Robotic Total Knee Replacement

Total knee replacement (TKR) is a successful surgery, reliably relieving pain and improving function in the setting of debilitating arthritic disease. However, studies show that up to 20% of patients remain unsatisfied with their knee replacement. Recent data from the American Joint Replacement Registry Annual Report showed that 88% of patients achieved a meaningful improvement after TKR in one validated outcome measure. Of course, this leaves 12% of patients who did not. For this reason, significant effort is spent trying to achieve better outcomes across all patients. The use of robotics in total knee replacement is currently gaining rapid popularity. In the last five years, robotic TKR in America has increased six-fold, from 1.8% in 2017 to 11.6% in 2022. Proponents feel the robot is the tool that will finally move the needle on outcomes in TKR.

One of the principal goals in TKR is achieving a balanced knee. This means making the knee move smoothly through an arc of motion – not too tight or too loose when the knee is straight or flexed. This is sometimes difficult in an arthritic knee. In addition to degenerative changes to the bone, there are changes to the soft tissues and ligaments around the knee. In a knee that is bowlegged, or “varus,” the medial collateral ligaments get tight and contracted and the lateral collateral ligaments get stretched and lax. The opposite happens for a knock knee, or “valgus” knee. Different strategies exist to overcome these changes and create a balanced knee. The primary benefit of the robot is that the entire surgery can be planned on a computer, creating a balanced knee before making any bone cuts.

It is important to understand how the robot works. The robot is just a tool, and the surgeon ultimately performs the surgery. After cutting skin and exposing the knee joint, the surgeon places tracking devices on the tibia and the femur. Infrared sensors on the computer sense the tracking devices to “see” the knee in space. Using a preoperative CT scan to create a 3D model of the knee, the computer knows what the knee looks like, and where the knee is on the operating table. The surgeon then tensions the medial and lateral sides of the knee in flexion and extension. The computer, which can detect submillimeter changes in knee positioning, provides information about how tight or loose each side of the knee is.

Next, the surgeon plans the surgery on the computer. Implant size is chosen to match the patient’s bone. Implant position is changed to balance the knee based on the patient’s soft tissues and the surgeon’s preference. Once the plan is finalized, the robotic arm is brought into the surgical field. The robotic arm uses a saw to make precise bone cuts according to the plan. The robot does not allow the saw to cut beyond the edges of the bone, protecting the surrounding soft tissue. At this point, the robot’s job is done. The surgeon verifies that the cuts are appropriate, and the final components are implanted.

The most important question remains: Does the robot improve clinical outcomes compared to conventional TKR? Research shows that the robot is significantly more accurate with implant positioning. Implant positioning outside of an accepted range puts the knee at risk of early failure. Robotic TKR has also been shown to be soft tissue friendly, with less local inflammatory reaction. This may improve postoperative pain and reduce narcotic usage. However, it is unclear whether patient-reported outcomes are better after robotic TKR. The official Clinical Practice Guidelines of the American Academy of Orthopaedic Surgeons states that evidence suggests no significant difference in function, outcomes or complications in the short term between robotic assisted and conventional TKR. There are also drawbacks with the robot, such as increased operative time, increased cost and the need for a preop CT scan. Research is ongoing, but for the moment, we cannot definitively say that robotic TKR is better. Surgeons who use the robot feel that it helps them consistently achieve their surgical goals. Use of the robot in TKR should be based on surgeon familiarity with the technique and a detailed discussion with the patient of risks and benefits. FBN

By Liam Bosch, M.D.

Flagstaff Bone and Joint is delighted to announce the addition of fellowship-trained orthopaedic surgeon, Dr. Liam Bosch, to their practice. Dr. Bosch brings his expertise in hip and knee replacement for patients suffering from arthritis. Additionally, he specializes in conducting revision surgeries for knee and hip implants, addressing any complications that may arise.

With a dedication to utilizing cutting-edge techniques, Dr. Bosch offers advanced procedures, such as anterior total hip arthroplasty and robotic total knee arthroplasty. His commitment to providing exceptional care and innovative treatments makes him a valuable asset to Northern and Central Arizona.

For further information, please visit: flagstaffboneandjoint.com.