3-D models give physicians an opportunity to plan and test techniques before performing face transplant surgery.

3-D models give physicians an opportunity to plan and test techniques before performing face transplant surgery.

3-D printing is being used for a variety of applications, both inside and outside of health care. Since inventor Charles Hull created the first functional 3-D printer in 1984, the technology has come a long way, now creating everything from car parts and fashion accessories to prosthetics and organs.

Here at BWH, 3-D printing is helping physicians prepare for face transplant surgeries, guide cancer resections and reconstructions, and more.

Preparing for complex procedures

Before face transplantation, BWH surgeon E.J. Caterson, MD, PhD, uses 3-D models of the skeletal structures to understand complex anatomy and prepare for the procedure. This work, led by principal investigator Bohdan Pomahac, MD, has produced breathtaking results that have captured the imagination of the medical community at large. Caterson, the craniofacial surgeon on the team, has extended his innovative approach to other complex facial reconstructions where 3-D models prove invaluable to reduce time in the operating room and improve outcomes for BWH patients.

The image-to-3-D-printed-model process starts with a CT scan. 3-D printing at BWH has been adopted for research, and now clinical purposes, by the Applied Imaging Science Laboratory (AISL) managed by Dimitrios Mitsouras, PhD, and former AISL Director Frank Rybicki, MD, PhD. The team includes research fellows Amir Imanzadeh, MD, and Tianrun Cai, MD, and Radiology residents Beth Ripley, MD, PhD, and Tatiana Kelil, MD. 3-D models are printed in the AISL by depositing materials, such as plastics, layer by layer, with every new layer attaching to the layers below it.

“The tissues that are 3-D printed in one piece are much better than photographs,” said Caterson. “They provide a better understanding of a patient’s facial structure than any two-dimensional representation can.”

The unique feature of 3-D models is the ability to touch and manipulate structures before surgery so that they can plan and test surgical techniques before the operation, not during it. Better understanding the nuances of each patient’s facial structure will lead to better surgical success and patient recovery.

Though models focus on facial bones, the team created a soft tissue 3-D model to understand the fragility of what was left of a patient’s real facial tissue and compare it to the robust, healthy tissue after full face transplantation.

“The soft tissue models are very important for understanding the differences before and after surgery,” said Imanzadeh. “Surgeons can use these and the bone models in the OR as a guide. Surgeons can also use the model to educate the patient about how the surgery works. It’s a fascinating way to communicate with your patient.”

The soft tissue models are being used to monitor the progress of face transplant recipients, especially the changes in the delicate tissues just under the skin after the procedure.

“Before this, we just used photographs,” said Mitsouras. “Now, with unprecedented accuracy, we can monitor how patients are progressing over time. It’s a remarkable technology.”

The AISL team has begun to extend clinical 3-D printing to other applications. Recently, Ripley, Cai, and Kelil printed the tricuspid valve of a BWH patient to potentially help plan surgical replacement.

“3-D printing is now becoming clinical feasible, and I hope that we can use this technology in cardiovascular and other hospital initiatives, as well as for education of our medical students and residents,” Ripley said.

A guide during oral cavity and mandibular cancer surgery

A 3-D printed prosthetic tricuspid valve with heavily calcified leaflets (left). The abnormal calcium can be electronically removed before the patient undergoes placement of a new valve.

A 3-D printed prosthetic tricuspid valve with heavily calcified leaflets (left). The abnormal calcium can be electronically removed before the patient undergoes placement of a new valve.

Earlier this year, BWH Otolaryngology’s Donald Annino, Jr., MD, DMD, and Laura Goguen, MD, used a CT-generated 3-D printed model to guide the mandibular resection, mandibular plating and fibula free flap contouring reconstruction in a 50-year-old patient with bone-invading cancer.

The innovative, 10-hour surgery happened to take place during one of this winter’s many major snowstorms, but the surgeons, ENT-focused nursing team, anesthesia team and a representative from the plating company were committed to coming in to perform the surgery. Team members either stayed at BWH overnight, stayed at a nearby hotel the prior evening or otherwise made it in through the storm.

The patient failed other therapies and was interested in an innovative surgery that would limit functional and cosmetic impacts to her jaw. She met with Annino, a head and neck surgeon, reconstructive surgeon and dentist, who offered reconstructive surgery with a 3-D printed model to facilitate a number of steps in the operation. While a 3-D printed model has been used for jaw reconstruction at BWH, this was the first time one was being used for a cancer resection jaw-related reconstruction.

To divide up the surgery, Goguen performed the cancer resection and Annino performed the reconstruction, which included taking part of the patient’s fibula to create a new jawbone.

“The 3-D printed model helped us in three different ways,” said Goguen. “It provided a titanium plate customized to the patient’s native mandible, gave use guides as to where to make our bone cuts around the cancer, and helped guide the cuts in the fibula to turn a straight bone into the curved bone that’s needed for the jaw. The models helped us accomplish the procedure more quickly and precisely.”

3-D printing and the future of tissue engineering

Ali Khademhosseini, PhD, a biomedical engineer and director of the BWH Biomaterials Innovation Research Center, and his lab are also using 3-D printing as an innovative, problem-solving tool. His team has made strides in fabricating artificial blood vessels, a critical challenge in the field of tissue engineering, and also in printing cells related to specific organs, such as the heart, liver and gut, allowing the team to study the function of human organs on a small scale.

You can find a video of the lab’s 3-D printing in action here: https://vimeo.com/70042201

The latter approach has enabled the team to create “organ-on-a-chip” platforms in which cells from various tissue types are printed in 3-D structures, mimicking human organs and tissue. These devices can be used to make predictions about the effects of drugs and toxins on the human body. Researchers have been working on creating models of the intestine, liver, lung, muscle and multiple organs in separate chambers on a single chip.

Recently, the team used a 3-D bioprinter to print layers of an agarose (naturally derived sugar-based molecule) fiber template, which serves as a mold for blood vessels. They then covered the mold with a gelatin-like substance called hydrogel, forming reinforcable cast over the mold. The printed fiber templates are strong enough that the team can physically remove them, constructing microchannel networks that can be embedded in a range of commonly used hydrogels.

“In the future, 3-D printing technology may be used to develop transplantable tissues customized to each patient’s needs or be used outside the body to develop drugs that are safe and effective,” said Khademhosseini.

Read about another application of 3-D printing in Science and Curiosity Save a Patient’s Life in BWH Bulletin.

Chris Peterson contributed to this article.