“The joint mapping involves using a stylus that is registering with the robot,” explained Levi W. Kindel, MD, an orthopaedic surgeon from Salina Ortho in Kansas. “You’re touching around the knee in certain landmarks, which creates a 3-D image for the robot.”
During the procedure, the robotic arm helps guide the surgeon to ensure precise implant placement and bone cuts so the implant feels as close to the patient’s natural knee as possible. These systems often incorporate haptic feedback that allows the surgeon to “feel,” via the robot, the virtual boundaries established in the operative plan.
Once the plan is finalized by the surgeon intraoperatively, with the use of haptics, the surgeon limits what the computerized robot, under the guidance of the surgeon’s hands, will cut. When these haptic limits are set, the robot will not allow the surgeon to cut beyond their planned cut, protecting the surrounding tissues.
“It is like having a magic coloring book that will not allow the crayon to go beyond the lines,” explained Dr. Ward. “The haptic feedback varies with each robotic system. The one I use allows you to actually stress the knee in different preset positions with your own hands and arms, and you get a reading of how much laxity and how much space there is to put the implants in.”
These readings allow the surgeon to revise the operative plan and reposition the implant, adjusting the bone cuts slightly to optimize both alignment and soft tissue balance. The adjustments are performed before the bone is actually cut, during the final stages of intraoperative planning. “Now, when you’re making the cut, you’re seeing it on the computer screen. You look at the screen and you look at the patient, back and forth, with haptic feedback guidance. The mechanical arm is moving within the range that you have set,” he said.
By providing real-time feedback, haptics enhance the surgeon’s control over the procedure, potentially contributing to better outcomes and a quicker recovery period.
“I still use a cutting block with the robotic system I use,” said Dr. Kindel. “I think of it as kind of hybrid robotic-manual procedure. I use the robot to place my implant cutting guides where I want them, and then I perform all the cuts like a normal manual knee procedure. I describe it to patients as you can hang a picture on the wall and look at it and say, ‘I think that’s pretty level,’ or you can use a level and know that it’s perfect. And the robot, to me, is the level.”
Is Robotic-Assisted Surgery Better?
Robotic-assisted TKA offers individualized surgical planning and enhanced component placement—but are patient outcomes higher than similar surgeries performed manually?
Assessing data from the National Inpatient Sample—a public database with information covering 7 million hospital stays annually in the US—researchers from The University of Texas Southwestern Medical Center in Dallas compared findings related to both approaches to TKA. Specifically, investigators identified 541,122 patients who received manual TKAs, and 17,249 who received robotic TKAs between 2016 and 2019.
The findings, published in 2024 in the Archives of Orthopaedic and Trauma Surgery, revealed that patients who received a robotic-assisted TKA intervention had hospital stays nearly half a day shorter and were less likely to exhibit complications, including infections, excessive blood loss, and fractures, dislocations, or mechanical complications of their prosthetic.4,5 A notable drawback of this approach was cost. Robotic TKAs were found to cost an average of $2,400 more than manual surgeries.
In terms of mortality rates, several recent studies have reported a decrease in the number of deaths with technology-assisted TKA compared to conventional instrumentation in primary TKA. In this context, “technology assisted” includes robotic and other technologies that avoid the use of intramedullary guide rods, according to Dr. Ward.
This leg is in full extension after final implants are in place during cementation.
Specifically, an analysis of the Australian Orthopaedic Association National Joint Replacement Registry published in the British Medical Journal found that “The use of conventional instrumentation during TKA is associated with higher odds of early postoperative death than when technology-assisted instrumentation is used. This difference may be explained by complications related to fat embolism secondary to intramedullary rods used in conventional instrumentation. Given the high number of TKAs performed annually worldwide, increasing the use of technology-assisted instrumentation may reduce early postoperative mortality.”6
Furthermore, a 2024 report in Clinical Orthopaedics and Related Research examining the American Joint Replacement Registry found that robotic-assisted TKAs were not associated with decreased odds of early revision; however, the study also reported a mortality rate of 0.3% (225 of 70,824) in patients with TKAs performed with conventional technique (1 in 315) versus a 0.03% mortality (3 of 8,853) with robotic-assistance (1 in 2,951). No further mortality analysis or data were provided.7
“Taken as a whole, these studies support patient preferences for lower mortality methodology, such as with a robot, at least until further research either refutes or confirms the lower mortality methodologies,” said Dr. Ward.
While these studies suggest promising applications for robotic-assisted TKA, manual procedures remain the predominant approach, with at least one study calling the benefits of both a draw, at least for now.
Orthopaedic surgeons from the Cleveland Clinic in Ohio analyzed 12 categories of data from 340 patients undergoing robotic-assisted or manual TKA.8 The results of the study were mixed, with the robot scoring better on length of hospital stay and home discharge, while manual surgery resulted in better flexion scores (bending motion of the knee) and shorter operative times for this cohort. Both procedures had virtually the same rate of postoperative complications.
“I operated without the robot for many years, and I trained many residents on how to do it manually,” said Dr. Ward. “There are ways to do it manually and get good results, but with the robot, you are less likely, at the end of the operation, to realize that the ligament is a little bit too tight. You just don’t get surprised with this approach. You cut where you plan to cut, and the post-op x-ray looks like it’s supposed to look.”
