Disclosure: Dr. Calendine serves as faculty and advisor to Stryker, the maker of the Mako robotic system. This content reflects his independent clinical perspective.
Want Dr. Calendine’s articles to stand out in your Google and AI search results? Add him as a preferred source (one tap).
Robotic knee replacement is one of the most common questions I hear in clinic, and it arrives in one of two forms: “Do I need the robot?” or “I don’t want a robot operating on me.” Both deserve the same honest answer. The robot is a tool. It changes what I can do in your operating room today, and the long-term evidence is still being written.
I’m Dr. Cory Calendine, a board-certified orthopaedic surgeon at the Bone and Joint Institute of Tennessee in Franklin. I perform more than 700 joint replacements a year and have used the Mako® robotic system since 2014; I also serve as faculty and advisor to Stryker, the company that makes it. Here is what this technology changes, what it does not, and how I talk it through with patients across Middle Tennessee.
What does the robot actually do in robotic knee replacement?
The robot makes no clinical decisions and does not move unless the surgeon directs it. Every judgment in your surgery belongs to me: the plan, the adjustments, and the final position of every component.
Here’s the comparison I use across the desk. Think of the GPS in your car: it gives you better information, and the good ones adjust to traffic in real time. But GPS is not driving the car, and even a self-driving car cannot tell you where you want to go.
That is the robot in my operating room. It gives me better information so I can make better decisions, then helps me carry those decisions out precisely. The judgment stays with the surgeon. It has to.
What does robotic knee replacement change during surgery?
Done well, robotic knee replacement rests on three things: a plan built from your real anatomy, a mid-surgery adjustment to your ligaments, and precise execution of that plan.
I describe it as a three-legged table. Any three points define a single plane, which is why a three-legged table cannot wobble; take a leg away and it does.
Pillar one: does the plan start with a CT scan of my knee?
On the platform I use, yes. Before surgery you get a CT scan of your knee, not just an X-ray, and that scan builds a full three-dimensional picture of your anatomy.
I call that anatomic truth. Your plan gets built on your knee, not an average knee or a template. For a closer look at the hardware, see my guide to the robotic arm used in joint replacement.
Pillar two: can the plan be adjusted to my ligaments?
Yes, and this is the piece no scan can give us ahead of time. A CT shows bone; it cannot tell me how your ligaments behave when the knee moves.
Every knee has its own ligament tension, and a knee replacement only feels right when the implants are balanced against your specific soft tissue. During surgery I can measure that tension and fine-tune the plan in real numbers, right there on the table.
Too tight on one side and the knee feels stiff. Too loose and it feels like something you cannot quite trust. Getting that balance right is a large part of what makes a replaced knee feel like your own.
That customization did not exist earlier in my career. For the technical version, see robotic knee balancing and how the tracking arrays work.
Pillar three: how precisely is the plan carried out?
A perfect plan is close to worthless if it cannot be executed precisely. The robotic arm helps me carry out the plan I just built and adjusted, with an accuracy that hands, jigs, and mechanical guides cannot match.
Truth, adjustment, execution. When a platform delivers all three, the table does not wobble. That is what robotic joint replacement changes today.
Is the robot doing my surgery?
No. The robot is an instrument in my hands, and it does nothing on its own.
I had a patient ask me directly not to use it; she was worried she would lose her surgeon to a machine. Her fear was not foolish, just a misunderstanding of how the technology gets used. I hear a version of it every month.
From your side, very little looks different. You add one appointment before surgery for the CT scan, and on surgery day the robot is one more piece of equipment in the room. The difference is in the information I’m working with while you’re asleep.
Is robotic knee replacement better? What the data actually shows
The honest answer: robotic knee replacement is proven to improve implant positioning accuracy, and there is data showing early clinical benefit, but long-term superiority has not been established in the literature. Anyone who says the question is settled is ahead of the science.
What did the early clinical study find?
