Biomechanical properties of the ex vivo porcine trachea: A benchmark for three-dimensional bioprinted airway replacements.

PURPOSE: Combining tissue engineering and three-dimensional (3D) printing may allow for the introduction of a living functional tracheal replacement graft. However, defining the biomechanical properties of the native trachea is a key prerequisite to clinical translation. To achieve this, we set out to define the rotation, axial stretch capacity, and positive intraluminal pressure capabilities for ex vivo porcine tracheas. STUDY DESIGN: Animal study. MATERIALS AND METHODS: Six full-length ex vivo porcine tracheas were bisected into 5.5 cm segments. Maximal positive intraluminal pressure was measured by sealing segment ends with custom designed 3D printed caps through which a pressure transducer was introduced. Axial stretch capacity and rotation were evaluated by stretching and rotating the segments along their axis between two clamps, respectively. RESULTS: Six segments were tested for axial lengthening and the average post-stretch length percentage was 148.92% (range 136.81-163.48%, 95% CI 153-143%). The mean amount of length gain achieved per cartilaginous ring was 7.82% (range 4.71-10.95%, 95% CI 6.3-9.35%). Four tracheal segments were tested for maximal positive intraluminal pressure, which was over 400 mmHg. Degree of rotation testing found that the tracheal segments easily transformed 180° in anterior-posterior bending, lateral bending, and axial rotational twisting. CONCLUSIONS: We define several biomechanical properties of the ex vivo porcine trachea by reporting the rotation, axial stretch capacity, and positive intraluminal pressure capabilities. We hope that this will aid future work in the clinical translation of 3D bioprinted airway replacement grafts and ensure their compatibility with native tracheal properties.

3-Dimensional Printed Alternative to the Standard Synthetic Flocked Nasopharyngeal Swabs Used for Coronavirus Disease 2019 Testing.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), can be detected in respiratory samples by real-time reverse transcriptase polymerase chain reaction (RT-PCR) or other molecular methods. Accessibility of diagnostic testing for COVID-19 has been limited by intermittent shortages of supplies required for testing, including flocked nasopharyngeal (FLNP) swabs. METHODS: We developed a 3-dimensional printed nasopharyngeal (3DP) swab as a replacement of the FLNP swab. The performance of 3DP and FLNP swabs were compared in a clinical trial of symptomatic patients at 3 clinical sites (n = 291) using 3 SARS-CoV-2 emergency use authorization tests: a modified version of the Centers for Disease Control and Prevention (CDC) RT-PCR Diagnostic Panel and 2 commercial automated formats, Roche Cobas and NeuMoDx. RESULTS: The cycle threshold-C(t)-values from the gene targets and the RNase P gene control in the CDC assay showed no significant differences between swabs for both gene targets (P = .152 and P = .092), with the RNase P target performing significantly better in the 3DP swabs (P < .001). The C(t) values showed no significant differences between swabs for both viral gene targets in the Roche cobas assay (P = .05 and P = .05) as well as the NeuMoDx assay (P = .401 and P = .484). The overall clinical correlation of COVID-19 diagnosis between all methods was 95.88% (Kappa 0.901). CONCLUSIONS: The 3DP swabs were equivalent to standard FLNP in 3 testing platforms for SARS-CoV-2. Given the need for widespread testing, 3DP swabs printed onsite are an alternate to FLNP that can rapidly scale in response to acute needs when supply chain disruptions affect availability of collection kits.

Robot-assisted stereoelectroencephalography electrode placement in twenty-three pediatric patients: a high-resolution analysis of individual lead placement time and accuracy at a single institution.

