Traffic Alert: Construction Impacting Travel Around MOR's Downtown Chicago Location

Robotic-Assisted Knee Replacement

Robotic assistance is a tool used during knee replacement surgery. It does not replace the surgeon — the surgeon plans the operation, controls the instruments, and makes every decision. What the technology adds is a detailed three-dimensional model of your knee and real-time feedback on implant sizing, positioning, and soft-tissue balance while the operation is underway.

At a glance: Robotic-assisted knee replacement uses a model of your knee to guide implant placement. The surgeon performs the operation; the system provides measurement and feedback intended to improve the precision of component positioning. It is used for both total and partial knee replacement.

The joint replacement surgeons at Midwest Orthopaedics at Rush use robotic assistance for both total knee replacement and partial knee replacement. Whether it is used in your case depends on your anatomy, the procedure planned, and your surgeon's assessment.

Is robotic knee replacement the same as minimally invasive or arthroscopic surgery?

No, and this is the most common misunderstanding about the procedure. Arthroscopic surgery is done through very small incisions using a camera inside the joint, and knee replacement is not an arthroscopic operation regardless of whether a robot assists.

A robotic-assisted knee replacement uses an incision comparable to a conventional knee replacement. The robot is not inserted into your knee. It is a positioning and measurement system that works alongside the surgeon, and it adds small additional incisions for the tracking pins described below. Robotic assistance is about accuracy, not about making the operation smaller.

What robotic assistance actually does

The term covers a sequence of steps rather than a single machine action:

  • Planning. A model of your knee is built, either from a CT scan taken before surgery or by mapping the joint surfaces at the start of the operation. The surgeon uses it to plan implant size, position, and alignment before any bone is prepared.
  • Registration. At the start of surgery, the surgeon touches defined points on the bone so the system knows precisely where your knee is in space relative to the plan.
  • Measurement during surgery. As the knee is moved through its range, the system reports how the soft tissues balance and how the planned implant position would behave in flexion and extension. The surgeon adjusts the plan in response — often before removing any bone.
  • Guided bone preparation. The system helps constrain the cutting instruments to the plan the surgeon has set.

What it does not do is operate independently. There is no scenario in which the robot decides anything or moves on its own. Every cut and every decision belongs to the surgeon.

Why implant position matters

A knee replacement is a mechanical construct inside a moving joint. Component alignment, rotation, and soft-tissue balance determine how the knee feels and functions through its arc of motion. Positioning outside the intended range is associated with pain, stiffness, and accelerated wear, and it is one of the reasons a replacement may eventually need revision surgery.

Robotic assistance is aimed squarely at that problem: making the executed position match the planned position more consistently, and reducing the outliers. It is a precision tool, and it is one factor among several — surgeon experience, implant selection, your anatomy, and your rehabilitation all bear on the result.

Does the surgeon need specialized training?

Yes. Robotic-assisted knee replacement requires training on the specific system being used, and there is a recognised learning curve — early cases typically take longer than the surgeon's conventional operations before the workflow becomes routine.

This is worth asking about directly. A reasonable question for any surgeon offering the procedure is how many robotic-assisted knee replacements they have performed and how long they have been using that system. The technology does not substitute for surgical judgment about implant selection, soft-tissue balance, or whether you should have a knee replacement at all.

Who is a candidate

Candidacy for robotic assistance follows candidacy for knee replacement itself. Your surgeon will evaluate:

  • The extent and pattern of arthritis on weight-bearing X-rays, which also determines whether a partial or total replacement is appropriate.
  • Deformity and prior surgery. Significant bony deformity or retained hardware from earlier operations can affect whether the technology adds value in your case.
  • Whether preoperative imaging is needed. Some systems require a CT scan in advance; others map the knee during surgery.
  • Body habitus and bone quality, which affect how securely the tracking pins can be placed.

Not every knee replacement calls for robotic assistance, and a well-performed conventional replacement remains a very good operation with decades of outcome data behind it. Your surgeon will tell you what they recommend for your knee and why.

If knee arthritis is limiting what you can do, an evaluation will establish which procedure fits your knee and whether robotic assistance is part of the plan.

Schedule an Appointment View Locations

Robotic assistance in partial knee replacement

Precision is arguably most consequential in partial knee replacement. Only one compartment is resurfaced, and the implant has to work alongside the patient's own remaining cartilage, bone, and ligaments — including an intact ACL. There is less margin for a component that sits slightly proud, slightly rotated, or slightly over-corrected, because the rest of the natural knee has to accommodate it.

Robotic assistance is used for both partial and total knee replacement, and your surgeon will discuss which procedure fits the pattern of arthritis in your knee.

What to expect around the day of surgery

If your surgeon uses a system that plans from a CT scan, that scan is done in advance — typically a short appointment, and the images are used to build your knee model before you arrive. Systems that map the knee during surgery need no advance imaging.

On the day itself, the experience is much the same as a conventional knee replacement: anesthesia (regional, general, or a combination), the operation, then recovery. The setup and registration steps can add some time in the operating room, which does not change what you experience under anesthesia. Many patients are candidates for a same-day discharge, depending on health history and support at home.

Recovery

Recovery after a robotic-assisted knee replacement follows the same path as the conventional operation: early walking with an assistive device, physical therapy focused on range of motion and quadriceps strength, and a gradual return to daily activity over the following months.

Timelines vary by patient, by whether a partial or total replacement was performed, and by your health and rehabilitation. Some patients go home the same day; others stay overnight. Your surgeon and physical therapist will set the milestones for your knee rather than working from a generic schedule.

