Effects of electromechanical reshaping on mechanical behavior of exvivo bovine tendon.

BACKGROUND: Electromechanical reshaping is a novel, minimally invasive means to induce mechanical changes in connective tissues, and has the potential to be utilized in lieu of current orthopedic therapies that involve tendons and ligaments. Electromechanical reshaping delivers an electrical current to tissues while under mechanical deformation, causing in situ redox changes that produce reliably controlled and spatially limited mechanical and structural changes. In this study, we examine the feasibility of altering Young's modulus and inducing a shape deformation using an ex vivo bovine Achilles tendon model. METHODS: Tendon was mechanically deformed in two different modes: (1) elongation to assess for tensile modulus and (2) compression to assess for compressive modulus. Electromechanical reshaping was applied to tendon specimens via flat plate platinum electrodes (6 V, 3 min) while simultaneously under mechanical strain for 15 min. FINDINGS: In elongation mode, post-electromechanical reshaping samples demonstrated a significant decrease in Young's modulus compared to pretreatment samples (66.02 and 45.12 MPa, respectively, p < 0.0049). In compression mode, posttreatment samples illustrated a significant shape change, with an increase in diameter (10.62 to 11.36 mm, p < 0.05) and decrease in thickness (4.13 to 3.62 mm, p < 0.05). INTERPRETATION: Results demonstrated a tissue softening effect without lengthening deformation during elongation, and a shortening effect without compromising compressive stiffness during compression. Electromechanical reshaping's reliable, low-cost, and efficacious methodology in inducing mechanical and structural connective tissue modifications illustrates a potential for future alternative orthopedic applications. Future studies will optimize and refine electromechanical reshaping to address clinically relevant geometries and methods such as needle techniques.

Diagnosis of subglottic stenosis in a rabbit model using long-range optical coherence tomography.

OBJECTIVES/HYPOTHESIS: Current imaging modalities lack the necessary resolution to diagnose subglottic stenosis. The aim of this study was to use optical coherence tomography (OCT) to evaluate nascent subglottic mucosal injury and characterize mucosal thickness and structural changes using texture analysis in a simulated intubation rabbit model. STUDY DESIGN: Prospective animal study in rabbits. METHODS: Three-centimeter-long sections of endotracheal tubes (ETT) were endoscopically placed in the subglottis and proximal trachea of New Zealand White rabbits (n = 10) and secured via suture. OCT imaging and conventional endoscopic video was performed just prior to ETT segment placement (day 0), immediately after tube removal (day 7), and 1 week later (day 14). OCT images were analyzed for airway wall thickness and textural properties. RESULTS: Endoscopy and histology of intubated rabbits showed a range of normal to edematous tissue, which correlated with OCT images. The mean airway mucosal wall thickness measured using OCT was 336.4 µm (day 0), 391.3 µm (day 7), and 420.4 µm (day 14), with significant differences between day 0 and day 14 (P = .002). Significance was found for correlation and homogeneity texture features across all time points (P < .05). CONCLUSIONS: OCT is a minimally invasive endoscopic imaging modality capable of monitoring progression of subglottic mucosal injury. This study is the first to evaluate mucosal injury during simulated intubation using serial OCT imaging and texture analysis. OCT and texture analysis have the potential for early detection of subglottic mucosal injury, which could lead to better management of the neonatal airway and limit the progression to stenosis. LEVEL OF EVIDENCE: NA Laryngoscope, 127:64-69, 2017.

Intraoperative long range optical coherence tomography as a novel method of imaging the pediatric upper airway before and after adenotonsillectomy.

BACKGROUND/OBJECTIVES: While upper airway obstruction is a common problem in the pediatric population, the first-line treatment, adenotonsillectomy, fails in up to 20% of patients. The decision to proceed to surgery is often made without quantitative anatomic guidance. We evaluated the use of a novel technique, long-range optical coherence tomography (LR-OCT), to image the upper airway of children under general anesthesia immediately before and after tonsillectomy and/or adenoidectomy. We investigated the feasibility of LR-OCT to identify both normal anatomy and sites of airway narrowing and to quantitatively compare airway lumen size in the oropharyngeal and nasopharyngeal regions pre- and post-operatively. METHODS: 46 children were imaged intraoperatively with a custom-designed LR-OCT system, both before and after adenotonsillectomy. These axial LR-OCT images were both rendered into 3D airway models for qualitative analysis and manually segmented for quantitative comparison of cross-sectional area. RESULTS: LR-OCT images demonstrated normal anatomic structures (base of tongue, epiglottis) as well as regions of airway narrowing. Volumetric rendering of pre- and post-operative images clearly showed regions of airway collapse and post-surgical improvement in airway patency. Quantitative analysis of cross-sectional images showed an average change of 70.52mm(2) (standard deviation 47.87mm(2)) in the oropharynx after tonsillectomy and 105.58mm(2) (standard deviation 60.62mm(2)) in the nasopharynx after adenoidectomy. CONCLUSIONS: LR-OCT is an emerging technology that rapidly generates 3D images of the pediatric upper airway in a feasible manner. This is the first step toward development of an office-based system to image awake pediatric subjects and thus better identify loci of airway obstruction prior to surgery.