A prospective study of 80 patients compared robotic-arm assisted knee replacement with conventional technique. The robotic group had less early postoperative pain, needed less pain medication, achieved a straight leg raise sooner, required fewer physiotherapy sessions, had better knee flexion at discharge, and went home faster: a median stay of 77 hours versus 105.
That is encouraging. It is also early, observational data from a single surgeon’s practice, which is not long-term proof.
What did the 2025 meta-analysis of 21 trials find?
A 2025 meta-analysis pooling 21 randomized trials and 2,692 patients found robotic assistance delivered significantly better mechanical alignment accuracy. It found no significant difference in patient-reported function on the WOMAC or Oxford Knee Scores at short to medium follow-up, and one secondary score differed by roughly a single point, which is too small for a patient to feel. Operative times ran about 20 minutes longer.
Read those studies together and the fair summary writes itself: precision is proven, and the payoff patients feel ten or twenty years out is still being measured. I believe it will come, and I wouldn’t use the robot on every knee I replace if I didn’t. But belief is not evidence.
What I can say with confidence is that the technology changes your surgery today. The next step for our field is connecting those better decisions in the operating room to the long-term results patients actually feel.
Are all robotic knee replacement systems the same?
No, and this is the part that bothers me. The word robotic on a billboard sounds like a single thing. It is not.
Not every platform starts with a CT scan, and some skip the anatomic truth entirely. The label by itself tells you nothing about whether the three pillars are present.
Three questions to ask about robotic knee replacement
If you are evaluating a surgeon and robotics comes up, three fair questions:
- Does my plan start with a CT scan or another three-dimensional image of my knee?
- Can you adjust that plan during surgery based on my ligaments?
- Does the robot help you execute the plan you made?
Three legs. If one is missing, the table can wobble.
Should I avoid a surgeon who doesn’t use a robot?
No, and that may surprise you coming from someone who uses one every day. Robotics is not the standard of care, and a surgeon operating the way they are most comfortable will give you their best result.
When the total knee system launched in 2016, our center was part of the limited market release, among the first in the country performing robotic total knees. I use it for every knee replacement I do.
And still: if your surgeon doesn’t use a robot, that does not make them the wrong surgeon for you. Anyone who tells you every other approach is second-rate is not telling you the full story.
Trust your surgeon, or find one you can trust. That relationship matters more than any machine in the room.
Does robotic knee replacement change my recovery?
The robot itself does not change your rehabilitation plan. Recovery depends far more on the surgical approach, your preparation before surgery, and the work you put in afterward.
Where technique does move the needle is muscle sparing. I pair robotics with the subvastus approach when anatomy allows, because leaving the quadriceps tendon intact changes those first weeks: subvastus knee replacement recovery. For the operation itself, start with total knee replacement.
Where can I get robotic knee replacement in Middle Tennessee?
I perform robotic knee replacement at the Bone and Joint Institute of Tennessee, 3000 Edward Curd Lane, Franklin, TN 37067, and see patients from Nashville, Brentwood, Columbia, Spring Hill, and Murfreesboro.
Here’s what I tell every patient who calls about the robot: come in and talk about your knee, not the technology. The right decision starts with your X-rays, your symptoms, and what you can no longer do.
Schedule a consultation with Dr. Calendine or call (615) 791-2630.
Watch: What I Wish You Knew About Robotic Knee Surgery
In this 9-minute video I walk through what the robot actually does in the operating room, the three pillars that separate platforms, and what the published evidence does and does not yet prove.
Medical disclaimer: This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Individual results vary. Always consult a qualified orthopaedic surgeon about your own condition.
References
- Kayani B, Konan S, Tahmassebi J, et al. Robotic-arm assisted total knee arthroplasty is associated with improved early functional recovery and reduced time to hospital discharge compared with conventional jig-based total knee arthroplasty. Bone Joint J. 2018;100-B(7):930-937. PubMed
- Mostafa O, et al. Robotic-assisted versus conventional total knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials. Ann Med Surg (Lond). 2025;87(2):867-879. PubMed