What the evidence shows

The case for robotic assistance rests on accuracy, and that case is well established. Across published studies, robotic-assisted knee replacement places components closer to the surgical plan and produces fewer knees that fall outside the intended alignment range than conventional instrumentation does. Reducing those outliers is the reason our surgeons use the technology.

Component position is not a technicality. Alignment, rotation, and soft-tissue balance are what determine how a replaced knee feels and moves, and positioning outside the intended range is associated with pain, stiffness, and accelerated wear. A technique that hits the plan more consistently is addressing the variable most within a surgeon's control.

Longer-term data on implant survival is still accumulating, simply because the technology has not been in widespread use for the twenty-year horizons that joint replacement is measured over. Our surgeons use robotic assistance where it adds precision to your particular knee, and will tell you directly whether they recommend it in your case.

Risks and considerations

The risks are those of knee replacement generally — infection, blood clots, stiffness, persistent pain, implant loosening or wear over time. Considerations more specific to robotic assistance include:

  • Pin sites. Tracking arrays are secured to bone with pins, which leave small additional incisions. Uncommonly these can be a site of infection or, rarely, a stress riser for fracture.
  • Radiation exposure from a preoperative CT scan, when the system used requires one. Systems that map the knee during surgery avoid this.
  • Operative time. Setup and registration can add time, particularly early in a surgeon's experience with a given system.
  • Cost and coverage. The technology adds expense to the procedure, which is generally borne by the hospital rather than billed separately — but coverage is worth confirming with your insurer.
  • Technical conversion. Occasionally the system cannot be used as planned and the surgeon completes the operation conventionally. This is not a complication; it is the surgeon exercising judgment.

Knee specialists at Midwest Orthopaedics at Rush

Robotic-assisted knee replacement is performed by board-certified, fellowship-trained orthopedic surgeons at Midwest Orthopaedics at Rush. Our knee and sports medicine surgeons completed subspecialty fellowship training after residency, and the group treats knee conditions across the full range — from first-time injuries through complex reconstruction.

Our joint replacement surgeons perform both total and partial knee replacement with robotic assistance, and several practise at high annual volume. Because there is a learning curve with any robotic system, it is a fair question to ask your surgeon how long they have used theirs — ours will answer it.

Browse our knee specialists to read individual profiles, see where each surgeon practices, and request an appointment directly. Appointments are available across our Chicago-area locations.

Schedule an Appointment View Locations

Frequently asked questions

Is robotic knee replacement covered by insurance or Medicare?

Knee replacement itself is generally a covered procedure when it is medically necessary, and robotic assistance is typically treated as part of how the operation is performed rather than as a separately billed service. Coverage still depends on your specific plan, your deductible, and the facility. Confirm the details with your insurer before surgery — our team can help you work through what to ask.

Does Medicare cover robotic knee replacement?

Medicare covers medically necessary knee replacement. Robotic assistance is generally not billed to the patient as a separate line item, but plan specifics, supplemental coverage, and facility setting all affect what you pay. Verify with Medicare and any supplemental plan directly.

What is the success rate of robotic knee replacement?

Studies consistently show robotic assistance improves the accuracy of implant positioning compared with conventional technique. Whether that produces measurably better function or longer implant survival over the long term is still being studied. Knee replacement overall has a strong track record, and your surgeon can discuss what the current evidence suggests for a patient in your situation.

Is robotic knee replacement better than traditional knee replacement?

Robotic assistance places implants more accurately and produces fewer knees outside the intended alignment range — that advantage is well documented, and it is why our surgeons use it. Conventional knee replacement is also a highly successful operation with decades of results behind it, and surgeon experience remains the largest single factor either way. The right question is not which technique is better in the abstract, but which approach your surgeon recommends for your knee.

Does a robot perform my knee replacement?

No. Your surgeon performs the operation. The system provides planning, measurement, and guidance; the surgeon controls the instruments and makes every decision.

Does robotic knee replacement heal faster or hurt less?

Some studies report modest advantages in early pain and function with robotic assistance. Recovery still follows the same broad path either way, and how you do depends most on your knee, your health, and how you engage with rehabilitation. Many patients are candidates for a same-day discharge regardless of technique.

Are muscles cut during robotic knee replacement?

The approach to the joint is essentially the same as a conventional knee replacement, and how much soft tissue is disturbed depends on the surgical approach your surgeon uses, not on whether a robot assists. Robotic assistance does not by itself make the operation less invasive.

How long does robotic knee replacement surgery take?

Broadly comparable to a conventional knee replacement, with some additional time for setup and registration. That difference tends to shrink as a surgeon accumulates experience with the system, and it does not change your experience under anesthesia.

Will I need a CT scan first?

It depends on the system. Some build the model from a CT scan taken in advance; others map the knee during the operation and need no advance imaging. Your surgeon will tell you which applies.

Can robotic assistance be used for a partial knee replacement?

Yes, and precision is particularly relevant there, because only one compartment is resurfaced and the rest of your natural knee has to work alongside the implant. See our page on partial knee replacement.

If knee arthritis is limiting what you can do, an evaluation is the first step in understanding which options fit your knee. Schedule an appointment with the knee specialists at Midwest Orthopaedics at Rush.

This page is general information about a surgical technique and is not medical advice. Talk with a physician about your own symptoms, imaging, and treatment options.

Schedule an Appointment