Medical implants that change shape inside the body

How close are 4D-printed or shape-memory medical devices that unfold or reshape after implantation?

Printed, bioresorbable airway splints have been placed in a small number of infants since 2013, first under an FDA emergency use exemption. Three infants were reported in 2015. A pivotal trial of a bioresorbable splint (NCT06406452) began recruiting in January 2025, with an estimated 35 pediatric participants and an estimated primary completion in September 2029. The splints change over time through growth and dissolving, not through a trigger such as heat or water. No marketing authorisation for the splint appears in the sources reviewed.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREPilots

Close. Early pilots are running in the real world.

Printed bioresorbable airway splints have been implanted in people in small numbers, in a single case report and a three-infant report, and a pivotal trial is now recruiting. That is pilot-level human use. The shape change in these devices comes from child growth and slow dissolving rather than from an external trigger, and no shape-changing printed implant on a designed external trigger has been shown in people in the sources reviewed. The stage is therefore pilot for airway splints and does not extend to triggered shape-changing devices.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: Medical implants that change shape inside the body Unlocked Being researched Locked
  1. 20144D printingResearch and prototypes Being researched.
  1. 2013First infant treated with a printed splint under emergency exemptionDone Unlocked.
  2. 2014Animal test of a printed airway splintDone Unlocked.
  3. 2015Three infants treated and reportedDone Unlocked.
  4. 2025Pivotal clinical trial of a bioresorbable airway splintIn progress Being researched.
  5. Date not recordedFDA marketing authorisation for the splintNot started Locked.
  1. GoalMedical implants that change shape inside the bodyGoalRequires: 4D printing, Animal test of a printed airway splint, First infant treated with a printed splint under emergency exemption, Three infants treated and reported, Pivotal clinical trial of a bioresorbable airway splint, FDA marketing authorisation for the splint. Locked.

The road so far

3 of 5 steps done, 1 in progress.

  1. Done · 2014Animal test of a printed airway splint

    A porcine model was used to test a printed airway splint, as described in a 2017 editorial that cites Zopf et al. (2014). Mortality in the experimental group was linked to infection from needle holes in the airway lining. The source does not give the number of animals. [3]

  2. Done · 23 May 2013First infant treated with a printed splint under emergency exemption

    A bioresorbable splint shaped to the child's airway was implanted in one infant with severe tracheobronchomalacia. The 2013 letter describes a bioresorbable airway splint created with a three-dimensional printer. The 2017 editorial describes the infant as three months old and says the device was used under an FDA emergency use exemption. [2][3]

  3. Done · 29 Apr 2015Three infants treated and reported

    Patient-specific splints were implanted in three infants aged 3 to 16 months, all previously on mechanical ventilation through a tracheostomy. At publication none had life-threatening airway disease, and long-term data showed continued growth of the primary airways. The 2017 editorial notes that one infant remained tracheostomy-dependent and another ventilator-dependent. Follow-up ranged from 11 to 38 months according to the editorial. A 2015 AAAS news report states that all three children had improved breathing and no complications related to the device. [1][5][3]

  4. In progress · 7 Jan 2025Pivotal clinical trial of a bioresorbable airway splint

    ClinicalTrials.gov lists NCT06406452, sponsored by the University of Michigan, for a bioresorbable tracheobronchial splint in tracheobronchomalacia. The estimated enrolment is 35 pediatric participants, and the record shows the status as recruiting, with an estimated primary completion of September 2029. These are registry estimates and may change. [4]

  5. Not startedFDA marketing authorisation for the splint

    No marketing authorisation for the splint appears in the sources reviewed. Reported use so far has been under an emergency use exemption and in the registered trial. [4][3]

Why it matters

Infants with severe airway collapse can have life-threatening breathing problems, and a device that is shaped to the child's own airway could treat the problem where standard options fall short. If the trial confirms safety and benefit, the same approach of printed devices that change over time could apply to other body parts. The evidence so far rests on very few patients.

What stands in the way

  • Shape change after implantation has not been shown with an external trigger such as heat or water in the sources reviewed. The airway splints change through growth and resorption over time, which the sources describe as designed behaviour.
  • The 2015 report covered three infants. The 2017 editorial says further studies are needed to validate the technique and to follow long-term outcomes.
  • Long-term outcomes after the splint has dissolved, including erosion and airway effects, are not yet known. The 2017 editorial calls for further studies to follow these outcomes.
  • In the animal model, deaths were linked to infection from needle holes in the airway lining (2017 editorial). Infection-risk data in people were not found in the sources reviewed.
  • The registry record lists open-chest surgery for implantation, which limits how widely the approach can be used. Design and manufacturing must also be refined within regulatory requirements, and the pivotal trial results and any regulatory decision are not yet available.

Signals to watch

  • Results of the pivotal trial NCT06406452 when it reports, after its estimated primary completion in September 2029.
  • Long-term follow-up published for the infants treated in the 2015 report, including the splint after it has dissolved.
  • An FDA marketing application for a bioresorbable airway splint, or a published FDA decision on one.
  • A printed device tested in people that changes shape on a designed external trigger, such as heat or water, rather than through growth and dissolving alone.

Sources

  1. peer reviewed paper
    Mitigation of tracheobronchomalacia with 3D-printed personalized medical devices in pediatric patients
    Robert J. Morrison, Scott J. Hollister, Matthew F. Niedner et al.. Science Translational Medicine, Apr 2015.
  2. peer reviewed paper
    Bioresorbable airway splint created with a three-dimensional printer
    David A. Zopf, Scott J. Hollister, Marc E. Nelson et al.. New England Journal of Medicine, 23 May 2013.
  3. review article
    Three-dimensional printing of external airway splints for tracheomalacia
    Hester F. Shieh, Russell W. Jennings. Journal of Thoracic Disease, Mar 2017.
  4. dataset
    Bioresorbable Airway Splint Pivotal Clinical Trial (NCT06406452)
    ClinicalTrials.gov, US National Library of Medicine, Jan 2025.
  5. news
    3D-Printed, Personalized Device Treats Airway Disease in Infants
    Jean Mendoza. AAAS (Science), 29 Apr 2015.

Last reviewed 22 Oct 2026.