PURPOSE: We describe a detailed evaluation of predictors associated with individual lead placement efficiency and accuracy for 261 stereoelectroencephalography (sEEG) electrodes placed for epilepsy monitoring in twenty-three children at our institution. METHODS: Intra- and post-operative data was used to generate a linear mixed model to investigate predictors associated with three outcomes (lead placement time, lead entry error, lead target error) while accounting for correlated observations from the same patients. Lead placement time was measured using electronic time-stamp records stored by the ROSA software for each individual electrode; entry and target site accuracy was measured using postoperative stereotactic CT images fused with preoperative electrode trajectory planning images on the ROSA computer software. Predictors were selected from a list of variables that included patient demographics, laterality of leads, anatomic location of lead, skull thickness, bolt cap device used, and lead sequence number. RESULTS: Twenty-three patients (11 female, 48%) of mean age 11.7 (± 6.1) years underwent placement of intracranial sEEG electrodes (median 11 electrodes) at our institution over a period of 1 year. There were no associated infections, hemorrhages, or other adverse events, and successful seizure capture was obtained in all monitored patients. The mean placement time for individual electrodes across all patients was 6.56 (± 3.5) min; mean target accuracy was 4.5 (± 3.5) mm. Lesional electrodes were associated with 25.7% (95% CI: 6.7-40.9%, p = 0.02) smaller target point errors. Larger skull thickness was associated with larger error: for every 1-mm increase in skull thickness, there was a 4.3% (95% CI: 1.2-7.5%, p = 0.007) increase in target error. Bilateral lead placement was associated with 26.0% (95% CI: 9.9-44.5%, p = 0.002) longer lead placement time. The relationship between placement time and lead sequence number was nonlinear: it decreased consistently for the first 4 electrodes, and became less pronounced thereafter. CONCLUSIONS: Variation in sEEG electrode placement efficiency and accuracy can be explained by phenomena both within and outside of operator control. It is important to keep in mind the factors that can lead to better or worse lead placement efficiency and/or accuracy in order to maximize patient safety while maintaining the standard of care.

The use of 3D printing in shared decision making for a juvenile aggressive ossifying fibroma in a pediatric patient.

Juvenile aggressive ossifying fibromas (JAOF) are rare, typically benign pediatric tumors that are locally aggressive and have high recurrence rates. A 7-year old male presented with a palatal mass and a 3D printed model was created and used as a visual aide to highlight the importance of management in terms of functional, cosmetic, and disease-free outcomes with the family. The patient ultimately underwent successful enucleation with final pathology consistent with JAOF. To our knowledge, this is the first description of the use of 3D printing to help in the shared decision-making process for the treatment of this aggressive tumor.

An Ex Vivo Model of Posterior Tracheomalacia With Evaluation of Potential Treatment Modalities.

OBJECTIVE: Posterior tracheomalacia (TM) is characterized by excessive intraluminal displacement of the tracheal membranous wall. Recently, novel surgical strategies for repair of posterior TM have been introduced. To our knowledge, these strategies have not been evaluated in a model of posterior TM. Thus, we sought to design an ex vivo mechanical model of posterior TM to evaluate potential repair interventions. METHODS: A model for posterior TM was created with partial thickness longitudinal incisions to the posterior aspect of ex vivo porcine trachea. Three groups of tracheas were tested: (1) control (unmanipulated), (2) posterior TM (injury), and (3) intervention (repair). Interventions included external splinting with 0.3 and 0.5 mm bioresorbable plates, posterior tracheopexy, and injection tracheoplasty with calcium hydroxylapatite. An airtight tracheal system was created to measure tracheal wall collapse with changes in negative pressure. A bronchoscope and pressure transducer were connected to either end. Cross-sectional area of the tracheal lumen was analyzed using ImageJ software (National Institutes of Health, Bethesda, MD). RESULTS: Average percent reduction in cross-sectional area of the tracheal lumen was compared using a two-tailed paired t-test. Significant differences were found between control and TM groups (p < 0.019). There was no significant difference between control and external splinting and posterior tracheopexy groups (p > 0.14). CONCLUSION: We describe an ex vivo model for posterior TM that replicates airway collapse. External splinting and tracheopexy interventions showed recovery of the injured tracheal segment. Injection tracheoplasty did not improve the TM. LEVEL OF EVIDENCE: N/A Laryngoscope, 133:2000-2006, 2023.

Dynamic, High-Fidelity, 3-Dimensional Pelvic Model Improves Education on Pelvic Organ Prolapse and the Pelvic Organ Prolapse Quantification System and Interest in Urogynecology.

IMPORTANCE: Pelvic organ prolapse (POP) affects millions of women globally. Still, medical students and obstetrics and gynecology residents gain minimal exposure to POP during training. OBJECTIVES: Our goal was to increase exposure to POP by creating a high-fidelity, dynamic, 3-dimensional pelvic model of prolapse and using it to teach through didactic learning sessions. STUDY DESIGN: This was a prospective cohort study from November 2021 to July 2022. Presession and postsession surveys were administered to assess for change in POP knowledge both subjectively and objectively. Statistical analysis was performed using the Wilcoxon signed-rank test with a P value of 0.05 denoting significance. RESULTS: Thirty-three learners participated in the study, including 18 residents and 15 medical students. Most participants had interacted with urogynecologists and had seen at least 1 patient with POP. Fewer participants had received prior education on POP and the Pelvic Organ Prolapse Quantification (POP-Q) examination, witnessed or performed a POP-Q examination, or participated in POP surgical procedures. After learning with the model, comfort with identifying POP doubled (P < 0.001), the ability to understand the POP-Q examination quadrupled (P < 0.001), the ability to perform a POP-Q examination tripled (P < 0.001), and the ability to teach a POP-Q examination doubled (P < 0.001). The median score on a multiple-choice knowledge assessment increased by 40% (P < 0.001). Learners felt that the pelvic model was an effective teaching tool that increased interest in the field of urogynecology. CONCLUSIONS: Using a high-fidelity, dynamic model in didactic sessions enhances education about POP and the POP-Q system and should be used to improve learner exposure and experience.

