RobotMD News

Chad Mitchell, MD, FAAOS
August 3, 2023

The emerging robotic technology in orthopedic surgery is quickly advancing, especially for partial and total knee replacements.  The computer mapping technology combined with the robotic-assistance makes a great combination for precision cuts and joint alignment.  Patients are seeing immediate ambulation and improved early knee range of motion following these surgeries.

The computer navigation and robotic-assistance surgeries are great for an arthritic knee, but can it help someone who may be having a problem with their previous knee replacement and need to have it revised?  The need for total knee replacement revision includes those components that are loose, unstable, or infected. 

Orthopedic knee replacement surgeons are using the computer navigation technology to maximize range of motion and stability outcomes following the revision surgery.  Traditionally, revision total knee arthroplasties have significantly less patient satisfaction which is thought to be due to increased scarring, bone loss, joint line elevation, difficulty visualizing the proper knee alignment, and decreased range of motion.  Revision knee replacements can have good results, but these revisions tend to have significantly lower range of motion and patient satisfaction scores.

To optimize knee function following a revision surgery, orthopedic surgeons are using computer navigation for mapping out the problem knee including the components.  Also, the anatomic joint line can be recreated virtually, so that the revision knee surgery restores the proper joint line.  A problem like an elevated joint line can lead to poor patient outcomes.^*  After mapping out the knee, the problem components are removed and the underlying bone defects are mapped into the computer system.  The surgeon can then use the mapping data to tell the robotic drill where to make the precise cuts that will allow the new revision knee components to function with good range of motion, stability, and proper joint line height.  All of this is an attempt to get a similar outcome to an original or primary knee replacement.  

 

A robotic drill is used to mill the computer generated cuts that give the best implant position with respect to range of motion and stability of the knee. Notice the reflectors that give the computer robotic system points of reference to make the precision cuts. This robotic-assisted revision knee arthroplasty usually preserves more bone with a better surface fit of the components and less use of additional metal components. 

Orthopedic surgeons who use robotic-assistance for revision knee replacements are anecdotally reporting that they are using less revision knee component parts and removing much less bone during the procedure.  For patients, this translates into more stable components, better alignment and better range of motion of their revision total knee replacement.  Some of these patients are also able to go home on the same day of surgery.  

In my opinion, a robotic-assisted knee replacement revision with computer navigation is an excellent option for obtaining a precision-aligned knee after complications with a primary knee replacement. In my experience, these patient’s recover faster and some can go home from the surgery same day.   As an orthopedic surgeon, it is encouraging to see the improved results of the robotic-assisted revision knee replacements over the previous methods used.  Robotics certainly has a place in improving the healthcare of patients. 

References:

[*] Buller LT, Metzger CM, Deckard ER, Meneghini RM. The Effect of Joint Line Elevation of Patient-Reported Outcomes After Contemporary Revision Total Knee Arthroplasty. The Journal of Arthroplasty. 2022;37;1146-1152.

Chad Mitchell, MD, FAAOS
June 2023

Artificial intelligence (AI) has notoriously grabbed the headlines recently over concerns that it could result in unintended harm to humanity.  Cyberattacks, autonomous weapons, misinformation campaigns, and loss of human autonomy are all valid concerns in a world of AI that can contradict our human or moral values.  From a medical prospective, AI could help find cures for diseases and make surgeries more effective by lowering the risks for complications, but there is also concern that it has the potential to cause unintended medical complications. 

Currently, partial and total knee replacement surgery is being transformed by the use of computer navigation and robotic-assistance systems.  Early results suggest that patients are seeing the benefits of this technology with improved range of motion and precision alignment of their implants.  Despite these benefits to patients, there is concern about possible unintended consequences from the technology.  Many patients are concerned about how the technology is used and if their surgeon has full control over the system.  These types of discussions usually lead to the question: is artificial intelligence used during a robotic knee replacement?

The answer to this question is yes. AI is used to help predict the best alignment of the knee replacement implants using the patient’s knee range of motion and stability data obtained at the time of surgery.  This alignment prediction helps the surgeon fine tune your implants to give you the best custom result possible; however, the AI used in the robotic knee replacement systems have defined limits, and the surgeon has the final input into positioning your knee implants. 

Artificial Intelligence (AI) is part of the computer robotic system used to perform partial and total knee replacement surgeries. This is an actual screen shot during a robotic surgery, and it shows the information available to the surgeon. The surgeon is able to fine-tune the implant placement while the AI keeps up with the predicted changes in stability and range of motion that would result from the surgeon's changes. This is done before a bone cut is made for the implants.

