Computer Assisted Surgery

Computer Assisted Surgery

A Giant Step Forward in Joint Replacement

Computer-assisted surgery is a giant step forward in joint replacement. Advanced computer-assisted surgical monitoring with the Stryker Navigation System helps your surgeon precisely align your hip or knee implant with computer imaging. The Stryker Navigation System gives your surgeon 3-D imaging of your leg during surgery, which may result in more exact placement of the implants.1

Your joints are involved in almost every activity you do. Simple movements such as walking, bending, and turning require the use of your hip and knee joints. Normally, all parts of these joints work together and the joints move easily and without pain. But when a joint becomes diseased or injured, the resulting pain can severely limit your ability to move and work.

Gaining as much knowledge as possible will help you choose the best course of treatment to help relieve your joint pain — and get you back into the swing of things.

You’ll learn more about how computer-assisted surgery works in this website. As you read, make a note of anything you don’t understand. Your doctor will be happy to answer your questions so that you’ll feel comfortable and confident with your chosen treatment plan.

Computer Assisted Surgery

Cutting Edge Technology for Joint Replacements

Computer-assisted total joint replacement is a surgical procedure that offers the ability to accurately align your new joint. Accurate alignment is important to the overall function of your new joint. This surgical navigation technology requires tracking devices that collect and send information to provide a comprehensive understanding of your joint mechanics before finalizing the joint procedure. Armed with this information, the surgeon can make intraoperative adjustments within a fraction of a degree, helping to ensure your new joint has the strength, stability, and range of motion needed for a successful replacement.

While the medical and computer science behind the Stryker Navigation System is extremely complex, the system is relatively easy for your surgeon to use. Minimally invasive wireless “trackers” send data about your joint movement to the system’s computer. It presents your surgeon with multiple views of your body and allows the review of your leg’s range of motion with the implant installed in its final position. Armed with this information, the surgeon can make adjustments within a fraction of a degree, helping to ensure the best outcome.

What Generally Happens During the Surgery

During computer-assisted total joint replacement surgery, the navigation system aids the surgeon in showing him or her where to remove the diseased bone tissue and cartilage from the joint. The healthy parts of the joint are left intact. Then, the surgeon replaces the diseased bone with new, artificial parts. The new joint is positioned and placed in alignment to your true anatomy with information received from the infrared instruments and camera.

Orthopaedic navigation technology is similar to directional tracking systems used in cars and ships — it is, in effect, a global positioning system (GPS) for the surgeon. Infrared sensors placed in the operating room act like satellites constantly monitoring the location of markers and instruments placed along a patient’s anatomy. Precise alignment is an important factor that may reduce joint wear and extend the life of the implant.2,3

Computer-Assisted Knee Replacement

As with any moving part, alignment is key to smooth movement and long-term wear, just as wheel alignment affects the life of automobile tires. This is also the case with knee replacement. For years, surgeons have used X-rays, specialized instrumentation, surgical techniques, and experience to ensure a proper fit and alignment of the knee implant.

While these technologies have served surgeons and their patients well, research has shown that accuracy to within one to two degrees and one to two millimeters is extremely important to the long-term outcome of your knee replacement. The Stryker Knee Navigation System was designed to assist the surgeon in achieving this degree of precision routinely and consistently.

Computer-Assisted Hip Replacement

Similar to “global positioning systems,” the Stryker Computer-Assisted “navigator” helps the surgeon align and orient the hip implant with more precision than ever before. The surgeon is able to view an interactive display of the lines, angles, and measurements needed to position your hip implant. This combination of computers with wireless cameras and infrared technology is significantly improving medical technology for orthopaedic surgery.

How does computer navigation work?

  • In the operating room infrared optics and tracking software continually monitor the position and mechanical alignment of the joint replacement components relative to your specific anatomy.
  • Minimally invasive smart wireless instruments send data about to the joint movements (kinematics) to a computer.
  • The computer analyzes and displays the kinematic data on the screen in the form of charts and graphs.
  • These images provide your surgeon with the angles, lines, and measurement needed to best align your hip or knee implant.

What are the potential benefits?

  • It allows your surgeon to make adjustments to within a fraction of a degree, helping to ensure optimal “fit” for your joint.
  • It provides your surgeon with a comprehensive view of your joint mechanics.
  • It helps your surgeon correctly position your joint in situations where it is otherwise difficult to get a good view of your anatomy.
  • It may lead to improved stability for your joint and optimal range of motion for you.*

* Widmer KH, Grutzner PA. Joint replacement total hip replacement with CT-based navigation. Injury. 2004 Jun; 35 Suppl 1:S-A8-9.

You Don’t Have to Live with Severe Joint Pain

You don’t have to live with severe joint pain and the limitations it puts on your activities. If you haven’t experienced adequate relief with medication and other conservative treatments, joint replacement may provide the pain relief you long for and enable you to return to your favorite activities. Remember, even if your doctor recommends knee replacement for you, it is still up to you to make the final decision.

For more information visit and contact your doctor.


  1. Sparmann, M., et al., “Positioning of Total Knee Arthroplasty with and without Navigation Support,” JBJS, August 2003.
  2. Sikorski, J.M., Chauhan, S., “Computer-Assisted Orthopaedic Surgery: Do We Need CAOS?” JBJS, 2003; 85-B:319-23.
  3. Noble, P.C., Sugano, N., Johnston, J.D., Thompson, M.T., Conditt, M.A., Engh, C.A. Sr, Mathis, K.B., “Computer Simulation: How Can It Help the Surgeon Optimize Implant Position?” CORR, 2003 Dec; (417):242-52