Wednesday, 22 July 2015

3D printing upgrades joint replacement

Surgeons are using custom guides and models to make their work more precise.

On a recent morning, Dr. Heinz Hoenecke of La Jolla used his laptop to make minute adjustments to a three-dimensional model of a patient’s shoulder.

The precision of the computer model, and the sophistication of the modeling software used to manipulate it, allowed him to find an optimal spot to anchor the prosthetics involved in a total shoulder replacement without ever making an incision.

Sliding a digital representation of a cupped insert, the computer calculated how well the device would sit in the shoulder socket and whether its mounting pegs would poke all the way through the patient’s bone, a problem that could eventually cause the implant to dislodge.

“This allows me to know what the issues are much more exactly. I can see if the ball will center itself in the socket,” said Hoenecke, a Scripps Clinic orthopedic surgeon and team physician for the San Diego Padres.

Once things appear to line up perfectly on the computer, he sends the resulting file off to a French company called Tornier that uses a 3D printer to sculpt a custom template. Then Hoenecke will slip that template over the socket during surgery, guiding his drill to just the perfect spot identified during the computer modeling process.

Though custom-printed 3D surgical guides often look like they belong in the recycling bin, they are revolutionizing orthopedic surgery.

Computer modeling, created using X-ray or magnetic resonance-based digital images, combined with the growing power of 3D printing have been shown to increase the exactness of joint-replacement surgery, said Dr. Jason Koh, an orthopedic surgeon in Illinois at NorthShore University HealthSystem who has extensive experience with the new technology.

“For patients, it means decreased operating room time and a more precise cut and fit,” Koh said.