With over 25 years experience performing knee replacement surgeries and 2.5 years experience performing robotic knee replacements, It is my opinion that these robotic systems are safe for patients, and I have not experienced any incidences of malfunction of the AI during surgery. Rest assured, surgeons have the ability to abort the computer navigation and robotic assistance at any time during the procedure and finish the knee replacement manually, if needed. Patients can also be assured that these robotic systems have gone through a rigorous approval process both with the designers and with the Food and Drug Administration (FDA) before being released for use in the general population. Patient safety and good outcomes are the focus of these advanced computer and robotic systems.

Model showing the components of a total knee replacement (total knee arthroplasty).

Although there are valid concerns about the future impact of AI on humanity,  its current use in robotic knee replacements is safe and very effective.  The increased precision in cuts and alignment over the manual technique has a huge impact on earlier recovery. As we move into the future, the hope is that patients will have less complications and longer lasting implants. AI is a large part of making life better for knee replacement patients.

 

Chad Mitchell, MD, FAAOS
April 2023

Patients often ask me, “What does the robot do during my joint replacement?” And “Why is it used or needed?” These can be complex answers given the various robotic systems available, but in this article, I will try to simplify this complex subject and unlock the mystery of a robotic-assisted joint replacement.

During a joint replacement, the focus is usually on the alignment of the components that would give the best range of motion, stability, and function. The gold standard for this has been various mechanical alignment guides and cutting guides that are used during the surgery to make the proper bone cuts for good fitment of the joint replacement components.

During surgery, there are various factors that come into play that can confound a surgeon’s ability to get the perfect alignment. Not all patients are the same size and shape, so their soft tissues may not make it easy to understand the fine points of the bony alignment without potentially making larger incisions or using intraoperative X-rays. Also, the human eye is not always precise in its evaluation of angles, degrees of motion, and fine measurements.

In the 1990s, there was concern that joint replacement alignments had a wide range of variability which possibly explained some of the joint replacement failures. In hopes of fine-tuning these surgeries, computer navigation was developed to add more precision to the alignment and motion of hip and knee arthroplasties. Computer navigation aided the surgeon by using bony points of reference along with reflective arrays to track the bones and alignment by computer. This helped with making the joint alignments more consistent and in a more narrow range, however, the surgical times were increased and the computer lag time made it less practical for most surgeons.

Shortly after the development of computer navigation, the first robot was used for a knee replacement. While the robot could offer more precision with the cuts, it was also slow and took up a significant amount of room in the operating room. Since that time, the technology has improved greatly. Now the computer navigation and robotics seem to work at real time speeds without the previous computer lag. The newer robotic systems are also smaller and take up less space in the operating room.

The robots of today are much more user friendly to your surgeon. The speed of the computer navigation and robotics is beneficial to getting the surgery done in a timely fashion. This increase in speed translates into less anesthesia time, less bleeding, and lower infection risks than the computer and robotic technology of the 90’s. The surgical robots of today also have patient safety functions built into the system.

Currently, the three most commonly used systems in the United States are the MAKO by Stryker, the CORI by Smith and Nephew, and the ROSA by Zimmer Biomet. These systems offer joint replacement surgeons an excellent way to assist with implanting brand specific joint replacement components to achieve optimal joint alignment, range of motion, and stability. Always consult your orthopedic surgeon for his or her recommendation on the brand of implant and robotic system.

Most of the current joint replacement robotic systems use a Computed Tomography (CT) scan to combine multiple x-rays into a 3D image of the bones and joint. A computer program will use this 3D image for the computer navigation to reference during the surgery. The computer navigation uses reflective arrays attached to the patient by the surgeon to know where the bones are at all times. With this information, the robot can know precisely where the cuts need to be made when the sizes are templated using the computer. The computer navigation also can predict which cuts are the best to give the patient the most stable implant with the best motion before the cuts are ever made. To make the cuts, most of the robots guide the cutting instrument or hold a cutting guide in place.

 

The technology is improving so fast that the size of the computers and robots is shrinking, thus freeing up space in the operating room. One of the systems is the CORI from Smith and Nephew. It does not need a CT scan, either. The surgeon simply paints the 3D image of the joint into the computer at the time of surgery. That same system has a small handheld robot for the surgeon to use to make the precise cuts. The smaller size of this system makes it ideal for use in surgery centers or small hospital operating rooms.

There is also a robot that makes the cuts for a knee replacement autonomously with the surgeon watching. It is the TMax from Think Surgical. While this robot is not FDA approved in the United States, it shows the direction the technology is headed. Soon, surgeons like myself, may be monitoring the robotic technology while no longer being an active part of making the cuts. Looks like my job could be in jeopardy!

For surgeons and patients that are concerned about outcomes, research studies are underway to determine the effectiveness of these technologies. In my opinion, the future looks bright for robots helping patients!