While there are other types of joint replacements, including elbow, shoulder and ankle, I focus on the hip and knee.
Indications for a Hip or Knee Replacement
You can treat arthritis with conservative treatment like injections, weight loss, therapy, or home exercises, which prolong the time until you need a joint replacement.
It’s time to have a hip or knee replacement when you have end stage arthritis in your joint, or when all of the cartilage is worn away from your joint, the bone is exposed and your joint is painful.
When the pain is at a level where it is limiting your function and preventing you from doing activities you like to do – whether walking, going to the store, going fishing, playing some type of sport, and so on – and the conservative treatments aren’t working, you can move toward surgery.
How a Hip or Knee Replacement Works
In a joint replacement, you cut off the diseased surface of the bone and you replace it with metal and plastic pieces in order to give the patient another surface to put weight on and not have any pain. The whole joint is not replaced, but we make cuts into the bone specific to the patient in order to put the pieces of the joint replacement in place so they can move.
The pieces that we use for the joint replacement are chosen specifically for each patient to best fit their joint. They provide stability and mobility to patients.
Everyone’s body is different: some people have bowed legs, some people have knock knees, some people have normal alignment. It’s very important that we tailor surgeries and implants specifically to address the needs of the patient. As patients develop arthritis, they may develop bowed legs or knock knees depending on how the joint wears. The goal in surgery is to give you a stable joint that also brings you back to the alignment that you had before arthritis.
In the operating room we have different size implants and tools so we can make sure we have the options that work best for you. The tools allow us to measure specifically the angle of an alignment for fitting the implant to your bone.
Surgical training takes 5 years, and most surgeons do an extra year of fellowship as well. The length of time is to provide us with the expertise to do these complex surgeries for different patients in different sizes and different walks of life and have it be successful for all of them.
Implant design has improved over the decades, so implants are lasting longer and longer. The design is also being tweaked to perform better and more naturally within your body.
Technology can be incorporated as well. There’s one type of knee replacement, for example, with an accelerometer build in. It allows the patient to connect their implant to an app to measure the steps that they’re taking, how wide their steps are, how their gait is, and how they’re doing in therapy.
Three well-known surgical robots are the Mako, Velys and the Rosa. There’s no real difference in what the robots offer, but different surgeons will have experience with different systems.
The robots don’t do surgery, but they help surgeons make surgery more reproducible. As a surgeon, after all the years of training and all the surgeries I’ve done, I’ve built an eye to know exactly what I’m doing. The robot provide validation. For example, the robot can confirm you’ve cut off exactly the amount of bone you planned to cut off, or that you cut at the angle that you planned to cut at.
Some of the robots required advanced imaging like a CAT scan or an MRI in order to plan the surgery while others only require an x-ray and still others allow you to plan out the surgery right before you do it. These systems allow you to make all of the decisions before the surgery so during surgery you can move more quickly and precisely.
Outside of robotic-assisted surgeries, there are other types of robots or similar technology that can help during surgery and planning surgery.
There are accelerometers that are about the size of a phone and can be attached to the surgical tools, which also help validate the angles and the cuts. Once again, they allow us to specifically treat every patient differently and give them an implant or a surgery that is specific for them.
One of the emerging technologies is augmented reality goggles that you wear during surgery. Instead of looking at a separate screen, these goggles give you an overlay in your surgical field of what you’re planning to do during the surgery.
Patient-specific implants are possible. For example, there are 3-D printed guides that can be created after a CAT scan or an MRI and show the surgeon exactly where to cut, even with all of the arthritis that a patient may have.
Frequently asked questions
Is robotics better suited for hip or knee surgeries?
Much of the current technology is for knee surgery, but there is a fair amount for hips as well. There’s also robotic shoulder and ankle surgery.
What is the recovery time after a robotic replacement?
The recovery time after a robotic replacement will be the same after a total knee or total hip replacements that is done manually without using any robotic assistance. Everyone's recovery is slightly different. Usually, around the four to six week mark, patients should be returning back to activities and not using walking aids. Around the three-month mark, most patients are back to almost baseline where they were before and back to regular activities. The full recovery is six months to a year because when you have arthritis for such an extended period of time, it takes time to rebuild back up that muscular strength.
Do you take measurements of the knee before the surgery to select the implant size?
Yes, we plan ahead. Sometimes your surgeon may have you get X-rays in clinic or right before surgery and there is a little white ball in the X-ray. This ball, called a marker ball, is used as a calibration mark for planning implants for your surgery. We make sure we have the right size implants available.
How long does a knee replacement surgery take? And is it longer or shorter with these technologies?
Hip and knee replacements usually take one to two hours to do. While sometimes surgery will be slightly longer with a robot since there are extra steps, if a surgeon is used to the robotic system that they’re using, it doesn’t affect their surgical time and the surgery is about the same length.
If somebody loses weight in order to meet the BMI cutoff for surgery and then they later regain that weight, will the implants fail?
No, they will not. Due to the way the implants are placed and fixed to your bone, even if you gain weight the implants will still support you.
If a new technology or a new type of robot comes out, how do you learn to use it?
First, you go to a lab where you learn how to operate the robot on bone models and sometimes a cadaver. You then go follow another surgeon and watch them do surgeries in order to understand how they’re using it and ways that you can apply that robot in your surgery. When it comes time to start using the robot on patients, you can do some cases with another surgeon who is experienced with that technology, so if any questions come up they can help. Hospitals and surgery centers have requirements of how many cases you must have done with a new technology before you can operate using it at that hospital.
In order to use a new technology, doctors go through extensive training to make sure that when they're doing the surgeries their patients are getting the best outcome.
If my surgeon doesn't use robots, is that okay?
Since technology can always fail, before we learn how to use robots all surgeons must learn how to do the surgery manually. Robots are just a tool that a surgeon uses to be more accurate and more reproducible. Your outcome will be the same.