Close

A painful problem.

In 2011, a six-year-old mixed-breed dog named Oreo suffered a dislocated left hind patella. The patella was removed to relieve the pain, but he became lame after the surgery. The veterinary practitioner then consulted the Orthopaedic Innovation Centre (OIC), a research and testing facility that serves the medical device market, about the possibility of creating an artificial implant for Oreo. The OIC regularly uses 3D printing as a means of shortening the design and production cycles for its clients, as well as the creation of low volume or customized products, and saw this as an excellent solution for Oreo.

Real solution.

“The tool we developed combines the two existing tools into a single unit,” says design engineer Richard Franks. “As the surgeon squeezes two handle pieces together, the ratchet tightens the screws.” The engineers produced a working polycarbonate ratchet strong enough to withstand testing on stainless steel set-screws and durable enough to survive an autoclave. In addition, says senior engineering manager Troy McDonald, “Surgeons are really rough on these prototypes while trying them out, so we have got to have tough material. FDM gave us the strength and durability we needed.”
“FDM is an ideal technology for implant manufacturing because it can produce strong, durable, biocompatible parts with the right physical properties.”
Martin Petrak, President, Orthopaedic Innovation Centre
X-ray of original hind stifle joint and patella.
X-ray of original hind stifle joint and patella.

To help Oreo, OIC obtained a donated patella that was used to generate a scaled digitized copy. A biomedical engineer then converted the file into a computer-aided design (CAD) model. X-ray radiographs of Oreo’s other patella were then used to modify the CAD design to match his femur.

 

“In Oreo’s case, we were able to produce a custom-tailored implant in only four days including design, analysis, physical testing, and manufacturing. As we move down the learning curve, it will probably be possible to produce similar implants in only a day or two.”

CAD model of patella.
CAD model of patella.

3D printed implant.

OIC built an artificial patella using FDM® technology, an additive manufacturing process that builds plastic parts layer-by-layer from CAD files, on its Stratasys® 3D printer using PC-ISO™ biocompatible polycarbonate (ISO 10993 USP Class VI). Physical testing was performed on the implant to validate its ability to provide the necessary mechanical strength. The implant was sterilized using ethylene oxide at 54°C (130°F) for one hour. During Oreo’s surgery, the implant was attached to the tendon and quadriceps using polypropylene sutures.