Dietary and botanical anxiolytics.

Drugs used to treat anxiety have many negative side effects including addiction, depression, suicide, seizures, sexual dysfunction, headaches and more. Anxiolytic medications do not restore normal levels of neurotransmitters but instead manipulate the brain chemistry. For example, selective serotonin reuptake inhibitors (SSRIs) prevent the reuptake of serotonin from the synapse allowing serotonin to remain in the area of activity for a longer period of time but does not correct the lack of serotonin production. Benzodiazepines, such as Valium and Xanax®, stimulate GABA receptors, thus mimicking the calming effects of GABA but again do not fix the lack of GABA production. Often, the brain becomes accustomed to these medications and they often lose their effectiveness, requiring higher doses or different drugs. In contrast to anxiolytic drugs, there are herbs and nutrients which can stimulates neurotransmitter synthesis and more naturally effect and even adjust brain chemistry in the absence of many of the side effects experienced with drugs. Therefore this paper explores several herbal and nutritional approaches to the treatment of anxiety.

Using the ROSA Robot for Lesion Resection: A Novel Adapter With Added Applications.

BACKGROUND: The ROSA robot (Medtech) has been shown to be a useful instrument in the surgeon's armamentarium for accurate placement of stereotactic electroencephlography depth electrodes. However, it has not yet been used as a navigation tool for lesion resection. Here, we demonstrate a novel adapter that allows the surgeon to use the ROSA robot with the NICO BrainPath for the resection of deep lesions. OBJECTIVE: To demonstrate the utility of an adapter that allows the ROSA robot to be used in conjunction with the NICO BrainPath tube for lesion resection. METHODS: A stainless steel adapter was made based on the specifications of the ROSA pointer instrument. Two 3D printed models were used to undergo a "mock" surgery using the adapter to assess for ease of use and applicability. RESULTS: The adapter allowed for adequate accessibility and visualization of the tumors in both mock cases. In addition, the stability of the ROSA robot and the design of the adapter allowed the surgeon to rest their hands on the instrument without jeopardizing its position. CONCLUSION: The ROSA adapter allowed for accurate navigation and exposure of these lesions, combining the accuracy and stability of the ROSA robot, with the retraction of the BrainPath tube.

A two-stage in vivo approach for implanting a 3D printed tissue-engineered tracheal replacement graft: A proof of concept.

OBJECTIVES: To optimize a 3D printed tissue-engineered tracheal construct using a combined in vitro and a two-stage in vivo technique. METHODS: A 3D-CAD (Computer-aided Design) template was created; rabbit chondrocytes were harvested and cultured. A Makerbot Replicator™ 2x was used to print a polycaprolactone (PCL) scaffold which was then combined with a bio-ink and the previously harvested chondrocytes. In vitro: Cell viability was performed by live/dead assay using Calcein A/Ethidium. Gene expression was performed using quantitative real-time PCR for the following genes: Collagen Type I and type II, Sox-9, and Aggrecan. In vivo: Surgical implantation occurred in two stages: 1) Index procedure: construct was implanted within a pocket in the strap muscles for 21 days and, 2) Final surgery: construct with vascularized pedicle was rotated into a segmental tracheal defect for 3 or 6 weeks. Following euthanasia, the construct and native trachea were explanted and evaluated. RESULTS: In vitro: After 14 days in culture the constructs showed >80% viable cells. Collagen type II and sox-9 were overexpressed in the construct from day 2 and by day 14 all genes were overexpressed when compared to chondrocytes in monolayer. IN VIVO: By day 21 (immediately before the rotation), cartilage formation could be seen surrounding all the constructs. Mature cartilage was observed in the grafts after 6 or 9 weeks in vivo. CONCLUSION: This two-stage approach for implanting a 3D printed tissue-engineered tracheal replacement construct has been optimized to yield a high-quality, printable segment with cellular growth and viability both in vitro and in vivo.

