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What can you tell me about the use of the new computer-assisted knee replacement surgery? I'm going to need a knee replacement in the next little bit. Is it worth it to seek out a surgeon who is using this modern invention or is it still a bit early in the game?

One of the newest ways to improve total knee replacement surgery is with computer-assisted navigation. Computer-assisted navigation uses an infrared tracker to help find the center of rotation for the femoral head. The infrared light helps the surgeon make bone cuts at exactly the right angle and thickness for the selected implant. X-rays taken after the procedure are done to verify the accuracy of implant placement. Patients have wondered if they aren't putting themselves at increased risk for complications with this new approach. But surgeons have persisted in trying to perfect this technique because the computer makes more accurate bone cuts and positions the implant more precisely. The results of at least one study have confirmed that although the computer-assisted procedure takes about 30 minutes longer than the conventional approach, there was no increase in complications reported. The authors performed total knee replacements on 32 adult patients who were having both knees replaced at the same time. Everyone received the same type of prosthesis and the same one in both knees. In order to compare conventional surgery with computer-assisted-navigation, the surgeons performed the standard surgical procedure on one knee. The second knee was replaced using computer navigation. Results showed a clear difference between the two methods with far superior results when using the computer-assisted navigation technique. In fact, when the surgeon used the computer program to help line the knee and implant up perfectly, there were no problems with axes angles (compared with a rate of 28 per cent in the conventional group who had more than a three-degree deviation from the norm). Only when a surgeon performed the procedure using the standard surgical techniques (without computer assistance) were there problems noted. Even though alignment is crucial to the survival of the prosthesis, there are other factors that affect how long a knee implant will last. Some are patient-related (e.g., age, activity level, bone density, body mass index or BMI). Some are surgeon-dependent (e.g., operative technique such as balancing the pull of opposing soft tissues during the procedure). But matching the normal anatomic joint axes (where the bones and joint surfaces line up horizontally and vertically) is probably the one the surgeon has the most control over. Studies show that any deviation from the norm more than three degrees throws the joint off enough that uneven wear and force-to-load ratios increase. The result of these changes is loosening of the knee prostheses (implant). We don't know the long-term results of knee replacements aided by computers. But for now we can say the computer-navigated technique provides a more accurate alignment for total knee replacements without increased problems or complications. And for some patients, that might be enough incentive to chase down a surgeon who is already using this approach!


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