GPS’ improves knee and hip replacement outcomes
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When you get new tires on your car, it’s important that they are balanced and in alignment. This will keep the car from vibrating or pulling in one direction and help the tires last longer.  

But you wouldn’t expect your mechanic to check tire alignment and balance just by eyeballing it. They have specialized tools to help them. It’s the same when the joints in your knees or hips are replaced.  

For many years, surgeons largely relied on bony landmarks and their intuition to make sure joint implants were placed in the correct position and properly aligned, leading to a straight leg. But not every person’s body is the same, so even an experienced surgeon could miss the mark by just a little. Being even slightly out of position can lead to an implant wearing down unevenly, requiring a new one years before expected.  

With people living longer and more people having joint replacement surgery at a younger age, it’s more important than ever to do what we can to extend the life of these implants and reduce the number of future procedures a person may need.  

Related reading: Am I too young for knee or hip replacement?

Thankfully, many surgical teams, including ours, now have surgical navigation systems that help position and align new joints with a degree of accuracy we can’t get by eyeballing it.  

‘GPS’ for knee and hip replacement

In traditional joint replacement surgeries such as knee replacement, we would use simple tools such as alignment jigs and rods inserted along the thigh bone (femur) to help us see and feel when the knee was properly positioned and aligned.  

A surgical navigation system is similar to a GPS system in a car. We input where in the limb we want to go, and the system shows us, in real time, the location and movement of our instruments. We can clearly see and test position, alignment and ligament tension every step of the way. 

Surgical navigation systems are similar to GPS in a car. Showing location and movement of our surgical tools in real time. via @MedStarWHC

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There are two types of navigation systems:  

  • Computer-assisted navigation systems provide information about our surgical tools and the implant in relation to the target position.  
  • Robot-assisted navigation takes this one step further, using robotic arms to align cutting guides and increase the precision of bone cuts. This doesn’t mean the robot does the procedure; it just refines our surgical execution. The surgeon still controls every step. This technology is still emerging and fairly expensive, so it’s not as common as computer-assisted navigation.

Benefits of using navigation during joint replacement surgery

Every person’s body is a little different, which can make getting an implant into the correct position tricky. We can’t always rely on bony landmarks and a patient’s anatomy. For example, if you have hip arthritis in addition to a spine disease, you may hold your pelvis in an odd way. Without a navigation system, we may place the implant slightly off of where it should go because of how you’ve held yourself for years.  

Navigation systems give us an extra set of eyes, along with a certain amount of confidence and predictability. Some benefits include:

  • Providing the surgeon with real-time information and the ability to correct potential errors during surgery
  • Improving overall function of the new joint, including greater stability and range of motion
  • Potentially allowing the use of less-invasive surgical techniques because the system gives us improved visualization of the field without large incisions
  • Increasing the life of the implant and reducing the need to replace the implant, known as revision surgery  

Revision surgery often is more complex than the original knee replacement or hip replacement surgery. The surgeon may need to remove some of the bone because the implant may have grown into it. This would require a bone graft, or transplanting a piece of bone from either another part of the body or from a donor to replace the removed bone along with the implant.  

A 2015 study showed that 5.2 percent of patients who had a total knee replacement without computer navigation needed revision surgery within nine years, compared with 4.6 percent who had computer-navigated surgery. This may look like a small variance, but if you have 1 million knee replacements, it could mean the difference of 6,000 of them avoiding revision surgery within nine years.  

Joint replacement surgery can dramatically improve a person’s quality of life, and demand for these procedures is growing. The American Academy of Orthopaedic Surgeons says nearly 1 million knee and hip replacements are performed every year in the United States. The organization predicts that number will rise to 4 million, due to an aging population and increase in obesity and osteoarthritis.  

As these procedures become even more common, computer- and robot-assisted navigation will continue to play a larger role in helping us improve patients’ outcomes and increase the longevity of their implants.

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