Almost two years ago, 3DPI had the opportunity to report on a life-changing procedure in which an infant named Kaiba received a first of its kind, 3D printed tracheal splint to treat his tracheobronchomalacia. Previously, this type of condition would ultimately lead to death, with the tracheas of these children collapsing due to weak cartilage. With the pioneering work of the University of Michigan and CS Mott Children’s Hospital, however, a slowly increasing number of patients facing this diagnosis have gone on to survive. The latest is an adolescent girl who is the fifth person to receive a 3D printed tracheal splint, thanks to the Michigan team.
Dr. Glenn Green, a paediatric otolaryngologist at CS Mott Children’s Hospital in Ann Arbor, developed the splint in conjunction with Dr. Scott Hollister, professor of biomedical engineering and lead researcher at the University of Michigan, as a means of supporting the growth of the trachea in patients with the congenital breathing condition. Using a patient’s own MRI or CT scans, the doctors are able to 3D print a patient-specific splint that supports the trachea, as it expands and functions, allowing the children to breathe normally and, eventually, on their own. Over the course of several years, the implant is almost entirely absorbed into the body.
The process was first thought up by Dr. Hollister in his research on the condition, which is estimated to affect one in every 2,000 children globally. “When I started designing my own porous scaffolds for anatomic reconstruction, I realized that 3D-printing would be ideal for creating the complex geometries I had in mind,” Dr. Hollister recalls. “It is now pretty automatic to generate an individualized splint design and print it; the whole process only takes about two days now instead of three to five.”
SLS system manufacturer EOS, and its AM materials, have been key for the doctors’ work. The University of Michigan purchased an EOS FORMIGA P 100 in 2006 for use in research around biomaterials and 3D printed scaffolds. And Polycaprolactone (PCL) was determined to be the best material for tracheal splints, due to its long resorption time and its ductility. This allows the implants to survive in the body for at least two years and, if it does fail, it does not produce any pieces that would puncture surrounding tissue. “I chose EOS because we were looking for a system that was flexible and allowed us to change parameter settings such as laser power, speed, powder bed temperature and so on, which we needed to do to customise our builds,” Dr. Hollister says. “Also, because biomaterials can be expensive and implants and scaffolds are typically not so big, we wanted a more limited build volume that didn’t use a lot of material. The FORMIGA P 100 fitted the bill for both of these requirements.
EOS even gave us access to software patches to enable us to change the range of parameters of the machine to best process the PCL material.”
Kaiba is now almost four years old and his implant has been almost entirely reabsorbed into his body, with his mature trachea taking over the role of the splint. While Dr. Green has tackled the use of 3D printed tracheal splints, Dr. Hollister’s team has expanded research into other areas, working to 3D print craniofacial, spine, long bone, ear, and nose scaffolds and implants for similar applications. “I see a time soon, probably within the next five years, when many hospitals and medical centres will print their own devices specifically for their own patients and not need to get them off the shelf,” Dr. Hollister explains. “If we can expand the number of biomaterials used in additive manufacturing, we can tackle a tremendous number of problems in all fields of reconstructive surgery and make enormous strides for the benefit of patients.”