr. Sheinkop. Soon, he will begin working with the navigated Zimmer-specific, MIS 2-incision hip solution. Dr. Sheinkop estimates that in five years, most orthopaedic procedures will be aided by navigation.

According to the American Academy of Orthopaedic Surgery, total knee arthroplasty (replacement) is a surgery performed for severe degeneration of the knee joint. More than 300.000 people a year undergo the procedure. Minimally invasive total knee arthroplasty is a method of performing knee replacement through an incision that is only three and a half to four inches long, with potentially less damage to the tissue around the knee.

Leslie Versweyveld

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