3D printing helped Sonoma Orthopedic give surgeons true-to-life training and surgery environments as they work with the company’s intramedullary device and test it out on 3D printed bone models.
“We’re working to find the best ways to mend bones with the least down time for patients, so we use as much technology as we can,” said Stephen McDaniel, Senior Project Engineer with Sonoma Orthopedics. “Conventional manufacturing of these models involves tooling and fixturing, and that takes weeks. I can’t get the same quality I get from 3D printing in just days with conventional manufacturing methods.”
Intramedullary fixation is an alternative surgical procedure used to fix larger bones like the femur (thigh) or tibia (shin), in which a special pin is placed inside of the medullary canal of the bone. This procedure is typically less invasive through smaller incisions, and eliminates the need for prominent hardware while providing precise bone alignment.
Traditionally, when clavicle, wrist or ankle fractures require surgery, doctors rely on plate fixation. Plate fixation requires a large incision over the damaged bones and the application of metal fixtures to the outside of the bone to hold the fragments in place during healing.
In intramedullary fixation the bone is prepared using special surgical instruments to allow the intramedullary pin to be properly positioned. The intramedullary pin is inserted into the bone cavity, joining the bone halves (or pieces) together into proper, pre-fracture alignment. Small screws are then drilled from the exterior through the bone to hold the device in place. Intramedullary fixation has proven to result in faster recovery and improved patient comfort.
Sonoma Orthopedics Products, Inc. has been pioneering technologies to facilitate the use of intramedullary devices for ankle, wrist and clavicle fracture repair, bones that have historically been too small to allow for this type of procedure. Their intramedullary fracture repair products involve a proprietary pin technique. After drilling into the bone and aligning the pin with a guide, the intramedullary pin releases fixation grippers in place of screws. The fixation grippers are located within the bone on the far end of the pin, and complemented with additional external screws on the near end. The combination aligns and immobilizes the fracture to guarantee proper bone alignment.
Training doctors and surgeons on proper intramedullary fracture repair procedures further decreases recovery time and increases patient quality of life. Sonoma Orthopedics wanted to create a model that mimicked bone, accurately recreated delicate fracture variations, and allowed surgeons to use Sonoma’s pins on the model during training.
Conventional bone training models include cadavers and special foam models. While cadavers could offer the brick and mortar, so to speak, of drilling into bone, cadavers are inconsistent in terms of bone issues they present, and are costly to use for repeated training. Foam models are unable to cost-effectively recreate fracture idiosyncrasies or model unique canal geometries on-demand.
Noted McDaniel, “For example, if I want a specific fracture and a specific bone canal, it’s impossible to achieve that using a cadaver and difficult or costly to recreate in foam when very specific details are needed.”
3D printing offered a viable, cost-effective solution to recreating accurate models with repeatable bone fracture types for multiple training scenarios.
3D printing can quickly and accurately reproduce a model directly from computer data, making it an ideal alternative to cadaver or foam bone models. 3D printed bone models provide quality-controlled fractures that actualize important nuances in fracture details from body to body. These models are also printed on-demand to reflect a specific patient’s fracture in order to prepare doctors for more challenging or complicated surgeries.
To prepare for the most likely fracture scenarios, Sonoma references an expansive CT-scan library. This library enables the engineers to create accurate representations of 20 to 50% of the average bone size and fracture configurations, which are then 3D printed as models. This method enables doctors to practice with the best average and learn how to heal the most common fractures and abnormalities.
“We partner with Stratasys Direct Manufacturing frequently because 3D printing builds models of fractures and canals that not only demonstrate our surgical device but actually teach surgeons, ‘Here’s how to insert our screw into the bone, here’s how to really use it,” said McDaniel. “We would not get the same quality that we get with 3D printing in three days through conventional means.”
3D printing is Sonoma Orthopedics’ go-to method for proof-of-concept prototyping and material experimentations. “With 3D printing, I’m able to send a model to Stratasys Direct Manufacturing and have it in-hand within days and that allows me to perform a new test much faster,” said McDaniel. “We don’t have these kinds of prototyping capabilities in-house, so having this ability in three days versus the six weeks it would normally take with conventional means makes our iterative design process much faster. I’m able to simply take the CT-scan and our intramedullary instrument and hold up the bone model and determine whether or not it’s the right fit.”
Sonoma relies on multiple 3D printing technologies for models, prototyping and even marketing collateral. Stereolithography is an ideal technology for large, lightweight parts with fine feature details thanks to its ability to print fine layers quickly and in a build volume of 20 x 20 x 20 in.
“Our 3D printed large scale model features fractures expanded to show the application of the screws and to show how the fracture is repaired,” said McDaniel. “We call the model Bigfoot.”
One unique case in which 3D printing was especially handy involved a clavicle fracture that had healed deformed. After plate fixation surgery and removal, the patient continued to experience limitations in her range of movements and was unable to return to favorite activities.
“The healed fracture looked normal on X-Ray, but after a more thorough CT-scan, the doctor noticed the bone had an abnormality,” said McDaniel. “It was the abnormality that was causing the patient discomfort.” The doctor determined that the patient’s clavicle bone would need to be re-fractured and healed using a new method: intramedullary fixation. “We created models of the patient’s unbroken clavicle and clavicle that had broken and healed abnormally for the doctor to compare,” said McDaniel. “We then 3D printed the badly healed clavicle model with Stratasys Direct Manufacturing so that the doctor could hold it in his hand and feel and see the abnormality in a way the X-ray couldn’t reveal to him.” The surgeon practiced the intramedullary fixation procedure using the 3D printed model and Sonoma’s intramedullary device. After the abnormality in the bone was re-fractured and healed with the intramedullary device, the patient regained full use of their shoulder once more.