There is no debate that the precision with which a surgeon can position and align the implant with the assistance of a robotic arm makes robot-assisted knee replacements superior to conventional surgery where the surgeon seats the implant manually. Convincing surgeons that a robotic arm improves outcomes vs. "ocular navigation" — their naked eye, hands and experience? That's another story. And that's where the arthroplasty debate rages on.

"The margin between where we are and where we need to be in joint replacement outcomes is greatest in knees," says Richard Illgen, MD, the co-director of the arthritis and joint replacement program at the University of Wisconsin School of Medicine and Public Health in Madison, Wis. "Robotics can help bridge that gap. The biggest challenge moving forward will be convincing surgeons that the technology offers significant improvement to the outcomes they achieve with manual surgery using ocular navigation."

Room for error

A robotic arm is a marketable technology that can differentiate your facility from the competition that's jockeying to capitalize on the skyrocketing demand for knee replacements, which is expected to jump by 700% over the next 30 years.

Surgeons who perform conventional knee replacements grab jigs, cutting guides and saws to place as-precise-as-possible cuts in the tibia and femur where implant components are placed to hopefully restore the joint's natural alignment and balance.

"But there's plenty of room for human error in placing the jigs and cutting guides, and in making accurate cuts,— says Kim Stearns, MD, an orthopedic surgeon at the Cleveland Clinic in Cleveland, Ohio.

Misaligning of the implant by only a degree or two can make a significant difference in the joint's post-op function. Dr. Illgen says 10% to 20% of knee replacement patients are dissatisfied with their new joints a year or two after undergoing surgery. "The implants are durable, but patients don't like how the knee feels," says Dr. Illgen. "Patient satisfaction is a big problem with total knees, and some of that is related to the technical difficulty of the surgery and improper implant placement."

That's where robotic assistance provides benefit. The technology guides the surgeon to make exact cuts based on anatomical images captured during pre-op CT scans of the knee joint. The scans are loaded into the robotic platform's computing system, which plots placement of the ideal cuts based on the patient's specific anatomy. During surgery, the computer guides surgeons to where the cuts should be made. "That means surgeons don't undercut or cut more than they should," says Dr. Stearns. ?

With the robot's navigation system guiding the surgeon's hand, he's able to make precise cuts in the bone and match placement of the implant to the overall alignment of the leg in a more anatomically exact way. In theory, the more precise cuts afforded by robotic assistance lead to better short-term outcomes and improved long-term durability of the implant. Although ongoing research is attempting to definitely confirm those clinical benefits.

The technology does add several minutes to case set-up times as surgeons register anatomical landmarks around the entire knee joint, including the femur and tibia, to inform the navigation system where in space the bones are located. Surgeons who operate with the robot also tend to go slower, according to Dr. Stearns, who says a few extra minutes of operative time is worth the wait. "The trade-off is you get more anatomic and more exact bone cuts, and a joint that is better balanced and in better alignment," he says.

Robotic-assistance also lets surgeons perform minimally invasive knee replacements that limit tissue damage and blood loss, according to Joseph Bosco, MD, a professor and vice chair in the department of orthopedic surgery at NYU Langone Health in New York, N.Y. He says the pre-op planning that's required to perform robotic surgeries eliminates the recuts and implant manipulation that often occur during manual knee placements and that result in additional blood loss and tissue trauma. Dr. Bosco believes those clinical benefits contribute to the continuing shift of the procedures from inpatient ORs to outpatient facilities.

Patients are discharged sooner and using less pain medication and have better post-op range of motion than patients who undergo conventional surgery, adds Dr. Illgen. He says joint function at one-year follow-up also appears to be better in patients who undergo robotic-assisted procedures than in those who undergo conventional surgery.

"The technology has been around long enough to show it makes a difference in outcomes," adds Dr. Illgen. "I'm confident that research will prove that robotics is a strong addition to the joint replacement armamentarium. Patients do well following manual surgery, but they do even better when procedures are performed with a robot."

Finding future value

The purchase price for a robot platform is between $400,000 and $1.2 million; annual maintenance agreements cost $40,000 to $150,000 per robot; and disposables add $750 to $1,300 to case costs.

"Patients do well following manual surgery, but they do better when procedures are performed with a robot."
— Richard Illgen, MD

A return on investment can be achieved after 1 year of performing approximately 20 total knee replacements or 50 partial knee replacements, according to Dr. Bosco.

Dr. Stearns says investing in robotic platforms has the potential to result in considerable savings and increased revenue due to better outcomes, which limit the need for revision surgeries. That's especially true when it comes to partial knee replacements, which are typically more difficult to perform and have a higher failure rate than total knees.

Surgeons can be within 5 degrees of the intended implant location when placing components during total knee replacements and achieve positive results, according to Dr. Illgen, but that same variance during partial knee replacements could lead to implant failure. "Most surgeons who use robotics to perform a partial knee replacement won't perform the procedure again without the technology," he says. There are about 1 million total knee procedures performed in the United States each year, compared with 70,000 partial knee replacements, notes Dr. Illgen. Even in a busy practice, he says, partial knees account for only 5% to 7% of joint replacement volume. But if there isn't a facility in your community that's performing the procedures, adding robotics could let you carve a profitable niche in the market.

Dr. Bosco points out there are non-quantifiable advantages realized by marketing your facility as being on the cutting edge of care. For NYU Langone Health, adding robotics quickly paid off.

The robot's manufacturer co-sponsored an advertising campaign to promote use of the technology for partial knee replacements. During the first 6 months of the campaign, about 80 patients called for more information about the procedure. NYU was able to convert 25 of those interested candidates into patients. Turns out, the patients were inappropriate candidates for partial knees and underwent total knee replacements, which were more profitable for the health system.

Dr. Illgen knows several surgeons who run surgery centers and says adding robotic-assisted surgery has improved their payer mix. He points out that patients with commercial insurance, which will pay more than Medicare for bundles of care that include use of robotics, often seek out facilities where they can have their knees replaced by surgeons who operate with the latest technology. "From a financial standpoint, the return on investment is fairly straightforward," says Dr. Illgen. OSM