Limitations of Robotic-Assisted Approach
The barriers associated with the robotic approach to TKA include higher costs, increased operative time, navigating the learning curve, and overcoming patient perceptions.
In terms of costs, not only can individual cases cost an average of $2,400 more than conventional surgeries, but there also is the increased expense associated with the disposable equipment necessary to perform the procedure, not to mention the acquisition of the robotic device itself, which can cost millions of dollars, depending on the vendor.
Another potential challenge related to robotic equipment is size. Robots typically occupy a large footprint in the OR of up to 600 feet, including the console and robotic arms.
An additional consideration when adopting this technology is time. In a study published in 2023, researchers looked at six randomized clinical trials covering 1,689 cases and found that robotic-assisted surgery is associated with a longer duration of surgery, with a mean difference of 32.9 minutes.9
Time also is a factor for surgeons seeking to master the learning curve associated with this technology; proficiency with this approach is essential for ensuring patient safety, efficiency, and overall outcomes. While the learning curve can vary considerably based on the skills of the individual surgeon, a study published in 2024 suggests that a reduction in operative times for robotic-assisted TKAs to levels comparable to manual surgeries occurred after performing 30 to 40 robotic procedures.10
Other studies underscore the learning curve’s wide range, suggesting that as few as 25 surgeries or as many as 70 are necessary to master the robotic device, depending on the manufacturer and distinct competencies of each surgeon.10
“Come do a case with me,” advised Dr. Ward as a way for colleagues to reframe perceived barriers to integrating this technology into practice. “Observe a case with someone who’s mastered this procedure.”
The robot is setting the distal femoral rotation and anteroposterior placement for the cutting block.
While reaching this level of proficiency presents challenges related to time spent away from the surgeon’s practice, researchers highlighted the importance of structured training programs that can accelerate the learning process and called for additional studies to examine approaches for optimizing these training protocols.
“Do it—just give it a chance,” added Dr. Kindel. “The biggest consideration regarding robotic knee technology, and I had to go through it, is the learning curve. You’ve got to figure out how to use the machine, and you have to determine what gaps or numbers you like. There’s no set, standardized number. The surgeon gets to decide what extension gap they like, what flexion gap they prefer, and you get to pick those numbers. Unfortunately, for you to be able to do that, you’ve got to do the cases. And it’s a big learning curve. But once you figure out those numbers, you’re done.”
Addressing patient misconceptions regarding the application of this technology is another potential hurdle for implementing the robot into practice. A 2024 study examined the results of an optional, anonymous survey presented to 360 patients during their initial consultation. It found that patient interest in robotic-assisted total joint arthroplasty varied (77.8% of respondents expressed interest in the robotic-assisted approach to some degree), and that many patients have a limited understanding of the procedure.11 In fact, more than 100 respondents expressed belief that robotics were capable of independently performing most or all of the procedure.
“The lay public may not understand what the robot is,” explained Dr. Kindel. “They sometimes think it’s a robot that enters the room and does the surgery. I tell them, ‘No, the robot is just another tool in my tool chest that I use during surgery.’ The big thing I relay to patients is that I’m still completely in control. I make all the cuts, and I make all the decisions.”
Training in Traditional TKA Is Indispensable
While both Drs. Kindel and Ward support robotic-assisted TKA for appropriate patients due to its enhanced precision capabilities, they assert that training in manual techniques is essential, particularly for managing unanticipated situations in the OR.
“Patients are usually fairly agreeable once they understand that I’ve had years of experience—and that if the computer were to malfunction, I still have what I call ocular navigation,” explained Dr. Ward. “I’m using my own eyes, and if something doesn’t look right, then I’m going to verify. So, if the robot breaks, I’m not totally out of luck. I know how to finish the case if I have to.”
In fact, a rising number of orthopaedic residency programs are incorporating robotic-assisted TKA into their training. In a survey of 220 senior orthopaedic residents attending a National Board Review course, 70% of respondents reported exposure to this technology during their training, with 20% reporting that more than half of their training involved robotics.12 While 45% found robotic training enhanced their understanding of the surgical procedure, 25% expressed concerns that training on a robotic device may negatively compromise their training with traditional instruments.
Dr. Kindel’s training was primarily focused on the manual approach. Following training, he performed manual TKA procedures for a year and half.
“Then I switched to the robot, and I’ve been doing the robot primarily for the last year. I’m pretty much straight robot, unless it’s an atypical case or I am doing a revision—then I’ll still do manual instrumentation,” he said.
While Dr. Kindel uses the robotic approach for TKA almost exclusively today, he remains an ardent champion of manual training during residency.
“During my residency, I had one attending who taught me manuals,” said Dr. Kindel. “If it wasn’t for him, I would’ve been trained primarily on the robot. Every resident should know how to do a manual total knee replacement, and then once you incorporate the robot, it’s a full light bulb moment when you completely understand and manipulate the knee differently. We’re able to make a very individualized knee replacement for the patient, depending on their deformity or their arthritic pattern. I’m very passionate about it.”
