The Orthopedic Surgeon's New Assistant? A Computer!

Putting in a new knee joint can be tricky. It's something like trying to hang a picture in just the right spot. The implant can be placed too far up or too far over. Since there are at least two major pieces to the implant, multiply the possibilities of mistakes by two. This will give you some idea of how many wrong spots there are for the knee implant!

Every surgeon has one key goal in mind when putting in a knee joint replacement: accuracy. Each piece must be set in the correct spot. The right angle and just the right amount of rotation are also needed. Scientists say there are almost five million possible choices for placement for each part of the implant. When we add size of the implant into the equation, the number of choices increases even more.

Right now, doctors make all these decision just by looking at the patient's joint and the nearby anatomy. The chance for error is great with this method. That's why doctors at the State University of New York in Buffalo are suggesting computers to help. Computers are fast, remember everything, and make all the math calculations. Imaging equipment to show the position of the implant can be combined with computers for the best fit.

Computer assisted orthopedic surgery (CAOS) can reduce errors to a range of 0.1 to 1.0 mm. This is much, much better than the "eye-balling" method. However, CAOS is only as good as the software that guides it. Detailed graphics and accuracy are very important.

The authors of this report think both hardware and software will continue to improve. Greater accuracy and convenience will be possible. CAOS will be simpler, easier, and less costly. It remains to be seen if CAOS will be present in every doctor's office or only in large surgery centers.



References: Kenneth A. Krackow, MD, et al. Computer-Assisted Total Knee Arthroplasty: Navigation in TKA. In Orthopedics. October 2003. Vol. 26. No. 10. Pp. 1017-1023.