Surgical Navigation

Computer-assisted surgical navigation of the partial and total knee replacement is a relatively new field. The technique can be combined with minimally-invasive surgical techniques both optimize accuracy of knee replacement while making recovery somewhat faster and easier. Computer-assisted knee replacement is identical to traditional total knee replacement in many ways and fundamentally different in a few others. Traditional knee replacement surgery and computer-assisted, surgically navigated knee replacement surgery both involve making an incision over the front of the knee and implanting knee replacement components.

Traditional knee replacement surgery and surgically navigated knee replacement surgery differ really in the method of determining the size and location of the implants and associated alignment and ligament balance of the knee.

Computer-assisted surgical navigation involves fixing reference frames to the femur and tibia. Reference frames are shaped a bit like small starfish and are temporarily fixed to the bone with small pins. An infrared stereoscopic camera can follow the movements of the reference frames so that the surgeon knows exactly where the femur and tibia are during surgery. The positions of all of the important surgical instruments can also be tracked by the camera. Knowing where the position of the surgical instruments compared to the bones during surgery allows the system to make accurate calculations about all of the important aspects of knee replacement surgery including size, position, alignment, motion, and ligament balance.

Computer-assisted surgical navigation allows for total knee replacement to be performed without drilling a hole in the end of the femur and pushing a metal rod into the femur to gauge alignment the way that traditional total knee replacement surgery does. It is very likely that studies will show that elimination of this rod in the femur will drastically reduce the incidence of micro-embolism of bone marrow, air, and fat during total knee replacement surgery. Micro-embolism is often a subtle problem that can cause temporary confusion and mild breathing trouble after surgery. Occasionally the problem can be more serious, especially if two knees are replaced at the same time. There are few, if any, additional risks with these techniques. However unlikely, it is theoretically possible that if a patient fell early after surgery, that person’s tibia or femur could crack through one of the small pin holes in the bone used to fix the reference frames. This was reported in one case performed in Europe in the past. What we do know is that the system can objectively track range of motion, ligament balance, and limb alignment more accurately than any surgeon can gauge on his own.

Dr. Murphy has performed more than 400 partial and total knee arthroplasties and this represents one of the longest and largest series of computer-assisted total knee arthroplasty in the United States. He also performed the first computer-assisted total knee arthroplasty in New England (May of 2002) and is the immediate past president and executive board member of the International Society for Computer Assisted Orthopedic Surgery. It is clear that these methods are efficient, accurate, and as safe or safer than traditional methods. More information about computer-assisted surgical navigation for total knee replacement surgery can be viewed on the links below.

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Percutaneous 2-Pin Fixation Frames for Computer-Assisted Total Knee Arthroplasty: Safety and Stability, International Conference on Computer-Assisted Orthopedic Surgery, Chicago, 2004

Limb Alignment following Computer-Assisted Total Knee Arthroplasty, International Conference on Computer-Assisted Orthopedic Surgery, Marbella, Spain, 2003.