The knee bone is connected to the hip bone … unless it is cut into while connected to a plastic femur and shin.

This is what played out in Powell Valley Healthcare’s cafeteria when Dr. Galen Mills demonstrated what a total knee replacement looks like with the help of Stryker Corporation’s Mako Smart Robotics.

The Mako, a robotic arm, is basically a tool to put in implants, the “ultimate goal of it is to make perfect cuts for implants,” Ben Nearpass, a robotic consultant with Stryker (the robot’s manufacturer) explained.

The Mako was stationed in Powell Valley Healthcare’s cafeteria on Thursday to demonstrate its effectiveness to hospital staff starting with an explanation of the machine and the modeling it utilizes.

At Powell Valley Healthcare the Mako is used for more precise total knee replacements, but it’s also capable of partial knee and total hip replacements. 

“Patients … come in with different amounts of wear, different amounts of tension, and so trying to find a perfect spot for their implant to take as little bone as possible is my goal,” Dr. Galen Mills said. 

Mills, an orthopedic surgeon for Powell Valley Healthcare and Billings Clinic-Cody, performed Monday’s surgery on the plastic leg and has done roughly 20 real surgeries with the robot since Oct. 14.

The Mako uses a CT scan obtained before surgery that allows Mills to figure out a variety of things about the knee including where the patient’s axis crosses the knee joint; if there are bony deformities and how much wear the knee has as well as “any other funky stuff that you have from the God-given knee that you walk into my clinic with.”

When Mills decides a patient is a good candidate for a total knee replacement, the patient is sent for a CT scan. That is then sent to Stryker’s segment patient team which makes a 3D bone model, Nearpass said.

“I’m the one that kind of goes in here, positions the implants, gets our sizes, so all this stuff's kind of being done in the background, from the time the patient's scanned to the time their surgery is ready,” he said. 

During surgery Mills still moves the Mako’s arm and makes the required cuts, but the clever robot will not allow him to make cuts outside of measurements mapped by Nearpass, who frequently travels from Billings for surgeries.

“If he goes 0.25 millimeters out of the plan it’s going to [shut down.] So basically it’s going to allow him to make perfect cuts every single time,” Nearpass explained to the audience.

While the cuts are faster and more precise, the surgery time is about the same, Nearpass said.

There are other benefits with the Mako: Surgeries are more consistent in balancing tension and flexion in the knee, Mills said.