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Computer-Assisted Total Knee Replacement?

What is Computer-Assisted Total Knee Replacement?

Computer-assisted total knee replacement is a procedure that utilizes sophisticated computer imaging to assure the highest level of precision during the knee replacement procedure. With the aid of a real time infrared based tracking system, we can achieve virtually perfect alignment and soft tissue balance, which are the two most critical components of a successful knee replacement.

Lance R. Macey, MD, FAAOS, from New Hampshire Orthopaedic Center offers this procedure here at St. Joseph Hospital

How does computer-assisted surgery work?

In some ways, computer-assisted surgery is similar to the commonly used GPS systems found in aircraft and automobiles. Both systems localize specific positions in space in relation to their surroundings. Where the GPS system uses satellites and the concept of triangulation to locate positions, the surgical navigation system uses an advanced stereotactic camera and an infrared light source to locate points in space. The sophisticated software system used during surgery measures the position of your bones and the surgeon's instruments in relation to each other simultaneously at all times throughout the procedure. To establish these critical relationships, specialized reflective markers are attached to the bones and the surgeon's instruments. The motion of the bones and instruments are then tracked by an infrared stereotactic camera, which is integrated into the system's computer. The navigation software then creates a 3-D animated model of the patient's actual knee joint. This model is displayed on the systems monitor for the surgeon to visualize during the procedure. With the data obtained, the navigation system computes precise distances and angles and alignment to assure the highest degree of accuracy in placing the prostheses. This level of precision is far greater than that achieved by conventional knee replacements (commonly used) where instruments that determine the new knee alignment are literally placed "by eye". This commonly used (by eye) approach can lead to malaligned surfaces in the knee, which results in early failure.

The importance of achieving precise alignment in total knee replacement is conceptually similar to the importance of alignment on the tires of a car. Tires that are not aligned perfectly will wear out on one side, resulting in the need to be replaced. When your knee replacement is not aligned precisely the forces across the components are uneven, which results in premature wear and failure of the surgery. The end result is the need for an early repeat or "revision" of your knee replacement. Avoiding a repeat knee replacement is an important goal and should be avoided if possible.

Who needs a computer-assisted knee replacement?

Any patient entertaining the idea of knee replacement surgery should seriously consider the benefits of computer-assisted surgery. Younger patients in particular can benefit from the precision alignment associated with computer-assisted knee replacement. With the perfect alignment and tissue balance achieved during this procedure, the young patient's knee replacement may very well last them a lifetime. The benefits of avoiding a revision (or repeat) knee replacement are many.

In addition, patients with retained hardware from treatment of previous fractures of the leg can benefit greatly from computer-assisted knee replacement. With the traditional (non-computer-assisted) knee replacement procedure, previously placed hardware frequently requires removal prior to performing the knee replacement. When using the computer-assisted technique, this additional surgery and hardware removal can be avoided.

In summary, computer-assisted knee replacement is the most technologically advanced precise method of performing your knee replacement today. Your body's everyday function is dependent upon a high degree of perfectly coordinated motions based on precision. Why would you want your knee replacements to be anything less?

For more information about this procedure or Dr. Macey, please visit