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What Is Computer-Assisted Joint Replacement Surgery?

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Updated April 20, 2009

What Is Computer-Assisted Joint Replacement Surgery?

A well positioned knee replacement should restore alignment of the extremity.

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Question: What Is Computer-Assisted Joint Replacement Surgery?
Joint replacement surgery is the last step in treatment for severe arthritis. Joint replacements are most commonly performed in the hip and knee. When a joint replacement surgery is performed, it is critical that the implanted prosthesis is properly positioned. Recent techniques seek to more reliably ensure proper positioning of the joint replacement implants.
Answer: Computer-assisted surgery, abbreviated CAS, uses special probes attached to the body to help your surgeon ensure proper positioning of the joint replacement implants. The probes are detected by an infrared camera that is connected to a computer terminal. The computer terminal constructs an electronic model of the knee or hip based on the information gathered by sensing the position of these probes. The computer can then help guide your surgeon's placement of the knee or hip replacement implants to ensure proper positioning of the joint replacement.

Positioning of Implants Is Critical

While you may not realize it, one of the most critical aspects of a joint replacement surgery is to ensure proper positioning of the implanted joint. An incorrectly aligned joint can lead to early wear and loosening of the joint replacement. Similar to the alignment of the wheels on your car, a poorly aligned joint replacement will cause problems with early wear of the replacement.

In an effort to prevent early wear and loosening of the joint replacement, surgeons are constantly searching for ways to ensure the implant is properly positioned. A computer-assisted surgery is one additional check to confirm proper placement of the joint replacement. Your surgeon can still check with standard referencing instruments that the positioning is correct, and the computer can provide confirmation of the placement.

Should I Have Computer-Assisted Surgery?

Computer-assisted surgery is just developing, and there is certainly not enough known about CAS to say that it will lead to better results than standard surgical procedures. CAS has been shown to make it less likely that limb alignment problems will occur after knee replacement surgery, but the computer models do not eliminate the chance of these errors being made. Furthermore, computer modeling does not take into account the soft tissues around the joint, which are as critical as the bone-alignment of the extremity. Therefore, current CAS only address a part of the problem of implant alignment.

CAS is an interesting development, but it is just that at this point. Efforts are being made to develop computer models that also take into account the soft tissues around the joint, so that a joint replacement implant can be as accurately placed as possible.

Sources:

Krackow KA, O'Connor MI. "The Role of CAS in TKA" AAOS Now. March 2009; Vol 3, No 3, p19-21.

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