Osteochondral Autograft Plugs versus Paste Graft: Ex Vivo Morselization Increases Chondral Matrix Production.

OBJECTIVE: Patients undergoing articular cartilage paste grafting have been shown in studies to have significant improvement in pain and function in long-term follow-ups. We hypothesized that ex vivo impacting of osteochondral autografts results in higher chondrocyte matrix production versus intact osteochondral autograft plugs. DESIGN: This institutional review board-approved study characterizes the effects of impacting osteochondral plugs harvested from the intercondylar notch of 16 patients into a paste, leaving one graft intact as a control. Cell viability/proliferation, collagen type I/II, SOX-9, and aggrecan gene expression via qRT-PCR (quantitative reverse transcription-polymerase chain reaction) were analyzed at 24 and 48 hours. Matrix production and cell morphology were evaluated using histology. RESULTS: Paste samples from patients (mean age 39.7) with moderate (19%) to severe (81%) cartilage lesions displayed 34% and 80% greater cell proliferation compared to plugs at 24 and 48 hours post processing, respectively (P = 0.015 and P = 0.021). qRT-PCR analysis yielded a significant (P = 0.000) increase of aggrecan, SOX-9, collagen type I and II at both 24 and 48 hours. Histological examination displayed cell division throughout paste samples, with accumulation of aggrecan around multiple chondrocyte lacunae. CONCLUSIONS: Paste graft preparation resulted in increased mobility of chondrocytes by matrix disruption without loss of cell viability. The impaction procedure stimulated chondrocyte proliferation resulting in a cellular response to reestablish native extracellular matrix. Analysis of gene expression supports a regenerative process of cartilage tissue formation and contradicts long-held beliefs that impaction trauma leads to immediate cell death. This mechanism of action translates into clinical benefit for patients with moderate to severe cartilage damage.

A 3D-printed nasopharyngeal swab for COVID-19 diagnostic testing.

The nasopharyngeal swab is a critical component of the COVID-19 testing kit. Supply chain remains greatly impacted by the pandemic. Teams from USF Health Radiology and Northwell Health System developed a 3D-printed stopgap alternative. This descriptive study details the workflow and provides guidance for hospital-based 3D printing labs to leverage the design to make a positive impact on the pandemic. Swab use is also outlined, and the early information regarding clinical use is described, including an ongoing multicenter trial methodology.

Robotic Surgical Assistant Rehearsal: Combining 3-Dimensional-Printing Technology With Preoperative Stereotactic Planning for Placement of Stereoencephalography Electrodes.

BACKGROUND: The use of frameless stereotactic robotic technology has rapidly expanded since the Food and Drug Administration's approval of the Robotic Surgical Assistant (ROSA) in 2012. Although the use of the ROSA robot has greatly augmented stereotactic placement of intracerebral stereoelectroencephalography (sEEG) for the purposes of epileptogenic focus identification, the preoperative planning stages remain limited to computer software. OBJECTIVE: To describe the use of a 3-dimensionally (3D)-printed patient model in the preoperative planning of ROSA-assisted depth electrode placement for epilepsy monitoring in a pediatric patient. METHODS: An anatomically accurate 3D model was created and registered in a preoperative rehearsal session using the ROSA platform. After standard software-based electrode trajectory planning, sEEG electrodes were sequentially placed in the 3D model. RESULTS: Utilization of the 3D-printed model enabled workflow optimization and increased staff familiarity with the logistics of the robotic technology as it relates to depth electrode placement. The rehearsal maneuvers enabled optimization of patient head positioning as well as identification of physical conflicts between 2 electrodes. This permitted revision of trajectory planning in anticipation of the actual case, thereby improving patient safety and decreasing operative time. CONCLUSION: Use of a 3D-printed patient model enhanced presurgical positioning and trajectory planning in the placement of stereotactic sEEG electrodes for epilepsy monitoring in a pediatric patient. The ROSA rehearsal decreased operative time and increased efficiency of electrode placement.

Robotic Surgical Assistant (ROSA™) Rehearsal: Using 3-Dimensional Printing Technology to Facilitate the Introduction of Stereotactic Robotic Neurosurgical Equipment.

