Robotic Knee Replacement Surgery

Surgical techniques for knee replacements have evolved considerably over the years. Today, many more knee replacements are being performed using robotic assistance. Surgeons who use surgical robots often find that this technology enhances our ability to aim for individualized surgical targets based on each patient’s unique anatomy and function.

Your knee replacement surgery may or may not include the use of robotics based on which surgical technique your surgeon thinks will provide the best outcome.

What does robotic surgery mean?

Your surgeon will use many different tools to execute the many steps involved with performing a knee replacement. A surgical robot is simply another one of these tools. A critical part of any knee replacement is the removal of arthritic or damaged cartilage. The surgeon must remove enough cartilage and bone to accommodate a well-positioned prosthesis, while avoiding excessive removal of bone that may lead to compromised structural support or abnormal tension of the ligaments around the knee. A surgical robot is one of the many newer technologies that helps surgeons to remove just the optimal amount of bone in the optimal orientation.

All surgical robotic systems involve the use of an optical tracking system that is able to track the position of the patient’s knee in real time during surgery. This allows the surgeon to assess the ligaments around the knee during the operation and virtually plan for just the right amount of bone and cartilage removal. The robotic system can then be oriented precisely to achieve the desired surgical target.

As with most surgeries, the devil is in the details. The targets that surgeons aim for with knee replacements are down to the millimeter—and robotic assistance enables precision at the sub-millimeter level that helps surgeons to hit very specific targets during the operation. However, robotics are not the only tools available that help surgeons successfully hit their targets during surgery. Your surgeon may use a variety of other instruments that help achieve their goals.

Is the robot doing the surgery in robotic knee replacement?

No. All robotic systems used at HSS require the orthopedic surgeon to be in direct control of anything that touches the patient, from obtaining safe access to the knee joint, to the removal of damaged cartilage, to the placement of the implant. There is no point at which the robot autonomously performs any part of the operation.

Robotic systems are typically used as a tool to precisely remove the optimal amount of cartilage and bone to accommodate a well-functioning prosthetic joint. This technology allows the surgeon to have three-dimensional control over the orientation of any cuts made within the knee, enabling the surgeon to execute the operation exactly as planned.

How does robotic knee replacement work?

There are several different robotic platforms that can be used for knee replacement surgery, and each one is a bit different. Most systems involve the following general steps, which include registration and assessment, virtual planning of implant position, and execution of the surgical plan.

Registration and assessment

Before we make any cuts to the bone, the dimensions of the knee are registered to the robotic system so that the robot’s virtual planning software can “see” what is happening in the real world. Most systems involve the use of a camera and optical arrays that are fixed to the bones around the knee, allowing for real-time tracking of the position of the knee during the operation. Some systems rely on preoperative imaging to assist with registration and some solely use data captured during surgery. Successful and accurate tracking of the knee in space during the operation facilitates the assessment of the ligaments around the knee and allows the robotic s to be programmed to be positioned in specific orientations that help the surgeon execute different steps of the surgery.

The surgeon then tensions the ligaments around the knee to get a sense of how it will function with the prosthesis in place. Most surgeons would agree that a successful knee replacement depends on having well-functioning ligaments that keep the knee stable through a range of motion. The ability to assess the behavior of each patient’s ligaments at the time of surgery allows some surgeons to make fine adjustments to the position of the implants to optimize ligament function.

Virtual planning of implant position

Using the information about the patient’s ligament tension around the knee, most robotic systems incorporate software that can be used to virtually plan the position of the implant in a way that optimizes ligament function throughout the range of motion. The dimensions of the knee can also be used to help ensure that a correctly sized implant is used that appropriately fits the anatomy of the patient. Often times, the adjustments made at this step are on the order of half a millimeter or half a degree.

Execution of the surgical plan

After the desired implant positioning is determined, the robotic system enables the surgeon to execute this plan with precision. Depending on the system, a wide range of tools are used for safe removal of the damaged cartilage and bone, which can include oscillating saws, high-speed burrs, or robotic cutting guides. After the robotically assisted resection is performed, test implants are placed so that the surgeon can verify that the knee replacement is functioning appropriately, after which permanent implants can be placed.

Does a surgeon have to undergo specialized training to perform robotic surgery?

Orthopedic surgeons with specialty training in hip and knee reconstruction will be familiar with the principles of successful knee replacement surgery. Most robotic systems require some type of additional training or certification. Surgeons at HSS use robotic systems associated with the most widely used orthopedic device manufacturers in North America:

• MAKO (Stryker)
• CORI (Smith & Nephew)
• ROSA (Zimmer-Biomet)
• VELYS (Depuy-Synthes)

Is robotic knee replacement an arthroscopic surgery?

No. Some types of knee surgery, including procedures involving the meniscus or ligaments around the knee, can be done arthroscopically. In knee replacement surgery, open exposure is necessary for the safe removal of damaged cartilage and bone and placement of a knee prosthesis.

With arthroscopic surgery, the surgeon performs the operation through a series of small incisions. A tiny camera is inserted through one incision, and specialized surgical instruments are inserted through others. The camera allows the surgeon to see what’s happening inside the knee and facilitates the other steps of the operation.

Knee replacements cannot be performed using arthroscopic techniques. With knee replacement, sections of the tibia (shin bone) and femur (thigh bone) are cut away and fitted with artificial parts to create a new joint. To do this, a longer incision is necessary to safely expose the knee. It is not possible to remove and replace sections of bone through the incisions that are used for arthroscopic surgery..

The phrase “minimally invasive” may be used for both types of surgery. This is a general term that refers to a surgical philosophy of sparing soft tissues and avoiding unnecessary dissection.

Is robotic knee replacement better than traditional surgery?

Knee replacement operations have excellent outcomes overall, regardless of whether a robot is used as a part of the surgery. While there is some research to show that the use of robotics can help with surgical precision, reproducibility, early recovery, and bone conservation, patient outcomes are generally excellent using many different surgical techniques. Ultimately, your surgeon will perform the operation using the tools that he or she believes will best achieve a great outcome.

Who can have robotic knee replacement?

Almost anyone who is a candidate for a first-time knee replacement is also a candidate for robotic surgery. There are very few patients for whom robotic surgery would not be appropriate. The use of robotic surgery for revision or re-do knee replacements is more limited.

What is the recovery time for robotic knee replacement?

Practically speaking, knee replacement surgery remains a substantial operation whether or not a robot is used. It typically takes between six months and a year for patients to fully recover, although most patients are walking without assistance, driving and performing other daily activities within six weeks, and gradually increase their activity over several months. In the long term, most patients say that the surgery was worth it.

Several studies have described an association between the use of robotics and shorter early recovery times, which may be due to limiting dissection and trauma to the soft tissues around the knee during the operation. But more studies are necessary to better understand this finding.

What is the success rate of robotic knee replacement?

Overall, the success rates for all knee replacement surgeries are high. After one year, between 80% and 90% of patients are happy with their outcome. Obviously, this also means that 10% to 20% of patients have some type of persistent issue after their surgery. Knee replacement surgeons are constantly working to understand this and find ways to improve outcomes for patients. The use of robotics and the techniques that it enables may help with this effort.

For patients with severe arthritis or joint degeneration in the knee, knee replacement surgery achieves excellent outcomes for the vast majority of patients.

Posted: 10/17/2024

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References

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