BACKGROUND: The use of frameless stereotactic robotic technology has rapidly expanded since the Food and Drug Administration's approval of the Robotic Surgical Assistant (ROSA™) in 2012. Although the safety and accuracy of the ROSA platform has been well-established, the introduction of complex robotic technology into an existing surgical practice poses technical and logistical challenges particular to a given institution. OBJECTIVES: To better facilitate the integration of new surgical equipment into the armamentarium of a thriving pediatric neurosurgery practice by describing the use of a three-dimensional (3D)-printed patient model with in situ 3D-printed tumor for presurgical positioning and trajectory optimization in the stereotactic biopsy of a pontine lesion in a pediatric patient. METHODS: A 3D model was created with an added silicone mock tumor at the anatomical position of the lesion. In a preoperative rehearsal session, the patient model was pinned and registered using the ROSA platform, and a mock biopsy was performed targeting the in Situ silicone tumor. RESULTS: Utilization of the 3D-printed model enabled workflow optimization and increased staff familiarity with the logistics of the robotic technology. Biopsy trajectory successfully reached intralesional tissue on the 3D-printed model. The rehearsal maneuvers decreased operative and intubation time for the patient and improved operative staff familiarity with the robotic setup. CONCLUSION: Use of a 3D-printed patient model enhanced presurgical positioning and trajectory planning in the biopsy of a difficult to reach pontine lesion in a pediatric patient. The ROSA rehearsal decreased operative time and increased staff familiarity with a new complex surgical equipment.

A Pilot Study Testing a Novel 3D Printed Amphibious Lower Limb Prosthesis in a Recreational Pool Setting.

INTRODUCTION: Adults with limb amputation and other physical disabilities are less likely to participate in physical activity than adults in the general population and have elevated risk of heart disease and stroke. Swimming is a physical activity often recommended for persons with limb amputation. However, a standard economical swim prosthesis that facilitates easy transition from land to water does not exist. OBJECTIVE: The objectives were (1) to measure ease of first-time use and likability of a novel U.S. Food and Drug Administration (FDA)-cleared 510(k) three-dimensional (3D) printed device, the "FIN," in a recreational pool; and (2) to determine differences in time to complete basic swim tasks using the novel 3D printed amphibious lower limb prosthesis or a standard Swim Ankle prosthesis. Our hypotheses were the following: (1) that the novel 3D printed amphibious lower limb prosthesis would be easy and likeable upon first use; and (2) that basic swim tasks would take comparable time to complete with either device. SETTING: Academic medical center and community pool in New York. PARTICIPANTS: Participants were (N = 10) English-speaking adults with a transtibial amputation who self-identified to swim comfortably in a recreational setting. INTERVENTIONS: Participants completed tasks typical of recreational swimming while wearing the novel 3D printed amphibious lower limb prosthesis or a Swim Ankle. MAIN OUTCOME MEASUREMENTS: Participants performed a series of recreational swim tasks at self-selected speeds: entering/exiting pool, walking, swimming, and treading water, and completed a survey to assess the primary outcomes: likability, ease of use, and adverse events (feasibility). RESULTS: Participants found the novel 3D printed amphibious lower limb prosthesis more likable compared to the Swim Ankle and easy to use. Time to exit the pool was significantly reduced with the novel 3D printed amphibious lower limb prosthesis, while time to complete a 25-m lap was comparable. Participants did not show significant changes in vital signs when using either prosthesis. CONCLUSIONS: The novel 3D printed amphibious lower limb prosthesis was likable and easy to use upon first use. This study supports conducting a larger clinical trial to determine if the data are broadly reproducible.

Three-Dimensional Bioprinting in Orthopaedics.

Three-dimensional (3D)-printing technology has evolved dramatically in the last 30 years, from large machines with poor resolution to those with micron-level capabilities that sit on a desktop. This technology is being utilized in numerous medical applications, particularly in orthopaedic surgery. Over the past decade, technological advances have allowed for the application of this technology to the field of tissue engineering through the process of 3D bioprinting. Of interest to orthopaedic surgeons, active areas of research utilizing this technology involve the bioprinting of articular cartilage, bone, menisci, and intervertebral discs.

A 3-dimensional bioprinted tracheal segment implant pilot study: Rabbit tracheal resection with graft implantation.

OBJECTIVES: Surgical reconstruction of tracheal disease has expanded to include bioengineering and three dimensional (3D) printing. This pilot study investigates the viability of introducing a living functional tracheal replacement graft in a rabbit animal model. METHODS: Seven New Zealand White rabbits were enrolled and six completed participation (one intraoperative mortality). Tracheal replacement grafts were created by impregnating 3D printed biodegradable polycaprolactone (PCL) tracheal scaffolds with rabbit tracheal hyaline chondrocytes. 2 cm of native trachea was resected and the tracheal replacement graft implanted. Subjects were divided into two equal groups (n = 3) that differed in their time of harvest following implantation (three or six weeks). Tracheal specimens were analyzed with intraluminal telescopic visualization and histopathology. RESULTS: The two groups did not significantly differ in histopathology or intraluminal diameter. All sections wherein the implant telescoped over native trachea (anastomotic ends) contained adequate hyaline cartilage formation (i.e. chondrocytes within lacuna, surrounding extracellular matrix, and strong Safranin O staining). Furthermore, the PCL scaffold was surrounded by a thin layer of fibrous tissue. All areas without membranous coverage contained inadequate or immature cartilage formation with inflammation. The average intraluminal stenosis was 83.4% (range 34.2-95%). CONCLUSIONS: We report normal cartilage growth in a tracheal replacement graft when chondrocytes are separated from the tracheal lumen by an intervening membrane. When no such membrane exists there is a propensity for inflammation and stenosis. These findings are important for future construction and implantation of tracheal replacement grafts. LEVEL OF EVIDENCE: Not applicable: this is an in vivo animal trial.

Optimization of Degradation Profile for New Scaffold in Cartilage Repair.

Objective To establish whether a novel biomaterial scaffold with tunable degradation profile will aid in cartilage repair of chondral defects versus microfracture alone in vitro and in a rat model in vivo. Design In vitro-Short- and long-term degradation scaffolds were seeded with culture expanded articular chondrocytes or bone marrow mesenchymal stem cells. Cell growth and differentiation were evaluated with cell morphological studies and gene expression studies. In vivo-A microfracture rat model was used in this study to evaluate the repair of cartilage and subchondral bone with the contralateral knee serving as the empty control. The treatment groups include (1) empty osteochondral defect, (2) polycaprolactone copolymer-based polyester polyurethane-urea (PSPU-U) caffold short-term degradative profile, and (3) PSPU-U scaffold long-term degradative profile. After placement of the scaffold, the rats were then allowed unrestricted activity as tolerated, and histological analyses were performed at 4, 8, and 16 weeks. The cartilage defect was measured and compared with the contralateral control side. Results In vitro-Long-term scaffolds showed statistically significant higher levels of aggrecan and type II collagen expression compared with short-term scaffolds. In vivo-Within 16 weeks postimplantation, there was new subchondral bone formation in both scaffolds. Short-term scaffolds had a statistically significant increase in defect filling and better qualitative histologic fill compared to control. Conclusions The PSPU short-term degradation scaffold may aid in cartilage repair by ultimately incorporating the scaffold into the microfracture procedure.

Ex vivo tracheomalacia model with 3D-printed external tracheal splint.

OBJECTIVE: To design and evaluate an ex vivo model of tracheomalacia with and without a three-dimensional (3D)-printed external tracheal splint. STUDY DESIGN: Prospective, ex vivo animal trial. METHODS: Three groups of ex vivo porcine tracheas were used: 1) control (unmanipulated trachea), 2) tracheomalacia (tracheal rings partially incised and crushed), and 3) splinted tracheomalacia (external custom tracheal splint fitted onto group 2 trachea). Each end of an ex vivo trachea was sealed with a custom-designed and 3D-printed cap; a transducer was placed through one end to measure the pressure inside the trachea. Although the negative pressure was applied to the tracheal lumen, the tracheal wall collapse was measured externally and internally using a bronchoscope. Each group had at least three recorded trials. Tracheal diameter was evaluated using ImageJ software (National Institutes of Health, Bethesda, MD) and was averaged between two raters. RESULTS: Average tracheal occlusion percentage was compared using Student t test. The average occlusion was 31% for group 1, 87.4% for group 2, and 20% for group 3. Significant differences were found between the control and tracheomalacia groups (P < 0.01) and the tracheomalacia and splinted tracheomalacia groups (P < 0.01). There was no significant difference between the control and splinted tracheomalacia groups (P = 0.13). Applied pressure was plotted against occlusion and regression line slope differed between the tracheomalacia (0.91) and control (0.12) or splinted tracheomalacia (0.39) groups. CONCLUSION: We demonstrate the potential for an ex vivo tracheomalacia model to reproduce airway collapse and show that this collapse can be treated successfully with a 3D-printed external splint. These results are promising and justify further studies. LEVEL OF EVIDENCE: N/A. Laryngoscope, 127:950-955, 2017.